Toxoplasma gondii infection causes structural changes in the jejunum of rats infected with different inoculum doses

Mastocytosis and intraepithelial lymphocytosis in the ileum and colon characterize chronic Toxoplasma gondii infection in mice

Toxoplasma gondii is the causative agent of toxoplasmosis, a common zoonotic disease affecting vertebrates with high global incidence. For the parasite to disseminate throughout the body, it crosses the intestinal barrier, triggering inflammatory reactions. This study aimed to assess the tissue response in the ileum and colon of mice following chronic infection with T. gondii. Fourteen mice were divided into two groups: the infected group received 1000 T. gondii oocysts via gavage, and after 60 days, the mice were euthanized. The ileum and colon were collected and processed for histological analysis, inflammatory marker measurement and myenteric neuron analysis. Chronic infection resulted in a significant increase in intraepithelial lymphocytes and mast cells, as well as morphometric changes such as increased total intestinal wall thickness of the ileum, crypt depth, collagen fiber area, and a decrease in myeloperoxidase activity, without altering nitric oxide levels. While the number of myenteric neurons remained unchanged, there was an increase in vasoactive intestinal peptide expression. These results suggest persistence intestinal inflammatory stimuli in chronic T. gondii infection.

Heligmosomoides bakeri and Toxoplasma gondii co-infection leads to increased mortality associated with changes in immune resistance in the lymphoid compartment and disease pathology

Co-infections are a common reality but understanding how the immune system responds in this context is complex and can be unpredictable. Heligmosomoides bakeri (parasitic roundworm, previously Heligmosomoides polygyrus) and Toxoplasma gondii (protozoan parasite) are well studied organisms that stimulate a characteristic Th2 and Th1 response, respectively. Several studies have demonstrated reduced inflammatory cytokine responses in animals co-infected with such organisms. However, while general cytokine signatures have been examined, the impact of the different cytokine producing lymphocytes on parasite control/clearance is not fully understood. We investigated five different lymphocyte populations (NK, NKT, γδ T, CD4+ T and CD8+ T cells), five organs (small intestine, Peyer's patches, mesenteric lymph nodes, spleen and liver), and 4 cytokines (IFN©, IL-4, IL-10 and IL-13) at two different time points (days 5 and 10 post T. gondii infection). We found that co-infected animals had significantly higher mortality than either single infection. This was accompanied by transient and local changes in parasite loads and cytokine profiles. Despite the early changes in lymphocyte and cytokine profiles, severe intestinal pathology in co-infected mice likely contributed to early mortality due to significant damage by both parasites in the small intestine. Our work demonstrates the importance of taking a broad view during infection research, studying multiple cell types, organs/tissues and time points to link and/or uncouple immunological from pathological findings. Our results provide insights into how co-infection with parasites stimulating different arms of the immune system can lead to drastic changes in infection dynamics.

Protective effect of alpha-ketoglutarate against water-immersion restraint stress-induced gastric mucosal damage in mice

Gastric lesions have several aetiologies, among which stress is the most prominent. Therefore, identification of new therapies to prevent stress is of considerable importance. Alpha-ketoglutarate (α-kg) several beneficial effects and has shown promise in combating oxidative stress, inflammation, and premature aging. Thus, this study aimed to evaluate the protective effect of α-kg in a gastric damage model by water-immersion restraint stress (WIRS). Pretreatment with α-kg decreased stress-related histopathological scores of tissue oedema, cell loss, and inflammatory infiltration. The α-kg restored the percentage of type III collagen fibres. Mucin levels were preserved as well as the structure and area of the myenteric plexus ganglia were preserved after pretreatment with α-kg. Myeloperoxidase (MPO) levels and the expression of pro-inflammatory cytokines (TNF-α and IL-1β) were also reduced following α-kg pretreatment. Decreased levels of glutathione (GSH) in the stress group were restored by α-kg. The omeprazole group was used as standard drug e also demonstrated improve on some parameters after the exposition to WIRS as inflammatory indexes, GSH and mucin. Through this, was possible to observe that α-kg can protect the gastric mucosa exposed to WIRS, preserve tissue architecture, reduce direct damage to the mucosa and inflammatory factors, stimulate the production of type III collagen and mucin, preserve the myenteric plexus ganglia, and maintain antioxidant potential. Due to, we indicate that α-kg has protective activity of the gastric mucosa, demonstrating its ability to prevent damage associated with gastric lesions caused by stress.

