Interferon-γ/CCR5 expression in invariant natural killer T cells and CCL5 expression in capillary veins of dermal papillae correlate with development of psoriasis vulgaris

Cytokines in psoriasis: From pathogenesis to targeted therapy

Psoriasis is a multifactorial disease that affects 0.84% of the global population and it can be associated with disabling comorbidities. As patients present with thick scaly lesions, psoriasis was long believed to be a disorder of keratinocytes. Psoriasis is now understood to be the outcome of the interaction between immunological and environmental factors in individuals with genetic predisposition. While it was initially thought to be solely mediated by cytokines of type-1 immunity, namely interferon-γ, interleukin-2, and interleukin-12 because it responds very well to cyclosporine, a reversible IL-2 inhibitor; the discovery of Th-17 cells advanced the understanding of the disease and helped the development of biological therapy. This article aims to provide a comprehensive review of the role of cytokines in psoriasis, highlighting areas of controversy and identifying the connection between cytokine imbalance and disease manifestations. It also presents the approved targeted treatments for psoriasis and those currently under investigation.

Advances in the modulation of ROS and transdermal administration for anti-psoriatic nanotherapies

Reactive oxygen species (ROS) at supraphysiological concentration have a determinate role in contributing to immuno-metabolic disorders in the epithelial immune microenvironment (EIME) of psoriatic lesions. With an exclusive focus on the gene-oxidative stress environment interaction in the EIME, a comprehensive strategy based on ROS-regulating nanomedicines is greatly anticipated to become the mainstay of anti-psoriasis treatment. This potential therapeutic modality could inhibit the acceleration of psoriasis via remodeling the redox equilibrium and reshaping the EIME. Herein, we present a marked overview of the current progress in the pathomechanisms of psoriasis, with particular concerns on the potential pathogenic role of ROS, which significantly dysregulates redox metabolism of keratinocytes (KCs) and skin-resident or -infiltrating cells. Meanwhile, the emergence of versatile nanomaterial-guided evolution for transdermal drug delivery has been attractive for the percutaneous administration of antipsoriatic therapies in recent years. We emphasize the underlying molecular mechanism of ROS-based nanoreactors for improved therapeutic outcomes against psoriasis and summarize up-to-date progress relating to the advantages and limitations of nanotherapeutic application for transdermal administration, as well as update an insight into potential future directions for nanotherapies in ROS-related skin diseases.

Diversity of T cells in the skin: Novel insights

T cells populate the skin to provide an effective immunosurveillance against external insults and to maintain tissue homeostasis. Most cutaneous T cells are αβ T cells, however, γδ T cells also exist although in much lower frequency. Different subsets of αβ T cells can be found in the skin, such as short-lived effector T cells, central memory T cells, effector memory T cells, and tissue-resident memory T cells. Their differential biology, function, and location provide an ample spectrum of immune responses in the skin. Foxp3+ memory regulatory T cells have a pivotal role in maintaining homeostasis in the skin and their dysregulation has been linked with different skin pathologies. The skin also contains populations of non-classical T cells, such as γδ T cells, NK T cells, and MR1-restricted T cells. Their role in skin homeostasis and response to pathogens has been well established in the past years, however, there is also growing evidence of their role in mediating allergic skin inflammation and promoting sensitization to allergens. In this review, we provide an updated overview on the different subsets of T cells that populate the skin with a specific focus on their role in allergic skin inflammation.

The role of Dipeptidyl Peptidase-4 in cutaneous disease

Dipeptidyl peptidase-4 (DPP4) is a multifunctional, transmembrane glycoprotein present on the cell surface of various tissues. It is present in multiple molecular forms including cell surface and soluble. The role of DPP4 and its inhibition in cutaneous dermatoses have been a recent point of investigation. DPP4 exerts a notable influence on T-cell biology, the induction of skin-specific lymphocytes, and the homeostasis between regulatory and effector T cells. Moreover, DPP4 interacts with a broad range of molecules, including adenosine deaminase, caveolin-1, CXCR4 receptor, M6P/insulin-like growth factor II-receptor and fibroblast activation protein-α, triggering downstream effects that modulate the immune response, cell adhesion and chemokine activity. DPP4 expression on melanocytes, keratinocytes and fibroblasts further alters cell function and, thus, has crucial implications in cutaneous pathology. As a result, DPP4 plays a significant role in bullous pemphigoid, T helper type 1-like reactions, cutaneous lymphoma, melanoma, wound healing and fibrotic disorders. This review illustrates the multifactorial role of DPP4 expression, regulation, and inhibition in cutaneous diseases.

