Taneja, Veena

Abstract HLA-DRB1*0401 has been associated with predisposition to develop rheumatoid arthritis (RA) while *0402 has been linked with resistance to develop RA. Using transgenic mice, we showed that *0401 mice are susceptible to develop collagen-induced arthritis (CIA) that mimics human disease in histopathology, production of autoantibodies and sex-bias while *0402 mice are not susceptible. In this study, we determined if *0401 mice have CD4 T cell repertoire that is predetermined to produce proinflammatory cytokines. The data shown here supports that both *0401 and *0402 mice can produce Th1/TH17 cytokines although conditions required for production of Th17 cytokines differ between the 2 strains. In context of CIA, *0402 mice generate a Th2 response that may explain its resistance to develop CIA. Further, our data supports that a significant subset of naïve CD4 T cells when activated in polarizing conditions can generate T regulatory cells in *0402 but not *0401 mice. We hypothesize that *0401 has been evolutionarily selected due to its ability to clear infection. Our data suggests that *0401 generates a storm of cytokines in response to bacterial products and may be more efficient in clearing infection than *0402. Autoimmunity is a bystander effect of the cytokine storm ensuing immune dysregulation along with the presence of lower number of T regulatory cells in *0401 mice.

Abstract HLA-DQB1*0302/DQA1*0301 renders humans and transgenic mice susceptible to develop arthritis while HLA-DQB1*0601/DQA1*0103 has been associated with resistance to arthritis in both. However, some patients of rheumatoid arthritis carry the non-associated alleles. Most of the studies do not take in to account the role of DQA1 alleles. DQB1*0604 generally occurs in linkage with DQA1*0102. To understand the role of trans-heterodimer, we generated DQB1*0604/ DQA1* 0103 transgenic mice lacking endogenous class II molecules. Previous studies have shown that DQB1*0601/DQA1*0103 transgenic mice are resistant to develop collagen-induced arthritis. The DQB1*0604/A1*0103 and DQA1*0103 mice developed severe arthritis and generated antigen-specific response in vitro. The DQB1*0604/ DQA1*0103 could present CII-derived peptides that are not presented by RA resistant DQ6 allele suggesting that trans-heterodimer molecules between two DQB1 and DQA1 molecules may result in presentation of unique antigens and susceptibility to develop arthritis. The data provides a possible explanation for the presence of HLA alleles not associated with arthritis in some patients.

AbstractObjectiveTo discover a novel peptoid antagonist that targets the interleukin‐15 (IL‐15) receptor and to evaluate its therapeutic efficacy in the treatment of inflammation and arthritis.MethodsA new compound (IFRA3, interleukin‐15 receptor antagonist 3) was discovered using a unique on‐bead two‐colour combinatorial cell screening of a peptoid library. The interaction of IFRA3 with IL‐15 receptor was assessed by in vitro pull‐down and thermal shift assays. The efficacy of IFRA3 in treating inflammation and arthritis was evaluated in mouse models.ResultsIFRA3Q1 (a tetrameric derivative of IFRA3) inhibited the activity of IL‐15 and suppressed CTLL‐2 cell proliferation (which depends on IL‐15 activity). IFRA3Q1 exhibited strong in vivo anti‐inflammatory activity in carrageenan‐induced inflammation in mice. Furthermore, IFRA3Q1 inhibited collagen‐induced arthritis in DBA/1J mice.ConclusionBy binding to and inhibiting the function of IL‐15 receptor, IFRA3Q1 exhibited significant anti‐arthritis activity. Our findings suggest that IFRA3Q1 represents a new paradigm for arthritis therapy by targeting IL‐15 signalling.

AbstractPeptides were designed to inhibit the protein–protein interaction of CD2 and CD58 to modulate the immune response. This work involved the design and synthesis of eight different peptides by replacing each amino acid residue in peptide 6 with alanine as well as grafting the peptide to the sunflower trypsin‐inhibitor framework. From the alanine scanning studies, mutation at position 2 of the peptide was shown to result in increased potency to inhibit cell adhesion interactions. The most potent peptide from the alanine scanning was further studied for its detailed three‐dimensional structure and binding to CD58 protein using surface plasmon resonance and flow cytometry. This peptide was used to graft to the sunflower trypsin inhibitor to improve the stability of the peptide. The grafted peptide, SFTI‐a1, was further studied for its potency as well as its thermal, chemical, and enzymatic stability. The grafted peptide exhibited improved activity compared to our previously grafted peptide and was stable against thermal and enzymatic degradation.

Rheumatoid arthritis (RA) is an autoimmune disorder with multifactorial etiology; both genetic and environmental factors are known to be involved in pathogenesis. Treatment with disease-modifying antirheumatic drugs (DMARDs) plays an essential role in controlling disease progression and symptoms. DMARDs have immunomodulatory properties and suppress immune response by interfering in various pro-inflammatory pathways. Recent evidence has shown that the gut microbiota directly and indirectly modulates the host immune system. RA has been associated with dysbiosis of the gut microbiota. Patients with RA treated with DMARDs show partial restoration of eubiotic gut microbiome. Hence, it is essential to understand the impact of DMARDs on the microbial composition and its consequent influences on the host immune system to identify novel therapies for RA. In this review, we discuss the importance of antirheumatic-drug-induced host microbiota modulations and possible probiotics that can generate eubiosis.

Abstract Objective Although the etiology of rheumatoid arthritis (RA) is unknown, recent studies have led to the concept that gut dysbiosis may be involved in onset. In this study, we aimed to determine if human gut commensals modulate the immune response and gut epithelial integrity in DQ8 mice. Methods DQ8 mice were orally gavaged with RA-associated (Eggerthella lenta or Collinsella aerofaciens) and non-associated (Prevotella histicola or Bifidobacterium sp.) on alternate days for 1 week in naïve mice. Some mice were immunized with type II collagen and oral gavage continued for 6 weeks and followed for arthritis. Epithelial integrity was done by FITC-Dextran assay. In addition, cytokines were measured in sera by ELISA and various immune cells were quantified using flow cytometry. Results Gut permeability was increased by the RA-associated bacteria and was sex and age-dependent. In vivo and in vitro observations showed that the RA-non-associated bacteria outgrow the RA-associated bacteria when gavaged or cultured together. Mice gavaged with the RA-non-associated bacteria produced lower levels of pro-inflammatory MCP-1 and MCP-3 and had lower numbers of Inflammatory monocytes CD11c+Ly6c+, when compared to controls. E. lenta treated naïve mice produce Th17 cytokines. Conclusions Our studies suggest that gut commensals influence immune response in and away from the gut by changing the gut permeability and immunity. Dysbiosis helps the growth of RA-associated bacteria and reduces the beneficial bacteria.