CPW partially attenuates DSS-induced ulcerative colitis in mice

Ulcerative colitis (UC) is a chronic inflammatory bowel disease (IBD) of the gastrointestinal tract. The etiology is not fully understood, but environmental, microbial, and immunologic factors, as well as a genetic predisposition, play a role. UC is characterized by episodes of abdominal pain, diarrhea, bloody stools, weight loss, severe colonic inflammation, and ulceration. Despite the increase in the frequency of UC and the deterioration of the quality of life, there are still patients who do not respond well to available treatment options. Against this background, natural products such as polysaccharides are becoming increasingly important as they protect the intestinal mucosa, promote wound healing, relieve inflammation and pain, and restore intestinal motility. In this study, we investigated the effect of a polysaccharide isolated from the biomass of Campomanesia adamantium and Campomanesia pubescens (here referred to as CPW) in an experimental model of acute and chronic ulcerative colitis induced by dextran sulfate sodium (DSS). CPW reversed weight loss, increased disease activity index (DAI), bloody diarrhea, and colon shortening. In addition, CPW reduced visceral mechanical hypersensitivity, controlled oxidative stress and inflammation, and protected the mucosal barrier. CPW is not absorbed in the intestine, does not inhibit cytochrome P450 proteins, and does not exhibit AMES toxicity. These results suggest that CPW attenuates DSS-induced acute and chronic colitis in mice and may be a potential alternative treatment for UC.

Perinatal and post-weaning exposure to a high-fat diet causes histomorphometric, neuroplastic, and histopathological changes in the rat ileum

Exposure to a diet with a high saturated fat content can influence the characteristics of the gastrointestinal tract, causing losses in the absorption of nutrients and favoring the appearance of diseases. The objective was to assess the effects of a high-fat diet (HFD) in the perinatal (pregnancy and lactation) and post-weaning period on the histomorphometry, neuroplasticity, and histopathology of the ileum. Wistar rats were divided into four subgroups: Control/Control (CC, n = 10) rats fed a control diet (C) throughout the trial period; Control/HFD (CH, n = 9) rats fed diet C (perinatal) and HFD after weaning; HFD/Control (HC, n = 10) rats fed HFD (perinatal) and diet C (post-weaning); HFD/HFD (HH, n = 9) rats fed HFD throughout the experimental period. There was atrophy of the Ileum wall with a reduction in the muscular tunic, submucosa, and mucosa thickness in the HH group of 37%, 28%, and 46%, respectively (p < 0.0001). The depth of the crypts decreased by 29% (p < 0.0001) and height increased by 5% (p < 0.0013). Villus height decreased by 41% and 18% in HH and HC groups (p < 0.0001) and width decreased by 11% in the HH (p < 0.0001). The height of the enterocytes decreased by 18% in the HH (p < 0.0001). There was a decrease in the area of the myenteric and submucosal plexus ganglia in the HH and HC groups (p < 0.0001). The number, occupation, and granules of Paneth cells increased in the HH and HC groups (p < 0.0001). Intraepithelial lymphocytes (IELs) increased in all groups exposed to the HFD. Goblet cells decreased in groups CH and HH (p < 0.0001). The evidence from this study suggests that the HFD had altered the histomorphometry, neuroplasticity, and histopathology of the ileum of the rats.

