T Cell Surveillance during Cutaneous Viral Infections.

The skin is a complex tissue that provides a strong physical barrier against invading pathogens. Despite this, many viruses can access the skin and successfully replicate in either the epidermal keratinocytes or dermal immune cells. In this review, we provide an overview of the antiviral T cell biology responding to cutaneous viral infections and how these responses differ depending on the cellular targets of infection. Much of our mechanistic understanding of T cell surveillance of cutaneous infection has been gained from murine models of poxvirus and herpesvirus infection. However, we also discuss other viral infections, including flaviviruses and papillomaviruses, in which the cutaneous T cell response has been less extensively studied. In addition to the mechanisms of successful T cell control of cutaneous viral infection, we highlight knowledge gaps and future directions with possible impact on human health.

Crosstalk Between Epithelial Cells, Neurons and Immune Mediators in HSV-1 Skin Infection.

Herpes simplex virus type 1 (HSV-1) infection is highly prevalent in humans, with approximately two-thirds of the world population living with this virus. However, only a fraction of those carrying HSV-1, which elicits lifelong infections, are symptomatic. HSV-1 mainly causes lesions in the skin and mucosae but reaches the termini of sensory neurons innervating these tissues and travels in a retrograde manner to the neuron cell body where it establishes persistent infection and remains in a latent state until reactivated by different stimuli. When productive reactivations occur, the virus travels back along axons to the primary infection site, where new rounds of replication are initiated in the skin, in recurrent or secondary infections. During this process, new neuron infections occur. Noteworthy, the mechanisms underlying viral reactivations and the exit of latency are somewhat poorly understood and may be regulated by a crosstalk between the infected neurons and components of the immune system. Here, we review and discuss the immune responses that occur at the skin during primary and recurrent infections by HSV-1, as well as at the interphase of latently-infected neurons. Moreover, we discuss the implications of neuronal signals over the priming and migration of immune cells in the context of HSV-1 infection.

Presencia de anticuerpos antifosfolipidos IgA en pacientes con lesiones pernioticas asociadas a COVID 19 / Immunoglobulin A Antiphospholipid Antibodies in Patients With Chilblain-like Lesions During the COVID-19 Pandemic

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iRHOM2: A Regulator of Palmoplantar Biology, Inflammation, and Viral Susceptibility.

The palmoplantar epidermis is a specialized area of the skin that undergoes high levels of mechanical stress. The palmoplantar keratinization and esophageal cancer syndrome, tylosis with esophageal cancer, is linked to mutations in RHBDF2 encoding the proteolytically inactive rhomboid protein, iRhom2. Subsequently, iRhom2 was found to affect palmoplantar thickening to modulate the stress keratin response and to mediate context-dependent stress pathways by p63. iRhom2 is also a direct regulator of the sheddase, ADAM17, and the antiviral adaptor protein, stimulator of IFN genes. In this perspective, the pleiotropic functions of iRhom2 are discussed with respect to the skin, inflammation, and the antiviral response.

Serum soluble Fas ligand levels and peripheral blood lymphocyte subsets in patients with drug-induced maculopapular rashes, dress, and viral exanthemas.

BACKGROUND: Fatty acid synthetase (Fas)/Fas ligand (FasL)-dependent apoptotic pathways have been reported as being involved in the pathogenesis of drug-induced maculopapular rashes. OBJECTIVE: We investigated serum soluble FasL (sFasL) levels and peripheral blood lymphocyte subtypes to discriminate maculopapular drug eruptions (MPDE) from viral exanthema (VE). PATIENTS/METHODS: Children with confirmed MPDE (group I), VE (group II), and drug rashes with eosinophilia and systemic symptoms (DRESS) or drug-induced hypersensitivity syndrome (DIHS) (group III) were included. Serum sFasL levels and peripheral blood lymphocyte subtypes were analyzed in groups I-III on admission, and repeated twice (only once for group IV - controls). RESULTS: There were no significant serum soluble FasL level differences among the groups for all the samples. In the initial samples, CD19+ cell numbers in group II were significantly higher than in group IV, and the CD4+/CD8+ ratio was higher than groups I and IV. In the second samples, CD4+ and CD19+ cell numbers were significantly higher in group II than group I. In the final samples, CD4+ cell numbers in group II were significantly higher than group I and group III. CD19+ cells numbers in group III were significantly lower than the other groups for all samples. CONCLUSION: Serum sFasL levels were not found to be useful in discriminating viral exanthemas from other drug rashes. The significant differences between MPDE, VE, and DRESS were high CD4+ and CD19+ cell-count numbers in VE but low B-cell numbers in DRESS. This might be important for discriminating VE from DRESS, and the low B-cell count in early symptoms might be a useful predictor of DRESS development.

