HIF-1 regulates pathogenic cytotoxic T cells in lupus skin disease.

Cutaneous lupus erythematosus (CLE) is a disfiguring autoimmune skin disease characterized by an inflammatory infiltrate rich in T cells, which are strongly implicated in tissue damage. How these cells adapt to the skin environment and promote tissue inflammation and damage is not known. In lupus nephritis, we previously identified an inflammatory gene program in kidney-infiltrating T cells that is dependent on HIF-1, a transcription factor critical for the cellular and developmental response to hypoxia as well as inflammation-associated signals. In our present studies using a mouse model of lupus skin disease, we find that skin-infiltrating CD4+ and CD8+ T cells also express high levels of HIF-1. Skin-infiltrating T cells demonstrated a strong cytotoxic signature at the transcript and protein levels, and HIF-1 inhibition abrogated skin and systemic diseases in association with decreased T cell cytotoxic activity. We also demonstrate in human CLE tissue that the T cell-rich inflammatory infiltrate exhibited increased amounts of HIF-1 and a cytotoxic signature. Granzyme B-expressing T cells were concentrated at sites of skin tissue damage in CLE, suggesting relevance of this pathway to human disease.

Lack of association between pandemic chilblains and SARS-CoV-2 infection.

An increased incidence of chilblains has been observed during the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic and attributed to viral infection. Direct evidence of this relationship has been limited, however, as most cases do not have molecular evidence of prior SARS-CoV-2 infection with PCR or antibodies. We enrolled a cohort of 23 patients who were diagnosed and managed as having SARS-CoV-2-associated skin eruptions (including 21 pandemic chilblains [PC]) during the first wave of the pandemic in Connecticut. Antibody responses were determined through endpoint titration enzyme-linked immunosorbent assay and serum epitope repertoire analysis. T cell responses to SARS-CoV-2 were assessed by T cell receptor sequencing and in vitro SARS-CoV-2 antigen-specific peptide stimulation assays. Immunohistochemical and PCR studies of PC biopsies and tissue microarrays for evidence of SARS-CoV-2 were performed. Among patients diagnosed and managed as "covid toes" during the pandemic, we find a percentage of prior SARS-CoV-2 infection (9.5%) that approximates background seroprevalence (8.5%) at the time. Immunohistochemistry studies suggest that SARS-CoV-2 staining in PC biopsies may not be from SARS-CoV-2. Our results do not support SARS-CoV-2 as the causative agent of pandemic chilblains; however, our study does not exclude the possibility of SARS-CoV-2 seronegative abortive infections.

Post-COVID-19 vaccination IgA vasculitis in an adult.

Leukocytoclastic vasculitis has been reported in the setting of COVID-19 infection and post-COVID-19 vaccination. We report a case of IgA vasculitis (IgAV) post-COVID-19 vaccination, with immunoglobulin A (IgA) immune deposits in the skin and renal involvement. SARS-CoV spike protein immunohistochemical staining was negative. IgAV with skin and renal involvement is a potential reaction to COVID-19 vaccination.

Delayed Localized Hypersensitivity Reactions to the Moderna COVID-19 Vaccine: A Case Series.

Importance: In response to the coronavirus disease 2019 (COVID-19) pandemic, 2 mRNA vaccines (Pfizer-BioNTech and Moderna) received emergency use authorization from the US Food and Drug Administration in December 2020. Some patients in the US have developed delayed localized cutaneous vaccine reactions that have been dubbed "COVID arm." Objective: To describe the course of localized cutaneous injection-site reactions to the Moderna COVID-19 vaccine, subsequent reactions to the second vaccine dose, and to characterize the findings of histopathologic examination of the reaction. Design, Setting, and Participants: This retrospective case series study was performed at Yale New Haven Hospital, a tertiary medical center in New Haven, Connecticut, with 16 patients referred with localized cutaneous injection-site reactions from January 20 through February 12, 2021. Main Outcomes and Measures: We collected each patient's demographic information, a brief relevant medical history, clinical course, and treatment (if any); and considered the findings of a histopathologic examination of 1 skin biopsy specimen. Results: Of 16 patients (median [range] age, 38 [25-89] years; 13 [81%] women), 14 patients self-identified as White and 2 as Asian. The delayed localized cutaneous reactions developed in a median (range) of 7 (2-12) days after receiving the Moderna COVID-19 vaccine. These reactions occurred at or near the injection site and were described as pruritic, painful, and edematous pink plaques. None of the participants had received the Pfizer-BioNTech vaccine. Results of a skin biopsy specimen demonstrated a mild predominantly perivascular mixed infiltrate with lymphocytes and eosinophils, consistent with a dermal hypersensitivity reaction. Of participants who had a reaction to first vaccine dose (15 of 16 patients), most (11 patients) developed a similar localized injection-site reaction to the second vaccine dose; most (10 patients) also developed the second reaction sooner as compared with the first-dose reaction. Conclusions and Relevance: Clinical and histopathologic findings of this case series study indicate that the localized injection-site reactions to the Moderna COVID-19 vaccine are a delayed hypersensitivity reaction. These reactions may occur sooner after the second dose, but they are self-limited and not associated with serious vaccine adverse effects. In contrast to immediate hypersensitivity reactions (eg, anaphylaxis, urticaria), these delayed reactions (dubbed "COVID arm") are not a contraindication to subsequent vaccination.

