The Role of T Helper 22 Cells in Dermatological Disorders

IL-22, a vital cytokine in autoimmune diseases

Interleukin-22 (IL-22) is a vital cytokine that is dysregulated in various autoimmune conditions including rheumatoid arthritis (RA), multiple sclerosis (MS), and Alzheimer's disease (AD). As the starting point for the activation of numerous signaling pathways, IL-22 plays an important role in the initiation and development of autoimmune diseases. Specifically, imbalances in IL-22 signaling can interfere with other signaling pathways, causing cross-regulation of target genes which ultimately leads to the development of immune disorders. This review delineates the various connections between the IL-22 signaling pathway and autoimmune disease, focusing on the latest understanding of the cellular sources of IL-22 and its effects on various cell types. We further explore progress with pharmacological interventions related to targeting IL-22, describing how such therapeutic strategies promise to usher in a new era in the treatment of autoimmune disease.

Emerging Biologic Therapies for the Treatment of Atopic Dermatitis

Atopic dermatitis (AD) is a prevalent inflammatory skin disease having a significant impact on patients' quality of life. Conventional treatments, including topical therapies and systemic immunosuppressants, often have limited efficacy and long-term safety concerns. Emerging biologic therapies target specific immune pathways implicated in AD pathogenesis, offering new therapeutic options in a disease known for its complex immune pathomechanisms. This review focuses on novel biologics under investigation, particularly those targeting specific immune pathways such as interleukin-4 (IL-4), IL-13, IL-22, IL-31, thymic stromal lymphopoietin (TSLP), and OX40-OX40L axis. Interleukin-4 and IL-13 inhibitors aim to reduce Th2-driven inflammation, while IL-22 inhibitors focus on restoring skin barrier function. Interleukin-31 inhibitors help alleviate pruritus, a major symptom in AD. OX40-OX40L pathway inhibitors can selectively suppress the activity of pathogenic T cells, without inducing significant immunosuppression. Bispecific antibodies targeting both IL-4 and IL-31 pathways are emerging as potential dual-action treatment for AD. Thymic stromal lymphopoietin inhibitors offer a novel strategy to control inflammation. While many of these therapies offer promising safety and efficacy profiles, long-term studies and real-world data are essential to confirm their lasting impact. This review highlights the potential of these emerging systemic therapies to continue transforming AD management and improve patient outcomes.

The role of OX40 ligand/OX40 axis signalling in atopic dermatitis

Atopic dermatitis (AD) is a heterogeneous inflammatory condition involving multiple immune pathways mediated by pathogenic T cells. OX40 ligand (OX40L) and OX40 are costimulatory immune checkpoint molecules that regulate effector and memory T-cell activity and promote sustained immune responses in multiple immunological pathways, including T helper (Th)2, Th1, Th17 and Th22. As such, OX40L/OX40 signalling between antigen-presenting cells (APCs) and activated T cells postantigen recognition promotes pathogenic T-cell proliferation and survival. Under inflammatory conditions, OX40L is upregulated on APCs, enhancing the magnitude of antigen-specific T-cell responses and secretion of proinflammatory cytokines. In AD, OX40L/OX40 signalling contributes to the amplification and chronic persistence of T-cell-mediated inflammation. Recent therapeutic success in clinical trials has highlighted the importance of the OX40L/OX40 axis as a promising target for the treatment of AD. Here, we discuss the many factors that are involved in the expression of OX40L and OX40, including the cytokine milieu, antigen presentation, the inflammatory environment in AD, and the therapeutic direction influenced by this costimulatory pathway.

T-cell immune profile in blood of systemic mastocytosis: Association with disease features

BACKGROUND

Systemic mastocytosis (SM) is a heterogeneous disease characterized by an expansion of KIT-mutated mast cells (MC). KIT-mutated MC display activated features and release MC mediators that might act on the tumour microenvironment and other immune cells. Here, we investigated the distribution of lymphocyte subsets in blood of patients with distinct subtypes of SM and determined its association with other disease features.

