Advances in Psoriatic Disease Research: Insights From GRAPPA Pilot Research Awardees.

Research progress from the Group for Research and Assessment of Psoriasis and Psoriatic Arthritis (GRAPPA) pilot award program was presented and discussed at the GRAPPA 2023 annual meeting. Topics included identification of protein biomarkers associated with enthesitis in psoriatic arthritis (PsA), the role of HLA-B27 on gut microbial dysbiosis in PsA, single-cell profiling of synovial fluid vs psoriatic skin lesions in PsA, and the role of mechanotransduction in hyperactivation of transforming growth factor-ß via αVß6 integrin in psoriatic epidermis.

GRAPPA 2023 Basic Science Workshop: What to Expect From Animal Models for Psoriatic Arthritis and Psoriasis.

Animal models help to drive research into psoriasis and psoriatic arthritis (PsA), particularly when studies in humans are not feasible. There are no animal models that perfectly mimic psoriatic disease (PsD) and so the pros and cons of each existing model must be considered for appropriate experimental design. Roughly, the existing animal models for PsD can be divided into 4 categories: (1) spontaneous models, (2) transgenic models, (3) inducible models, and (4) xenotransplantation models. Animal models in PsD are extremely important for dissecting and understanding molecular mechanisms of the disease process and for developing novel drugs. Animal models remain highly valuable for research in PsD in 2 scenarios. The first scenario is when complex interventions or analyses are required that are not feasible in humans due to technical, safety, or economic reasons. The second is when well-controlled study environments are required, such as dietary modifications, that would be challenging in humans. This topic was presented as part of the basic science workshops during the Group for Research and Assessment of Psoriasis and Psoriatic Arthritis (GRAPPA) 2023 annual meeting.

JAK-STAT Signaling and Beyond in the Pathogenesis of Spondyloarthritis and Their Clinical Significance.

PURPOSE OF REVIEW: Janus kinase-signal transducers and activators of transcription cell signaling proteins (JAK-STATs) play a key regulatory role in functioning of several inflammatory cytokines. JAK-STAT signaling proteins are the key regulators of the cytokine/cytokine receptor system involved in the pathogenesis of various autoimmune disease including spondyloarthritis (SpA). This article mainly highlights the JAK-STAT signaling system, its association with the relevant cytokine/cytokine-receptor system, and its regulatory role in pathogenesis of SpA. Also, we have briefly addressed the principle for the use JAKi in SpA and the current status of use of JAK inhibitors (JAKi) in SpA. RECENT FINDINGS: Recent developments with newer JAK molecules as well as other molecules beyond JAK inhibitors are now an exciting field for the development of novel therapies for autoimmune diseases and various malignant conditions. In this article, we have provided a special emphasis on how various cell signaling systems beyond JAK/STAT pathway are relevant to SpA and have provided a comprehensive review on this upcoming field in respect to the novel TYK2 inhibitors, RORγT inhibitors, mTOR inhibitors, NGF inhibitors, and various STAT kinase inhibitors. SpA are a group of autoimmune diseases with multifactorial etiologies. SpA is linked with genetic predisposition, environmental risk factors, and the immune system-mediated systemic inflammation. Here, we have provided the regulatory role of JAK/STAT pathway and other intracellular signaling system in the pathogenesis of SpA and its therapeutic relevance.

Modulation of Interleukin-23 Signaling With Guselkumab in Biologic-Naive Patients Versus Tumor Necrosis Factor Inhibitor-Inadequate Responders With Active Psoriatic Arthritis.