T Cells in Autoimmunity-Associated Cardiovascular Diseases

T cells are indisputably critical mediators of atherosclerotic cardiovascular disease (CVD), where they secrete pro-inflammatory cytokines that promote vascular pathology. Equally well-established is the fact that autoimmune diseases, which are mediated by autoreactive T cells, substantially increase the risk of developing CVD. Indeed, as immunomodulatory treatments have become more effective at treating end-organ pathology, CVD has become a leading cause of death in patients with autoimmune diseases. Despite this, investigators have only recently begun to probe the mechanisms by which autoreactive T cells promote CVD in the context of autoimmune diseases. T cells are best-studied in the pathogenesis of systemic vasculitides, where they react to self-antigen in the vessel wall. However, newer studies indicate that T cells also contribute to the increased CVD risk associated with lupus and rheumatoid arthritis. Given the central role of T-cell-derived cytokines in the pathogenesis of psoriasis, the role of these factors in psoriatic CVD is also under investigation. In the future, T cells are likely to represent major targets for the prevention and treatment of CVD in patients with autoimmune diseases.

Age-related changes in the vasculature of the dermis of the upper lip vermilion

Lip redness is unique to humans and creates an important facial impression, but this redness decreases with age. Here, using histological and immunohistological staining of human upper lip vermilion from donors of different ages, we investigated blood vessels in the upper lip dermis and age-dependent histological changes. We found that both total vessel area in the dermis and vessel number in the upper dermis decreased with aging. Moreover, vessel number in the upper dermis correlated positively with development of rete ridges, which flattened with age, despite no significant change in the thickness of the stratified squamous epithelium. These findings suggest that age-related reductions in lip redness result from a decrease of blood vessels, which in turn leads to a flattening of the epithelium caused by the loss of rete ridges. This is the first study to histologically demonstrate age-related reductions in blood vessels in the lip. Our results provide an opportunity for enhancing blood flow/vascularization to improve the aesthetic appearance of the lips in the elderly.

Psoriatic arthritis under the influence of IFNγ

Psoriasis is a common multifactorial autoimmune disease of the skin, and in a large percentage of patients, immune responses involve nail and joint pathology, which develop psoriatic arthritis (PsA). Historically, T helper 1 (Th1)-derived-IFN-γ was abundantly detected in psoriatic skin and its correlation with development and severity of PsO, led to an early classification of psoriasis as a Th1-mediated disease. Investigations of the cellular and molecular mechanisms of PsO pathogenesis in recent years, together with impressive results of biologics against interleukin 17A (IL-17) have shifted focus on IL-17A. However, the contributions of IFN-γ in IL-17 induced pathology and its involvement in the development of PsA have been largely overshadowed. This review summarizes the current knowledge on IFN-γ and provides new insights on the contribution of IFN-γ to PsO and PsA disease pathogenesis and development.

Interleukin-33 alleviates psoriatic inflammation by suppressing the T helper type 17 immune response

Psoriasis is a chronic inflammatory skin disease with unclear pathogenesis. Interleukin-33 (IL-33) is highly expressed in patients with psoriasis, but its role in psoriasis is unknown. The aim of this study was to investigate the possible role of IL-33 in the pathogenesis and treatment of psoriasis. IL-33 expression was determined using enzyme-linked immunosorbent assay, real-time fluorescent quantitative polymerase chain reaction and immunohistochemical staining. CD4⁺ T cells were sorted using magnetic beads and treated with or without IL-33. Imiquimod (IMQ) was used to induce psoriatic inflammation in mice. The frequency of immune cells was determined using flow cytometry. The cytokine level in mouse skin was measured using cytometric bead array. Our results showed that IL-33 was highly expressed in the lesional skin and serum of patients with moderate-to-severe plaque psoriasis. IL-33 inhibited the expression of IL-17 in CD4⁺ T cells of psoriasis patients. Subcutaneous injection of IL-33 alleviated the IMQ-induced psoriatic inflammation in mice, reduced tumor necrosis factor-α and IL-23 expression, and decreased the proportion of T helper type 17 (Th17) cells in the skin-draining lymph nodes in the mice. Our results suggest that IL-33 plays a protective role in the pathogenesis of psoriasis by suppressing Th17 cell differentiation and function. The potential therapeutic effect of IL-33 in treating psoriasis warrants further investigation.

