The Indian Rheumatology Association

The Professional Organization of Rheumatologists and other Health Professionals in India

Basic Science

Basic Science
Compiled By

Dr Sanat Pathak
KEM Hospital Research Centre - Pune

Dr Debanjali
Kolkata

Dr Arvind Hegde
CMC, Vellore

Dr Sakir Ahmed
KIMS, Bhubhneshwar

 

Dr Nibha Jain
University Hospital - Leicester

Dr Dhaval
Medanta, Delhi

Dr Rutviz
SGPGI, Lucknow

Basic Immunology

A. February - May 2019

Tolerance and auto-reactivity: peripheral tolerance, like central tolerance, is also controlled by the AIRE gene

The mechanism of central tolerance in the thymus was tweaked out from the rare disease autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) syndrome characterized by defective central T cell tolerance and the production of many autoantibodies targeting tissue-specific antigens and cytokines. The AIRE (AutoImmune REgulator) gene is responsible for expression of "cryptic" or tissue specific antigens in the thymus so that naïve T-cells get exposure and hence tolerance towards these. Now by studying CD3- and AIRE-deficient patients, Joel Sng and associates have shown that AIRE-mediated T-cell/Treg selection normally prevents the expansion ofautoreactive naïve B cells recognizing peripheral self-antigens. This means that AIRE gene also controls peripheral tolerance!!

AIRE expression controls the peripheral selection of autoreactive B cells.

Sng J, Ayoglu B, Chen JW, Schickel JN, Ferre EMN, Glauzy S, Romberg N, Hoenig M, Cunningham-Rundles C, Utz PJ, Lionakis MS, Meffre E.

Sci Immunol. 2019 Apr 12;4(34). pii: eaav6778. doi: 10.1126/sciimmunol.aav6778.

PMID:30979797

Boosting T-cell memory:

T-cell memory has important clinical significance in the field of vaccinology. Also with the upcoming T-cell based therapies, ways to boost T-cell memory will have clinically important applications.

Borsa et al. have developed a strategy to enhance the ability of memory T cells: They show that transient inhibition of the mTOR pathway using rapamycin enhances the memory potential of CD8+ T cells and their ability to undergo ACD (Asymmetric Cell Division). The ACD ensures that one clone "retains" the memory phenotype while the other can differentiate into an effector.

Modulation of asymmetric cell division as a mechanism to boost CD8+ T cell memory.

Borsa M, Barnstorf I, Baumann NS, Pallmer K, Yermanos A, Gräbnitz F, Barandun N, Hausmann A, Sandu I, Barral Y, Oxenius A.

Sci Immunol. 2019 Apr 12;4(34). pii: eaav1730. doi: 10.1126/sciimmunol.aav1730.

PMID:30979796

Sex differences in autoimmune disease: why?

Most autoimmune diseases are more common in females. It is known that individuals with multiple X-chromosomes are at increased risk for developing SLE; however, the mechanisms underlying this genetic basis are unclear. Syrett CM and associates have shown X-chromosome inactivation (XCI) maintenance is altered in T cells of SLE patients and late-stage-disease NZB/W F1 female mice. They also showed that X-linked genes are abnormally upregulated in SLE patient T cells. SLE T cells also have altered expression of XIST RNA interactome genes, accounting for perturbations of Xi epigenetic features. Thus, abnormal XCI maintenance is a feature of SLE disease, and they propose that Xist RNA localization at the Xi could be an important factor for maintaining dosage compensation of X-linked genes in T cells.

Altered X-chromosome inactivation in T cells may promote sex-biased autoimmune diseases.

Syrett CM, Paneru B, Sandoval-Heglund D, Wang J, Banerjee S, Sindhava V, Behrens EM, Atchison M, Anguera MC.

JCI Insight. 2019 Apr 4;4(7). pii: 126751. doi:

10.1172/jci.insight.126751. eCollection 2019 Apr 4.

PMID:30944248

SLE

A. October 2018 - January 2019

Role of NETosis

Last 3 months a number of papers were published looking at NETosis. TLR7 and role of B cells in lupus. Starting with B cells, a distinct subset of B cells was identified where authors showed The authors show that extra-follicular autoreactive CD27- IgD- CXCR5- CD11c+ (Double Negative) B cells, are expanded in lupus patients. These cells demonstrate hyper-responsivess to innate activation by TLR 7 mediated mechanisms and generative auto-reactive plasmablasts. [1] .

In another study authors tried discriminating canonical and non-canonical pathway leading to NETosis as former which is NOX dependent has less capacity to activate endothelial cells. In the canonical pathway of NET release, often referred to as nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX)-dependent or lytic NET formation, the assembly of NOX at cytoplasmic or phagosomal membranes and the subsequent generation of reactive oxygen species (ROS) initiates a series of events which culminate in explosive cell death accompanied by NET release. In the non-canonical pathway, i.e. NOX-independent NET formation, neutrophils are not lysed, but instead they release NETs through blebbing of the nuclear envelope and the subsequent vesicular inside-out transportation of NETs. Activated platelets appear to be potent inducers of NOX-independent NET formation.

The predominant protease within NETs, neutrophil elastase, cleaves N-terminal histone tails from NETs formed via a NOX-dependent pathway, a phenomenon that does not occur during NOX-independent NET formation. Pieterse E et al [2] proposed that the use of antibodies recognising N-terminal histone tails in MPO-based ELISAs can discriminate between NETs that have been generated through either NOX-dependent or NOX-independent NET formation pathways.

NOX-independent NETs displayed an increased capacity to activate endothelial cells when compared with NOX-dependent NETs. Hence, the discrimination between the two pathways is important. Previously, there were no tools to differentiate between the two NET-forming pathways. This is for the first time that the authors have tried to develop a serological method allowing discrimination between NETs generated through NOX-dependent or NOX-independent pathways

Role of membrane bound IgG1 in Lupus

Role of membrane bound IgG1 (G396R variant) was highlighted and found to positively correlate with systemic lupus erythematosus. G390R variant lowers the threshold for BCR activation by promoting phosphorylation of the ITT motif via the LYN tyrosine kinase, resulting in enhanced recruitment of downstream signalling molecules GRB2 and BTK to the immunological synapses. The identification of this SNP is lupus could help in prognostication and also provide an avenue of therapy target. [3]

Role of Authophagy in Lupus

Excessive NET production by SLE neutrophils is driven by autophagy, a process normally involved in degradation and recycling of cellular components. Lupus serum induces in neutrophils autophagy and NETosis by upregulating the hypoxia and stress-response protein DDIT4/REDD1.