METHODS

We studied the distribution of TCD4+ and TCD4- cytotoxic cells and their subsets, as well as total NK- and B cells, in blood of 115 SM patients-38 bone marrow mastocytosis (BMM), 67 indolent SM (ISM), 10 aggressive SM (ASM)- and 83 age-matched healthy donors (HD), using spectral flow cytometry and the EuroFlow Immunomonitoring panel, and correlated it with multilineage KITD816V, the alpha-tryptasemia genotype (HαT) and the clinical manifestations of the disease.

RESULTS

SM patients showed decreased counts (vs. HD) of TCD4- cytotoxic cells, NK cells and several functional subsets of TCD4+ cells (total Th1, Th2-effector memory, Th22-terminal effector and Th1-like Tregs), together with increased T-follicular-helper and Th1/Th17-like Treg counts, associated with different immune profiles per diagnostic subtype of SM, in multilineal versus MC-restricted KITD816V and in cases with a HαT+ versus HαT- genotype. Unique immune profiles were found among BMM and ISM patients with MC-restricted KITD816V who displayed HαT, anaphylaxis, hymenoptera venom allergy, bone disease, pruritus, flushing and GI symptoms.

CONCLUSION

Our results reveal altered T- and NK-cell immune profiles in blood of SM, which vary per disease subtype, the pattern of involvement of haematopoiesis by KITD816V, the HαT genotype and specific clinical manifestations of the disease.

The role of Interleukin-22 in severe acute pancreatitis

Severe acute pancreatitis (SAP) begins with premature activation of enzymes, promoted by the immune system, triggering a potential systemic inflammatory response that leads to organ failure with increased mortality and a bleak prognosis. Interleukin-22 (IL-22) is a cytokine that may have a significant role in SAP. IL-22, a member of the IL-10 cytokine family, has garnered growing interest owing to its potential tissue-protective properties. Recently, emerging research has revealed its specific effects on pancreatic diseases, particularly SAP. This paper provides a review of the latest knowledge on the role of IL-22 and its viability as a therapeutic target in SAP.

Effect of abrocitinib on skin biomarkers in patients with moderate-to-severe atopic dermatitis

BACKGROUND

This is the first report on the effects of abrocitinib, a Janus kinase 1-selective inhibitor, on the expression of skin biomarkers in patients with moderate-to-severe atopic dermatitis (AD).

METHODS

JADE MOA (NCT03915496) was a double-blind Phase 2a trial. Adults were randomly assigned 1:1:1 to receive monotherapy with once-daily abrocitinib 200 mg, abrocitinib 100 mg, or placebo for 12 weeks. The primary endpoint was change from baseline in markers of inflammation (matrix metalloproteinase [MMP]-12), epidermal hyperplasia (keratin-16 [KRT16]), T-helper 2 (Th2) immune response (C-C motif chemokine ligand [CCL]17, CCL18, and CCL26), and Th22 immune response (S100 calcium binding protein A8, A9, and A12 [S100A8, S100A9, and S100A12]) in skin through 12 weeks.

RESULTS

A total of 46 patients received abrocitinib 200 mg (n = 14), abrocitinib 100 mg (n = 16), or placebo (n = 16). Abrocitinib improved AD clinical signs and reduced itch. Gene expression of MMP-12, KRT16, S100A8, S100A9, and S100A12 was significantly decreased from baseline with abrocitinib 200 mg (at Weeks 2, 4, and 12) and abrocitinib 100 mg (at Weeks 4 and 12) in a dose-dependent manner. Abrocitinib 200 mg resulted in significant decreases from baseline in CCL17 expression at Week 12 and CCL18 expression at Weeks 2, 4, and 12; no significant decreases were observed for CCL26.

CONCLUSIONS

Alongside improvements in clinical signs and symptoms of AD, 12 weeks of abrocitinib treatment resulted in downregulation of genes associated with inflammation, epidermal hyperplasia, and Th2 and Th22 immune responses in the skin of patients with moderate-to-severe AD.

Th22 is the effector cell of thymosin β15-induced hair regeneration in mice

BACKGROUND

Thymosin beta family has a significant role in promoting hair regeneration, but which type of T cells play a key role in this process has not been deeply studied. This research aimed to find out the subtypes of T cell that play key role in hair regeneration mediated by thymosin beta 15 (Tβ15).

