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The role of T cell subpopulations in human disease is in a transition phase due to continuous discovery of new subsets of T cell, one of which is Th17, characterized by the production of signature cytokine IL-17. In the last couple of years, many articles are coming out on the role of Th17 and its signature cytokine IL-17 in different autoimmune diseases like rheumatoid arthritis, psoriasis, psoriatic arthritis (PsA), SLE and multiple sclerosis. Psoriasis and PsA are immune-mediated diseases, affecting the skin and joints, respectively. Initially, it was thought that psoriasis and PsA were Th1-mediated diseases; however, studies in knockout animal models (IL-17 knockout mice) as well as human experimental data indicate that Th17 and its signature cytokine IL-17 have a critical role in the pathogenesis of psoriatic disease. Th17 cells have been identified from the dermal extracts of psoriatic lesions. Subsequently, our research group has substantiated this observation that Th17 cells are enriched in the papillary dermis of psoriatic plaques and in freshly isolated effector T lymphocytes from the synovial fluid of PsA patients, and we have reported that the majority of these CD4 + IL-17+ T cells are of memory phenotype (CD4RO + CD45RA − CD11a + ). Recent reports also suggest that the synovial tissue in psoriatic arthritis is enriched with IL-17R, and its most well recognized receptor IL-17RA is functionally active in psoriatic arthritis. In this review article, we have discussed the role of IL-17 in psoriatic disease and have narrated about the novel IL17/IL-17R antibodies currently in preparation for its therapeutic uses in autoimmune diseases.

To delineate the functional significance of IL-17 Receptor (IL-17RA) and characterize the IL-17 producing T cell (T h 17) subpopulation in psoriatic arthritis (PsA). Mononuclear cells from blood and synovial fluid (SF) were obtained from PsA ( n  = 20), rheumatoid arthritis (RA, n  = 20) and osteoarthritis (OA, n  = 20) patients. Synoviocytes (FLS) were isolated from the synovium of RA ( n  = 5), PsA ( n  = 5) and OA ( n  = 5) patients. IL-17RA expression in FLS was identified by western blotting (WB) and flowcytometry. T lymphocytes derived from the SF of these patients were studied to identify and phenotype the T h 17 cells. The functional significance of IL-17RA was determined by evaluating its regulatory role on the production of proinflammatory cytokines and endopeptidase. IL-17RA expression was found to be significantly higher in FLS of RA (15.7% ± 4.9) and PsA (4.5% ± 0.9) in comparison to OA (1.14% ± 0.9). Western blot analyses showed that the relative intensity (RI) of IL-17RA protein was higher in RA and PsA compared to OA (Fisher exact, P  < 0.01). A significant enrichment of IL-17-producing CD4+ T cells (7.9% ± 2.8) was observed in the SF of PsA patients compared to that of OA patients ( P  < .001). Compared to OA-FLS, recombinant IL-17 induced higher levels of IL-6, IL-8, and MMP-3 production in PsA-FLS. Blockage of IL-17RA with an anti-IL-17RA antibody inhibited the production of IL-6, IL-8, and MMP-3. This is the first report to demonstrate the functional significance of IL-17RA in PsA. Results of this study support the hypothesis that IL-17RA blocking antibodies have the potential to be a therapeutic option for psoriatic arthritis.

Psoriasis is a chronic disabling complex inflammatory disorder prevalent worldwide with environmental and genetic components that involve predominantly skin in addition to nails and joints associated with various systemic comorbidities having periods of exacerbations and remissions. Psoriasis is characterized by hyper-proliferation as well as abnormal differentiation of epidermal keratinocytes and lymphocyte infiltration (mainly T cells) with resultant inflammatory cytokines and chemokines. Immunological and genetic studies over the last decade have identified genetic susceptibility risk alleles, molecular, cellular and immunological mechanisms involved in immunopathogenesis of psoriasis. The current disease model emphasizes the role of aberrant Th1 and Th17 responses regulated by a complex network of different cytokines, including TNF-α, IL-17 and IL-23; signal transduction pathways downstream to the cytokine receptors; and various activated transcription factors, including NF-κB, interferon regulatory factors and signal transducer and activator of transcriptions. Cytokines targeting biologics (IL-17, IL-23 and TNFα) therapies have revolutionized the management of severe skin disease having beneficial effects on joints and systemic inflammation of psoriasis as well. Further better understanding of immunopathogenesis of psoriasis will pave way for precision medicine based on specific immunopathogenic targets in a given phenotype of disease. Complex interplay of psoriasis with associated comorbidities is also a future area of research for overall better patient management and to improve their quality of life.

Th17 cells are a discrete subset of T cell subpopulation, which produce IL-17 and certain other pro-inflammatory cytokines. A regulatory role of Th17 cells have been proposed in several autoimmune diseases including psoriasis, psoriatic arthritis (PsA), ankylosing spondylitis (AS), rheumatoid arthritis, inflammatory bowel disease, systemic lupus erythematosus, and multiple sclerosis. Psoriatic disease is an autoimmune disease which mainly involves skin and joints. Until recently, psoriasis and PsA were thought to be Th1 mediated disease, but after the discovery of IL-17 and IL-17 knockout animal studies as well as human experimental data indicate a crucial role of the Th17 cells in the pathogenesis of psoriasis and PsA. Our research group have not only found abundance of CD4 + IL-17 + T cells, mainly the memory phenotype (CD4RO + CD45RA − CD11a + ) in the synovial fluid, but also have shown the existence of a functional IL-17 receptor in synovial fibroblast of psoriatic arthritis patients. Similarly, both animal and human studies indicate a regulatory role of the Th17 cells in AS; most critical observations are that Th17 cytokines (IL-17 and IL-22) can contribute to bone erosion, osteitis and new bone formation the hall mark skeletal features associated with the pathophysiology of AS. In this review article, we have discussed the contributing role of the IL-23/IL-17 axis in the pathogenesis of PsA and AS.

