Allopurinol suppresses expression of the regulatory T-cell migration factors TARC/CCL17 and MDC/CCL22 in HaCaT keratinocytes via restriction of nuclear factor-κB activation

Effect of Skin Barrier on Atopic Dermatitis

The skin acts as the body's primary physical and immune barrier, maintaining the skin microbiome and providing a physical, chemical, and immune barrier. A disrupted skin barrier plays a critical role in the onset and advancement of inflammatory skin conditions such as atopic dermatitis (AD) and contact dermatitis. This narrative review outlines the relationship between AD and skin barrier function in preparation for the search for possible markers for the treatment of AD.

A systematic review of case-control studies of cytokines in blister fluid and skin tissue of patients with Stevens Johnson syndrome and toxic epidermal necrolysis

Stevens Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are severe cutaneous adverse reactions characterised by keratinocyte apoptosis, necroptosis and epidermal detachment. Several cytokines and cytotoxic proteins have been shown to be elevated in the blood and skin of SJS/TEN sufferers and biologics such as intravenous immune globulin and tumour necrosis factor (TNF)-alpha inhibitors have demonstrated good therapeutic potential. The exact pathogenic model of SJS/TEN however remains elusive. This systematic review aimed to evaluate the case-control studies of cytokines and cytotoxic proteins in the blister fluid and skin of adults with Stevens Johnson syndrome and/or toxic epidermal necrolysis. This review was registered with INPLASY and conducted in accordance with the PRISMA reporting guidelines. Potential bias was assessed using the NIH criteria. Eleven articles describing results from 96 cases and 170 controls were included. Fas, Fas ligand, Interleukin (IL)-8 and B-cell lymphoma (Bcl)-2 were elevated in SJS/TEN blister fluid and skin tissue, compared with healthy controls. IL-2, IL-6, TNF-alpha, tumour necrosis factor-related apoptosis-inducing ligand (TRAIL), interferon-gamma and matrix metalloproteinase-2 were elevated in SJS/TEN blister fluid compared with fluid sampled from lesional controls. Granulysin, IL-33, TGF-beta-1 and IL-13 were elevated in SJS/TEN skin tissue compared with lesional lichen planus tissue, as was IL-13, IFN-gamma, IL-2 and IL-5, when compared with erythema multiforme tissue. A wide array of cytokines and cytotoxic proteins are present at higher concentrations in the blister fluid and skin tissue of SJS/TEN patients compared with healthy and lesional controls. Our findings suggest that these proteins may be pathogenic, as well as possibly markers for diagnosis, disease severity and course. They may also prove to be useful therapeutic targets. More research is needed.

Pathological changes in various organs in HLA-B*57:01 transgenic mice with abacavir-induced skin eruption

Several patients with cutaneous adverse drug reactions exhibit extracutaneous organ damages, and it becomes severe in a few patients resulting in death due to multiorgan failure. Understanding the sequential changes in various organs in patients with cutaneous eruption following drug administration will help understand disease onset and progression, aiding the development of prevention strategies and interventions. Therefore, we aimed to understand the effects of abacavir (ABC) on various organs in patients with ABC-induced eruptions by evaluating its effects in a mouse model. We found pathological changes in various organs of HLA-B*57:01 transgenic mice (B*57:01-Tg) following oral administration of ABC (20 mg/body/day). B*57:01-Tg exhibited a significant body weight decrease from day 1 of ABC administration, and reddening of the auricle was observed from day 5, and approximately 2/3 mice died by day 7. Histopathological examination revealed severe thymic atrophy after day 3, infiltration of inflammatory cells, predominantly lymphocytes with neutrophils, not only in the skin but also in the liver, kidney, and lung after day 5, and an increased number of lymphocytes with enlarged nuclei and granulocytic hematopoiesis were observed in the spleen after day 5. Blood chemistry revealed that albumin/globulin ratio was below 1.0 on day 5, reflecting a systemic inflammatory response, and the aspartate aminotransferase concentration rose to 193 ± 93.0 U/L on day 7, suggesting that cell damage may have occurred in various organs including liver accompanying inflammatory cell infiltration. These examinations of a mouse model of ABC-induced skin eruption show that disorders in various organs other than the skin should be considered and provide insights into the unexpected early systemic responses dependent on HLA-B*57:01.