Hydroa vacciniforme: a distinctive form of Epstein-Barr virus-associated T-cell lymphoproliferative disorders.

Hydroa vacciniforme (HV) is a cutaneous subset of Epstein-Barr virus (EBV)-associated T/NK lymphoproliferative disorders (LPDs). Our previous case series study clearly showed a clinical spectrum of EBV-associated T/NK LPDs including HV, hypersensitivity to mosquito bites (HMB), chronic active EBV infection (CAEBV), and hemophagocytic lymphohistiocytosis (HLH). Patients with HV are divided into two groups: a benign subtype designated "classic HV" (cHV) and more serious systemic HV (sHV), also called "HV-like LPD" in the 2017 World Health Organization (WHO) classification. Patients with cHV usually have an increased number of EBV-infected γδT cells and patients with sHV without HMB are further classified into two groups: γδT-cell- and αßT-cell-dominant types. Patients with HMB, with or without HV-like eruptions, have an increased number of EBV-infected NK cells in the blood. Patients with cHV and γδT-cell-dominant sHV show a favourable prognosis, but the other subtypes such as αßT-cell-dominant sHV and HMB have a poor prognosis with mortality rates of 11.5 and 3.51 per 100 person-years, respectively. In addition to the clinical subtypes and the dominant lymphocyte subsets, the poor prognostic indicators include onset age over nine years and expression of the reactivation marker, BZLF1 mRNA. No prognostic correlation has been reported for anti-EBV antibody titres or EBV DNA load. The clinical subtypes and their prognostic factors should be considered for therapeutic interventions.

Cutaneous cytomegalovirus manifestations, diagnosis, and treatment: a review.

The possible presentations of cytomegalovirus (CMV) are vast not only in its systemic manifestations, but also in the various cutaneous lesions that may result. Cutaneous cytomegalovirus is rarely reported in the literature because the clinical and pathologic features can be difficult to identify. Its identification, however, is vital as cutaneous human CMV infection can signal systemic disease and an unfavorable prognosis. The objective of this study is to aid in recognition, diagnosis, and treatment of CMV according to dermatological evidence. A complete literature search was performed within PubMed, resulting in the inclusion of 58 patient cases. The most common dermatologic manifestation was perianal or oral ulcers, but the locations and types of lesions noted throughout the review were numerous. Treatment is often simple, yet incorrect diagnoses along with concurrent illnesses can often complicate management. It is imperative for CMV to be detected early in its course to prevent mortality, especially in the immunocompromised. Dermatological presentations are often the first sign of this deadly virus' activity and it is essential that these diagnoses are made more efficient and accurate.

Classical Type 1 Dendritic Cells Dominate Priming of Th1 Responses to Herpes Simplex Virus Type 1 Skin Infection.