Evaluation of HCP5 and Chemokine C Receptor type 5 Gene Polymorphisms in Indian Psoriatic Patients

Background:

Genetic variations associated with nonprogression of HIV infection to AIDS are enriched in psoriasis patients. HCP5 gene 335 T > G and chemokine C receptor type 5 (CCR5) gene Δ32 polymorphisms are associated with HIV nonprogression phenotype.

Aim:

The aim of this study was to determine the association of HCP5 gene 335 T > G (rs2395029) and CCR5 gene Δ32 (rs333) polymorphisms with psoriasis vulgaris (PV).

Materials and Methods:

Genotype of HCP5 gene 335 T > G and CCR5 gene Δ32 polymorphisms were determined by polymerase chain reaction (PCR)-restriction fragment length polymorphism and allele-specific PCR methods, respectively.

Results:

The frequency of HCP5 gene 335 T > G SNP was ~7 times higher in PV patients than in the control group (P = 1.49 × 10^–8; odds ratio [OR] = 10.2; 0.95 confidence interval [CI]: 3.9–26.8). OR for the occurrence of HCP5 335 G allele in either homozygous or heterozygous genotype in PV patients was 13.1 (0.95 CI: 4.7–36.1). The strength of association was higher with moderate-to-severe subgroup (P = 3.29 × 10^–9; OR = 18.4; 0.95 CI: 6.2–54.9) than with mild subgroup (P = 2.1 × 10^–4; OR = 8.3; 0.95 CI: 2.6–23.3). In addition, the strength of association was higher with Type I (P = 9.53 × 10^–8; OR = 15.3; 0.95 CI: 5.1–46.5) than with Type II subgroup (P = 6.8 × 10^–6; OR = 11.0; 0.95 CI: 3.6–33.9). Type I gene Δ32 polymorphism was observed neither among psoriatic nor among healthy individuals.

Conclusions:

Our results indicate that HCP5 gene 335 T > G polymorphism and not CCR5 gene Δ32 polymorphism is associated with the increased risk of developing PV.

The association of genetic variants in chemokine genes with the risk of psoriasis vulgaris in Chinese population: A case-control study

This study aimed to investigate the influence of polymorphisms in chemokine genes, including MCP1, CCR2, and CCR5 with psoriasis vulgaris (PV) risk in a Chinese population.The genotyping of studied polymorphisms through polymerase chain reaction (PCR) and sequencing was conducted in 142 PV patients and 147 healthy controls. The genotype distribution of the polymorphisms in the control group was checked to determine whether it conformed to Hardy-Weinberg equilibrium (HWE). The genotype and allele frequencies were compared between PV patients and the healthy controls using Chi-square test. Odds ratio (OR) with 95% confidence interval (95% CI) was calculated to assess the relative risk of PV related to genetic variants.CCR2 rs1799864 polymorphism was associated with significantly elevated risk of PV (AA+AG vs GG: OR = 1.62, 95% CI = 1.02-2.59; A vs G: OR = 1.48, 95% CI = 1.02-2.16). In the meanwhile, CCR5 rs1800024 polymorphism also exhibited significant differences in genotype and allele distribution (P < .05), demonstrating its promoting effect on the risk of PV under heterozygous model (OR = 1.73, 95% CI = 1.06-2.82), dominance model (OR = 1.83, 95% CI = 1.14-2.94), and allele model (OR = 1.68, 95% CI = 1.13-2.48).CCR2 rs1799864 and CCR5 rs1800024 polymorphisms may function as independent risk factors for PV in Chinese population.

ACKR2: Nature's Decoy Receptor Lures Unsuspecting Chemokines in Psoriasis

While we know much about the processes mediated by the Th17 inflammatory pathway that is crucial in psoriasis, we actually know little about the processes by which most psoriatic patients maintain what grossly looks like non-inflamed, normal skin in the face of massive inflammatory changes in nearby affected skin. Other molecular regulators that defend the skin from global inflammation are likely to be involved, including molecules such as ACKR2, an atypical chemokine receptor whose role in psoriasiform dermatitis is explored by Shams et al.

