The Th2 Response and Alternative Activation of Macrophages Triggered by Strongyloides venezuelensis Is Linked to Increased Morbidity and Mortality Due to Cryptococcosis in Mice.

Cryptococcosis is a systemic mycosis that causes pneumonia and meningoencephalitis. Strongyloidiasis is a chronic gastrointestinal infection caused by parasites of the genus Strongyloides. Cryptococcosis and strongyloidiasis affect the lungs and are more prevalent in the same world regions, i.e., Africa and tropical countries such as Brazil. It is undeniable that those coincidences may lead to the occurrence of coinfections. However, there are no studies focused on the interaction between Cryptococcus spp. and Strongyloides spp. In this work, we aimed to investigate the interaction between Strongyloides venezuelensis (Sv) and Cryptococcus gattii (Cg) in a murine coinfection model. Murine macrophage exposure to Sv antigens reduced their ability to engulf Cg and produce reactive oxygen species, increasing the ability of fungal growth intracellularly. We then infected mice with both pathogens. Sv infection skewed the host's response to fungal infection, increasing lethality in a murine coinfection model. In addition to increased NO levels and arginase activity, coinfected mice presented a classic Th2 anti-Sv response: eosinophilia, higher levels of alternate activated macrophages (M2), increased concentrations of CCL24 and IL-4, and lower levels of IL-1ß. This milieu favored fungal growth in the lungs with prominent translocation to the brain, increasing the host's tissue damage. In conclusion, our data shows that primary Sv infection promotes Th2 bias of the pulmonary response to Cg-infection and worsens its pathological outcomes.

Staphylococcus aureus triggers a protective inflammatory response against secondary Cryptococcus gattii infection in a murine model.

Prior infections can provide protection or enhance susceptibility to a subsequent infection through microorganism's interaction or host immunomodulation. Staphylococcus aureus (SA) and Cryptococcus gattii (CG) cause lungs infection, but it is unclear how they interact in vivo. This study aimed to study the effects of the primary SA lung infection on secondary cryptococcosis caused by CG in a murine model. The mice's survival, fungal burden, behavior, immune cells, cytokines, and chemokines were quantified to evaluate murine cryptococcosis under the influence of a previous SA infection. Further, fungal-bacterial in vitro interaction was studied in a culture medium and a phagocytosis assay. The primary infection with SA protects animals from the subsequent CG infection by reducing lethality, improving behavior, and impairing the fungal proliferation within the host. This phenotype was associated with the proinflammatory antifungal host response elicited by the bacteria in the early stage of cryptococcosis. There was no direct inhibition of CG by SA, although the phagocytic activity of macrophages was reduced. Identifying mechanisms involved in this protection may lead to new approaches for preventing and treating cryptococcosis.

Fcγ RIIb protects from reperfusion injury by controlling antibody and type I IFN-mediated tissue injury and death.

Intestinal ischemia and reperfusion (I/R) is accompanied by an exacerbated inflammatory response characterized by deposition of IgG, release of inflammatory mediators, and intense neutrophil influx in the small intestine, resulting in severe tissue injury and death. We hypothesized that Fcγ RIIb activation by deposited IgG could inhibit tissue damage during I/R. Our results showed that I/R induction led to the deposition of IgG in intestinal tissue during the reperfusion phase. Death upon I/R occurred earlier and was more frequent in Fcγ RIIb-/- than WT mice. The higher lethality rate was associated with greater tissue injury and bacterial translocation to other organs. Fcγ RIIb-/- mice presented changes in the amount and repertoire of circulating IgG, leading to increased IgG deposition in intestinal tissue upon reperfusion in these mice. Depletion of intestinal microbiota prevented antibody deposition and tissue damage in Fcγ RIIb-/- mice submitted to I/R. We also observed increased production of ROS on neutrophils harvested from the intestines of Fcγ RIIb-/- mice submitted to I/R. In contrast, Fcγ RIII-/- mice presented reduced tissue damage and neutrophil influx after reperfusion injury, a phenotype reversed by Fcγ RIIb blockade. In addition, we observed reduced IFN-ß expression in the intestines of Fcγ RIII-/- mice after I/R, a phenotype that was also reverted by blocking Fcγ RIIb. IFNAR-/- mice submitted to I/R presented reduced lethality and TNF release. Altogether our results demonstrate that antibody deposition triggers Fcγ RIIb to control IFN-ß and IFNAR activation and subsequent TNF release, tailoring tissue damage, and death induced by reperfusion injury.

Anti-inflammatory and antioxidant effects of the nanocomposite Fullerol decrease the severity of intestinal inflammation induced by gut ischemia and reperfusion.

Intestinal ischemia is a vascular emergency that arises when blood flow to the intestine is compromised. Reperfusion is necessary to restore intestinal function but might lead to local and systemic inflammatory responses and bacterial translocation, with consequent multiple organ dysfunction syndrome (MODS). During reperfusion occurs production of reactive oxygen species. These species contribute to intestinal injury through direct toxicity or activation of inflammatory pathways. Fullerol is a nanacomposite which has been shown to act as reactive oxygen species and reactive nitrogen species (RNS) scavengers. Thus, our aim was to evaluate whether Fullerol confer anti-inflammatory activity during intestinal ischemia and reperfusion (IIR). Intestinal ischemia was induced by total occlusion of the superior mesenteric artery. Groups were treated with vehicle or Fullerol 10 min before reperfusion. Mice were euthanized after 6 h of reperfusion, and small intestines were collected for evaluation of plasma extravasation, leukocyte influx, cytokine production and histological damage. Bacterial translocation to the peritoneal cavity and reactive oxygen and nitrogen species production by lamina propria cells were also evaluated. Our results showed that treatment with Fullerol inhibited bacterial translocation to the peritoneal cavity, delayed and decreased the lethality rates and diminished neutrophil influx and intestinal injury induced by IIR. Reduced severity of reperfusion injury in Fullerol-treated mice was associated with blunted reactive oxygen and nitrogen species production in leukocytes isolated from gut lamina propria and decreased production of pro-inflammatory mediators. Thus, the present study shows that Fullerol is a potential therapy to treat inflammatory bowel disorders associated with bacterial translocation, such as IIR.