CD4+ T cell responses are crucial for the control of many intracellular pathogens, yet the requirements for their induction are not fully understood. To better understand the role that various dendritic cell (DC) subtypes play in CD4+ T cell priming, we compared in vivo T cell responses to skin inoculation of mice with infectious or UV-inactivated HSV type 1. Localized infection elicited a Th1 response that was primed in skin-draining lymph nodes involving Ag presentation by migratory dermal and lymph node-resident DC. However, expansion and Th1 differentiation was impaired in response to UV-inactivated virus (UV-HSV), and this defect correlated with a restriction of Ag presentation to migratory CD103- dermal DC. A similar differentiation defect was seen in infected mice lacking CD8α+ and CD103+ classical type 1 DC (cDC1). Finally, Th1 differentiation after UV-HSV inoculation was rescued by targeted Ag delivery to CD8α+ and CD103+ cDC1 using an anti-Clec9A Ab construct. This suggests that Ag presentation by cDC1 is crucial for optimal Th1 immunity to HSV type 1 infection and potentially other pathogens of the skin.

Dermal CD207-Negative Migratory Dendritic Cells Are Fully Competent to Prime Protective, Skin Homing Cytotoxic T-Lymphocyte Responses.

Dendritic cells (DCs) are important inducers and regulators of T-cell responses. They are able to activate and modulate the differentiation of CD4+ and CD8+ T cells. In the skin, there are at least five phenotypically distinct DC subpopulations that can be distinguished by differential expression of the cell surface markers CD207, CD103, and CD11b. Previous studies have suggested that dermal CD11b-CD207+ conventional type 1 DCs are indispensable for the priming of a skin homing cytotoxic T-lymphocyte response. However, conventional type 1 DCs are also the only skin DC subset capable of cross-presenting exogenous antigens on major histocompatibility complex class I. Thus, it remained unclear whether for antigens that do not require cross-presentation, such as viruses that infect DCs, other DC subtypes in the skin can contribute to cytotoxic T-lymphocyte priming. To address this question, we used a transgenic mouse model that allows inducible expression and presentation of a model antigen on selected subsets of dermal DCs. We show that for antigens presented via the conventional major histocompatibility complex class I presentation pathway, CD207- dermal DCs are fully competent to prime a skin homing cytotoxic T-lymphocyte response that is capable of protection against a local virus challenge and gives rise to skin resident memory CD8+ T cells.

Cross-sectional associations between cutaneous viral infections and regulatory T lymphocytes in circulation.

BACKGROUND: Cutaneous viral infections and immune suppression are risk factors for some forms of nonmelanoma skin cancer; however, their interrelationship is poorly understood. OBJECTIVES: To examine cross-sectional associations between cutaneous viral infections and circulating forkhead-box P3 (FOXP3)-expressing T-regulatory (Treg) cells, suppressive cells that dampen effective antitumour immunity. MATERIALS AND METHODS: Blood, eyebrow hair (EBH) and skin swab (SSW) samples were collected from 352 patients 60 years and older undergoing skin screening, without prevalent skin cancer, while participating in an ongoing prospective cohort study of cutaneous viral infections and skin cancer. DNA corresponding to 98 cutaneous human papillomavirus (HPV) types and five human polyomaviruses (HPyV) was assessed in EBH and SSW. Distinct classes of circulating Treg-cell subpopulations were defined by flow cytometry including cutaneous lymphocyte antigen (CLA) and CCR4high Treg cells, both previously associated with cutaneous diseases. Age- and sex-adjusted associations between circulating T-cell populations and infection were estimated using logistic regression. RESULTS: Total Treg-cell proportion in peripheral blood was not associated with ß HPV or HPyV infection. However, the proportion of circulating CLA+ Treg cells was inversely associated with γ HPV EBH infection [odds ratio (OR) 0·54, 95% confidence interval (CI) 0·35-0·84]. Interestingly, circulating Treg cells expressing markers indicative of antigen activation (CD27- CD45RA- FOXP3+ CD4+ ) were also inversely associated with γ HPV infection in SSW (OR 0·55, 95% CI 0·30-0·99) and EBH (OR 0·56, 95% CI 0·36-0·86). CONCLUSIONS: Inverse associations between circulating Treg cells and γ HPV infection suggest that localized viral infection may promote immunosuppressive cell migration into skin.

The Biology and Clinical Features of Cutaneous Polyomaviruses.