METHODS

Ready-to-use adenovirus expressing mouse Tmsb15b (thymosin beta 15 overexpression, Tβ15 OX) and lentivirus-Tβ15 short hairpin RNA (Tβ15 sh) were used to evaluate the role of Tβ15 in hair regeneration and development. The effect of Th22 cells on hair regeneration was further studied by optimized Th22-skewing condition medium and IL-22 binding protein (IL-22BP, an endogenous antagonist of IL-22, also known as IL-22RA2) in both ex vivo culture C57BL/6J mouse skin and BALB/c nude mice transplanted with thymus organoid model.

RESULTS

The results show that Tβ15, the homologous of Tβ4, can promote hair regeneration by increasing the proliferation activity of hair follicle cells. In addition, high-level expression of Tβ15 can not only increase the number of Th22 cells around hair follicles but also accelerate the transformation of hair follicles to maturity. Consistent with the expected results, when the IL-22BP inhibitor was used to interfere with Th22, the process of hair regeneration was blocked.

CONCLUSIONS

In conclusion, Th22 is the key effector cell of Tβ15 inducing hair regeneration. Both Tβ15 and Th22 may be the potential drug targets for hair regeneration.

Cellular Mechanisms of Psoriasis Pathogenesis: A Systemic Review

Psoriasis is a common inflammatory skin disease characterized by abnormal proliferation of epidermal keratinocytes and massive infiltration of inflammatory cells. Many kinds of cells, including keratinocytes, T lymphocytes, dendritic cells, neutrophils, and macrophages, are reported to play critical roles in the pathogenesis and progression of psoriasis. However, to date, the role of each kind of cell in the pathogenesis and development of psoriasis has not been systematically reviewed. In addition, although antibodies developed targeting cytokines (e.g. IL-23, IL-17A, and TNF-α) released by these cells have shown promising results in the treatment of psoriasis patients, these targeted antibodies still do not cure psoriasis and only provide short-term relief of symptoms. Furthermore, long-term use of these antibodies has been reported to have adverse physical and psychological effects on psoriasis patients. Therefore, gaining a deeper understanding of the cellular and molecular pathogenesis of psoriasis and providing new thoughts on the development of psoriasis therapeutic drugs is of great necessity. In this review, we summarize the roles of various cells involved in psoriasis, aiming to provide new insights into the pathogenesis and development of psoriasis at the cellular level and hoping to provide new ideas for exploring new and effective psoriasis treatments.

IL-22 as a target for therapeutic intervention: Current knowledge on its role in various diseases

IL-22 has emerged as a crucial cytokine mediating protective response against pathogens and tissue regeneration. Dysregulated production of IL-22 has been shown to play a pivotal role in the pathogenesis of various diseases like malignant tumours, viral, cardiovascular, allergic and autoimmune disorders. Interleukin 22 belongs to IFN-IL-10 cytokine family. It is a major proinflammatory cytokine secreted by activated Th1 cells (Th22), though can also be secreted by many other immune cells like group 3 innate lymphocytes, γδ T cells, NK cells, NK T cells, and mucosal associated invariant T cells. Th22 cells exclusively release IL-22 but not IL-17 or IFN-γ (as Th1 cells releases IFN-γ along with IL-22 and Th17 cells releases IL-17 along with IL-22) and also express aryl hydrocarbon receptor as the key transcription factor. Th22 cells also exhibit expression of chemokine receptor CCR6 and skin-homing receptors CCR4 and CCR10 indicating the involvement of this subset in bolstering epithelial barrier immunity and promoting secretion of antimicrobial peptides (AMPs) from intestinal epithelial cells. The function of IL-22 is modulated by IL-22 binding protein (binds to IL-22 and inhibits it binding to its cell surface receptor); which serves as a competitor for IL-22R1 chain of IL-22 receptor. The pathogenic and protective nature of the Th22 cells is modulated both by the site of infected tissue and the type of disease pathology. This review aims to discuss key features of IL-22 biology, comparisons between IL and 22 and IFN-γ and its role as a potential immune therapy target in different maladies.