Atopic dermatitis (AD) is a chronic and inflammatory skin disease with intense pruritus and xerosis. AD pathogenesis is multifactorial, involving genetic, environmental, and immunological factors, including the participation of Staphylococcus aureus. This bacterium colonizes up to 30–100% of AD skin and its virulence factors are responsible for its pathogenicity and antimicrobial survival. This is a concise review of S. aureus superantigen-activated signaling pathways, highlighting their involvement in AD pathogenesis, with an emphasis on skin barrier disruption, innate and adaptive immunity dysfunction, and microbiome alterations. A better understanding of the combined mechanisms of AD pathogenesis may enhance the development of future targeted therapies for this complex disease.

Sézary syndrome (SS) is a rare and aggressive type of cutaneous T-cell lymphoma, with an abnormal inflammatory response in affected skin. The cytokines IL-1B and IL-18, as key signaling molecules in the immune system, are produced in an inactive form and cleave to the active form by inflammasomes. In this study, we assessed the skin, serum, peripheral mononuclear blood cell (PBMC) and lymph-node samples of SS patients and control groups (healthy donors (HDs) and idiopathic erythroderma (IE) nodes) to investigate the inflammatory markers IL-1B and IL-18 at the protein and transcript expression levels, as potential markers of inflammasome activation. Our findings showed increased IL-1B and decreased IL-18 protein expression in the epidermis of SS patients; however, in the dermis layer, we detected increased IL-18 protein expression. In the lymph nodes of SS patients at advanced stages of the disease (N2/N3), we also detected an enhancement of IL-18 and a downregulation of IL-1B at the protein level. Moreover, the transcriptomic analysis of the SS and IE nodes confirmed the decreased expression of IL1B and NLRP3, whereas the pathway analysis indicated a further downregulation of IL1B-associated genes. Overall, the present findings showed compartmentalized expressions of IL-1B and IL-18 and provided the first evidence of their imbalance in patients with Sézary syndrome.

Atopic dermatitis (AD) is a chronic inflammatory skin disease characterized by a complex interaction between genetic, immunological, and environmental factors. The combination of immune dysregulation and skin barrier dysfunction plays a crucial role in the pathogenesis of the disease. The inflammasome, an important intracellular complex of pattern recognition receptors (PRRs), plays a crucial role in the cutaneous inflammatory response, activating caspase-1 and promoting the release of pro-inflammatory cytokines such as interleukin (IL)-1β and IL-18. The role of inflammasome components in regulating the inflammatory response in AD highlights how the activation of these complexes exacerbates inflammation and contributes to the worsening of the disease and tissue damage. The review included observational and experimental studies investigating inflammasome activation in AD and other inflammatory skin diseases. The main mechanisms of inflammasome activation and their impact on the inflammatory environment and skin barrier integrity were discussed. Understanding the role of the inflammasome in AD is essential for the development of new therapeutic approaches aimed at both modulating the immune response and restoring the skin barrier, improving more effective clinical management and patients' quality of life.

Zika virus (ZIKV) infection during pregnancy is a critical driver of Congenital Zika Syndrome (CZS), yet the mechanisms of pathogenesis at the placental barrier remain incompletely understood. This article is a translational, observational, and experimental study combining clinical placental analyses, placental explants cultures and in vivo murine model to investigate the mechanisms involved in ZIKV infection. We evaluate the histopathological analyses to verify presence of inflammation in ZIKV-infected human placentas from newborns with CZS and without CZS (N-CZS), identifying more intense Hofbauer cell hyperplasia, villitis and decidual inflammation in CZS group. Moreover, placental immunohistochemistry analyses identified decreased TLR4 expression in the villi and reduced TNF and IL-10 levels across placental layers of CZS group. Next, we investigated the effects of inflammation on viral replication and explored whether the flavonoid Naringenin (NGN) could modulate this inflammation. Using a placental villous explant model, we verified that inflammation induced by LPS exacerbates viral replication and pathological markers. Notably, treatment with the NGN rescued the inflammatory and virological outcomes. These findings were further validated in a murine model of congenital infection, where NGN administration alleviated microcephaly-related structural alterations in ZIKV-exposed neonates. Our results indicate that placental inflammation is a key provocateur of ZIKV replication and subsequent fetal brain malformation. Furthermore, we identify NGN as a promising bifunctional antiviral and anti-inflammatory candidate for mitigating the developmental impacts of ZIKV infection.

SARS-CoV-2, a β-coronavirus, primarily affects the lungs, with non-specific lesions and no cytopathic viral effect in the skin. Cutaneous antiviral mechanisms include activation of TLR/IRF pathways and production of type I IFN. We evaluated the antiviral mechanisms involved in the skin of COVID-19 patients, including skin samples from 35 deceased patients who had contracted COVID-19 before the launch of the vaccine. Detection of SARS-CoV-2 in the skin was performed using transmission electron microscopy and RT-qPCR. Microscopic and molecular effects of the virus in skin were evaluated by histopathology, RT-qPCR, and immunohistochemistry (IHC). The results revealed the presence of SARS-CoV-2 and microscopic changes, including microvascular hyaline thrombi, perivascular dermatitis, and eccrine gland necrosis. There was increased transcription of TBK1 and a reduction in transcription of TNFα by RT-qPCR in the COVID-19 group. IHC revealed reduced expression of ACE2, TLR7, and IL-6, and elevated expression of IFN-β by epidermal cells. In the dermis, there was decreased expression of STING, IFN-β, and TNF-α and increased expression of IL-6 in sweat glands. Our results highlight the role of type I IFN in the skin of COVID-19 patients, which may modulate the cutaneous response to SARS-CoV-2.