Cytokines play a critical role in the pathogenesis of psoriatic arthritis, ankylosing spondylitis, and other types of spondyloarthritis (SpA). Besides IFN-γ and TNF-α; IL-23/IL-17 cytokines play a dominant role in the inflammatory and proliferative cascades of SpA. Recently, in a series of elegant experiments using mouse models and human tissues, it has been demonstrated that IL-23-induced Th17 cytokines (IL-17 and IL-22) can contribute to following pathologic events associated with SpA: development of psoriatic plaque, pannus formation in the joint, joint erosion, and new bone formation. In this review article, we have discussed the contributing role of the IL-23/IL-17 cytokine axis in the pathogenesis of PsA and AS. IL-23/IL-17-targeted therapies are very promising for SpA, and we have provided an outline about usefulness of these new groups of biologics in SpA.

Increasing evidence points to a role for the extra-neuronal nerve growth factor (NGF) in acquired immune responses. However, very little information is available about its role and underlying mechanism in innate immunity. The role of innate immunity in autoimmune diseases is becoming increasingly important. In this study, we explored the contribution of pleiotropic NGF in the innate immune response along with its underlying molecular mechanism with respect to IL-1β secretion. Human monocytes, null and NLRP3 deficient THP-1 cell lines were used for this purpose. We determined the effect of NGF on secretion of IL-1β at the protein and mRNA levels. To determine the underlying molecular mechanism, the effect of NGF on NLRP1/NLRP3 inflammasomes and its downstream key protein, activated caspase-1, were evaluated by ELISA, immunoflorescence, flow cytometry, and real-time PCR. In human monocytes and null THP-1 cell line, NGF significantly upregulates IL-1β at protein and mRNA levels in a caspase-1 dependent manner through its receptor, TrkA. Furthermore, we observed that NGF induces caspase-1 activation through NLRP1/NLRP3 inflammasomes, and it is dependent on the master transcription factor, NF-κB. To best of our knowledge, this is the first report shedding light on the mechanistic aspect of a neuroregulatory molecule, NGF, in innate immune response, and thus enriches our understanding regarding its pathogenic role in inflammation. These observations add further evidence in favor of anti-NGF therapy in autoimmune diseases and also unlock a new area of research about the role of NGF in IL-1β mediated diseases.

Increasing evidence supports an important role for inflammation in all phases of atherosclerosis, from initiation of the fatty streak to final culmination in acute coronary syndromes. Numerous inflammatory biomarkers including cell adhesion molecules, cytokines, chemokines, and acute-phase reactants such as fibrinogen, serum amyloid A, and C-reactive protein (CRP) have been shown to predict cardiovascular (CVD) events. Several prospective studies have shown a consistent and robust relationship between levels of high-sensitivity CRP and the risk of future CVD events. Toll-like receptors are pattern recognition receptors and members of the innate immune system that contribute to inflammation and appear to play key roles in atherosclerosis. Lipoprotein-associated phospholipase A2 may also be an independent CVD risk factor. Psoriasis has been associated with an increasing risk for atherosclerosis, including coronary artery disease and stroke. Patients with psoriasis have a 5-year shorter life expectancy, most frequently due to CVD. Psoriasis is associated with a chronic inflammatory state and with elevated levels of CRP and other inflammatory cytokines and these may play a causative role in the increased risk of psoriatic patients for CVD. Patients with psoriasis may represent an emerging risk population and patients with moderate to severe psoriasis should be screened and aggressively treated for CVD risk factors.

Methods Mononuclear cells of peripheral blood (PBMC) and synovial fluid (SFMC) from patients with PsA (n=15) and PBMC from age/sex matched normal individuals (n=15) were collected. Figure 1; Interleukin (IL) 23 induces phosphorylation of JAK2 and STAT3 in mononuclear cells of peripheral blood (PBMC) of psoriatic arthritis (PsA) and that can be inhibited by tofacitinib. Figure 2; (A, B) Hi-D FACS studies of the mononuclear cells of peripheral blood from patients with psoriatic arthritis demonstrated that- (i) rIL-23 induced marked upregulation of IL-17 in the CD4+ memory T cells (CD11a+CD45RO+) (A) and that (ii) rIL-23 induced IL-17 expression could be markedly inhibited by tofacitinib (p<0.001, t-test) (B).

Ion channels have recently attracted attention as potential mediators of skin disease. Here, we explored the consequences of genetically encoded induction of the cell volume-regulating Ca2+-activated KCa3.1 channel (Kcnn4) for murine epidermal homeostasis. Doxycycline-treated mice harboring the KCa3.1+-transgene under the control of the reverse tetracycline-sensitive transactivator (rtTA) showed 800-fold channel overexpression above basal levels in the skin and solid KCa3.1-currents in keratinocytes. This overexpression resulted in epidermal spongiosis, progressive epidermal hyperplasia and hyperkeratosis, itch and ulcers. The condition was accompanied by production of the pro-proliferative and pro-inflammatory cytokines, IL-β1 (60-fold), IL-6 (33-fold), and TNFα (26-fold) in the skin. Treatment of mice with the KCa3.1-selective blocker, Senicapoc, significantly suppressed spongiosis and hyperplasia, as well as induction of IL-β1 (-88%) and IL-6 (-90%). In conclusion, KCa3.1-induction in the epidermis caused expression of pro-proliferative cytokines leading to spongiosis, hyperplasia and hyperkeratosis. This skin condition resembles pathological features of eczematous dermatitis and identifies KCa3.1 as a regulator of epidermal homeostasis and spongiosis, and as a potential therapeutic target.