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Koren and Feldman et al. report a distinct population of Thy1-expressing stem cells in the basal layer of the mouse epidermis. These stem cells do not compete neutrally and contribute long-term to both epidermal replenishment and wound repair. The presence of distinct stem cells that maintain the interfollicular epidermis is highly debated. Here, we report a population of keratinocytes, marked by Thy1, in the basal layer of the interfollicular epidermis. We find that epidermal cells expressing differential levels of Thy1 display distinct transcriptional signatures. Thy1(+) keratinocytes do not express T cell markers, express a unique transcriptional profile, cycle significantly slower than basal epidermal progenitors and display significant expansion potential in vitro. Multicolor lineage tracing analyses and mathematical modeling reveal that Thy1(+) basal keratinocytes do not compete neutrally alike interfollicular progenitors and contribute long-term to both epidermal replenishment and wound repair. Importantly, ablation of Thy1(+) cells strongly impairs these processes, thus indicating the non-redundant function of Thy1(+) stem cells in the epidermis. Collectively, these results reveal a distinct stem cell population that plays a critical role in epidermal homeostasis and repair.

Efforts to cure HIV have focused on reactivating latent proviruses to enable elimination by CD8(+) cytotoxic T-cells. Clinical studies of latency reversing agents (LRA) in antiretroviral therapy (ART)-treated individuals have shown increases in HIV transcription, but without reductions in virologic measures, or evidence that HIV-specific CD8(+) T-cells were productively engaged. Here, we show that the SARS-CoV-2 mRNA vaccine BNT162b2 activates the RIG-I/TLR - TNF - NF kappa b axis, resulting in transcription of HIV proviruses with minimal perturbations of T-cell activation and host transcription. T-cells specific for the early gene-product HIV-Nef uniquely increased in frequency and acquired effector function (granzyme-B) in ART-treated individuals following SARS-CoV-2 mRNA vaccination. These parameters of CD8(+) T-cell induction correlated with significant decreases in cell-associated HIV mRNA, suggesting killing or suppression of cells transcribing HIV. Thus, we report the observation of an intervention-induced reduction in a measure of HIV persistence, accompanied by precise immune correlates, in ART-suppressed individuals. However, we did not observe significant depletions of intact proviruses, underscoring challenges to achieving (or measuring) HIV reservoir reductions. Overall, our results support prioritizing the measurement of granzyme-B-producing Nef-specific responses in latency reversal studies and add impetus to developing HIV-targeted mRNA therapeutic vaccines that leverage built-in LRA activity. Here, the authors show in a cohort of people with HIV, COVID mRNA vaccination is followed by a transient boost in a particular profile of HIV-specific T-cell responses and a corresponding decrease in residual HIV RNA - suggesting productive immune engagement with infected cells.

Background The Curing Coma Campaign (CCC) is a multidisciplinary global initiative focused on evaluation, diagnosis, treatment, research, and prognostication for patients who are comatose due to any etiology. To support this mission, the CCC Ethics Working Group conducted a survey of CCC collaborators to identify the ethics priorities of the CCC and the variability in priorities based on country of practice. Methods An electronic survey on the ethics priorities for the CCC was developed using rank-choice questions and distributed between May and July 2021 to a listserv of the 164 collaborators of the CCC. The median rank for each topic and subtopic was determined. Comparisons were made on the basis of country of practice. Results The survey was completed by 93 respondents (57% response rate); 67% practiced in the United States. On the basis of respondent ranking of each topic, the prioritization of ethics topics across respondents was as follows: (1) clinical care, (2) diagnostic definitions, (3) clinical research, (4) implementation/innovation, (5) family, (6) data management, (7) public engagement/perceptions, and (8) equity. Respondents who practiced in the United States were particularly concerned about public engagement, the distinction between clinical care and research, disclosure of results from clinical research to families, the definition of "personhood," and the distinction between the self-fulfilling prophecy/nihilism and medical futility. Respondents who practiced in other countries were particularly concerned about diagnostic modalities for clinical care, investigational drugs/devices for clinical research, translation of research into practice, and the definition of "minimally conscious state." Conclusions Collaborators of the CCC considered clinical care, diagnostic definitions, and clinical research the top ethics priorities of the CCC. These priorities should be considered as the CCC explores ways to improve evaluation, diagnosis, treatment, research, and prognostication of patients with coma and associated disorders of consciousness. There is some variability in ethics priorities based on country of practice.

