Innate immune receptors are differentially expressed in mice during experimental Schistosoma mansoni early infection.

BACKGROUND: The impact of Schistosoma mansoni infection over the immune response and the mechanisms involved in pathogenesis are not yet completely understood. OBJECTIVES: This study aimed to evaluate the expression of innate immune receptors in three distinct mouse lineages (BALB/c, C57BL/6 and Swiss) during experimental S. mansoni infection with LE strain. METHODS: The parasite burden, intestinal tissue oogram and presence of hepatic granulomas were evaluated at 7- and 12-weeks post infection (wpi). The mRNA expression for innate Toll-like receptors, Nod-like receptors, their adaptor molecules, and cytokines were determined at 2, 7 and 12 wpi in the hepatic tissue by real-time quantitative polymerase chain reaction (qPCR). FINDINGS: Swiss mice showed 100% of survival, had lower parasite burden and intestinal eggs, while infected BALB/c and C57BL/6 presented 80% and 90% of survival, respectively, higher parasite burden and intestinal eggs. The three mouse lineages displayed distinct patterns in the expression of innate immune receptors, their adaptor molecules and cytokines, at 2 and 7 wpi. MAIN CONCLUSIONS: Our results suggest that the pathogenesis of S. mansoni infection is related to a dynamic early activation of innate immunity receptors and cytokines important for the control of developing worms.

Toxoplasma gondii infection damages the perineuronal nets in a murine model.

BACKGROUND: Behavioral and neurochemical alterations associated with toxoplasmosis may be influenced by the persistence of tissue cysts and activation of an immune response in the brain of Toxoplasma gondii-infected hosts. The cerebral extracellular matrix is organised as perineuronal nets (PNNs) that are both released and ensheath by some neurons and glial cells. There is evidences to suggest that PNNs impairment is a pathophysiological mechanism associated with neuropsychiatric conditions. However, there is a lack of information regarding the impact of parasitic infections on the PNNs integrity and how this could affect the host's behavior. OBJECTIVES: In this context, we aimed to analyse the impact of T. gondii infection on cyst burden, PNNs integrity, and possible effects in the locomotor activity of chronically infected mice. METHODS: We infected mice with T. gondii ME-49 strain. After thirty days, we assessed locomotor performance of animals using the open field test, followed by evaluation of cysts burden and PNNs integrity in four brain regions (primary and secondary motor cortices, prefrontal and somesthetic cortex) to assess the PNNs integrity using Wisteria floribunda agglutinin (WFA) labeling by immunohistochemical analyses. FINDINGS AND MAIN CONCLUSIONS: Our findings revealed a random distribution of cysts in the brain, the disruption of PNNs surrounding neurons in four areas of the cerebral cortex and hyperlocomotor behavior in T. gondii-infected mice. These results can contribute to elucidate the link toxoplasmosis with the establishment of neuroinflammatory response in neuropsychiatric disorders and to raise a discussion about the mechanisms related to changes in brain connectivity, with possible behavioral repercussions during chronic T. gondii infection.

IgG seroprevalence of Toxoplasma gondii and Leishmania infantum in leprosy patients: Implications for screening and management of co-infections.

Parasitic co-infections are common in developing countries and can interfere with leprosy treatment, leading to an increased risk of inflammatory leprosy reactions. This study assessed serum immunoglobulin G (IgG) levels against Toxoplasma gondii and Visceral Leishmaniasis (VL) antigens in 270 leprosy patients from Brazilian states. Regarding the respective cut-offs, the prevalence of IgG seropositivity for T. gondii and VL were 21.05 % and 47.36 % in the leprosy-negative group, and 77.7 % and 52.6 % in the leprosy-positive group. Of the 270 leprosy patients, 158 (58.5 %) presented with inflammatory leprosy reactions. Of those, 72 (59.5 %) had neuritis, 35 (48.6 %) had reverse reactions, and 28 (38.9 %) had ENL in both Brazilian states. Leprosy patients with anti-Leishmania IgG seropositivity were 3.25 times more likely to develop neuritis (95 % C.I.: 1.187 - 9.154; p = 0.019). These findings are particularly relevant for clinical settings where both leprosy and parasitic diseases are prevalent and could provide essential guidance for detecting and addressing complications arising from parasitic co-infections in leprosy patients, thereby improving clinical management strategies.