Moderate intestinal immunopathology after acute oral infection with Toxoplasma gondii oocysts is associated with expressive levels of serotonin

BACKGROUND

Invasion of the intestinal mucosa by T. gondii elicits a local immune response of variable intensity. These reactions can be lethal in C57BL/6 mice. The tissue damage caused by inflammation and the functional effects depend on the host immunity, strain, and developmental form of the parasite. We investigated the effects of acute oral infection with T. gondii on histoarchitecture, enteric nervous system (ENS), and inflammatory markers in the jejunum and ileum of mice.

METHODS

Female C57BL/6 mice were divided into a control group and a group orally infected with 1000 sporulated T. gondii oocysts (ME-49 strain). After 5 days, jejunum and ileum were collected and processed for analyzes (e.g., histological and histopathological examinations, ENS, cytokine dosage, myeloperoxidase, nitric oxide activity).

MAIN RESULTS

In infected mice, we observed a significant increase in serotonin-immunoreactive cells (5-HT IR) in the intestinal mucosa, as well as cellular infiltrates in the lamina propria, periganglionitis, and ganglionitis in the myenteric plexus. We also noted decreased neuron density in the jejunum, increased population of enteric glial cells in the ileum, histomorphometric changes in the intestinal wall, villi, and epithelial cells, remodeling of collagen fibers, and increased myeloperoxidase activity, cytokines, and nitric oxide in the intestine.

CONCLUSIONS AND INFERENCES

Acute infection of female mice with T. gondii oocysts resulted in changes in ENS and a marked increase in 5-HT. These changes are consistent with its modulatory role in the development of moderate acute inflammation. The use of this experimental model may lend itself to studies aimed at understanding the pathophysiological mechanisms of intestinal inflammation in humans involving ENS.

Acute infection with Toxoplasma gondii oocysts preferentially activates non-neuronal cells expressing serotonin in the jejunum of rats

The interaction of Toxoplasma gondii with the gastrointestinal tract of its host is highly regulated. Once ingested, the parasite crosses the epithelium without altering the permeability of the intestinal barrier. Nevertheless, many studies report alterations ranging from structural to functional damage in cells and tissues that make up the wall of the small and large intestine. Although the immune response to the parasite has been extensively studied, the role of serotonin (5-HT) in toxoplasmosis is poorly understood. Here we investigate the distribution of cells expressing 5-HT and its effects on cells and tissues of the jejunal wall of rats after 2, 3, or 7 days of T. gondii infection. KEY RESULTS: Our results show that transposition of the jejunal epithelium by T. gondii leads to ruptures in the basement membrane and activation of the immune system, as confirmed by the decrease in laminin immunostaining and the increase in the number of mast cells, respectively. CONCLUSIONS AND INFERENCES: We showed an increase in the number of enterochromaffin cells and mast cells expressing 5-HT in the jejunal wall. We also observed that the percentage of serotonergic mast cells increased in the total population. Thus, we can suggest that oral infection by T. gondii oocysts preferentially activates non-neuronal cells expressing 5-HT. Together, these results may explain both the changes in the extracellular matrix and the morphology of the enteric ganglia.

Toxoplasma gondii infection impairs the colonic motility of rats due to loss of myenteric neurons

BACKGROUND

Toxoplasma gondii infection causes intestinal inflammation and diarrhea indicating possible intestinal motor dysfunction. Anatomical studies have shown alterations in the colonic myenteric plexus, but it is unknown whether this impacts motility and therefore whether motility is a target for treatment. We determined whether colonic coordinated movements are compromised by toxoplasmic infection and how it is associated with anatomical changes.

METHODS

Male Wistar rats were evaluated at 6, 12, 24, 48, and 72 hours and 30 days postinfection (dpi) and controls. Infected rats received orally 5 × 10³ sporulated oocysts of strain ME-49 (genotype II) of T gondii. The colon was collected for anatomical analysis (including the myenteric plexus immunolabeled with HuC/D, nNOS, and ChAT) and motility analysis in vitro (conventional manometry). Fecal output was measured daily.