Patients with inborn errors of immunity (IEI) are prone to develop infections, either due to a broad spectrum of pathogens or to only one microbe. Since skin is a major barrier tissue, cutaneous infections are among the most prevalent in patients with IEI due to high exposures to many microbes. In the general population, human papillomaviruses (HPVs) cause asymptomatic or self-healing infections, but, in patients with IEI, unusual clinical expression of HPV infection is observed ranging from epidermodysplasia verruciformis (EV) (a rare disease due to beta-HPVs) to profuse, persistent, and recalcitrant warts (due to alpha-, gamma-, and mu-HPVs) or even tree man syndrome (due to HPV2). Mutations in EVER1, EVER2, and CIB1 are associated with EV phenotype; GATA2, CXCR4, and DOCK8 mutations are typically associated with extensive HPV infections, but there are several other IEI that are less frequently associated with severe HPV lesions. In this review, we describe clinical, immunological, and genetic patterns of IEI related to severe HPV cutaneous infections and propose an algorithm for diagnosis of IEI with severe warts associated, or not, with lymphopenia.

The CST-Pol alpha/primase complex is essential for telomere maintenance and functions to counteract resection at double-strand breaks. We report a 4.6-angstrom resolution cryo-EM structure of human CST-Pol alpha/primase, captured prior to catalysis in a recruitment state stabilized by chemical cross-linking. Our structure reveals an evolutionarily conserved interaction between the C-terminal domain of the catalytic POLA1 subunit and an N-terminal expansion in metazoan CTC1. Cross-linking mass spectrometry and negative-stain EM analysis provide insight into CST binding by the flexible POLA1 N-terminus. Finally, Coats plus syndrome disease mutations previously characterized to disrupt formation of the CST-Pol alpha/primase complex map to protein-protein interfaces observed in the recruitment state. Together, our results shed light on the architecture and stoichiometry of the metazoan fill-in machinery.

Clinical recommendations for Acute Myeloid Leukemia (AML) classification and risk-stratification remain heavily reliant on cytogenetic findings at diagnosis, which are present in <50% of patients. Using comprehensive molecular profiling data from 3,653 patients we characterize and validate 16 molecular classes describing 100% of AML patients. Each class represents diverse biological AML subgroups, and is associated with distinct clinical presentation, likelihood of response to induction chemotherapy, risk of relapse and death over time. Secondary AML-2, emerges as the second largest class (24%), associates with high-risk disease, poor prognosis irrespective of flow Minimal Residual Disease (MRD) negativity, and derives significant benefit from transplantation. Guided by class membership we derive a 3-tier risk-stratification score that re-stratifies 26% of patients as compared to standard of care. This results in a unified framework for disease classification and risk-stratification in AML that relies on information from cytogenetics and 32 genes. Last, we develop an open-access patient-tailored clinical decision support tool. Classification and risk-stratification for Acute Myeloid Leukemia (AML) at diagnosis are primarily based on cytogenetics and only a few gene mutations. Here, the authors study the genomic landscape of 3653 AML patients and characterize 16 non-overlapping molecular subgroups of clinical relevance for disease classification and risk prognostication.