OBJECTIVE: We assessed and compared immunologic differences and associations with clinical response to guselkumab, a fully human interleukin (IL)-23p19 subunit inhibitor, in participants with active psoriatic arthritis (PsA) who were biologic-naive or had inadequate response to tumor necrosis factor inhibitors (TNFi-IR). METHODS: Serum biomarker levels at baseline and after treatment with guselkumab 100 mg every 8 weeks were compared between biologic-naive (n = 251) and TNFi-IR (n = 93) subgroups identified in the pooled DISCOVER-1/DISCOVER-2/COSMOS data set. Baseline biomarker levels determined by achievement of week 24 clinical responses (≥75%/90% improvement in Psoriasis Area and Severity Index [PASI 75/90], Investigator's Global Assessment [IGA] of psoriasis score 0/1 and ≥2-point improvement], ≥20% improvement in American College of Rheumatology criteria [ACR20]) were compared between prior treatment subgroups. RESULTS: Baseline IL-22, TNFα, and beta defensin-2 (BD-2) levels were significantly lower in biologic-naive than in TNFi-IR participants. With guselkumab, week 24 IL-17A, IL-17F, IL-22, serum amyloid A, C-reactive protein, IL-6, and BD-2 levels were significantly reduced from baseline in biologic-naive and TNFi-IR participants (≥1.4-fold difference, nominal P < 0.05). Clinical responders to guselkumab exhibited significantly higher baseline levels of several biomarkers than nonresponders (IL-17A, IL-17F, BD-2 in biologic-naive PASI 90 responders; IL-17A, BD-2 in TNFi-IR IGA 0/1 responders; IL-22, BD-2 in TNFi-IR PASI 90 responders [nominal P < 0.05]) and trended higher in TNFi-IR ACR20 responders. CONCLUSION: Guselkumab modulates IL-23 signaling and provides consistent pharmacodynamic effects in both biologic-naive and TNFi-IR PsA patients. Significantly elevated baseline IL-22, TNFα, and BD-2 levels and associations between baseline IL-22, IL-17A, and BD-2 levels and skin responses to guselkumab suggest greater dysregulation of IL-23/Th17 signaling in patients with TNFi-IR.

JAK-STAT inhibitors in Immune mediated diseases: An Overview.

For any biological response, transmission of extracellular signals to the nucleus is required for DNA transcription and gene expression. In that respect, cytokines/chemokines are well-known inflammatory agents which play a critical role in signalling pathways by activating the Janus kinase-signal transducers and activators of transcription (JAK-STAT) signalling proteins (Janus kinase-signal transducers and activators of transcription) which are a group of intracellular kinase molecules. Cytokines are a category of small proteins (∼5-25 kDa) that play a major role in cell signalling and are major drivers of an autoimmune response. Here we will discuss the role of Janus kinase-signal transducers and activators of transcription kinase cascades in the inflammatory-proliferative cascades of autoimmune disease and about the recent progress in the development of oral synthetic Janus kinase inhibitors (JAKi) and their therapeutic efficacies in dermatologic and systemic autoimmune diseases. Therapeutic efficacy of Janus kinase inhibitors is now well established in the treatment of array of autoimmune and inflammatory disease: spondylarthritis with a special focus on psoriatic arthritis (PsA) and its dermatologic manifestations (psoriasis) and ankylosing spondylitis (AS), atopic dermatitis (AD), alopecia areata (AA), rheumatoid arthritis (RA) and inflammatory bowel disease (IBD). In addition to the first-generation Janus kinase inhibitors several new-generation Janus kinase inhibitors are currently being evaluated. It is expected that these Janus kinase inhibitors likely have higher potency and less adverse effects as compared to their predecessors. Here we have discussed: (1) the functional significance of the Janus kinase-signal transducers and activators of transcription kinase cascades in the inflammatory-proliferative processes of autoimmune diseases and its cellular/molecular mechanisms and (2) progress in the development of oral synthetic Janus kinase inhibitors and their therapeutic efficacies in several systemic and cutaneous autoimmune diseases.

Janus kinase inhibitors for the treatment of psoriatic arthritis.