KEY RESULTS

At 12 hours postinfection, T gondii caused hypertrophy of the muscularis externa layer of the distal colon. There was loss of total, nitrergic, and cholinergic myenteric neurons in the proximal colon at 30 day postinfection (dpi); however, only loss of cholinergic neurons was found in the distal colon. Contractile complexes in the middle and distal colon were longer in duration in infected animals, which was associated with slower migration of the colonic motor complex. However, gastrointestinal transit time and fecal pellet output remained unchanged during the T gondii infection.

CONCLUSIONS AND INFERENCES

Toxoplasma gondii caused myenteric neuronal loss in the proximal and distal colon and altered the motility pattern in the middle and distal colon to a more propulsive phenotype.

Adaptative responses of myenteric neurons of Sphoeroides testudineus to environmental pollution

Contamination in estuarine regions affects the local biota damaging the ecosystems and reaching humans. The gastrointestinal tract is a dynamic environment capable of obtaining nutrients and energy from food while it protects the host against harmful toxins and pathogens from the external environment. These functions are modulated by the enteric nervous system and changes in its structure can result in gastrointestinal disorders. The objective of this study was to evaluate if the environmental contaminants have effects on the myenteric neuronal plasticity of pufferfish Sphoeroides testudineus. Animals were collected in Barra do Una River, located at Jureia-Itatins Mosaic of Protected Areas (reference area - RA) and in the Santos Estuarine System (impacted area - IA). Morpho-quantitative analyses of the general and metabolically active myenteric neuronal populations of the proximal and distal intestine were made. Disarrangement was observed in the general organization of the myenteric plexus, with an expressive reduction of the neuronal groups (nodes) in the animals of IA. The vulnerability of the myenteric plexus was evidenced by a decrease in density and cellular profile of the general neuronal population, followed by an increase of the metabolism of the remaining neurons, which in turn was verified by a growth of the area of the cellular and nuclear profiles of the metabolically active neuronal population. Through these analyses, we concluded that animals inhabiting polluted regions present alterations in the myenteric neuronal plasticity, as a way of maintaining the functions of the gastrointestinal tract.

Toxoplasma gondii causes increased ICAM-1 and serotonin expression in the jejunum of rats 12 h after infection

OBJECTIVE

To analyze the remodeling dynamics of total collagen, type I and III, the expression of ICAM-1 and 5-HT in the jejunum of rats.

METHODS

Twenty-eight Wistar rats were randomly assigned to two experimental groups: the control group (CG, n = 7) and the infected group (receiving 5,000 sporulated T. gondii oocysts - ME49 strain, genotype II, n = 21). Seven infected rats each at 6 (G6), 12 (G12), and 24 (G24) hours post infection were sacrificed and segments of jejunum were collected for standard histological, histochemical, and immunohistochemistry processing techniques.

RESULTS

The infection promoted ICAM-1 and 5-HT expression, type III collagen, and total mast cell increases. However, it also caused a reduction in the area occupied by type I collagen fibers, and in submucosa thickness, and caused ganglion and peri-ganglion alterations.

CONCLUSION

The structural damage caused by toxoplasmic infection is intense during the first 24 h post inoculation. At peak dissemination, from 12 to 24 h, there is an increase in ICAM-1 and 5-HT expression, with intense migration of mast cells to the site of infection. There was also a reduction in submucosa thickness, and an effective loss of extracellular matrix (ECM) organization, which included changes in the dynamics of type I and III total collagen deposition.

Acute Toxoplasma gondii infection alters the number of neurons and the proportion of enteric glial cells in the duodenum in Wistar rats

BACKGROUND

Toxoplasma gondii infection can occur through the ingestion of raw meat that contains tissue cysts or food that contains oocysts. Through the ingestion of oocysts, the parasite crosses the intestinal barrier, where the enteric nervous system is located. The objective was to investigate the kinetics of neuronal and glial responses during acute T. gondii infection.