STAT5A Modulates Chemokine Receptor CCR6 Expression and Enhances Pre-B Cell Growth in a CCL20-Dependent Manner

Signal transducer and activator of transcription 5A (STAT5A) contributes to B-cell responses to cytokines through suppressor of cytokine signaling (Socs) genes in innate immunity. However, its direct roles in B-cell responses to chemokines are poorly understood. In this study, we examined the role of STAT5A in the innate immune response. We found that STAT5A upregulated the transcription of C-C motif receptor 6 (Ccr6) to induce responses to its ligand, CCL20. STAT5A transcriptional activity proceeded through binding to the interferon-γ activation site (GAS) element in the CCR6 promoter in the genome of pre-B cells. High levels of STAT5A and CCR6 increased CCL20-dependent colony growth of pre-B cells. In human B-lymphoblastic lymphoma with inflammation, STAT5A phosphorylation was correlated with CCR6 expression (P > 0.05 compared with that in cases without inflammation). In conclusion, our data supported our hypothesis that STAT5A enhanced the response of pre-B cells to CCL20 to promote their growth.   J. Cell. Biochem. 117: 2630-2642, 2016. © 2016 Wiley Periodicals, Inc.

A role for CCR5(+)CD4 T cells in cutaneous psoriasis and for CD103(+) CCR4(+) CD8 Teff cells in the associated systemic inflammation

Recent results have identified critical components of the T cell response involved in the initiation and amplification phases of psoriasis. However the link between T cell responses arising in the skin and the systemic inflammation associated with severe psoriasis is largely unknown. We hypothesized that specific subsets of memory T cells recirculating from the skin could play a role. We therefore dissected the circulating memory T cell compartment in patients by analyzing the TCM, TEM and Teff phenotype, the pattern of CCR4 and CCR5 chemokine receptor expression and the expression of the tissue homing molecule CD103. For each subset we calculated the correlation with the Psoriasis Area and Severity Index (PASI) and with the extent of systemic inflammation measured as serum level of the prototypic short pentraxin, C reactive protein (CRP). Validation was performed by comparison with gene expression data in psoriatic plaques. We found that circulating CD103(+)CCR4(+)CCR5(+) and CCR4(+)CCR6(-) CD8(+) Teff cells, were highly correlated with CRP levels as well as with the validated index PASI, reflecting a link between skin involvement and systemic inflammation in patients with severe psoriasis. In addition we observed a contraction of circulating CCR5(+) T cells in psoriasis patients, with a highly significant inverse correlation between CCR5(+)CD4 T cells and the PASI score. Increased expression of CCR5 and CCL5 genes in psoriatic skin lesions was consistent with an accumulation of CCR5(+) cells in psoriatic plaques indicating a role for CCR5/CCL5 axis in disease pathogenesis.

Using Imiquimod-Induced Psoriasis-Like Skin as a Model to Measure the Skin Penetration of Anti-Psoriatic Drugs

Objective

Psoriasis is a chronic inflammatory skin disease and topical therapy remains a key role for treatment. The aim of this study is to evaluate the influence of psoriasis-like lesions on the cutaneous permeation of anti-psoriatic drugs.

Methods

We first set up imiquimod-induced dermatitis in mice that closely resembles human psoriasis lesions. The development of the lesions is based on the IL-23/IL17A axis for phenotypical and histological characteristics. Four drugs, 5-aminolevulinic acid (ALA), tacrolimus, calcipotriol, and retinoic acid, were used to evaluate percutaneous absorption.

Results

The most hydrophilic molecule, ALA, revealed the greatest enhancement on skin absorption after imiquimod treatment. Imiquimod increased the skin deposition and flux of ALA by 5.6 to 14.4-fold, respectively, compared to normal skin. The follicular accumulation of ALA was also increased 3.8-fold. The extremely lipophilic drug retinoic acid showed a 1.7- and 3.8-fold increase in skin deposition and flux, respectively. Tacrolimus flux was enhanced from 2 to 21 μg/cm²/h by imiquimod intervention. However, imiquimod did not promote skin deposition of this macrolide. The lipophilicity, but not the molecular size, dominated drug permeation enhancement by psoriatic lesions. The in vivo percutaneous absorption of ALA and rhodamine B examined by confocal microscopy confirmed the deficient resistance of epidermal barrier for facilitating cutaneous delivery of drugs via psoriasis-like skin.

Conclusion

We established the topical delivery profiles of anti-psoriatic drugs via imiquimod-treated psoriasis-like skin.