Acute Chikungunya Virus Infection Triggers a Diverse Range of T Helper Lymphocyte Profiles.

Chikungunya virus (CHIKV) is an arbovirus causing acute febrile illness with severe joint pain, often leading to chronic arthralgia. This study investigated the adaptive immune responses during the early stages of symptomatic acute CHIKV infection, focusing on the transcription factors and cytokines linked to Th1, Th2, Th17, and Treg cells. Thirty-six individuals were enrolled: nine healthy controls and 27 CHIKV-positive patients confirmed by qRT-PCR. Blood samples were analyzed for the mRNA expression of transcription factors (Tbet, GATA3, FoxP3, STAT3, RORγt) and cytokines (IFN-γ, IL-4, IL-17, IL-22, TGF-ß, IL-10). The results showed the significant upregulation of Tbet, GATA3, FoxP3, STAT3, and RORγt in CHIKV-positive patients, with RORγt displaying the highest increase. Correspondingly, cytokines IFN-γ, IL-4, IL-17, and IL-22 were upregulated, while TGF-ß was downregulated. Principal component analysis (PCA) confirmed the distinct immune profiles between CHIKV-positive and healthy individuals. A correlation analysis indicated that higher Tbet expression correlated with a lower viral load, whereas FoxP3 and TGF-ß were associated with higher viral loads. Our study sheds light on the intricate immune responses during acute CHIKV infection, characterized by a mixed Th1, Th2, Th17, and Treg response profile. These results emphasize the complex interplay between different adaptive immune responses and how they may contribute to the pathogenesis of Chikungunya fever.

Genetic diversity of Toxoplasma gondii in South America: occurrence, immunity, and fate of infection.

Toxoplasma gondii is an intracellular parasite with a worldwide distribution. Toxoplasma gondii infections are of great concern for public health, and their impact is usually most severe in pregnant women and their foetuses, and in immunocompromised individuals. Displaying considerable genetic diversity, T. gondii strains differ widely according to geographical location, with archetypal strains predominantly found in the Northern Hemisphere and non-archetypal (atypical) strains, with highly diverse genotypes, found mainly in South America. In this review, we present an overview of the identification and distribution of non-archetypal strains of T. gondii. Special attention is paid to the strains that have been isolated in Brazil, their interaction with the host immunological response, and their impact on disease outcomes. The genetic differences among the strains are pivotal to the distinct immunological responses that they elicit. These differences arise from polymorphisms of key proteins released by the parasite, which represent important virulence factors. Infection with divergent non-archetypal strains can lead to unusual manifestations of the disease, even in immunocompetent individuals.

Chronic infection by atypical Toxoplasma gondii strain induces disturbance in microglia population and altered behaviour in mice.

Toxoplasma gondii chronic infection is characterized by the establishment of tissue cysts in the brain and increased levels of IFN-γ, which can lead to brain circuitry interference and consequently abnormal behaviour in mice. In this sense, the study presented here sought to investigate the impact of chronic infection by two T. gondii strains in the brain of infection-resistant mice, as a model for studying the involvement of chronic neuroinflammation with the development of behavioural alterations. For that, male BALB/c mice were divided into three groups: non-infected (Ni), infected with T. gondii ME49 clonal strain (ME49), and infected with TgCkBrRN2 atypical strain (CK2). Mice were monitored for 60 days to establish the chronic infection and then submitted to behavioural assessment. The enzyme-linked immunosorbent assay was used for measurement of specific IgG in the blood and levels of inflammatory cytokines and neurotrophic factors in the brain, and the cell's immunophenotype was determined by multiparametric flow cytometry. Mice infected with ME49 clonal strain displayed hyperlocomotor activity and memory deficit, although no signs of depressive- and/or anxiety-like behaviour were detected; on the other hand, chronic infection with CK2 atypical strain induced anxiety- and depressive-like behaviour. During chronic infection by CK2 atypical strain, mice displayed a higher number of T. gondii brain tissue cysts and inflammatory infiltrate, composed mainly of CD3+ T lymphocytes and Ly6Chi inflammatory monocytes, compared to mice infected with the ME49 clonal strain. Infected mice presented a marked decrease of microglia population compared to non-infected group. Chronic infection with CK2 strain produced elevated levels of IFN-γ and TNF-ɑ in the brain, decreased NGF levels in the prefrontal cortex and striatum, and altered levels of fractalkine (CX3CL1) in the prefrontal cortex and hippocampus. The persistent inflammation and the disturbance in the cerebral homeostasis may contribute to altered behaviour in mice, as the levels of IFN-γ were shown to be correlated with the behavioural parameters assessed here. Considering the high incidence and life-long persistence of T. gondii infection, this approach can be considered a suitable model for studying the impact of chronic infections in the brain and how it impacts in behavioural responses.

