Research ArticleInfectious Disease

CXCR1-mediated neutrophil degranulation and fungal killing promote Candida clearance and host survival

Science Translational Medicine  20 Jan 2016:
Vol. 8, Issue 322, pp. 322ra10
DOI: 10.1126/scitranslmed.aac7718

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Candida camera

The yeast Candida albicans can live symbiotically in human gut and skin, but when it penetrates the mucosal barrier and enters the bloodstream, it can cause life-threatening systemic infection. Now, Swamydas et al. provide a look at how neutrophils control Candida. They show that the neutrophil-selective chemokine receptor Cxcr1 plays a critical role in antifungal host defense. Mice lacking Cxcr1 were more susceptible to systemic candidiasis because of defective neutrophil-mediated fungal killing. Neutrophils from humans with a mutant CXCR1 allele also had defective fungal response. These data suggest that Cxcr1 is critical for innate host defense against fungal infection.

Abstract

Systemic Candida albicans infection causes high morbidity and mortality and is now the leading cause of nosocomial bloodstream infection in the United States. Neutropenia is a major risk factor for poor outcome in infected patients; however, the molecular factors that mediate neutrophil trafficking and effector function during infection are poorly defined. Using a mouse model of systemic candidiasis, we found that the neutrophil-selective CXC chemokine receptor Cxcr1 and its ligand, Cxcl5, are highly induced in the Candida-infected kidney, the target organ in the model. To investigate the role of Cxcr1 in antifungal host defense in vivo, we generated Cxcr1−/− mice and analyzed their immune response to Candida. Mice lacking Cxcr1 exhibited decreased survival with enhanced Candida growth in the kidney and renal failure. Increased susceptibility of Cxcr1−/− mice to systemic candidiasis was not due to impaired neutrophil trafficking from the blood into the infected kidney but was the result of defective killing of the fungus by neutrophils that exhibited a cell-intrinsic decrease in degranulation. In humans, the mutant CXCR1 allele CXCR1-T276 results in impaired neutrophil degranulation and fungal killing and was associated with increased risk of disseminated candidiasis in infected patients. Together, our data demonstrate a biological function for mouse Cxcr1 in vivo and indicate that CXCR1-dependent neutrophil effector function is a critical innate protective mechanism of fungal clearance and host survival in systemic candidiasis.

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