Phenotype and pathological significance of MCAM+ (CD146+) T cell subset in psoriatic arthritis.

BACKGROUND: CD146 (MCAM-melanoma cell adhesion molecule) is a cell surface adhesion molecule for Laminin 411. T cells expressing MCAM are mainly responsible for IL-17 production. IL-17 secreting T helper cells (Th17 cells) are critical for the pathogenesis of psoriatic arthritis (PsA). Here we hypothesized enrichment of CD146+IL-17+ memory T cells in PsA synovium and studied the association of CD146 expression and CD4+IL-17+ activated memory (CD11a+CD45RO+) T cells in synovial fluid and blood of PSA, rheumatoid arthritis (RA, a positive control) and osteoarthritis (OA) patients. METHODS: Hi-D FACS studies were done to identify IL-17 in CD4+CD146+CD45RO+ and CD8+CD146+CD45RO+ T cells. RESULTS: We observed that effector CD146+(MCAM+) T cells are enriched at the synovial inflammation site in PsA. CONCLUSION: As CD146+ T cells are a key resource for IL-17 it is likely that the enrichment of these MCAM+ pathologic cells are critical for the disease process of PsA.

Functional significance of MAIT cells in psoriatic arthritis.

BACKGROUND: Mucosal-associated invariant T (MAIT) cells are gaining more relevance for autoimmune diseases because of its (i) innate and adaptive immune response (ii) tissue homing properties (iii) production of IL-17A. These cells are predominantly CD8+ cells, because of its strong association with MHC-I. Tc17 CD8+/MAIT cells likely to have a critical role in psoriatic arthritis (PsA). Herein, we have explored pathological significance of MAIT cell in PsA. METHODS: Peripheral blood mononuclear cells (PBMC) and synovial fluid mononuclear cells (SFMC) were collected from age/sex matched (n = 10 for each) PsA, rheumatoid arthritis (RA) and osteoarthritis patients (OA). Hi-D FACS studies were performed: (i) activated memory cells (CD3+CD45RO+) T cells were identified (ii) gating strategies were made to identity the MAIT (CD3+Vα7.2TCR+CD161hi) cells, its phenotype pattern; and functional significance in respect to IL-17A production and responsiveness to human rIL-23. Anti CD3/CD28 ab cocktail was used to activate cells along with rIL-23 to culture and enrich the MAIT cells. The percentages of each cell population and the mean fluorescence intensity (MFI) were analyzed using Flow Jo software. RESULTS: MAIT cells were enriched in synovial fluid of PsA (4.29 ±â€¯0.82%) compared to PBMC (1.04 ±â€¯0.71). With stimulation, SFMC MAIT cells produced significantly more IL-17A (32.66 ±â€¯4.01%) compared to that of RA (23.93 ±â€¯2.81%, p < 0.05) and OA (5.02 ±â€¯0.16%, p < 0.05). MAIT cells were predominantly CD8+ (>80%). Significant upregulation of IL-23R was noted in synovial fluid MAIT cells of PsA (24.97 ±â€¯2.33%, p < 0.001) and RA (21.93 ±â€¯2.29%, p < 0.001) compared to that of OA (2.13 ±â€¯2.29). This IL-23R was functionally active as evidenced by profound mitotic effect in presence of rIL-23. CONCLUSION: MAIT cells are poly functional; produce multiple cytokines (IL-17A, IFN-γ, TNF-α). Here, we demonstrated synovial fluid MAIT cells as a major source of IL-17A and majority of MAIT cells were CD8+. Functionally active IL-23R on these migrated MAIT cells brings a new dimension. They may not need MR1 associated activation rather lesional IL-23 in the synovium can independently regulate these critical Tc17 CD8+ MAIT cells. Thus, these cells likely to be a part of the IL-23/IL-17A cytokine network and play a critical role in the pathogenesis of PsA.

Quantitative tracking of inflammatory activity at the peak and trough plasma levels of tofacitinib, a Janus kinase inhibitor, via in vivo 18 F-FDG PET.

PURPOSE: To assess the capability of in vivo positron emission tomography (PET) using 18 F-fluorodeoxyglucose (18 F-FDG) to quantify changes in inflammatory activity in response to tofacitinib, a Janus kinase (JAK) inhibitor, over a timeframe of a few hours to few days in a preclinical model of rheumatoid arthritis (RA). METHODS: Twenty-four mice with collagen-induced arthritis in the following groups were assessed: Group 1, where the changes in PET measures for the extremity joints were evaluated at the peak and trough plasma drug levels after administration of a single dose of tofacitinib (4 hours apart); Group 2, where joint PET measures were assessed before treatment and after 6 days of administration of a daily dose of tofacitinib; and group 3 (controls), where joint PET measures were derived from the same mice, 6 days apart. RESULTS: At about peak plasma levels of the drug after a single tofacitinib administration, there was a reduction in PET measures compared to pretreatment values, suggesting decreased inflammatory activity. These measures were equivalent to those obtained after 6 days of daily dosing by tofacitinib. However, PET measures at trough plasma levels of the drug from tofacitinib administration were significantly higher than those at peak plasma drug levels and equivalent to pretreatment measures. There were insignificant changes in PET measures for the control animals. CONCLUSION: 18 F-FDG PET can detect changes in inflammatory activity occurring in response to the JAK inhibitor tofacitinib: (a) during peak and trough plasma drug levels, that is within mere hours of treatment; and (b) over a span of days.

IL-9 receptor: Regulatory role on FLS and pannus formation.