Frangou E et al [4] analysed NET formation and NET-related proteins in the peripheral blood and biopsies from discoid lupus and proliferative nephritis, using immunofluorescence, immunoblotting, quantitative PCR and ELISA. Autophagy was assessed by immunofluorescence and immunoblotting. Neutrophils from patients with active SLE exhibited increased basal autophagy levels leading to enhanced NET release, which was inhibited in vitro by hydroxychloroquine. NETosis in SLE neutrophils correlated with increased expression of the stress-response protein REDD1. SLE NETs were decorated with tissue factor (TF) and interleukin-17A (IL-17A), which promoted thrombin generation and the fibrotic potential of cultured skin fibroblasts.

So, it can be concluded that autophagy-mediated release of TF-bearing and IL-17A-bearing NETs provides a link between thromboinflammation and fibrosis in SLE. Targeting the REDD1/autophagy axis or its mediators by existing agents through drug repositioning or other novel agents may alleviate neutrophil-mediated inflammation in SLE.

Defects in autophagy contribute to the pathogenesis of SLE. Qi Y et al [5] demonstrated that autophagy is activated in LN, especially in podocyte. In in-vitro assays, many of the most important mediators of the disease—patients’ sera, patients’IgG and IFN-α —could induce autophagy in both murine and human podocytes. Autophagy activation negatively associated with podocyte injury. In intervention, autophagy activator could protect podocyte injury whereas its inhibitor aggravated it.

Interferon Signature in Lupus

The interferon signature is an important biomarker for disease activity and vascular disease in systemic lupus erythematosus and antiphospholipid syndrome. The interferon signature is assessed by gene-expression analysis which hampers its implication in clinical practice.

In this study, Van den Hoogen LL et al [6] measured the serum levels of galectin-9, CXCL-10 (IP-10) and tumour necrosis factor receptor type II (TNF-RII) in patients with SLE, SLE+APS and primary APS (PAPS) and healthy controls. Galectin-9, CXCL-10 and TNF-RII, all three were elevated in patients with SLE, SLE+APS and PAPS (p < 0.05) and correlated with disease activity and tissue factor expression. Galectin-9 correlated stronger than CXCL-10 or TNF-RII with the IFN score (r=0.70, p < 0.001) and was superior to CXCL-10 or TNF-RII in detecting the IFN signature (area under the curve (AUC) 0.86). Importantly, in patients with SLE(±APS), galectin-9 was also superior to anti-dsDNA antibody (AUC 0.70), or complement C3 (AUC 0.70) and C4 (AUC 0.78) levels in detecting the IFN signature.

Galectin-9 another disease biomarker in Lupus?

Galectin-9 correlates with disease activity and is a robust and easy to measure serum biomarker to detect the interferon signature in systemic lupus erythematosus and antiphospholipid syndrome and can be reliably detected in serum samples stored for long periods.

In addition to targeting type I IFN signaling pathway, blocking innate immune signaling pathways, which could inhibit the production of both type I IFN and many other pro-inflammatory cytokines, is an important alternative strategy for the treatment of SLE. Cyclic GMP-AMP (cGAMP) synthase (cGAS) has recently been described as a sequence-independent cytosolic DNA sensor, converting ATP and GTP into cyclic dinucleotide cGAMP. cGAMP then functions as an endogenous secondary messenger binding directly to the endoplasmic reticulumm-resident stimulator of interferon genes (STING). STING recruits and activates downstream TBK1, which in turn phosphorylates the transcription factor IRF3, and ultimately leads to the production of type I IFN. The activity of cGAS-STING signaling pathway was higher in monocytes from active SLE patients compared to monocytes from inactive SLE patients. Previous studies demonstrated that IFIT3 was involved in RIG-I signaling pathway, functioning as a molecular bridge between MAVS and TBK1, which is also an important component in cGAS-STING signal transduction. Wang et al [7] collected monocytes from SLE patients and healthy controls and examined these for activity of the cGAS/STING signaling pathway and expression levels of IFIT3. They found enhanced activity of the cGAS/STING signaling pathway and elevated levels of IFIT3 in the SLE monocytes. Their results showed that there was a significant decrease of the activation of cGAS-STING pathway by VACV70, when IFIT3 was depleted. These findings suggested that IFIT3 is one of the genes that contributes to the overactive cGAS/STING signaling pathway in human SLE monocytes. IFIT3 may therefore serve as a novel therapeutic target for blocking the production of type I IFN and other proinflammatory cytokines by the cGAS/STING signaling pathway in patients with SLE.

ACE inhibitors – Super hero?

Moving slightly away from pure basic papers, Nestor et al demonstrated the role of ACE inhibitors mediated mitigation of cognitive impairment that was caused by antibodies to NMDA receptors in a lupus mouse model. This cerebroprotective action offered by ACE inhibitors in CNS lupus needs to confirmed in clinical settings. [8]

Blame the lifestyle

9

Western lifestyle is linked to autoimmune and metabolic diseases, driven by changes in diet and gut microbiota composition. Using Toll-like receptor 7 (TLR7)-dependent moudise models of systemic lupus erythematosus (SLE), authors dissected dietary effects on the gut microbiota and found that Lactobacillus reuteri can drive autoimmunity but is ameliorated by dietary resistant starch (RS). [9]

References

B. February - May 2019

Sustained B cell depletion by CD19-targeted CAR T cells is a highly effective treatment for murine lupus

After the unprecedented success of Chimeric antigen receptor (CAR) T cells in cancer, it was only a matter of time that these were tried in autoimmune diseases.

CAR-T cells targeting CD-19 are one step ahead of antiCD-20 therapy like Rituximab that has shown promise for lupus. Rita Kansal and associates used two murine models of lupus (NZBxNZW) F1 and MRL fas/fas to demonstrate the efficacy of CD8+ T cells expressing CD19-targeted chimeric antigen receptors (CARs). This CAR T cells eliminated autoantibody production, reversed disease manifestations in target organs, and extended life spans in both mice models. The CAR T cells persisted till one year showing that they can provide sustained B cell depletion with was a stable and effective way to treat murine lupus.