Supplementary Information

The online version contains supplementary material available at 10.1007/s43188-023-00220-1.

Unraveling the gut-skin axis in atopic dermatitis: exploiting insights for therapeutic strategies

Gut microbiota exert functions of high importance in the intestine. Furthermore, there is increasing evidence for its role in immune regulation and maintenance of homeostasis in many physiological processes taking place in distant tissues. In particular, in this review, we explore the impact of metabolites produced by the gut microbiota on the development of atopic dermatitis (AD). Probiotics and prebiotics balance the microbiota and promote the generation of bacterial metabolites, such as short-chain fatty acids and tryptophan derivates, which promote the regulation of the exacerbated AD immune response through regulatory T cells and IL-10 and TGF-β cytokines. Metabolites also have a direct action on keratinocytes once they reach the bloodstream. Besides, probiotics decrease the levels of metabolites associated with AD onset, such as phenols. Understanding all these crosstalk processes between the gut and the skin reveals a number of possibilities, mainly through the manipulation of the gut microbiome, which may represent therapeutic strategies that can contribute to the standard treatments of AD patients to improve their quality of life.

Regulatory T Cells Exhibit Interleukin-33-Dependent Migratory Behavior during Skin Barrier Disruption

Regulatory T cells (Tregs) suppress immune responses and maintain immunological self-tolerance and homeostasis. We currently investigated relationships between skin barrier condition and Treg behavior using skin barrier-disrupted mice. Skin barrier disruption was induced by repeated topical application of 4% sodium dodecyl sulfate (SDS) on mice. The number of CD4⁺ forkhead box protein P3 (Foxp3)⁺ Tregs was higher in 4% SDS-treated skins than in controls. This increasing was correlated with the degree of acanthosis. The numbers of interleukin (IL)-10⁺ and transforming growth factor (TGF)-β⁺ Tregs also increased in 4% SDS-treated skins. Localization of IL-33 in keratinocytes shifted from nucleus to cytoplasm after skin barrier disruption. Notably, IL-33 promoted the migration of Tregs in chemotaxis assay. The skin infiltration of Tregs was cancelled in IL-33 neutralizing antibody-treated mice and IL-33 knockout mice. Thus, keratinocyte-derived IL-33 may induce Treg migration into barrier-disrupted skin to control the phase transition between healthy and inflammatory conditions.

What does elevated TARC/CCL17 expression tell us about eosinophilic disorders?

Eosinophilic disorders encompass a large spectrum of heterogeneous diseases sharing the presence of elevated numbers of eosinophils in blood and/or tissues. Among these disorders, the role of eosinophils can vary widely, ranging from a modest participation in the disease process to the predominant perpetrator of tissue damage. In many cases, eosinophilic expansion is polyclonal, driven by enhanced production of interleukin-5, mainly by type 2 helper cells (Th2 cells) with a possible contribution of type 2 innate lymphoid cells (ILC2s). Among the key steps implicated in the establishment of type 2 immune responses, leukocyte recruitment toward inflamed tissues is particularly relevant. Herein, the contribution of the chemo-attractant molecule thymus and activation-regulated chemokine (TARC/CCL17) to type 2 immunity will be reviewed. The clinical relevance of this chemokine and its target, C-C chemokine receptor 4 (CCR4), will be illustrated in the setting of various eosinophilic disorders. Special emphasis will be put on the potential diagnostic, prognostic, and therapeutic implications related to activation of the TARC/CCL17-CCR4 axis.

Current Pharmacogenetic Perspective on Stevens-Johnson Syndrome and Toxic Epidermal Necrolysis

Adverse drug reactions are a public health issue that draws widespread attention, especially for Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) which have high mortality and lack of efficacious treatment. Though T-cell-mediated HLA-interacted immune response has been extensively studied, our understanding of the mechanism is far from satisfactory. This review summarizes infection (virus, bacterial, and mycoplasma infection), an environmental risk factor, as a trigger for SJS/TEN. The mutations or polymorphisms of drug metabolic enzymes, transporters, receptors, the immune system genes, and T-cell-mediated apoptosis signaling pathways that contribute to SJS/TEN are discussed and summarized. Epigenetics, metabolites, and mobilization of regulatory T cells and tolerogenic myeloid precursors are emerged directions to study SJS/TEN. Ex vivo lymphocyte transformation test has been exploited to aid in identifying the causative drugs. Critical questions on the pathogenesis of SJS/TEN underlying gene polymorphisms and T cell cytotoxicity remain: why some of the patients carrying the risky genes tolerate the drug and do not develop SJS/TEN? What makes the skin and mucous membrane so special to be targeted? Do they relate to skin/mucous expression of transporters? What is the common machinery underlying different HLA-B alleles associated with SJS/TEN and common metabolites?