METHODS

We used 45 Wistar rats that were divided into a control group and infected groups that were evaluated at 6, 12, 24, 48, 72 hours, 7 days, 10 days, and 15 days after infection. The rats received 5000 sporulated oocysts of the parasite orally. To detect neurons and enteric glia cells, the myenteric and submucosal plexuses of the duodenum underwent double-labeling immunohistochemical techniques to evaluate HuC/HuD and S100, HuC/HuD and ChAT, and HuC/HuD and nNOS.

KEY RESULTS

We observed a reduction of the total neuron population in the submucosal plexus 72 hours after infection. Cholinergic neurons decreased in the submucosal plexus 15 days after infection, and nitrergic neurons decreased in the myenteric plexus 72 hours after infection. A decrease in the number of glial cells was observed 7 days after infection in the submucosal plexus, and an increase in the enteric glial cell (EGC)/neuron ratio was found in both plexuses 48 hours after infection.

CONCLUSIONS AND INFERENCES

We found decrease of neurons and increase in the EGC/neuron ratio in both plexuses caused by acute T. gondii infection, with major alterations 72 hours after oral infection. The number of cholinergic neurons decreased in the submucosal plexus, and the number of nitrergic neurons decreased in the myenteric plexus. A decrease in the number of enteric glial cells was observed in the submucosal plexus, and an increase in the enteric glial cell/neuron ratio was observed in both ganglionate plexuses of the duodenum.

Assemblages A and B of Giardia duodenalis reduce enteric glial cells in the small intestine in mice

Infection of Giardia duodenalis is one of the most common human parasitic disease worldwide. This infection may be related to important changes in the enteric nervous system. The objective of this study was to evaluate the myenteric and submucosal plexuses, the intestinal muscle layer, and gastrointestinal transit in mice infected with assemblages A and B of G. duodenalis. Swiss albino mice (Mus musculus) were infected with assemblages A and B of G. duodenalis for 15 days. Gastrointestinal transit time was evaluated before euthanasia. Duodenum and jejunum were removed for histological and immunohistochemical analyses. It was observed a reduction in the enteric glial cell count and a decrease in the ratio of enteric glial cells to neurons. The number of neurons did not change, but morphological changes were observed in the duodenum and jejunum in both plexuses, including an increase in the nuclear area and a reduction of cell bodies in the myenteric plexus and a decrease in the nuclear area in the submucosal plexus. A reduction of the thickness of the muscle layer was observed in the duodenum, with no significant differences in the gastrointestinal transit times. Assemblages A and B of G. duodenalis decrease the number of enteric glial cells in the myenteric and submucosal plexuses, decrease the thickness of the muscle layer, and change the morphology of neurons. Graphical abstract ᅟ.

Comparative study of effects of assemblages AII and BIV of Giardia duodenalis on mucosa and microbiota of the small intestine in mice

AIMS

Giardiasis is one of the major causes of diarrhea worldwide and its symptoms vary in intensity, which can be attributed to different parasite assemblages. The goal of the present study was to compare the effects of infection caused by assemblages AII and BIV ofGiardia duodenalis on the response of the small intestine, microbiota, and behavioral parameters in mice.

MAIN METHODS

Swiss mice were infected with assemblages AII and BIV of G. duodenalis for 15 days. Leucometry, pain, intestinal microbiota and histological parameters of the duodenum and jejunum were evaluated in the experimental groups.

KEY FINDINGS

Both assemblages modified the composition of the intestinal microbiota. Infection with assemblage AII promoted leukocytosis, reflected by increasing number of polymorphonuclear cells, intraepithelial lymphocytes and pain-related behavior, indicating that this was the more aggressive assemblage with regard to its effects on the intestinal mucosa and duodenum.

SIGNIFICANCE

The specific assemblage of the parasite is an important parameter that affects symptomatology in the host.