This may have exciting implications that can be explored in clinical trials for human lupus!

Kansal R, Richardson N, Neeli I, Khawaja S, Chamberlain D, Ghani M, Ghani QU, Balazs L, Beranova-Giorgianni S, Giorgianni F, Kochenderfer JN, Marion T, Albritton LM, Radic M.

Sci Transl Med. 2019 Mar 6;11(482).

Suppression of Murine Lupus by CD4+ and CD8+ Treg Cells Induced by T Cell–Targeted Nanoparticles Loaded With Interleukin‐2 and Transforming Growth Factor β

David and colleagues devised a novel strategy to upregulate Treg cells using nanoparticles. The nanoparticles were targeted to T cells using anti CD2/CD4 antibodies. (C57BL/6 × DBA/2)F1 (BDF1) mice were used. The administration of anti‐CD2/CD4 antibody–coated NPs encapsulating IL‐2 and TGFβ resulted in the expansion of CD4+ and CD8+ Treg cells, marked suppression of anti‐DNA antibody production, and reduced renal disease. This approach, which enables the expansion of Treg cells in vivo and inhibits pathogenic immune responses in SLE, could represent a potential new therapeutic modality in autoimmune conditions characterized by impaired Treg cell function associated with IL‐2 deficiency.

David A. Horwitz MD   Sean Bickerton MS   Michael Koss MD   Tarek M. Fahmy PhD   Antonio La Cava MD, PhD

Transcriptomics can predict successful pregnancy outcomes in lupus:

Lupus predominantly affects women of reproductive age-group and a successful pregnancy is often a matter of great concern for this group of women! a recent study has longitudinally profiled the blood transcriptome of 92 lupus patients and 43 healthy women during pregnancy and postpartum. They have convincingly showed that (early and sustained) abrogation of interferon and plasma cell signatures in the transcriptome profile could predict successful pregnancies free of complications like preeclampsia and foetal adverse outcomes.

Longitudinal profiling of human blood transcriptome in healthy and lupus pregnancy.

Hong S, Banchereau R, Maslow BL, Guerra MM, Cardenas J, Baisch J, Branch DW, Porter TF, Sawitzke A, Laskin CA, Buyon JP, Merrill J, Sammaritano LR, Petri M, Gatewood E, Cepika AM, Ohouo M, Obermoser G, Anguiano E, Kim TW, Nulsen J, Nehar-Belaid D, Blankenship D, Turner J, Banchereau J, Salmon JE, Pascual V.

J Exp Med. 2019 May 6;216(5):1154-1169. doi:

10.1084/jem.20190185. Epub 2019 Apr 8.

PMID:30962246

Immune complex deposition in lupus: time for a paradigm shift!

The classical theory of lupus nephritis was that immune complex deposition was the basic insult that led to a vicious cycle of inflammation and further immune complex deposition. Using a mouse model based on the human SLE susceptibility locus TNFAIP3-interacting protein 1 (TNIP1), it was found that glomerulonephritis was driven by TLRs but, remarkably, proceeded independently of ICs. Rather, disease in 3 different mouse models and patients with SLE was characterized by glomerular accumulation of patrolling monocytes (PMos), a cell type with an emerging key function in vascular inflammation. monocyte-specific deletion of ABIN1 promoted kidney disease, whereas selective elimination of PMos provided protection. In contrast to GN, PMo elimination did not protect from reduced survival or disease symptoms such as IC generation and splenomegaly, suggesting that GN and other inflammatory processes are governed by distinct pathogenic mechanisms.

Patrolling monocytes promote the pathogenesis of early lupus-like glomerulonephritis.

Kuriakose J, Redecke V, Guy C, Zhou J, Wu R, Ippagunta SK, Tillman H, Walker PD, Vogel P, Häcker H.

J Clin Invest. 2019 Apr 29;130:2251-2265. doi: 10.1172/JCI125116. eCollection 2019 Apr 29.

PMID: 31033479

Targeting a negative immune checkpoint in murine lupus:

The success of targeting immune checkpoints in cancers is well established. Now similar targets are being explored in autoimmune diseases like lupus. In one such study, The TIGIT (T cell immunoreceptor with Ig and ITIM domains) protein that is a co-inhibitory receptor, has been targeted with an recombinant monoclonal antibody.

Mice with lupus that were treated with the TIGIT-Ig fusion protein, the onset of proteinuria was delayed, serum concentrations of autoantibodies, such as antinuclear antibodies, were reduced without a decrease in the total IgG concentrations, and the survival rate was significantly increased compared to those of the controls

Treatment of murine lupus with TIGIT-Ig.

Liu S, Sun L, Wang C, Cui Y, Ling Y, Li T, Lin F, Fu W, Ding M, Zhang S, Lei C, Hu S.

Clin Immunol. 2019 Apr 18;203:72-80. doi: 10.1016/j.clim.2019.04.007. [Epub ahead of print]

PMID:31005675

Rheumatoid Arthritis

A. October 2018 - January 2019

Role of Tenascin-C in Pathogenesis of RA

Tenasin C is an alarmin, damage associated molecular pattern molecule which is a component of extra-cellular matrix. This article explores the role of tenascin-C in pathogenesis of RA and how it can be utilised therapeutically to abrogate RA pathogenesis [1]

Neutrophil nanoparticles in experimental models of RA

Neutrophil by way of generation of natural vesicles (such as exosomes and microparticles) control inflammation and have been shown to be joint-protective in mouse models of RA . Investigators show that intra-articular injection of neutrophil-nanoparticles reduced disease severity and joint damage in two mouse models of RA (collagen-induced arthritis and a transgenic model of inflammatory arthritis) to a level comparable with mice treated with anti-TNF or anti-IL-1β antibodies.