Interferon-induced transmembrane proteins (IFITM1, 2, and 3) are important antiviral proteins that are active against many viruses, including influenza A virus (IAV), dengue virus (DENV), Ebola virus (EBOV), Zika virus (ZIKV), and severe acute respiratory syndrome coronavirus (SARS-CoV). IFITM proteins exhibit specificity in activity, but their distinct mechanisms of action and regulation are unclear. Since S-palmitoylation and cholesterol homeostasis are crucial for viral infections, we investigated IFITM interactions with cholesterol by photoaffinity cross-linking in mammalian cells along with molecular dynamic simulations and nuclear magnetic resonance analysis in vitro. These studies suggest that cholesterol can directly interact with S-palmitoylated IFITMs in cells and alter the conformation of IFITMs in membrane bilayers. Notably, we discovered that the S-palmitoylation levels regulate differential IFITM protein interactions with cholesterol in mammalian cells and specificity of antiviral activity toward IAV, SARS-CoV-2, and EBOV. Our studies suggest that modulation of IFITM S-palmitoylation levels and cholesterol interaction influence host susceptibility to different viruses.

Amino acids and their metabolites are key regulators of immune responses, and plasma levels may change profoundly during acute disease states. Using targeted metabolomics, we evaluated concentration changes in plasma amino acids and related metabolites in community-acquired pneumonia (CAP, n = 29; compared against healthy controls, n = 33) from presentation to hospital through convalescence. We further aimed to identify biomarkers for acute CAP vs. the clinically potentially similar infection-triggered COPD exacerbation (n = 13). Amino acid metabolism was globally dysregulated in both CAP and COPD. Levels of most amino acids were markedly depressed in acute CAP, and total amino acid concentrations on admission were an accurate biomarker for the differentiation from COPD (AUC = 0.93), as were reduced asparagine and threonine levels (both AUC = 0.92). Reduced tryptophan and histidine levels constituted the most accurate biomarkers for acute CAP vs. controls (AUC = 0.96, 0.94). Only kynurenine, symmetric dimethyl arginine, and phenylalanine levels were increased in acute CAP, and the kynurenine/tryptophan ratio correlated best with clinical recovery and resolution of inflammation. Several amino acids did not reach normal levels by the 6-week follow-up. Glutamate levels were reduced on admission but rose during convalescence to 1.7-fold above levels measured in healthy control. Our data suggest that dysregulated amino acid metabolism in CAP partially persists through clinical recovery and that amino acid metabolism constitutes a source of promising biomarkers for CAP. In particular, total amino acids, asparagine, and threonine may constitute plasma biomarker candidates for the differentiation between CAP and infection-triggered COPD exacerbation and, perhaps, the detection of pneumonia in COPD.

Vertebrate replication forks arrested at interstrand DNA cross-links (ICLs) engage the Fanconi anemia pathway to incise arrested forks, 'unhooking' the ICL and forming a double strand break (DSB) that is repaired by homologous recombination (HR). The FANCP product, SLX4, in complex with the XPF (also known as FANCQ or ERCC4)-ERCC1 endonuclease, mediates ICL unhooking. Whether this mechanism operates at replication fork barriers other than ICLs is unknown. Here, we study the role of mouse SLX4 in HR triggered by a site-specific chromosomal DNA-protein replication fork barrier formed by the Escherichia coli-derived Tus-Ter complex. We show that SLX4-XPF is required for Tus-Ter-induced HR but not for error-free HR induced by a replication-independent DSB. We additionally uncover a role for SLX4-XPF in DSB-induced long-tract gene conversion, an error-prone HR pathway related to break-induced replication. Notably, Slx4 and Xpf mutants that are defective for Tus-Ter-induced HR are hypersensitive to ICLs and also to the DNA-protein cross-linking agents 5-aza-2 '-deoxycytidine and zebularine. Collectively, these findings show that SLX4-XPF can process DNA-protein fork barriers for HR and that the Tus-Ter system recapitulates this process. Elango et al. identify a new class of substrates on which the Fanconi anemia SLX4-XPF nuclease operates to mediate homologous recombination at DNA-protein replication fork barriers and promote cellular tolerance of DNA-protein cross-links.