Murine Inducible Nitric Oxide Synthase Expression Is Essential for Antifungal Defenses in Kidneys during Disseminated Cryptococcus deneoformans Infection

Abstract

Disseminated cryptococcosis has a nearly 70% mortality, mostly attributed to CNS infection, with lesser-known effects on other organs. Immune protection against Cryptococcus relies on Th1 immunity with M1 polarization, rendering macrophages fungicidal. The importance of M1-upregulated inducible NO synthase (iNOS) has been documented in pulmonary anticryptococcal defenses, whereas its role in disseminated cryptococcosis remains controversial. Here we examined the effect of iNOS deletion in disseminated (i.v.) C. deneoformans 52D infection, comparing wild-type (C57BL/6J) and iNOS−/− mice. iNOS−/− mice had significantly reduced survival and nearly 100-fold increase of the kidney fungal burden, without increases in the lungs, spleen, or brain. Histology revealed extensive lesions and almost complete destruction of the kidney cortical area with a loss of kidney function. The lack of fungal control was not due to a failure to recruit immune cells because iNOS−/− mice had increased kidney leukocytes. iNOS−/− mice also showed no defect in T cell polarization. We conclude that iNOS is critically required for local anticryptococcal defenses in the kidneys, whereas it appears to be dispensable in other organs during disseminated infection. This study exemplifies a unique phenotype of local immune defenses in the kidneys and the organ-specific importance of a single fungicidal pathway.

Batf3-dependent orchestration of the robust Th1 responses and fungal control during cryptococcal infection, the role of cDC1

“…To further understand the implications of Batf3-dependent cDC1, we probed their potential impact on the host’s ability to effectively combat fungal infection. We first examined the transcript level of the Nos2 (inducible nitric oxide synthase 2), a widely used marker of classical macrophage activation and fungicidal macrophages ( 39 – 41 ). We found a sharp decline in Nos2 gene expression in the lungs, brains, and spleens of Batf3 −/− mice in contrast to their WT counterparts ( Fig.…”

Acidity‐Activatable Nanoparticles with Glucose Oxidase‐Enhanced Photoacoustic Imaging and Photothermal Effect, and Macrophage‐Related Immunomodulation for Synergistic Treatment of Biofilm Infection

“…Activated by the innate immune system, an acute inflammatory reaction is initiated by immune cells enabling secretion of the cytokines to recruit other immune cells to the infectious site. [ 55 ] Infection is accompanied by the production of proinflammatory cytokines (such as IL‐6 and TNF‐α), which causes a proinflammatory immune microenvironment that facilitates bacteria clearance and biofilm eradication in vivo. [ 56 ] The immunofluorescence staining images (Figure 9d) displayed that the secretion of IL‐6 and TNF‐α by M1 macrophages for GB@P+NIR and GB@P was higher than PBS, PBS+NIR, B@P, and B@P+NIR.…”

The Cryptococcus neoformans Flc1 Homologue Controls Calcium Homeostasis and Confers Fungal Pathogenicity in the Infected Hosts

“…All isolated cells were stained with fixable live/dead dye (Life Technologies), blocked with anti-CD16/32, and stained with CD45. Flow cytometry protocol was adapted from previous work ( 81 , 82 ). Gating of CD45 subpopulations on CD4 and CD8 generated CD4 + T cells, CD8 + T cells, CD4 + /CD8 + cells and CD4 − /CD8 − cells.…”

“…(vi) Histology. Histology was performed as previously described ( 81 ). Lungs were slightly perfused with PBS, then inflated with 10% neutral buffered formalin prior to removal and fixation with 10% neutral buffered formalin.…”