Neutrophil membrane-coated nanoparticles inhibit synovial inflammation and alleviate joint damage in inflammatory arthritis [2]

A nanoparticle-based broad-spectrum anti-inflammatory strategy for rheumatoid arthritis [3]

Rheumatoid arthritis is a common chronic inflammatory disorder and a major cause of disability. Despite the progress made with recent clinical use of anti-cytokine biologics, the response rate of rheumatoid arthritis treatment remains unsatisfactory, owing largely to the complexity of cytokine interactions and the multiplicity of cytokine targets. Here, the authors how a nanoparticle-based broad-spectrum anti-inflammatory strategy for rheumatoid arthritis management. By fusing neutrophil membrane onto polymeric cores, they prepare neutrophil membrane-coated nanoparticles that inherit the antigenic exterior and associated membrane functions of the source cells, which makes them ideal decoys of neutrophil-targeted biological molecules. It is shown that these nanoparticles can neutralize proinflammatory cytokines, suppress synovial inflammation, target deep into the cartilage matrix, and provide strong chondroprotection against joint damage. In a mouse model of collagen-induced arthritis and a human transgenic mouse model of arthritis, the neutrophil membrane-coated nanoparticles show significant therapeutic efficacy by ameliorating joint damage and suppressing overall arthritis severity.

Genome-wide meta-analysis reveals shared new loci in systemic seropositive rheumatic diseases

Systemic Seropositive Rheumatic diseases share symptoms, progressions, environmental risk factors, high rates of familial aggregation and susceptibility genes, pointing to a shared genetic architecture. The assessment of a shared genetic component among these conditions has not been performed before in a systematic fashion.Acosta-Herrera M et al [4] conducted the first large-scale cross-disease genome-wide meta-analysis, including more than 11,000 cases and 19,000 non-overlapping controls aiming to improve our knowledge regarding the genetic resemblances among systemic seropositive rheumatic diseases. They identified 27 shared loci among systemic seropositive rheumatic immune-mediated inflammatory diseases, five of which were new. The remaining were known susceptibility genes in autoimmunity. The associated variants were enriched in marks related with gene activation in immune cells and constitute shared expression quantitative trait loci. Most of these conditions do not have specific treatments, therefore, therapy repositioning among genetically related conditions could be feasible among them.

More ADAM than EVE

ADAM15 is a transmembrane anchored multi-domain protein belonging to the family of disintegrin metalloproteinases. ADAM15 has been shown to significantly contribute to apoptosis resistance of RA synovial fibroblasts (RASF) by inducing pro-survival Src and focal adhesion kinase (FAK) signalling. The cytoplasmic domain of ADAM15 provides a scaffold for FAK and Src binding complemented by the engagement of CaM following its coactivation in the context of the apoptotic signal. Thus, Fas ligation triggers a CRAC/Orai dependent CaM recruitment to Fas/CD95 and ADAM15 in the cell membrane. Janczi et al [5]showed for the first time Ca2+-dependent binding of ADAM15 to CaM. Simultaneously, Src associated with CaM was shown to become engaged in the ADAM15 complex also containing cytoplasmic bound FAK. This ADAM15-dependent formation of a pro-survival signaling complex in the CD95-Cap was associated with an increased survival. The pathway, however, was shown to be sensitive to pharmacologic interference with either the calmodulin inhibitor TFP or the CRAC/Orai channel inhibitor BTP-2. [5]

Beat the TANK-binding kinase 1

TANK-binding kinase 1 (TBK1) is an IKK-related Serine/Threonine kinase that is critical for the induction of IRF3-driven type I IFN responses in nucleic acid sensing pathways, such as TLR3/4-TRIF, RIG-I/MDA5-MAVS and cGAS-STING . TBK1 regulates IL-6 expression in response to TLR3 ligands 22 and to cytosolic DNA downstream of STING. TBK‐1 was also recently identified as a critical kinase for ICOS signalling in TFH cells, hence involved in the maturation of GC follicular helper T (Tfh) cells. Cynthia Louis et al [6] engineered a relatively selective small molecule inhibitor of TBK1, known as WEHI-112. TBK1 inhibition alleviated the progression of established autoantibody-mediated CIA, but not the antibody-independent, antigen induced arthritis (AIA) model, nor the K/BxN serum transfer-induced arthritis (STIA) model. This approach may have therapeutic potential in RA and in other GC‐associated autoantibody‐driven inflammatory diseases.

References

B. February - May 2019

Beyond Autoantibodies: Biologic Roles of Human Autoreactive B Cells in Rheumatoid Arthritis Revealed by RNA‐Sequencing

 The authors profiled citrulline specific B cells from patients with RA to study their transcriptome. The cells were selected by flow cytometry and the transcriptome profile by RNA sequencing. SOMAscan assay was used to see protein expression. Significant differences were found in the IL15R expression of citrulline specific cells, and they were more likely to produce amphiregulin. Amphiregulin production, in turn, led to the migration of fibroblast like synoviocytes and osteoclast differentiation. This study is pioneering in assessing the target-specific cells and identifies potential pathways for targeting. It will be interesting to see how transcriptomic profiles differ in ACPA negative patients and in B cells from patients with other diseases. Patients from one Indian centre were included.

Mahendra A, Yang X, Abnouf S, Adolacion JRT, Park D, Soomro S, Roszik J, Coarfa C, Romain G, Wanzeck K, Bridges SL Jr, Aggarwal A, Qiu P, Agarwal SK, Mohan C, Varadarajan N. Beyond Autoantibodies: Biologic Roles of Human Autoreactive B Cells in Rheumatoid Arthritis Revealed by RNA-Sequencing. Arthritis Rheumatol. 2019 Apr;71(4):529-541.

Prevotellacopri in individuals at risk for rheumatoid arthritis

Gut microbiome changes, primarily Prevotella species expansion have been known to be associated with RA. When do these changes appear? In a cohort of first degree relatives or RA patients, individuals who had developed ACPA or RF or clinical features were identified as cases and those who had no antibodies as controls. On gut microbiome analysis (by culture-independent methods), the microbiota was altered in the preclinical RA stage itself. There was significant enrichment of Prevotella species as compared to controls. Through its cohort design, this study addresses the ‘chicken and egg' of microbiome change, and clinical inflammation/ drug exposure that will always be a question in cross-sectional studies. 

lpizar-Rodriguez D, Lesker TR, Gronow A, Gilbert B, Raemy E, Lamacchia C, Gabay C, Finckh A, Strowig T. Prevotellacopri in individuals at risk for rheumatoid arthritis. Ann Rheum Dis. 2019 May;78(5):590-593.

