Cell composition analysis of bulk genomics using single-cell data.

Single-cell RNA sequencing (scRNA-seq) is a rich resource of cellular heterogeneity, opening new avenues in the study of complex tissues. We introduce Cell Population Mapping (CPM), a deconvolution algorithm in which reference scRNA-seq profiles are leveraged to infer the composition of cell types and states from bulk transcriptome data ('scBio' CRAN R-package). Analysis of individual variations in lungs of influenza-virus-infected mice reveals that the relationship between cell abundance and clinical symptoms is a cell-state-specific property that varies gradually along the continuum of cell-activation states. The gradual change is confirmed in subsequent experiments and is further explained by a mathematical model in which clinical outcomes relate to cell-state dynamics along the activation process. Our results demonstrate the power of CPM in reconstructing the continuous spectrum of cell states within heterogeneous tissues.

Gene polymorphisms in pattern recognition receptors and susceptibility to idiopathic recurrent vulvovaginal candidiasis.

OBJECTIVE: Approximately 5% of women suffer from recurrent vulvovaginal candidiasis (RVVC). It has been hypothesized that genetic factors play an important role in the susceptibility to RVVC. The aim of this study was to assess the effect of genetic variants of genes encoding for pattern recognition receptors (PRRs) on susceptibility to RVVC. STUDY DESIGN: For the study, 119 RVVC patients and 263 healthy controls were recruited. Prevalence of polymorphisms in five PRRs involved in recognition of Candida were investigated in patients and controls. In silico and functional studies were performed to assess their functional effects. RESULTS: Single nucleotide polymorphisms (SNPs) in TLR1, TLR4, CLEC7A, and CARD9 did not affect the susceptibility to RVVC. In contrast, a non-synonymous polymorphism in TLR2 (rs5743704, Pro631His) increased the susceptibility to RVVC almost 3-fold. Furthermore, the TLR2 rs5743704 SNP had deleterious effects on protein function as assessed by in silico analysis, and in vitro functional assays suggested that it reduces production of IL-17 and IFNγ upon stimulation of peripheral blood mononuclear cells with Candida albicans. No effects were observed on serum mannose-binding lectin concentrations. CONDENSATION: This study demonstrates the association of susceptibility to RVVC with genetic variation in TLR2, most likely caused by decreased induction of mucosal antifungal host defense. CONCLUSION: Genetic variation in TLR2 may significantly enhance susceptibility to RVVC by modulating host defense mechanisms against Candida. Additional studies are warranted to assess systematically the role of host genetic variation for susceptibility to RVVC.

Role of autophagy genetic variants for the risk of Candida infections.

Candida albicans can cause candidemia in neutropenic and critically ill patients and oropharyngeal candidiasis in human immunodeficiency virus (HIV)-positive patients with low CD4(+) counts. Because all patients at risk do not develop Candida infections, it is possible that a patient's genetic background might play a role in his or her susceptibility to infection. Autophagy mediates pathogen clearance and modulation of inflammation. Our aim was to assess the effect of genetic variations in the ATG16L1 and IRGM autophagy genes on the susceptibility of patients with candidemia and oropharyngeal candidiasis. We assessed genetic variations in the ATG16L1 and IRGM genes in a cohort of candidemia patients of both African and European origin. In addition, we evaluated the effect of these polymorphisms on the susceptibility to oropharyngeal candidiasis of an HIV-positive cohort from Tanzania. Functional studies have been performed to assess the effect of the ATG16L1 and IRGM genetic variants on both in vitro and in vivo cytokine production. The results indicate that ATG16L1 variants modulate production of tumor necrosis factor-alpha, but not other cytokines, while no effects were seen in the presence of IRGM polymorphisms. In addition, no significant associations between the single-nucleotide polymorphisms in the ATG16L1 and IRGM genetic variants and the incidence of candidemia or oropharyngeal candidiasis were identified. Despite moderate effects on the modulation of proinflammatory cytokine production, genetic variation in the autophagy genes ATG16L1 and IRGM has a minor impact on the susceptibility to both mucosal and systemic Candida infections.

IRGM gene polymorphisms and risk of gastric cancer.