Cytokines/Chemokines: Novel Biomarkers Associated with Severe Cutaneous Adverse Reactions

Although the incidence of severe cutaneous adverse reactions (SCARs) is very low, if it is not diagnosed and treated in time, it can not only cause skin and mucous membrane involvement, but can also cause multiple organ failure and even death. The diagnostic criteria and treatment guidelines for severe drug eruptions have not been unified. Many medical centers have used human leukocyte antigen alleles to diagnose SCARs. Some prospective studies have shown that susceptibility gene testing can prevent SCARs as early as possible, but the widespread implementation of its technology is limited by being ethnically specific. With the unique advantages of cytokine detection technology, cytokines are increasingly important for the diagnosis and treatment of SCARs. Related cytokines/chemokines involved in the pathogenesis, adjuvant diagnosis, and treatment of SCARs are discussed.

Macrophage-derived CCL22 promotes an immunosuppressive tumor microenvironment via IL-8 in malignant pleural effusion

Immune dysfunction often occurs in malignant pleural effusion (MPE). In our previous study, TGF-β derived predominantly from macrophages plays an important role in impairing T cell cytotoxicity in MPE. Therefore, we aimed to investigate whether other immunoregulatory cells and factors mediated TGF-β secretion from macrophages, involved in the immunosuppressive microenvironment of MPE, and to provide clues for potential immune therapy for MPE as well. We found that CCL22 level in MPE was significantly higher than that in non-malignant pleural effusion. The high level of CCL22 was closely associated with poor survival in MPE patients with lung cancer. CCL22 was dominantly produced by tumor-associated macrophages (TAMs) in MPE. Meanwhile, TAM-derived TGF-β mediated CCL22 expression in TAMs via c-Fos. CCL22 promoted the recruitment of regulatory T cells (Tregs) in MPE. Lastly, Treg-secreted high level of IL-8 further induced TGF-β production from TAMs, and promoted the immunosuppressive tumor microenvironment in MPE. Our results indicate that macrophage-derived CCL22 plays an important role in the immunosuppressive tumor microenvironment via IL-8 in MPE.

Biologic TNF-alpha inhibitors in the treatment of Stevens-Johnson syndrome and toxic epidermal necrolysis: a systemic review

Background: Stevens-Johnson syndrome and toxic epidermal necrolysis (SJS-TEN) is one of severe cutaneous adverse reactions with low morbidity but high mortality. Different systemic immunomodulating treatments are proposed but still remain controversial. Tumor necrosis factor (TNF)-alpha is long thought to be a vital mediator of epithelial cell death in SJS-TEN, indicating a potential target for therapy.Objective: The aim of this systemic review is to evaluate the efficacy and safety of biologic TNF-alpha inhibitors in the treatment of SJS-TEN.Methods: We reviewed the published literature by searching from PubMed, EMBASE, Web of Science and ClinicalTrial.gov. A total of 27 articles fulfilling our inclusion criteria were found and analyzed.Results: There were 21 case reports, four case series and two randomized controlled trials (RCTs) on the biologic TNF-alpha inhibitors for SJS-TEN therapy, comprising 91 patients. TNF-alpha inhibitors were used as monotherapy, second-line therapy or combination therapy. Among them, 79 patients (86.8%) responded well and discharged with few side effects and complications.Conclusions: Biologic TNF-alpha inhibitors are a safe and effective treatment for SJS-TEN. But further, larger RCTs need to be conducted to provide more evidence for clinical application.