Citrullinated Aggrecan Epitopes as Targets of Autoreactive CD4+ T Cells in Patients With Rheumatoid Arthritis

Emerging data suggest the role of citrullinated matrix protein aggrecan as an autoantigen in rheumatoid arthritis. This study looked at autoreactive CD4+ T cells reacting to citrullinated aggrecan using Tetramer Technology. The identified aggrecan reactive CD4+ T cell clones correlated with levels of antibodies against citrullinated aggrecan in RA. This correlation raises the possibility that antigen‐specific T cell help may contribute to antibody responses. This adds to the growing list of proteins when citrullinated acting as autoantigens. Aggrecan is an extracellular matrix proteoglycan, and aggrecan fragments are present within the synovial fluid, where it can be presented to T cells as a citrullinated antigen by either FLS or professional APCs leading to inflammation. Authors claim “These results suggest that Cit‐aggrecan–specific CD4+ T cells could play a role in the etiology of RA. However, future studies of the frequency, phenotype, and role of Cit‐aggrecan–specific T cells in various stages of the disease are warranted."

Cliff Rims MHS  Hannes Uchtenhagen PhD  Mariana J. Kaplan MD  Carmelo Carmona‐River PhD 

Philip Carlucci BS  Katalin Mikecz MD, PhD  AdriennMarkovics MD, PhD  Jeffrey Carlin MD 

 Jane H. Buckner MDEddie A. James PhD 

Noninvasive ultrasound stimulation of the spleen to treat inflammatory arthritis.

In a novel study, it has been shown that in a murine model of RA, ultrasound stimulation of the spleen can alleviate murine inflammatory arthritis. The K/BxN serum-transferred model of rheumatoid arthritis was used with ultrasound stimulation of the spleen at 1 MHz with the 1 s on/5 s off pulse pattern. The ultrasound at 350 kPa for 2 min per day reduced the ankle thickness and clinical score by day 7.

Zachs DP, Offutt SJ, Graham RS, Kim Y, Mueller J, Auger JL, Schuldt NJ, Kaiser CRW, Heiller AP, Dutta R, Guo H, Alford JK, Binstadt BA, Lim HH.

Nat Commun. 2019 Mar 12;10(1):951.

Shared epitope versus Valine 11 and phenylalanine 13 in determining suspectibility to RA:

The classical shared epitope (SE) encodes for amino-acids 70-74 of the HLA-DRB1, and has been one of the oldest known determinants of susceptibility to RA. Recent computational analyses had revealed that positions 11 and 13 of the HLA-DRB1 molecules were also important in determining susceptibility. But these were association studies only. Recently, Bitoun and colleagues have shown that that the most important HLA positions to induce a T-cell response against Citrullinated peptides were Val11 and Phe13 and not the 70-74 SE in macaques. Since macaques do not have linkage disequilibrium between SE and Val11/Phe13, this is even more significant. Also this is a functional demonstration of the effect of the nucleotide polymorphisms.

Valine 11 and phenylalanine 13 have a greater impact on the T-cell response to citrullinated peptides than the 70-74 shared epitope of the DRB1 molecule in macaques.

Bitoun S, Roques P, Maillere B, Le Grand R, Mariette X.

Ann Rheum Dis. 2019 Jul;78(7):917-921. doi: 10.1136/annrheumdis-2019-215114. Epub 2019 Apr 25.

PMID:31023654

Role of Fra-1 in arthritis

Fos-related antigen 1 (FRA1) has been shown to be involved in the pathogenesis of systemic sclerosis. It is closely related to nuclear factor kappa B (NF-κB) and activator protein 1 (AP-1) that help in the polarization of macrophages. While exploring the role of macrophages in inflammatory arthritis, Hannemann and colleagues have shown, using macrophage-specific Fra-1- or Fra-2- deficient mice, an enhanced expression and activity of Arg1 and a reduction of arthritis in the absence of Fra-1, but not of Fra-2. Chromatin-immunoprecipitation (ChIP)-sequencing and standard ChIP analyses of macrophages identified arginase 1(Arg1) as a target of Fra-1. Thus it can impede the resolution of inflammation by reducing the function of Arg1 thus contributing to the chronicity of arthritis!

Transcription factor Fra-1 targets arginase-1 to enhance macrophage-mediated inflammation in arthritis.

Hannemann N, Cao S, Eriksson D, Schnelzer A, Jordan J, Eberhardt M, Schleicher U, Rech J, Ramming A, Uebe S, Ekici A, Cañete JD, Chen X, Bäuerle T, Vera J, Bogdan C, Schett G, Bozec A.

J Clin Invest. 2019 Apr 16;130. pii: 96832. doi: 10.1172/JCI96832.

PMID:30990796

Concomitant cIAP1/2 and TNF blockade in inflammatory arthritis

TNF-α inhibitors have revolutionized the treatment of rheumatoid arthritis (RA), although not all patients respond. It has been shown that anti-TNF therapy can lead paradoxical exacerbation of TH17 responses. With this background, inhibition of cIAP1/2 (cellular inhibitors of apoptosis 1 and 2) was attempted along with TNF-blockade with etanercept in murine models. . Inhibition of cIAP1/2 abrogated CD4+ IL-17A differentiation and IL-17 production, abrogated disease activity, which was associated with an increase in Tregs and was sustained after therapy retraction. Thus such dual inhibition may hold promise to reduced relapses during drug free remission.

cIAP1/2 inhibition synergizes with TNF inhibition in autoimmunity by down-regulating IL-17A and inducing Tregs.

Kawalkowska JZ, Ogbechi J, Venables PJ, Williams RO.

Sci Adv. 2019 May 1;5(5):eaaw5422. doi: 10.1126/sciadv.aaw5422. eCollection 2019 May.

PMID:31049403

Psoriatic arthritis

A. October 2018 - January 2019

Psoriatic arthritis (PsA) has a higher heritability than psoriasis, indicating the presence of a specific genetic risk component. So far, very little genetic variation has been specifically associated with the development of PsA. Using a pathway-based genome-wide association study on two case–control cohorts, Aterido A et al [1] have identified multiple pathways associated with PsA risk. The glycosaminoglycan (GAG) metabolism pathway is specifically associated with PsA risk and is not associated with purely cutaneous psoriasis or rheumatoid arthritis. Their analyses suggest that FDA-approved drugs hyaluronic acid drug (HAd) and tromethamine drug (TMd) are good candidates for repurposing for PsA, since they target central genes in the GAG metabolism network and have a significant impact on its functionality.