Psoriatic arthritis (PsA), a systemic disease, has multi-domain musculoskeletal pathologies along with dermatological manifestations. The current recommendations and the standard of care for the treatment of PsA is to address the domain-based pathologies and the disease severity of the six clinical domains unique to PsA, namely, arthritis of the large and small joints, skin involvement, nail involvement enthesitis, dactylitis and axial disease. With currently available therapies, there are good numbers of primary/secondary non-responders and there are added concerns because of intolerance and adverse effects. In that respect, JAK/STAT inhibitors bring new options for many such patients with psoriasis and PsA. Here, we will discuss currently approved JAK inhibitors for PsA and the others which are in different phases of development, including the TYK2 inhibitors.

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.

Feasibility of dual-phase 99mTc-MDP SPECT/CT imaging in rheumatoid arthritis evaluation.

BACKGROUND: To prospectively demonstrate the feasibility of performing dual-phase SPECT/CT for the assessment of the small joints of the hands of rheumatoid arthritis (RA) patients, and to evaluate the reliability of the quantitative and qualitative measures derived from the resulting images. METHODS: A SPECT/CT imaging protocol was developed in this pilot study to scan both hands simultaneously in participants with RA, in two phases of 99mTc-MDP radiotracer uptake, namely the soft-tissue blood pool phase (within 15 minutes after radiotracer injection) and osseous phase (after 3 hours). Joints were evaluated qualitatively (normal vs. abnormal uptake) and quantitatively [by measuring a newly developed metric, maximum corrected count ratio (MCCR)]. Qualitative and quantitative evaluations were repeated to assess reliability. RESULTS: Four participants completed seven studies (all four were imaged at baseline, and three of them at follow-up after 1-month of arthritis therapy). A total of 280 joints (20 per hand) were evaluated. The MCCR from soft-tissue phase scans was significantly higher for clinically abnormal joints compared to clinically normal ones; P<0.001, however the MCCR from the osseous phase scans were not different between the two joint groups. Intraclass Correlation Coefficient (ICC) for MCCR was excellent [0.9789, 95% confidence interval (CI): 0.9734-0.9833]. Intra-observer agreement for qualitative SPECT findings was substantial for both the soft-tissue phase (kappa =0.78, 95% CI: 0.72-0.83) and osseous-phase (kappa =0.70, 95% CI: 0.64-0.76) scans. CONCLUSIONS: Extracting reliable quantitative and qualitative measures from dual-phase 99mTc-MDP SPECT/CT hand scans is feasible in RA patients. SPECT/CT may provide a unique means for assessing both synovitis and osseous involvement in RA joints using the same radiotracer injection.

Targeting the CCR6/CCL20 Axis in Entheseal and Cutaneous Inflammation.

OBJECTIVE: To assess the involvement of the CCR6/CCL20 axis in psoriatic arthritis (PsA) and psoriasis (PsO) and to evaluate its potential as a therapeutic target. METHODS: First, we quantified CCL20 levels in peripheral blood and synovial fluid from PsA patients and examined the presence of CCR6+ cells in synovial and tendon tissue. Utilizing an interleukin-23 minicircle DNA (IL-23 MC) mouse model exhibiting key features of both PsO and PsA, we investigated CCR6 and CCL20 expression as well as the preventive and therapeutic effect of CCL20 blockade. Healthy tendon stromal cells were stimulated in vitro with IL-1ß to assess the production of CCL20 by quantitative polymerase chain reaction and enzyme-linked immunosorbent assay. The effect of conditioned media from stimulated tenocytes in inducing T cell migration was interrogated using a Transwell system. RESULTS: We observed an up-regulation of both CCR6 and CCL20 in the enthesis of IL-23 MC-treated mice, which was confirmed in human biopsy specimens. Specific targeting of the CCR6/CCL20 axis with a CCL20 locked dimer (CCL20LD) blocked entheseal inflammation, leading to profound reductions in clinical and proinflammatory markers in the joints and skin of IL-23 MC-treated mice. The stromal compartment in the tendon was the main source of CCL20 in this model and, accordingly, in vitro activated human tendon cells were able to produce this chemokine and to induce CCR6+ T cell migration, the latter of which could be blocked by CCL20LD. CONCLUSION: Our study highlights the pathogenic role of the CCR6/CCL20 axis in enthesitis and introduces the prospect of a novel therapeutic approach for treating patients with PsO and PsA.

