HIV-Associated Immune Dysregulation in the Skin: A Crucible for Exaggerated Inflammation and Hypersensitivity

HIV-Associated Dermatological Alterations: Barrier Dysfunction, Immune Impairment, and Microbiome Changes

Human Immunodeficiency Virus (HIV) significantly impacts skin structure, immune responses, and the microbiome, contributing to diverse dermatological conditions. The epidermis, a key physical and immunological barrier, undergoes structural changes such as hyperplasia and inflammatory infiltrates. Skin adnexal structures like hair follicles also play a role in immune modulation but are affected by HIV-related disruptions. Innate and adaptive immune systems are compromised due to CD4+ T-cell depletion, cytokine imbalances, and altered immune regulation, leading to conditions such as hypersensitivity and inflammatory dermatoses. The skin microbiome in HIV patients shows distinct shifts, including reduced Cutibacterium species and increased opportunistic microbes, independent of CD4+ levels. Age, sex, and environmental stressors exacerbate these changes, with women exhibiting stronger immune responses but higher risks of autoimmune diseases and aging men experiencing accelerated immunosenescence. Understanding these interconnected alterations is essential for developing targeted therapies to manage skin complications and improve the overall health of HIV patients.

Seborrheic Dermatitis: Exploring the Complex Interplay with Malassezia

Seborrheic dermatitis (SD) is a chronic inflammatory skin condition often involving the sebaceous-rich areas, characterized by erythematous scaly lesions. It is frequently observed in individuals with immune dysregulation, suggesting the interplay between the immune system and disease development. An altered immune environment leads to an exaggerated inflammatory response with the activation of innate immunity, involving the participation of mast cells, γδ T cells, and the NOD-LRR-pyrin-domain-containing protein 3 (NLRP3) inflammasome. This review aims to assess the complex relationship between Malassezia and the immune system in the pathogenesis of SD. We will explore how an impaired immune response predisposes the skin to Malassezia overgrowth and infection. We will examine the role of adaptive immunity, particularly T helper cells, in driving chronic inflammation in SD. All actors involved, whether part of innate or adaptive immunity, are responsible for the release of pro-inflammatory cytokines, which contribute to the progression of the disease. Therapeutic strategies aimed at the modulation of the immune response in SD have been tested in clinical trials evaluating the efficacy of immunomodulatory treatments in the management of SD. This review synthesizes insights from immunological studies and clinical trials to present an in-depth analysis of the immune mechanisms underpinning SD, thereby proposing targeted therapeutic strategies for its management.

COVID-19 and severe cutaneous allergic reactions to sulfonamides

Background: Sulfonamides are associated with severe cutaneous adverse reactions (SCARs). Coronavirus disease 2019 (COVID-19) triggers an immune response, which may increase the likelihood of developing a hypersensitivity reaction. Objectives: We sought to explore the impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection on the probability of developing SCARs and/or erythema multiforme (EM) reactions to sulfonamides. Methods: In the propensity score-matched cohort study by using the de-identified TriNetX Research data base, patients who had an exposure to antibiotic or non-antibiotic sulfonamides between March 1, 2020, and January 1, 2023, were divided into two groups based on the presence or absence of a previous COVID-19 infection within 6 months of starting the sulfonamide agent. The outcomes studied were the 30-day risk of developing SCARs or EM (Stevens-Johnson syndrome, toxic epidermal necrolysis, drug reaction with eosinophilia and systemic symptoms, or EM) within 3 months of sulfonamide exposure. Cohorts were matched based on baseline demographics; malignant lymphoid neoplasms; human immunodeficiency virus; systemic lupus erythematosus; bone marrow transplantation; diabetes; psoriasis; seizures; gout; solid organ or stem cell transplantation; COVID-19 vaccination; and exposure to risk medications, including allopurinol, levetiracetam, carbamazepine, lamotrigine, oxcarbazepine, phenytoin, phenobarbital, abacavir, nevirapine, piroxicam, tenoxicam, or mexiletine. Results: When comparing 345,119 patients on sulfonamides and with previous COVID-19 to an equal number of sulfonamides users without a previous COVID-19, patients with COVID-19 had a lower risk of developing any form of SCARs (relative risk 0.39 [95% confidence interval, 0.26, 0.58]; p < 0.001). Conclusion: Previous SARS-CoV-2 infection seems to be associated with a lower probability of developing SCARs or EM among patients using sulfonamides.