OBJECTIVE: Functions of the Th9 cells and its signature cytokine IL-9 in human autoimmune diseases is currently under extensive research. Here we are reporting new functions of IL-9-receptor (IL-9R); its regulatory role on (i) FLS (fibroblast like synoviocyte) biology and (ii) pannus formation in rheumatoid arthritis (RA) and psoriatic arthritis (PsA). METHODS: RA, PsA, and OA synovial tissue biopsies were obtained; FLS were derived and cultured from these tissues. T quantify protein and messenger RNA levels of IL9-receptor (IL-9R) Western blot and real-time PCR techniques were used. For Pro-growth/survival effect of IL-9 (rIL-9) Annexin-V (apoptosis assay) and MTT assays were used. RESULTS: Immunoblot and RT-PCR studies demonstrated IL9-R in FLS of RA, PsA, and OA. IL9-R was functionally active. rIL-9 induced significant proliferation of FLS (p < 0.001) and had an inhibitory effect on TNF-α induced apoptosis. Proliferation of FLS induced by rIL-9 could be significantly inhibited (p < 0.001) with an IL-9R antibody. Further we observed, rIL-9 induced increased secretion of IL-6, IL-8 and also unregulated MMP-3 expression in FLS. CONCLUSIONS: Proliferation of FLS, induction of pro-nflammatory cytokines and upregulation of metaloprotinase (MMP 3) the key pathologic events for pannus formation are regulated by IL-9 and its recptor. Thus the IL-9/IL-9R system is a new contributing factor in the cytokine network of PsA and RA.

IL-9, a local growth factor for synovial T cells in inflammatory arthritis.

OBJECTIVE: The regulatory role of the Th9 cells along with its signature cytokine IL-9 in human immune system and its aberrant activation in autoimmune diseases is currently under investigation. We are reporting the functional significance of IL-9 in the pathogenesis of autoimmune inflammatory arthritis. METHODS: CD3(+) T cells were obtained from peripheral blood (PB) and synovial fluid (SF) of psoriatic arthritis (PsA), rheumatoid arthritis (RA), and osteoarthritis (OA) patients. MTT, FACS based CFSE dilution assay and apoptosis assay (Annexin-V) were performed to determine the pro-growth/survival effect of human recombinant IL-9 on activated CD3(+) T cells. Immunoblots were performed to determine the signaling proteins responsible for the progrowth/survival effect of IL-9. RESULTS: SF of PsA and RA was enriched with IL-9 producing CD3(+) T cells compared to the SF in OA. IL-9 level measured by ELISA was significantly elevated in PsA and RA patients compared to SF in OA (<.001). Activated T cells of PsA and RA had higher levels of IL-9 receptors. IL-9 promoted proliferation and survival of the CD3(+) T cells of PB and SF of PsA and RA and compared to untreated (media) controls (p<.005, t-test). IL-9 induced proliferation of T cells was dependent on PI3K/Akt/mTOR signaling pathway. CONCLUSION: IL-9 is functionally active, and is a pro-growth/survival factor for the localized pathologic T cells in the synovium of inflammatory arthritis. The pro-growth/survival effect is mediated by the activation of mTOR kinase cascade. To our knowledge, this is the first report of a functional role of IL-9 in human autoimmune arthritis.

Severe combined immunodeficiency mouse-psoriatic human skin xenograft model: a modern tool connecting bench to bedside.

Psoriasis is a multifactorial chronic inflammatory disease. Research into the pathogenesis of this disease is hindered by the lack of a proper animal model. Over the past two decades, many scientists were involved in the development of animal models that nearly mirror the immunopathogenesis of psoriasis. One such model, which has opened doors to the study of molecular complexities of psoriasis as well as its treatment, is the severe combined immunodeficiency (SCID) mouse-human skin chimera model. This model not only mirrors the clinical and histopathological features of psoriasis but also help in the study of cell proliferation, angiogenesis, function of T cells, neurogenic inflammation and cytokines involved in inflammatory reactions. In this article, we have reviewed the prospects and the limitations of the SCID mouse model of psoriasis.

1α,25-Dihydroxyvitamin-D3-3-bromoacetate regulates AKT/mTOR signaling cascades: a therapeutic agent for psoriasis.

The efficacy of 1α,25-dihydroxyvitamin D3 (Vit-D) limits its topical use despite its profound effects on cellular differentiation, proliferation, and immunomodulation. Therefore, in search for a more effective analog of Vit-D, in this study we have evaluated the antiproliferative and proapoptotic effects of 1α,25-dihydroxyvitamin D3-3-bromoacetate (BE). Proliferation and apoptosis studies in normal human epidermal keratinocytes (NHEKs) were conducted by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide), CFSE (carboxy fluorescein succinimidyl ester) dilution, and Annexin V assays. Western blot analysis and real-time PCR were performed to determine its effect on signal transduction. A reconstructed human epidermis (RHE) model was used to further validate the therapeutic role of BE in psoriasis. BE was significantly more potent than an equivalent concentration of Vit-D in inhibiting growth and survival of human keratinocytes. The antimitotic effect was found to be due to the inhibition of phosphorylation of serine/threonine protein kinase (AKT) and its downstream target, mammalian target of rapamycin (mTOR). In the RHE model, BE reversed IL-22-induced psoriasiform changes more effectively than Vit-D. Interestingly, BE inhibited the IL-22-induced gene expression of AKT1, MTOR, chemokines [IL-8 and RANTES (regulated upon activation, normal T-cell expressed and secreted)], and psoriasin (S100A7) more significantly than Vit-D. These results suggest the potential of BE as a prospective therapeutic agent for psoriasis.