Neide Maria Silva

Toxoplasma gondii triggered ileitis is a commonly used model for diseases affecting the small intestine, such as Crohn's Disease. Inflammation is primarily dependent on Th1‐mediated killing of Paneth cells, which consequently promotes intestinal dysbiosis and boosts inflammation and pathology in the organs. Priming of the immune system with soluble Toxoplasma antigen (STAG) has been shown to induce immune regulation in several inflammatory diseases. Herein, we describe how protection of Paneth cells by priming with STAG is associated with protection against T. gondii triggered ileitis. We observed that STAG priming diminished intestinal pathology and modulated cytokine profile, and specifically downregulates interferon expression. Consequently, priming with STAG sustained Paneth‐cell numbers during infection, unlike non‐immunized controls, and thus also retained antimicrobial protein expression. Interestingly, we show that naturally resistant BALB/c mice did not undergo total Paneth‐cell ablation, but upon additional Paneth‐cell depletion, presented intestinal pathology and tissue parasitism levels similar to susceptible C57BL/6. Finally, we show that the STAG‐primed groups presented a different intestinal microbiota, primarily through promotion of a protective microbiota enriched in Firmicutes and depleted of Enterobacteriaceae. Thus, the results suggest that priming with STAG is able to prevent Paneth‐cell depletion and is associated with resistance to T. gondii triggered ileitis.

Chronic toxoplasmosis begins when tachyzoites cross the blood–brain barrier and enter the Central Nervous System (CNS). There, they differentiate into bradyzoites, which persist in tissue cysts. Here, we investigate changes in host gene expression in the mouse brain by RNA sequencing at different time points during chronic toxoplasmosis. We show a conserved gene expression pattern caused by the infection, primarily associated with cytotoxic immune responses against the parasite and neuronal degeneration, regardless of the time point. Surprisingly, we observed that genes associated with B cell function continuously increased over time, whilst cytotoxic responses decreased. Immunoglobulin gene expression and IgA staining showed that B cells were absent from healthy brains. Following infection, they accumulated near penetrating vessels and infiltrated the brain parenchyma. Additionally, these plasma cells produced T. gondii -specific IgA. Our results show a previously unrecognized expansion of brain B cells in late chronic toxoplasmosis.

Anais do Congresso de Fisiologia e Patologia (978-65-272-1162-4) - Impacto Do Toxoplasma Gondii No Sistema Nervoso Central: Alterações Comportamentais E Aspectos Neuroinflamatórios

Toxoplasmosis is a neglected disease that represents a significant public health problem. The antigenic profile of T. gondii is complex, and the immune response can lead to either susceptibility or resistance. Some antigens, such as surface antigen glycoprotein (SAG), are expressed on the surface of tachyzoite stages and interact with the host immune cells. In this study, we investigated the potential of the recombinant SAG2A protein of T. gondii to control parasitism and modulate the immune response in the peritoneal exudate cells (PECs) of both susceptible (C57BL/6) and resistant (BALB/c) mice using an in vitro infection model, gene expression, proteomic analysis, and bioinformatic tools. Our results showed that rSAG2A-treated PECs presented a lower parasitism in C57BL/6 mice but not in the PECs from BALB/c mice, and induced a pro-inflammatory cytokine profile in C57BL/6 mice (iNOS, TNF-α, and IL-6). rSAG2A modulated different exclusive proteins in each mouse lineage, with PECs from the C57BL/6 mice being more sensitive to modulation by rSAG2A. Additionally, biological processes crucial to parasite survival and immune response were modulated by rSAG2A in the C57BL/6 PECs, including fatty acid beta-oxidation, reactive oxygen species metabolism, interferon production, and cytokine-mediated signaling pathways. Together, our study indicates that rSAG2A controls T. gondii parasitism in susceptible C57BL/6 PECs through the modulation of pro-inflammatory cytokines and enhanced expression of proteins involved in the cytotoxic response.

The murine model of experimental cerebral malaria (ECM) induced by Plasmodium berghei ANKA was used to investigate the relationship among pro-inflammatory cytokines, alterations in renal function biomarkers, and the induction of the TRAIL apoptosis pathway during malaria-associated acute kidney injury (AKI). Renal function was evaluated through the measurement of plasma creatinine and blood urea nitrogen (BUN). The mRNA expression of several cytokines and NaPi-IIa was quantified. Kidney sections were examined and cytokine levels were assessed using cytometric bead array (CBA) assays. The presence of glomerular IgG deposits and apoptosis-related proteins were investigated using in situ immunofluorescence assays and quantitative real-time PCR, respectively. NaPi-IIa downregulation in the kidneys provided novel insights into the pathogenesis of hypophosphatemia during CM. Histopathological analysis revealed characteristic features of severe malaria-associated nephritis, including glomerular collapse and tubular alterations. Pro-inflammatory cytokines, such as TNF-α, IL-1β, and IL-6, were upregulated. The TRAIL apoptosis pathway was significantly activated, implicating its role in renal apoptosis. The observed alterations in renal biomarkers and the downregulation of NaPi-IIa shed light on potential mechanisms contributing to renal dysfunction in ECM. The intricate balance between pro- and anti-inflammatory cytokines, along with the activation of the TRAIL apoptosis pathway, highlights the complexity of malaria-associated AKI and provides new therapeutic targets.