Allelic heterogeneity in disease-causing genes presents a substantial challenge to the translation of genomic variation to clinical practice. Few of the almost 2,000 variants in the cystic fibrosis transmembrane conductance regulator (CFTR) gene have empirical evidence that they cause cystic fibrosis. To address this gap, we collected both genotype and phenotype data for 39,696 cystic fibrosis patients in registries and clinics in North America and Europe. Among these patients, 159 CFTR variants had an allele frequency of ≥0.01%. These variants were evaluated for both clinical severity and functional consequence with 127 (80%) meeting both clinical and functional criteria consistent with disease. Assessment of disease penetrance in 2,188 fathers of cystic fibrosis patients enabled assignment of 12 of the remaining 32 variants as neutral while the other 20 variants remained indeterminate. This study illustrates that sourcing data directly from well-phenotyped subjects can address the gap in our ability to interpret clinically-relevant genomic variation.

Severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) has rapidly caused a global pandemic associated with a novel respiratory infection: coronavirus disease-19 (COVID-19). Angiotensin-converting enzyme-2 (ACE2) is necessary to facilitate SARS-CoV-2 infection, but—owing to its essential metabolic roles—it may be difficult to target it in therapies. Transmembrane protease serine 2 (TMPRSS2), which interacts with ACE2, may be a better candidate for targeted therapies. Using publicly available expression data, we show that both ACE2 and TMPRSS2 are expressed in many host tissues, including lung. The highest expression of ACE2 is found in the testes, whereas the prostate displays the highest expression of TMPRSS2. Given the increased severity of disease among older men with SARS-CoV-2 infection, we address the potential roles of ACE2 and TMPRSS2 in their contribution to the sex differences in severity of disease. We show that expression levels of ACE2 and TMPRSS2 are overall comparable between men and women in multiple tissues, suggesting that differences in the expression levels of TMPRSS2 and ACE2 in the lung and other non–sex-specific tissues may not explain the gender disparities in severity of SARS CoV-2. However, given their instrumental roles for SARS-CoV-2 infection and their pleiotropic expression, targeting the activity and expression levels of TMPRSS2 is a rational approach to treat COVID-19.

Microglia are specialized brain macrophages that play numerous roles in tissue homeostasis and response to injury. Colony stimulating factor 1 receptor (CSF1R) is a receptor tyrosine kinase required for the development, maintenance, and proliferation of microglia. Here we show that in adult mice peripheral dosing of function-blocking antibodies to the two known ligands of CSF1R, CSF1, and IL-34, can deplete microglia differentially in white and gray matter regions of the brain, respectively. The regional patterns of depletion correspond to the differential expression of CSF1 and IL-34. In addition, we show that while CSF1 is required to establish microglia in the developing embryo, both CSF1 and IL-34 are required beginning in early postnatal development. These results not only clarify the roles of CSF1 and IL-34 in microglia maintenance, but also suggest that signaling through these two ligands might support distinct sub-populations of microglia, an insight that may impact drug development for neurodegenerative and other diseases.

Pathogenic yeasts from the genus Candida can cause serious infection in humans particularly, in immunocompromised patients and are now recognized as major agents of hospital acquired (nosocomial) infections. In the recent years, there has been a marked increase in the incidence of treatment failures in candidiasis patients receiving long-term antifungal therapy, which has posed a serious problem in its successful use in chemotherapy. Candida cells acquire drug resistance (MDR) during the course of the treatment. The mechanisms of resistance to azole antifungal agents have been elucidated in Candida species and can be mainly categorized as (i) changes in the cell wall or plasma membrane, which lead to impaired drug (azole) uptake; (ii) alterations in the affinity of the drug target Erg11p (lanosterol 14alpha-demethylase) especially to azoles or in the cellular content of Erg11p due to target site mutation or overexpression of the ERG11 gene; and (iii) the efflux of drugs mediated by membrane transport proteins belonging to the ATP-binding cassette (ABC) transporters, namely CDR1 and CDR2 or to the major facilitator superfamily (MFS) transporter, CaMDR1. Many such manifestations are associated with the formation of Candida biofilms including those occurring on devices like indwelling intravascular catheters. Biofilm-associated Candida show uniform resistance to a wide spectrum of antifungal drugs. A combination of different resistance mechanisms is responsible for drug resistance in clinical isolates of Candida species.

Alarmins are a group of structurally diverse host defense antimicrobial peptides that are important immune activators. Here we present a novel role of two potent alarmins, human beta defensin 2 and 3 (HBD2 and 3) in promoting IFN-α production by human plasmacytoid DCs (pDCs). We demonstrate that HBD2 and 3 activate pDCs by enhancing the intracellular uptake of CpG and self DNA and promote DNA induced IFN-α production in a TLR9 dependent manner. Both CpG and host DNA form aggregates that resemble DNA nets when combined with HBD2 and 3. Isothermal Titration Calorimetry (ITC) studies to elucidate the nature of HBD3-CpG complexes demonstrates involvement of enthalpy driven interactions in addition to hydrophobic interactions with the formation of complexes at a molar ratio of 2:1 defensin/CpG. Intravenous administration of HBD3-CpG complexes induced proinflammatory cytokines like IL-12, IFN-γ, IL-6, IFN-α and IL-10 in serum associated with an increased recruitment of antigen presenting cells (APCs) in the spleen. Subcutaneous injections of these complexes showed enhanced infiltration of inflammatory cells at injection site indicating a potential pathophysiological role of alarmin/DNA complexes in contributing to inflammation. Intraperitoneal immunization of HBD3/CpG complexes with OVA enhanced both cellular and humoral responses in response to OVA as compared to OVA/HBD3 or OVA/CPG alone, indicative of a much more potent adjuvant effect of the HBD3/CpG complexes. Thus the ability of defensins to enhance cellular uptake of nucleic acids can lead to improved vaccine formulations by promoting their uptake by various cells resulting in an enhanced immune response.