References

Systemic sclerosis

A. February - May 2019

Circulating follicular helper T cells are increased in systemic sclerosis and promote plasmablast differentiation through the IL-21 pathway which can be inhibited by ruxolitinib

The authors in this study for the first time aimed to perform a quantitative and functional analysis of circulating T follicular cells in SSc.Using flow cytometry, they analysed cTfh cells from 50 patients with SSc and 32 healthy controls (HC). They observed that cTfh cell numbers are increased in patients with SSc compared with HC. The increase in cTfhcorrelated with disease activity. cTfh cells from patients with SSc present an activated Tfh phenotype, with high expression of BCL-6, increased capacity to produce IL-21 in comparison with healthy controls.cTfh sorted from the blood of patients with SSc were cocultured with autologous B cells in the presence of recombinant IL-21RFc or in the presence of ruxolitinib. It reduced the Tfh cells’ capacity to stimulate the plasmablasts and decreased Ig production. IL21 pathway blockade in systemic sclerosis needs further research to elucidate the role in SSc.

Laure Ricard  Vincent Jachiet   Florent MalardYishan Ye  Nicolas Stocker

Sébastien Rivière,  Patricia Senet  Jean-Benoit Monfort  Olivier Fain  Mohamad MohtyBéatriceGauglerArsèneMekinian

Targeting of dermal myofibroblasts through death receptor 5 arrests fibrosis in mouse models of scleroderma

Most of the anti-fibrotic agents that work in SSc murine model do not translate into use in human disease. But the search continues for the elusive anti-fibrotic. Jong-Sung Park and associates use dermal fibroblasts from skin biopsies obtained from patients of SSc and morphea to demonstrate the increased Death Receptor-5 (DR5) on collagen producing myofibroblasts. They go on further to demonstrate that a PEGylated long-acting recombinant human TRAIL called TLY012, was effective in inducing apoptosis of these myofibroblasts in vivo.

Park JS, Oh Y, Park YJ, Park O, Yang H, Slania S, Hummers LK, Shah AA, An HT, Jang J, Horton MR, Shin J, Dietz HC, Song E, Na DH, Park EJ, Kim K, Lee KC, Roschke VV, Hanes J, Pomper MG, Lee S.

Nat Commun. 2019 Mar 8;10(1):1128. doi: 10.1038/s41467-019-09101-4.

Circulating follicular helper T cells are increased in systemic sclerosis and promote plasmablast differentiation through the IL-21 pathway which can be inhibited by ruxolitinib.

Laure Ricard and associates report circulating CD4 + CXCR5 + PD-1 +   Tfh in patients with SSc that to induce the differentiation of plasmocytes leading to secretion of immunoglobulins (Ig). Their levels correlated with the severity of SSc, and also with the presence of pulmonary arterial hypertension.

This group went further using the JAK1/2 inhibitor ruxolitinib to block the stimulation of Tfh on plasmablasts. This reduced immunoglobulin production from plasmablasts opening up the avenue of targeting this pathway in SSc.

Ricard L, Jachiet V, Malard F, Ye Y, Stocker N, Rivière S, Senet P, Monfort JB, Fain O, Mohty M, Gaugler B, Mekinian A.

Ann Rheum Dis. 2019 Apr;78(4):539-550.

Machine learning to classify systemic sclerosis:

High-throughput gene expression profiling of tissue samples from patients with systemic sclerosis(SSc) has identified into four molecular subsets (normal -like, limited, inflammatory, and fibroproliferative) based on their gene expression patterns. The basic idea of supervised machine learning is that it uses inputs (such as gene expression data ) to generate a model that best allows us to determine an output (such as patient classification ). In an external validation, the classifier achieved average accuracy of 85.4%.

A Machine Learning Classifier for Assigning Individual Patients with Systemic Sclerosis to Intrinsic Molecular Subsets.

Franks JM, Martyanov V, Cai G, Wang Y, Li Z, Wood TA, Whitfield ML.

Arthritis Rheumatol. 2019 Mar 28. doi: 10.1002/art.40898. [Epub ahead of print]

PMID: 30920766

Sjogren’s Syndrome

A. February - May 2019

Blockade of CD40-CD154 pathway interactions suppresses ectopic lymphoid structures and inhibits pathology in the NOD/ShiLtJ mouse model of Sjögren's syndrome

There are few drugs with proven efficacy in primary Sjogren syndrome. CD40 is a co-stimulatory molecule that has been implicated in Hyper IgM syndrome. Grazyna Wieczorek and associates have used inhibition of the interaction of CD40 with its receptor CD154 in a mouse model of Sjogren syndrome. The NOD/ShiLtJ mouse model was treated with an anti-CD154 antibody that MR1 suppressed CD40 pathway genes and sialadenitis, inhibited ectopic lymphoid structure formation and autoantibody production.

Wieczorek G, Bigaud M, Pfister S, Ceci M, McMichael K, Afatsawo C, Hamburger M, Texier C, Henry M, Cojean C, Erard M, Mamber N, Rush JS.

Ann Rheum Dis. 2019 Mar 22

Osteoarthritis

A. February - May 2019

Active immunization targeting nerve growth factor attenuates chronic pain behavior in murine osteoarthritis.

Viral particles derived from the cucumber mosaic virus were conjugated with recombinant  Nerve growth factor (NGF) to make a novel vaccine. A murine model of OA ( partial meniscectomy model) was vaccinated either before surgery or once the pain was established. Both prophylactic and therapeutic vaccination demonstrated a reversal of pain behavior by incapacitance testing. Thus the vaccine against NGF could alleviate spontaneous pain behavior in surgically induced murine OA.

von Loga IS, El-Turabi A, Jostins L, Miotla-Zarebska J, Mackay-Alderson J, Zeltins A, Parisi I, Bachmann MF, Vincent TL.

Ann Rheum Dis. 2019 May;78(5):672-675.

Exploration of CRISPR/Cas9-based gene editing as therapy for osteoarthritis.