Epidermolysis bullosa pruriginosa treated with dupilumab.

Epidermolysis bullosa pruriginosa (EBP) is a variant of dystrophic epidermolysis bullosa characterized by intense pruritus and prurigo nodularis-like lesions. While medical therapies for EBP exist, current treatments are not consistently effective, and symptoms often cause decreased quality of life. Here, we report two cases of EBP treated with dupilumab, which decreased symptoms of pruritus and improved skin findings. Both patients have been on dupilumab for over one year with sustained improvement and no adverse effects; although in one patient, increased dosing was required to attain optimal control of disease.

Cutaneous Lupus Erythematosus: Current and Future Pathogenesis-Directed Therapies.

Cutaneous lupus erythematosus (CLE) is an autoimmune disease of the skin with significant morbidity. Current treatments are often inadequate to control disease and there are no Food and Drug Administration (FDA)-approved therapies for this potentially debilitating disease, underscoring an unmet medical need. Recent insights into disease pathogenesis have implicated innate and adaptive immune components, including type I and type III interferons in the development of CLE. Promising clinical trials based on these insights are now underway. However, the full spectrum of immune cells, cytokines, and environmental triggers contributing to disease remain to be elucidated. In this review, we will highlight the current understanding of CLE immunopathogenesis, the ongoing clinical trial landscape, and provide a framework for designing future therapeutic strategies for CLE based on new insights into disease pathogenesis.

Cooperative recruitment of HMGB1 during V(D)J recombination through interactions with RAG1 and DNA.

During V(D)J recombination, recombination activating gene (RAG)1 and RAG2 bind and cleave recombination signal sequences (RSSs), aided by the ubiquitous DNA-binding/-bending proteins high-mobility group box protein (HMGB)1 or HMGB2. HMGB1/2 play a critical, although poorly understood, role in vitro in the assembly of functional RAG-RSS complexes, into which HMGB1/2 stably incorporate. The mechanism of HMGB1/2 recruitment is unknown, although an interaction with RAG1 has been suggested. Here, we report data demonstrating only a weak HMGB1-RAG1 interaction in the absence of DNA in several assays, including fluorescence anisotropy experiments using a novel Alexa488-labeled HMGB1 protein. Addition of DNA to RAG1 and HMGB1 in fluorescence anisotropy experiments, however, results in a substantial increase in complex formation, indicating a synergistic binding effect. Pulldown experiments confirmed these results, as HMGB1 was recruited to a RAG1-DNA complex in a RAG1 concentration-dependent manner and, interestingly, without strict RSS sequence specificity. Our finding that HMGB1 binds more tightly to a RAG1-DNA complex over RAG1 or DNA alone provides an explanation for the stable integration of this typically transient architectural protein in the V(D)J recombinase complex throughout recombination. These findings also have implications for the order of events during RAG-DNA complex assembly and for the stabilization of sequence-specific and non-specific RAG1-DNA interactions.

Promoters, enhancers, and transcription target RAG1 binding during V(D)J recombination.

V(D)J recombination assembles antigen receptor genes in a well-defined order during lymphocyte development. This sequential process has long been understood in the context of the accessibility model, which states that V(D)J recombination is regulated by controlling the ability of the recombination machinery to gain access to its chromosomal substrates. Indeed, many features of "open" chromatin correlate with V(D)J recombination, and promoters and enhancers have been strongly implicated in creating a recombinase-accessible configuration in neighboring chromatin. An important prediction of the accessibility model is that cis-elements and transcription control binding of the recombination-activating gene 1 (RAG1) and RAG2 proteins to their DNA targets. However, this prediction has not been tested directly. In this study, we use mutant Tcra and Tcrb alleles to demonstrate that enhancers control RAG1 binding globally at Jα or Dß/Jß gene segments, that promoters and transcription direct RAG1 binding locally, and that RAG1 binding can be targeted in the absence of RAG2. These findings reveal important features of the genetic mechanisms that regulate RAG binding and provide a direct confirmation of the accessibility model.

CD1d function is regulated by microsomal triglyceride transfer protein.

CD1d is a major histocompatibility complex (MHC) class I-related molecule that functions in glycolipid antigen presentation to distinct subsets of T cells that express natural killer receptors and an invariant T-cell receptor-alpha chain (invariant NKT cells). The acquisition of glycolipid antigens by CD1d occurs, in part, in endosomes through the function of resident lipid transfer proteins, namely saposins. Here we show that microsomal triglyceride transfer protein (MTP), a protein that resides in the endoplasmic reticulum of hepatocytes and intestinal epithelial cells (IECs) and is essential for lipidation of apolipoprotein B, associates with CD1d in hepatocytes. Hepatocytes from animals in which Mttp (the gene encoding MTP) has been conditionally deleted, and IECs in which Mttp gene products have been silenced, are unable to activate invariant NKT cells. Conditional deletion of the Mttp gene in hepatocytes is associated with a redistribution of CD1d expression, and Mttp-deleted mice are resistant to immunopathologies associated with invariant NKT cell-mediated hepatitis and colitis. These studies indicate that the CD1d-regulating function of MTP in the endoplasmic reticulum is complementary to that of the saposins in endosomes in vivo.