ERK/STAT3 activation through CCL17/CCR4 axis-mediated type 2 cytokine-involved signaling pathways in Th2 cells regulates cutaneous drug reactions

Cutaneous drug reactions (CDRs) are common drug-induced allergic reactions that cause severe consequences in HIV/AIDS patients. The CCL17/CCR4 axis is involved in the immune mechanism of allergic diseases, but its role in the CDRs has not been determined. Here, we aimed to determine the role of the CCL17/CCR4 axis and the underlying mechanism involved in CDRs. In this study, the serum cytokine levels in patients with CDR and healthy controls were measured. The CCL17-triggered allergic profile was screened via a PCR array. Apoptosis of keratinocytes cocultured with CCL17-stimulated Th2 cells was analyzed by flow cytometry. An NVP-induced rat CDR model was established, and dynamic inflammatory factor levels and Th2 cells in the peripheral blood of the rats were measured. Rat skin lesions and signaling pathways in Th2 cells were also analyzed. We showed that the serum CCL17 level was significantly upregulated in CDR patients (P = 0.0077), and the Th2 cell subgroup was also significantly elevated in the CDR rats. The CCL17/CCR4 axis induces Th2 cells to release IL-4 and IL-13 via the ERK/STAT3 pathway. The CCR4 antagonist compound 47 can alleviate rash symptoms resulting from NVP-induced drug eruption, Th2 cell subgroup, IL-4, and IL-13 and inhibit keratinocyte apoptosis. Taken together, these findings indicate that the CCL17/CCR4 axis mediates CDR via the ERK/STAT3 pathway in Th2 cells and type 2 cytokine-induced keratinocyte apoptosis.

Immunological Mechanisms in Cutaneous Adverse Drug Reactions

Adverse drug reactions (ADRs) are an inherent aspect of drug use. While approximately 80% of ADRs are predictable, immune system-mediated ADRs, often unpredictable, are a noteworthy subset. Skin-related ADRs, in particular, are frequently unpredictable. However, the wide spectrum of skin manifestations poses a formidable diagnostic challenge. Comprehending the pathomechanisms underlying ADRs is essential for accurate diagnosis and effective management. The skin, being an active immune organ, plays a pivotal role in ADRs, although the precise cutaneous immunological mechanisms remain elusive. Fortunately, clinical manifestations of skin-related ADRs, irrespective of their severity, are frequently rooted in immunological processes. A comprehensive grasp of ADR morphology can aid in diagnosis. With the continuous development of new pharmaceuticals, it is noteworthy that certain drugs including immune checkpoint inhibitors have gained notoriety for their association with ADRs. This paper offers an overview of immunological mechanisms involved in cutaneous ADRs with a focus on clinical features and frequently implicated drugs.

A Comprehensive Review on HIV-Associated Dermatologic Manifestations: From Epidemiology to Clinical Management

Dermatological disorders are among the most prevalent manifestations of HIV infection/acquired immunodeficiency syndrome (AIDS). In this review, we aimed to characterize the various dermatologic presentations among HIV-infected patients with a detailed categorization of the mucocutaneous signs and symptoms, their etiopathogenic factors, and clinical management. In fact, cutaneous manifestations of HIV are quite various, ranging from AIDS-specific skin eruptions (xerosis, pruritic papular eruptions, eosinophilic folliculitis, and acne), opportunistic infections (herpes simplex, molluscum contagiosum, cutaneous leishmaniasis, bacillary angiomatosis, disseminated histoplasmosis, disseminated cryptococcosis, and zoster) to AIDS-related malignancies (Kaposi's sarcoma, lymphoma, and nonmelanoma skin cancers) and antiretroviral therapy (ART)-associated drug eruptions. We tried to classify HIV-related cutaneous presentations which can help clinicians for a better understanding of the various specific and nonspecific features of AIDS-associated cutaneous manifestations and management of the condition.

Novel insights into molecular and cellular aspects of delayed drug hypersensitivity reactions

INTRODUCTION

Delayed drug hypersensitivity reactions (DDHRs) represent a major health problem. They are unpredictable and can cause life-long disability or even death. The pathophysiology of DDHRs is complicated, multifactorial, and not well understood mainly due to the lack of validated animal models or in vitro systems. The role of the immune system is well demonstrated but its exact pathophysiology still a matter of debate.

AREA COVERED

This review summarizes the current understanding of DDHRs pathophysiology and abridges the available new evidence supporting each hypothesis. A comprehensive literature search for relevant publications was performed using PubMed, Google Scholar, and Medline databases with no date restrictions and focusing on the most recent 10 years.

EXPERT OPINION

Although multiple milestones have been achieved in our understanding of DDHRs pathophysiology as a result of the development of useful experimental models, many questions are yet to be fully answered. A deeper understanding of the mechanistic basis of DDHRs would not only facilitate the development of robust and reliable diagnostic assays for diagnosis, but would also inform therapy by providing specific target(s) for immunomodulation and potentially permit pre-therapeutic risk assessment to pursue the common goal of safe and effective drug therapy.

HIV-associated photodermatitis in African populations

Photosensitive dermatoses are seen in 5% of HIV-infected persons. These include drug- and chemical-induced photoallergic and phototoxic reactions, chronic actinic dermatitis of HIV, photo lichenoid drug eruptions, and porphyria. Data on photodermatitis in HIV are limited to case reports and series. The pathogenesis is not completely understood and includes a th2 phenotype in HIV which results in impaired barrier function and resultant allergen sensitisation as well as immune dysregulation. The objective of this manuscript is to review the literature on the clinical phenotype, pathogenesis, role of photo and patch testing, outcomes, and treatment of photodermatitis in HIV in an African population.