Impact of HIV-ART on the restoration of Th17 and Treg cells in blood and female genital mucosa

The aim of this study was to evaluate the effectiveness of antiretroviral treatment (ART) on the proportion and functions of Th17 and Treg cells in peripheral blood and female genital tract (FGT) respectively. To this aim, samples from 41 HIV-neg, 33 HIV+ ART-naïve and 32 HIV+ ART+ subjects were obtained. In peripheral blood, altered Th17 and Th17/Treg proportions were normalized in HIV+ ART+, but certain abnormal Treg and activated T-cell proportions were still observed. In FGT, abnormal patterns of secretion for Th17-related cytokines were observed in cervical mononuclear cells (CMCs) from HIV+ women, even in those from HIV+ ART+, compared to the HIV-neg group. Moreover, these altered patterns of secretion were associated with diminished levels of CXCL5 and CXCL1 chemokines and with an immunoregulatory skew in the CCL17/CCL20 ratio in ectocervix samples of these women. Finally, ART did not restore proportions of Th17-precursor cells with gut-homing potential in PBMCs, and positive correlations between these cells and the levels of IL-17F and IL-21 production by CMCs may suggest that a better homing of these cells to the intestine could also imply a better restoration of these cells in the female genital tract. These results indicate that antiretroviral treatment did not restore Th17-related immune functions completely at the female mucosal level.

Dehydroxymethylepoxyquinomicin suppresses atopic dermatitis-like lesions in a stratum corneum-removed murine model through NF-κB inhibition

Background: Dehydroxymethylepoxyquinomicin (DHMEQ) is a specific and potent inhibitor of nuclear factor-kappa B (NF-κB) and has been shown to possess promising potential as an anti-inflammation including anti-atopic dermatitis (AD)-like skin lesions. Objective: To further evaluate the activity of DHMEQ in vivo modified AD-like lesion model in BALB/c mice and in vitro AD-like lesion cell model in human keratinocytes. Materials and methods: In this study, in vivo modified AD-like lesion model in BALB/c mice was chronically induced by the repetitive and alternative application of 2,4-dinitrochlorobenzene (DNCB) and oxazolone (OX) on ears, and stratum corneum of the ear skin was additionally stripped off with surgical tapes before each challenge with DNCB/OX. Moreover, in vitro AD-like lesion cell model in human keratinocytes (HaCaT) achieved by stimulating HaCaT cells with tumor necrosis factor (TNF)-α plus interferon (IFN)-γ was used to investigate mechanisms of the action. Results: The lesions derived from the stratum corneum-removed AD-like lesion model reaches to peak as well as DHMEQ arrives to its efficacy a week earlier than the data previously obtained from the common AD-like lesion model. Results showed that the drug reduced the ear thickness, epidermal thickness, mast cell infiltration, and gene expressions of interleukin (IL)-4, IL-13, and interferon (IFN)-γ in ear tissues. It significantly inhibited the expression of cytokines IL-6 and IL-1β, chemokines thymus and activation-regulated chemokine (TARC)/CCL17, and macrophage-derived chemokine (MDC)/CCL22 in the stimulated HaCaT cells. Discussion and conclusion: This study indicated that the action of DHMEQ's anti-AD like lesions might be related to its inhibition on NF-κB.

Comparison of the Inhibitory Activities of 5,6-Dihydroergosterol Glycoside α- and β-Anomers on Skin Inflammation

Chronic skin inflammatory diseases, such as atopic dermatitis, are associated with a dysfunctional skin barrier due to an increase in various inflammatory stimuli, for instance inflammatory cytokines and chemokines. In particular, CCL17 and CCL22 expression is increased in patients with chronic skin inflammation. In this study, we synthesized several α- and β-anomers of dihydroergosterol (DHE)-glycosides and assessed their effects on CCL17 and CCL22 expression. We confirmed that the β-anomers of DHE-glycosides were superior to α-anomers of DHE-glycosides in inhibiting CCL17 and CCL22 mRNA and protein expression. In addition, we determined that DHE-glycoside β-anomers showed strong inhibitory activity towards pro-inflammatory cytokine mRNA and protein expression, including that of TNF-α, IL-6, and IL-1β- in stimulated HaCaT cells. These results imply that DHE-glycoside α- and β-anomers should be separated during synthesis of drugs for chronic skin inflammation. Our results also suggest that β-anomers of DHE-glycosides may play an important role as new drugs for chronic skin inflammation because of their ability to inhibit the skin inflammatory biomarker proteins CCL17 and CCL22.