Another group used an adeno-associated virus expressing CRISPR/Cas9 components to target each of the genes encoding MMP13, IL-1β, and NGF in a surgical mouse model of OA. Only targeting NGF reduced pain but worsened the pain. However, targeting three targets together mitigates the adverse effects of NGF blockade on the joints.

Zhao L, Huang J, Fan Y, Li J, You T, He S, Xiao G, Chen D.

Ann Rheum Dis. 2019 May;78(5):676-682.

Wnt16 attenuates osteoarthritis progression through a PCP/JNK-mTORC1-PTHrP cascade

Wnt16 is implicated in bone fracture and bone mass accrual both in animals and humans. In this study, the authorsanalyzed its mechanistic association and functional relationship in OA progression in chondrocyte lineage.

Wnt16 deficiency exaggerated OA progression, whereas overexpression by intra-articular injection of adenoviral vector with Wnt16 attenuated ACLT-induced OA. Further work indicated that Wnt16 activates PCP/JNK and crosstalk with mTORC1-PTHrP pathway to inhibit chondrocyte hypertrophy. The study provides novel insight in the pathogenesis of OA and potential therapeutic target.

Wenxue Tong Yelin Zeng Dick Ho Kiu Chow Wai Yeung Jiankun Xu Yujie Deng Shihui Chen Hui Zhao Xiaoling Zhang Kevin Kiwai Ho Ling Qin Kingston King-lunMak

Osteoarthritis: can we "produce" cartilage?

Stem cells can be "instructed" to evolve into cartilage in vitro. But the problem lies in forming the tissue level architecture of cartilage, that is quite different from just differentiation into cartilage cells. This paper was the successful implementation of a biomimetic scaffold along with biomechanical and biochemical stimuli to induce spatial regulation of fibrochondrocyte differentiation. This artificially engineered menisci demonstrated long-term chondroprotection of the knee joint in a rabbit model of OA. Thus problems with the use of stem cells are gradually being resolved with the utilization of cross-disciplinary sciences

Orchestrated biomechanical, structural, and biochemical stimuli for engineering anisotropic meniscus.

Zhang ZZ, Chen YR, Wang SJ, Zhao F, Wang XG, Yang F, Shi JJ, Ge ZG, Ding WY, Yang YC, Zou TQ, Zhang JY, Yu JK, Jiang D.

Sci Transl Med. 2019 Apr 10;11(487). pii: eaao0750. doi:

10.1126/scitranslmed.aao0750.

Connection between stress and chondrocyte senescence: miR204

In response to senescence signals transcription factors GATA4 and NF-κB upregulate the microRNA miR204. Up-regulated miR-204 simultaneously targets multiple components of the sulfated proteoglycan (PG) biosynthesis pathway, effectively shutting down PG anabolism. Ectopic expression of miR-204 in joints triggers spontaneous cartilage loss and OA development, whereas miR-204 inhibition ameliorates experimental OA. Thus this stress induced pathway may be targetable to maintain cartilage homeostasis.

Stress-activated miR-204 governs senescent phenotypes of chondrocytes to promote osteoarthritis development.

Kang D, Shin J, Cho Y, Kim HS, Gu YR, Kim H, You KT, Chang MJ, Chang CB, Kang SB, Kim JS, Kim VN, Kim JH.

Sci Transl Med. 2019 Apr 3;11(486). pii: eaar6659. doi:

10.1126/scitranslmed.aar6659.

PMID:30944169

Spondyloarthritis

A. February - May 2019

New insights from uncultivated genomes of the global human gut microbiome.

In a massive meta-analysis of clinical gut-microbiome studies, a completely new species have been found to be associated with AS! The species belongs to the Negativicutes class (with identifier OTU 14148). This species was strongly depleted in patients relative to healthy controls and eight orders of magnitude more significant than any previously known species  (adjusted P = 5.3 × 10−28)!!!

Nayfach S, Shi ZJ, Seshadri R, Pollard KS, Kyrpides NC

Nature. 2019 Mar 13.

Interleukin‐17A Inhibition Diminishes Inflammation and New Bone Formation in Experimental Spondyloarthritis

Since inhibiting TNF has minimal effect on new bone formation, this study evaluated the effect of IL17A on osteoblast differentiation and new bone formation. The authors used osteoblastic differentiation assay using SpA fibroblast‐like synoviocytes (FLS) differentiated with dexamethasone, β‐glycophosphatase, and ascorbic acid. HLA–B27/human β2‐microglobulin (hβ2m)–transgenic rats, served as a model for SpA. Both prophylactic and therapeutic inhibition of IL‐17A diminished inflammation and new bone formation in HLA‐B27/hβ2m–transgenic rats. Taken together with the ability of IL‐17A to promote osteoblastic differentiation of human SpA FLS, these data suggest a direct link between IL‐17A–driven inflammation and pathologic new bone formation in SpA.

van Tok MN, van Duivenvoorde LM, Kramer I, Ingold P, Pfister S, Roth L, Blijdorp IC, van de Sande MGH, Taurog JD, Kolbinger F, Baeten DL.

Arthritis Rheumatol. 2019 Apr;71(4):612-625

Syndesmophytes positions depend on extrinsic mechanical factors: explicitly with distance from aortic rim!

In a study of 60 patients with ankylosing spondylitis, CT scans of thoraco-lumbar spine were evaluated to assess the relationship between syndesmophyte formation and distance from the aorta. Syndesmophytes occurred less commonly and were smaller at the thoracolumbar vertebral rim near the aorta. These findings suggest that mechanical factors extrinsic to the spine and not solely vertebral inflammation, influence syndesmophyte developmentin AS.

Aortic-vertebral interaction in ankylosing spondylitis: syndesmophyte development at the juxta-aortic vertebral rim.

Tan S, Dasgupta A, Flynn JA, Ward MM.

Ann Rheum Dis. 2019 Jul;78(7):922-928. doi: 10.1136/annrheumdis-2018-214675. Epub 2019 Apr 6.