Human polyomaviruses are double-stand DNA viruses with a conserved genomic structure, yet they present with diverse tissue tropisms and disease presentations. Merkel cell polyomavirus, trichodysplasia spinulosa polyomavirus, human polyomavirus 6 and 7, and Malawi polyomavirus are shed from the skin, and Merkel cell polyomavirus, trichodysplasia spinulosa polyomavirus, human polyomavirus 6 and 7 have been linked to specific skin diseases. We present an update on the genomic and clinical features of these cutaneous polyomaviruses.

DOCK8 deficiency: Insights into pathophysiology, clinical features and management.

Dedicator of cytokinesis 8 (DOCK8) deficiency is a combined immunodeficiency that exemplifies the broad clinical features of primary immunodeficiencies (PIDs), extending beyond recurrent infections to include atopy, autoimmunity and cancer. It is caused by loss of function mutations in DOCK8, encoding a guanine nucleotide exchange factor highly expressed in lymphocytes that regulates the actin cytoskeleton. Additional roles of DOCK8 have also emerged, including regulating MyD88-dependent Toll-like receptor signaling and the activation of the transcription factor STAT3. DOCK8 deficiency impairs immune cell migration, function and survival, and it impacts both innate and adaptive immune responses. Clinically, DOCK8 deficiency is characterized by allergic inflammation as well as susceptibility towards infections, autoimmunity and malignancy. This review details the pathophysiology, clinical features and management of DOCK8 deficiency. It also surveys the recently discovered combined immunodeficiency due to DOCK2 deficiency, highlighting in the process the emerging spectrum of PIDs resulting from DOCK protein family abnormalities.

Current Status of Dedicator of Cytokinesis-Associated Immunodeficiency: DOCK8 and DOCK2.

DOCK8 deficiency is an autosomal recessive combined immunodeficiency disease associated with elevated IgE, atopy, recurrent sinopulmonary and cutaneous viral infections, and malignancy. The DOCK8 protein is critical for cytoskeletal organization, and deficiency impairs dendritic cell transmigration, T-cell survival, and NK cell cytotoxicity. Early hematopoietic stem cell transplantation is gaining prominence as a definitive treatment given the potential for severe complications and mortality in this disease. Recently, DOCK2 deficiency has been identified in several patients with early-onset invasive bacterial and viral infections.

Cutaneous involvement by cytomegalovirus in a renal transplant recipient as an indicator of severe systemic infection.

Cytomegalovirus is an opportunistic virus that commonly affects immunosuppressed patients. Cutaneous involvement by this virus is rare and occurs in significantly immunocompromised hosts, with a poor prognosis. Skin ulcers may represent the first sign of systemic infection by cytomegalovirus in these patients. Herein, a case of a systemic infection by Cytomegalovirus presenting as genital and oral ulcers in a kidney-transplant recipient is reported.

Cutaneous involvement by cytomegalovirus in a renal transplant recipient as an indicator of severe systemic infection

Abstract Cytomegalovirus is an opportunistic virus that commonly affects immunosuppressed patients. Cutaneous involvement by this virus is rare and occurs in significantly immunocompromised hosts, with a poor prognosis. Skin ulcers may represent the first sign of systemic infection by cytomegalovirus in these patients. Herein, a case of a systemic infection by Cytomegalovirus presenting as genital and oral ulcers in a kidney-transplant recipient is reported.

Disseminated varicella-zoster virus in an immunocompetent adult.

Varicella-zoster is the virus that causes varicella (chicken pox), herpes zoster (shingles), and rarely, severe disseminated disease including diffuse rash, encephalitis, hepatitis, and pneumonitis. Disseminated disease is most often seen in immunocompromised patients. We describe a case of disseminated zoster in an immunocompentent patient who had previously been immune to VZV. This case is also unusual in that his clinical presentation was most consistent with varicella while his laboratory data was most consistent with herpes zoster. For the purpose of rapid diagnosis and initiation of appropriate therapy, clinicians should be aware of these more atypical presentations of VZV infection.