Redox profile and mediators of the unfolded protein response (UPR) in the placenta of rats during pregnancy.

CONTEXT: Proliferation, differentiation, migration and apoptosis of trophoblastic cells are influenced by hypoxia, as well as adequate modulation of oxidative stress and the unfolded protein response (UPR) pathway. AIMS: We aimed to evaluate the expression profile of redox and UPR mediators in the placenta of rats throughout pregnancy. METHODS: Placental expression of hypoxia-inducible factor 1α (HIF1α), 8-Hydroxy-2'-deoxyguanosine (8-OHdG), superoxide dismutase 1 (SOD1), glutathione peroxidase (GPX), catalase (Cat), activating transcription factor 6 (ATF6), protein kinase RNA-like endoplasmic reticulum kinase (PERK), 78 kD glucose-regulated protein (GRP78) and C/EBP-homologous protein (CHOP), as well as reactive oxygen species (ROS) and peroxynitrite production, were evaluated in Wistar rats on the 10th, 12th, 14th, 16th and 18th day of pregnancy (DP). KEY RESULTS: Increased immunostaining of HIF1α was observed on the 16th and 18th DP, while 8-OHdG and ROS production were greater on the 14th DP. SOD1 and Cat had increased immunostaining on the 14th and 18th DP, while staining of GPX1/2, GRP78 and CHOP was greater on the 18th DP. With regard to gene expression, Hif1α and Sod1 showed increased mRNA expression on the 12th and 16th DP, while Gpx1 had increased expression on the 10th and 16th DP. Cat , Perk and Grp78 gene expression was greater on the 14th DP, unlike Atf6 , which showed greater expression on the 12th DP. In contrast, Chop maintained increased expression from the 12th to the 18th DP. CONCLUSIONS: The placental expression of redox and UPR mediators in rats is influenced by gestational age, with greater expression in periods of greater HIF1α and 8-OHdG expression and at the end of the pregnancy. IMPLICATIONS: This study provides data on the physiological modulation of redox and UPR mediators during placental development in rats.

The absence of microbiota delays the inflammatory response to Cryptococcus gattii.

The inflammatory response plays a crucial role in infectious diseases, and the intestinal microbiota is linked to maturation of the immune system. However, the association between microbiota and the response against fungal infections has not been elucidated. Our aim was to evaluate the influence of microbiota on Cryptococcus gattii infection. Germ-free (GF), conventional (CV), conventionalized (CVN-mice that received feces from conventional animals), and LPS-stimulated mice were infected with C. gattii. GF mice were more susceptible to infection, showing lower survival, higher fungal burden in the lungs and brain, increased behavioral changes, reduced levels of IFN-γ, IL-1ß and IL-17, and lower NFκBp65 phosphorylation compared to CV mice. Low expression of inflammatory cytokines was associated with smaller yeast cells and polysaccharide capsules (the main virulence factor of C. gattii) in the lungs, and less tissue damage. Furthermore, macrophages from GF mice showed reduced ability to engulf, produce ROS, and kill C. gattii. Restoration of microbiota (CVN mice) or LPS administration made GF mice more responsive to infection, which was associated with increased survival and higher levels of inflammatory mediators. This study is the first to demonstrate the influence of microbiota in the host response against C. gattii.

Heteroresistance to Itraconazole Alters the Morphology and Increases the Virulence of Cryptococcus gattii.

Cryptococcus gattii is the main etiological agent of cryptococcosis in immunocompetent individuals. The triazole drug itraconazole is one of the antifungals used to treat patients with cryptococcosis. Heteroresistance is an adaptive mechanism to counteract the stress of increasing drug concentrations, and it can enhance the ability of a microorganism to survive under antifungal pressure. In this study, we evaluated the ability of 11 C. gattii strains to develop itraconazole heteroresistance. Heteroresistant clones were analyzed for drug susceptibility, alterations in cell diameter, capsule properties, and virulence in a murine model. Heteroresistance to itraconazole was intrinsic in all of the strains analyzed, reduced both the capsule size and the cell diameter, induced molecular heterogeneity at the chromosomal level, changed the negatively charged cells, reduced ergosterol content, and improved the antioxidant system. A positive correlation between surface/volume ratio of original cells and the level of heteroresistance to itraconazole (LHI) was observed in addition to a negative correlation between capsule size of heteroresistant clones and LHI. Moreover, heteroresistance to itraconazole increased the engulfment of C. gattii by macrophages and augmented fungal proliferation inside these cells, which probably accounted for the reduced survival of the mice infected with the heteroresistant clones and the higher fungal burden in lungs and brain. Our results indicate that heteroresistance to itraconazole is intrinsic and increases the virulence of C. gattii. This phenomenon may represent an additional mechanism that contributes to relapses of cryptococcosis in patients during itraconazole therapy.