Efficacy and safety of tildrakizumab in patients with active psoriatic arthritis: results of a randomised, double-blind, placebo-controlled, multiple-dose, 52-week phase IIb study.

OBJECTIVES: To evaluate efficacy and safety of the anti-interleukin-23p19 monoclonal antibody tildrakizumab in patients with psoriatic arthritis (PsA). METHODS: In this randomised, double-blind, placebo-controlled, phase IIb study, patients with active PsA were randomised 1:1:1:1:1 to tildrakizumab 200 mg every 4 weeks (Q4W); tildrakizumab 200, 100 or 20 mg Q12W; or placebo Q4W. Patients receiving tildrakizumab 20 mg or placebo switched to tildrakizumab 200 mg Q12W at W24; treatment continued to W52. The primary efficacy endpoint was proportion of patients with ACR20 response (≥20% improvement by American College of Rheumatology criteria) at W24. Secondary efficacy endpoints were assessed without adjustment for multiplicity. Safety was evaluated from treatment-emergent adverse events (TEAEs). RESULTS: 391/500 patients screened were randomised and treated. At W24, 71.4%-79.5% of tildrakizumab-treated versus 50.6% of placebo-treated patients achieved ACR20 (all p<0.01). Patients receiving tildrakizumab versus placebo generally achieved higher rates of ACR50, Disease Activity Score in 28 joints with C reactive protein <3.2, minimal disease activity and 75%/90%/100% improvement from baseline Psoriasis Area and Severity Index responses at W24 and through W52. Improvement in dactylitis and enthesitis was not observed; results were mixed for other outcomes. Responses in patients switched to tildrakizumab 200 mg at W24 were consistent with treatment from baseline. TEAEs and serious TEAEs occurred in 64.5% and 3.3%, respectively, of all patients through W52 and were comparable among treatment arms. CONCLUSIONS: Tildrakizumab treatment significantly improved joint and skin manifestations of PsA other than dactylitis and enthesitis. Treatment was generally well tolerated through W52. Clinicaltrials.gov NCT02980692.

The cutaneous and intestinal microbiome in psoriatic disease.

Psoriasis (PsO) and psoriatic arthritis (PsA) are chronic immune-mediated inflammatory diseases of multifactorial etiology. In addition to genetic and environmental factors, evidence supports involvement of a dysregulated human microbiome in the pathogenesis of psoriatic disease. In particular, alterations in the composition of the microbiome, termed dysbiosis, can result in downstream proinflammatory effects in the gut, skin, and joints. Both the cutaneous and intestinal microbial populations are implicated in the pathogenesis of psoriatic disease, although exact mechanisms are unclear. Herein, we review the relationship between the human microbiome and psoriatic disease. Further insight into the functions of the microbiome may allow for greater understanding of inflammatory disease processes and identification of additional therapeutic targets.

Updated therapies for the management of Psoriatic Arthritis.

Psoriatic arthritis (PsA) is a large volume of our clinical practice and its management can be challenging. Traditional DMARDs have been used over last six decades and observational studies have substantiated an effective use of many of these drugs. However, in last two decades use of anti-TNF agents has brought a new dimension in treatment of PsA and in many other autoimmune diseases. Regulatory role of the Th17 cells and its cytokines in the pathogenesis of PsA has successfully paved the foundations of anti-IL antibody based therapies in PsA. Newer therapies targeting the IL-23/IL-17 cytokines and its signaling proteins are now in development and bringing new promises for management of PsA. Herein, we provide an overview of the landscape of drug therapies, including IL-17, IL-12/23, IL-23 inhibitors, and janus kinase (JAK) inhibitors, as well as those in development, such as RORγt inhibitors, anti-NGF agents, mTOR inhibitors and T cell ion-channel blockers.