Colonization by Enterobacteriaceae is crucial for acute inflammatory responses in murine small intestine via regulation of corticosterone production.

Although dysbiosis in the gut microbiota is known to be involved in several inflammatory diseases, whether any specific bacterial taxa control host response to inflammatory stimuli is still elusive. Here, we hypothesized that dysbiotic indigenous taxa could be involved in modulating host response to inflammatory triggers. To test this hypothesis, we conducted experiments in germ-free (GF) mice and in mice colonized with dysbiotic taxa identified in conventional (CV) mice subjected to chemotherapy-induced mucositis. First, we report that the absence of microbiota decreased inflammation and damage in the small intestine after administration of the chemotherapeutic agent 5-fluorouracil (5-FU). Also, 5-FU induced a shift in CV microbiota resulting in higher amounts of Enterobacteriaceae, including E. coli, in feces and small intestine and tissue damage. Prevention of Enterobacteriaceae outgrowth by treating mice with ciprofloxacin resulted in diminished 5-FU-induced tissue damage, indicating that this bacterial group is necessary for 5-FU-induced inflammatory response. In addition, monocolonization of germ-free (GF) mice with E. coli led to reversal of the protective phenotype during 5-FU chemotherapy. E. coli monocolonization decreased the basal plasma corticosterone levels and blockade of glucocorticoid receptor in GF mice restored inflammation upon 5-FU treatment. In contrast, treatment of CV mice with ciprofloxacin, that presented reduction of Enterobacteriaceae and E. coli content, induced an increase in corticosterone levels. Altogether, these findings demonstrate that Enterobacteriaceae outgrowth during dysbiosis impacts inflammation and tissue injury in the small intestine. Importantly, indigenous Enterobacteriaceae modulates host production of the anti-inflammatory steroid corticosterone and, consequently, controls inflammatory responsiveness in mice.

N-acetylcysteine reduces amphotericin B deoxycholate nephrotoxicity and improves the outcome of murine cryptococcosis.

Cryptococcosis is a life-threatening fungal infection, and its current treatment is toxic and subject to resistance. Drug repurposing represents an interesting approach to find drugs to reduce the toxicity of antifungals. In this study, we evaluated the combination of N-acetylcysteine (NAC) with amphotericin B (AMB) for the treatment of cryptococcosis. We examined the effects of NAC on fungal morphophysiology and on the macrophage fungicidal activity 3 and 24 hours post inoculation. The therapeutic effects of NAC combination with AMB were investigated in a murine model with daily treatments regimens. NAC alone reduced the oxidative burst generated by AMB in yeast cells, but did not inhibit fungal growth. The combination NAC + AMB decreased capsule size, zeta potential, superoxide dismutase activity and lipid peroxidation. In macrophage assays, NAC + AMB did not influence the phagocytosis, but induced fungal killing with different levels of oxidative bursts when compared to AMB alone: there was an increased reactive oxygen species (ROS) after 3 hours and reduced levels after 24 hours. By contrast, ROS remained elevated when AMB was tested alone, demonstrating that NAC reduced AMB oxidative effects without influencing its antifungal activity. Uninfected mice treated with NAC + AMB had lower concentrations of serum creatinine and glutamate-pyruvate transaminase in comparison to AMB. The combination of NAC + AMB was far better than AMB alone in increasing survival and reducing morbidity in murine-induced cryptococcosis, leading to reduced fungal burden in lungs and brain and also lower concentrations of pro-inflammatory cytokines in the lungs. In conclusion, NAC + AMB may represent an alternative adjuvant for the treatment of cryptococcosis.

Pioglitazone as an adjuvant of amphotericin B for the treatment of cryptococcosis.

Approximately 180,000 people worldwide die from cryptococcosis each year, probably due to the ineffectiveness and toxicity of drugs currently available to treat the disease. Amphotericin B (AMB) is effective for killing the fungus, but has serious adverse effects linked to excessive production of reactive oxygen species which compromise renal function. Pioglitazone (PIO) is a peroxisome proliferator-activated receptor-γ agonist widely repositioned as an adjuvant of various drugs that have toxic effects due to its antioxidant and anti-inflammatory effects. This study evaluated PIO in combination with AMB for the treatment of cryptococcosis. PIO was found to reduce serum creatinine and glutamic-oxalacetic transaminase levels in mice treated with PIO+AMB. In vitro, PIO was able to control harmful oxidative bursts induced by AMB without compromising the antifungal effect. In vivo, PIO+AMB increased the survival rate compared with AMB alone, and improved the morbidity of the animals. PIO+AMB was more efficient than AMB alone for inhibiting fungal transmigration from the lungs to the brain, and killing yeasts that reached the central nervous system, avoiding the establishment of meningoencephalitis. In a phagocytosis assay, PIO did not influence the engulfment and fungicidal activity of macrophages induced by AMB, but reduced the oxidative bursts after the reduction of fungal burden, pointing to control of the pathogen without leading to excessive stress which can be damaging to the host. In conclusion, PIO+AMB was found to ameliorate cryptococcosis in a murine model, indicating that it is a promising therapeutic adjuvant for combating and controlling this fungal infection.