OBJECTIVE: The study aimed to assess the possible association of polymorphisms in the autophagy gene IRGM (rs13361189 and rs4958847) with the risk of gastric cancer. METHODS: A total of 102 patients with gastric adenocarcinoma, 52 with chronic gastritis and 351 healthy controls were included in this study. IRGM allelic variants were genotyped by quantitative real-time polymerase chain reaction. The association between polymorphisms and gastric cancer risk was estimated by odds ratios (OR) and 95% confidence interval (CI). RESULTS: A significant difference was found for rs4958847 A allele. Carriers of the A allele were protected against gastric cancer (OR = 0.58, 95% CI 0.35-0.97, P = 0.038). Moreover, the presence of this allele seems to play an important role in decreasing the risk for the intestinal type of gastric cancer (OR = 0.47, 95% CI 0.23-0.94, P = 0.03). In contrast, the rs13361189 IRGM polymorphism was not associated with susceptibility to gastric cancer. None of the targeted polymorphisms were associated with chronic gastritis. CONCLUSION: IRGM rs4958847 polymorphism influences susceptibility to gastric cancer, mainly for the intestinal type.

Variation in genes of ß-glucan recognition pathway and susceptibility to opportunistic infections in HIV-positive patients.

Opportunistic infections are the main cause of morbidity and death among HIV-positive patients. Most of these infections are linked to the immunodeficiency due to low CD4+ counts. However, not all patients with low CD4+ counts are equally susceptible to infections, and we hypothesize that variability in genes of innate immunity may also play an important role. The dectin-1/CARD9 pathway is crucial for recognition of both fungal and bacterial pathogens. The aim of this study was to assess the possible association between the occurrence of opportunistic infections and single nucleotide polymorphisms in DECTIN-1 and CARD9 in a cohort of 187 HIV-infected patients. The incidence of oropharyngeal candidiasis and other opportunistic infections was not influenced by either the Y238X DECTIN-1 or the S12N CARD9 polymorphism. Surprisingly however, the prevalence of pneumonia was significantly higher in patients bearing the defective variant DECTIN-1 allele. These results suggest a role of dectin-1 in the host defense against respiratory bacterial infections, and future studies are warranted to confirm this association.

Genetic variation in the dectin-1/CARD9 recognition pathway and susceptibility to candidemia.

BACKGROUND: Candidemia is an important cause of morbidity and mortality in critically ill patients or patients undergoing invasive treatments. Dectin-1 is the main ß-glucan receptor, and patients with a complete deficiency of either dectin-1 or its adaptor molecule CARD9 display persistent mucosal infections with Candida albicans. The role of genetic variation of DECTIN-1 and CARD9 genes on the susceptibility to candidemia is unknown. METHODS: We assessed whether genetic variation in the genes encoding dectin-1 and CARD9 influence the susceptibility to candidemia and/or the clinical course of the infection in a large cohort of American and Dutch candidemia patients (n = 331) and noninfected matched controls (n = 351). Furthermore, functional studies have been performed to assess the effect of the DECTIN-1 and CARD9 genetic variants on cytokine production in vitro and in vivo in the infected patients. RESULTS: No significant association between the single-nucleotide polymorphisms DECTIN-1 Y238X and CARD9 S12N and the prevalence of candidemia was found, despite the association of the DECTIN-1 238X allele with impaired in vitro and in vivo cytokine production. CONCLUSIONS: Whereas the dectin-1/CARD9 signaling pathway is nonredundant in mucosal immunity to C. albicans, a partial deficiency of ß-glucan recognition has a minor impact on susceptibility to candidemia.

STAT1 mutations in autosomal dominant chronic mucocutaneous candidiasis.

BACKGROUND: Chronic mucocutaneous candidiasis (CMC) is characterized by susceptibility to candida infection of skin, nails, and mucous membranes. Patients with recessive CMC and autoimmunity have mutations in the autoimmune regulator AIRE. The cause of autosomal dominant CMC is unknown. METHODS: We evaluated 14 patients from five families with autosomal dominant CMC. We incubated their peripheral-blood mononuclear cells with different combinations of stimuli to test the integrity of pathways that mediate immunity, which led to the selection of 100 genes that were most likely to contain the genetic defect. We used an array-based sequence-capture assay, followed by next-generation sequencing, to identify mutations. RESULTS: The mononuclear cells from the affected patients were characterized by poor production of interferon-γ, interleukin-17, and interleukin-22, suggesting that the defect lay within the interleukin-12 receptor and interleukin-23 receptor signaling pathways. We identified heterozygous missense mutations in the DNA sequence encoding the coiled-coil (CC) domain of signal transducer and activator of transcription 1 (STAT1) in the patients. These mutations lead to defective responses in type 1 and type 17 helper T cells (Th1 and Th17). The interferon-γ receptor pathway was intact in these patients. CONCLUSIONS: Mutations in the CC domain of STAT1 underlie autosomal dominant CMC and lead to defective Th1 and Th17 responses, which may explain the increased susceptibility to fungal infection. (Funded by the Netherlands Organization for Scientific Research and others.).