Incidence, Clinical Features, Management, and Prevention of Herpes Zoster in Patients Receiving Antitumor Necrosis Factor Therapy: A Clinical Review.

Tumor necrosis factor (TNF) inhibitors have been used as an excellent therapeutic option in a variety of chronic inflammatory conditions. However, a recognized significant adverse effect of TNF inhibitor therapy is the increased risk of infections. The influence of TNF inhibitors on the course of coexisting or newly developed viral infections has not been extensively investigated. Therefore, we reviewed the recent publications to highlight the incidence, clinical features, management, and prevention of herpes zoster in patients who are receiving TNF inhibitors.

Conditional KCa3.1-transgene induction in murine skin produces pruritic eczematous dermatitis with severe epidermal hyperplasia and hyperkeratosis.

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-ß1 (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-ß1 (-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.

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.

Risk of tuberculosis with anti-tumor necrosis factor-alpha therapy in patients with psoriasis and psoriatic arthritis in Indian population.

Anti-tumor necrosis factor-alpha (TNF-α) immunotherapy has revolutionized the treatment of inflammatory diseases, such as psoriasis and psoriatic arthritis. However, a major concern is that patients receiving this therapy have an increased risk of infection, particularly of reactivation of latent tuberculosis (TB). There were an estimated 10.4 million new cases of tuberculosis in 2016, worldwide, and India has one of the largest TB case burden with an estimated incidence of 2.79 million cases of TB in the same year. Anti-TNF agents like etanercept and infliximab are available in India approved for psoriasis and psoriatic arthritis. But long-term use of these agents possesses a risk of reactivation of latent TB. In this review article, we assessed the risk of TB with anti-TNF therapy especially in patients with psoriasis and psoriatic arthritis in India. At the end of the article, we have also suggested a recommendation for screening of latent tuberculosis and its management, before starting anti-TNF-α therapy.

Is It Possible to Discontinue Tumor Necrosis Factor Antagonists after Psoriasis Remission?

Tumor necrosis factor (TNF) antagonists are highly effective treatments for psoriasis. These agents provide the opportunity to improve disease activity and achieve clinical remission. Despite its efficacy, long-term use of biologics is associated with high financial costs and possibly life-threatening adverse events. Recently, there has been an increasing interest in discontinuing TNF antagonists in patients with psoriasis who have achieved a positive clinical response. However, there is a paucity of data and clinical guidelines concerning the cessation TNF antagonists in psoriasis treatment. Several factors, including cost, subsequent treatment efficacy, relative risks, and tolerability, should be considered before the decision is made to discontinue TNF antagonists. Well-designed clinical trials are necessary to identify factors that may trigger disease exacerbation after medication discontinuation in order to recognize the potential disadvantages of discontinuing treatment in patients who are previously successfully managed on TNF antagonists.

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.

Meta-analysis of RNA sequencing datasets reveals an association between TRAJ23, psoriasis, and IL-17A.

Numerous studies of relatively few patients have linked T cell receptor (TCR) genes to psoriasis but have yielded dramatically conflicting results. To resolve these discrepancies, we have chosen to mine RNA-Seq datasets for patterns of TCR gene segment usage in psoriasis. A meta-analysis of 3 existing and 1 unpublished datasets revealed a statistically significant link between the relative expression of TRAJ23 and psoriasis and the psoriasis-associated cytokine IL-17A. TRGV5, a TCR-γ segment, was also associated with psoriasis but correlated instead with IL-36A, other IL-36 family members, and IL-17C (not IL-17A). In contrast, TRAJ39 was strongly associated with healthy skin. T cell diversity measurements and analysis of CDR3 sequences were also conducted, revealing no psoriasis-associated public CDR3 sequences. Finally, in comparison with the expression of TCR-αß genes, the expression of TCR-γδ genes was relatively low but mildly elevated in psoriatic skin. These results have implications for the development of targeted therapies for psoriasis and other autoimmune diseases. Also, the techniques employed in this study have applications in other fields, such as cancer immunology and infectious disease.