PMID:30954970

Gene microbiota interaction initiates Crohn’s like colitis in mice

In furthering our understanding on how microbiota influence disease initiation, an important requirement is to understand the interactions between disease susceptibility genes and microbiota. In a seminal study, colitis was induced by Mucispirillum schaedleri, a Gram-negative mucus-dwelling anaerobe. NOD2 and CYBB knockouts led to marked accumulation of Mucispirillum, which was associated with impaired neutrophil recruitment and killing of the bacterium by luminal neutrophils. Thus this provides evidence that dysbiosis can be a cause, and not just the effect of colitis!

A specific gene-microbe interaction drives the development of Crohn's disease-like colitis in mice.

Caruso R, Mathes T, Martens EC, Kamada N, Nusrat A, Inohara N, Núñez G.

Sci Immunol. 2019 Apr 19;4(34). pii: eaaw4341. doi: 10.1126/sciimmunol.aaw4341.

PMID:31004013

GOUT

A. February - May 2019

mTOR inhibition by metformin impacts monosodium urate crystal-induced inflammation and cell death in gout: a prelude to a new add-on therapy?

mTOR is involved in nutrient sensing in many cells including immune cells and has been implicated in metabolic and cardiovascular disease. It is known that in vitro, MSU crystals can induce mTOR signaling in mononuclear cells encountering the crystals. The authors replicated this by stimulating healthy immune cells with MSU in vitro which led to mTOR activation (especially in monocytes). mTOR activation was also seen in unstimulated cells from patients with gout. These cells then go on to initiate cell death with a cytokine release. The inflammatory and cell death response could be partially reversed by inhibiting mTOR (by metformin or rapamycin). In the clinic, this is buttressed by the fact that diabetic patients on metformin have a lower frequency of gout attacks. The study opens up the possibility of targeting mTOR in gout.

Vazirpanah N, Ottria A, van der Linden M, Wichers CGK, Schuiveling M, van Lochem E, Phipps-Green A, Merriman T, Zimmermann M, Jansen M, Radstake TRDJ, Broen JCA. mTOR inhibition by metformin impacts monosodium urate crystal-induced inflammation and cell death in gout: a prelude to a new add-on therapy? Ann Rheum Dis. 2019 May;78(5):663-671.

JIA

A. February - May 2019

Machine learning identifies an immunological pattern associated with multiple juvenile idiopathic arthritis subtypes.

The authors profiled the adaptive immune system of 85 patients with JIA and 43 age-matched controls with in-depth flow cytometry and machine learning approaches. This was hoped to explain the clinical heterogeneity of JIA. The immune signature observed was shared across a broad spectrum of childhood inflammatory diseases. The immune signature was identified in clinically distinct subsets of JIA, but was accentuated in patients with systemic JIA and those patients with active disease. Despite the extensive overlap in the immunological spectrum exhibited by healthy children and patients with JIA, machine learning analysis of the data set proved capable of discriminating patients with JIA from healthy controls with ~90% accuracy. This pilot provides proof of principle for the use of machine learning in grouping individuals and possibly identifying treatment responders in the future. 

Van Nieuwenhove E, Lagou V, Van Eyck L, Dooley J, Bodenhofer U, Roca C, Vandebergh M, Goris A, Humblet-Baron S, Wouters C, Liston A. Machine learning identifies an immunological pattern associated with multiple juvenile idiopathic arthritis subtypes. Ann Rheum Dis. 2019 May;78(5):617-628.

Myositis

A. February - May 2019

[18F]Florbetapir positron emission tomography: identification of muscle amyloid in inclusion body myositis and differentiation from polymyositis.

[18F]florbetapir amyloid PET was evaluated as a specific indicator of IBM. In 10 patients with IBM and 6 with PM, this modality had sensitivity and specificity (for IBM) of 80% and 100%, respectively. Thus this may help in misclassification of early IBM as PM.

Lilleker JB, Hodgson R, Roberts M, Herholz K, Howard J, Hinz R, Chinoy H.

Ann Rheum Dis. 2019 May;78(5):657-662.

Miscellaneous

A. October 2018 - January 2019

Reverse Signalling of RANKL is linked with Bone formation

RANKL acts as bidirectional signalling molecule and produce intracellular reverse signalling. Previously, osteoblasts were thought to be the main producers of RANKL; however, mounting evidence suggests that osteocytes are the main source during bone remodelling. In this study, the researchers showed that maturing osteoclasts secreted vesicular RANK (vRANK), which binds to osteoblastic RANKL and activates reverse signalling through Runx2. The stimulation also increased the mineralization of osteoblasts.

Role of Integrin beta like protein 1 in prevention of OA

Integrin β-like protein 1 (ITGBL1) is an ECM molecule which plays a role in modulating integrin-mediated chondrocyte activity. The authors were able to show prevention of cartilage damage and osteophyte formation in an animal model of OA with intra-articular delivery with adenoviral vector of ITGBL1

ITGBL1 modulates integrin activity to promote cartilage formation and protect against arthritis [2].

IL-2 in autoimmune rheumatic diseases

The dose of IL-2 and treatment scheme used selectively activate and expand Tregs and are safe across different diseases and concomitant treatments. This and preliminary indications of clinical efficacy should licence the launch of phase II efficacy trial of ld-IL2 in various autoimmune and inflammatory diseases. [3].

References

B. February - May 2019

NETosis is required for thrombosis in APS and can be abrogated by adenosine agonism:

Potentiation of neutrophil extracellular trap (NET) release is one mechanism by which antiphospholipid antibodies (aPL Abs) effect thrombotic events in patients with antiphospholipid syndrome (APS). selective agonism of the adenosine A2Areceptor (CGS21680) suppresses aPL Ab-mediated NETosis in protein kinase A-dependent fashion. CGS21680 also reduces thrombosis in the inferior vena cavae of both control mice and mice administered aPL Abs. The antithrombotic medication dipyridamole is known to potentiate adenosine signalling by increasing extracellular concentrations of adenosine and interfering with the breakdown of cAMP.

Adenosine receptor agonism protects against NETosis and thrombosis in antiphospholipid syndrome.

Ali RA, Gandhi AA, Meng H, Yalavarthi S, Vreede AP, Estes SK, Palmer OR, Bockenstedt PL, Pinsky DJ, Greve JM, Diaz JA, Kanthi Y, Knight JS.

Nat Commun. 2019 Apr 23;10(1):1916. doi: 10.1038/s41467-019-09801-x.

PMID:31015489