Blood-stage antiplasmodial activity and oocyst formation-blockage of metallo copper-cinchonine complex.

In the fight against malaria, the key is early treatment with antimalarial chemotherapy, such as artemisinin-based combination treatments (ACTs). However, Plasmodium has acquired multidrug resistance, including the emergence of P. falciparum strains with resistance to ACT. The development of novel antimalarial molecules, that are capable of interfering in the asexual and sexual blood stages, is important to slow down the transmission in endemic areas. In this work, we studied the ability of the mettalo copper-cinchonine complex to interfere in the sexual and asexual stages of Plasmodium. The tested compound in the in vitro assay was a cinchonine derivative, named CinCu (Bis[Cinchoninium Tetrachlorocuprate(II)]trihydrate). Its biological functions were assessed by antiplasmodial activity in vitro against chloroquine-resistant P. falciparum W2 strain. The mice model of P. berghei ANKA infection was used to analyze the antimalarial activity of CinCu and chloroquine and their acute toxicity. The oocyst formation-blocking assay was performed by experimental infection of Anopheles aquasalis with P. vivax infected blood, which was treated with different concentrations of CinCu, cinchonine, and primaquine. We found that CinCu was able to suppress as high as 81.58% of parasitemia in vitro, being considered a molecule with high antiplasmodial activity and low toxicity. The in vivo analysis showed that CinCu suppressed parasitemia at 34% up to 87.19%, being a partially active molecule against the blood-stage forms of P. berghei ANKA, without inducing severe clinical signs in the treated groups. The transmission-blocking assay revealed that both cinchonine and primaquine were able to reduce the infection intensity of P. vivax in A. aquasalis, leading to a decrease in the number of oocysts recovered from the mosquitoes' midgut. Regarding the effect of CinCu, the copper-complex was not able to induce inhibition of P. vivax infection; however, it was able to induce an important reduction in the intensity of oocyst formation by about 2.4 times. It is plausible that the metallo-compound also be able to interfere with the differentiation of parasite stages and/or ookinete-secreted chitinase into the peritrophic matrix of mosquitoes, promoting a reduction in the number of oocysts formed. Taken together, the results suggest that this compound is promising as a prototype for the development of new antimalarial drugs. Furthermore, our study can draw a new pathway for repositioning already-known antimalarial drugs by editing their chemical structure to improve the antimalarial activity against the asexual and sexual stages of the parasite.

Innate immune receptors are differentially expressed in mice during experimental Schistosoma mansoni early infection

BACKGROUND The impact of Schistosoma mansoni infection over the immune response and the mechanisms involved in pathogenesis are not yet completely understood. OBJECTIVES This study aimed to evaluate the expression of innate immune receptors in three distinct mouse lineages (BALB/c, C57BL/6 and Swiss) during experimental S. mansoni infection with LE strain. METHODS The parasite burden, intestinal tissue oogram and presence of hepatic granulomas were evaluated at 7- and 12-weeks post infection (wpi). The mRNA expression for innate Toll-like receptors, Nod-like receptors, their adaptor molecules, and cytokines were determined at 2, 7 and 12 wpi in the hepatic tissue by real-time quantitative polymerase chain reaction (qPCR). FINDINGS Swiss mice showed 100% of survival, had lower parasite burden and intestinal eggs, while infected BALB/c and C57BL/6 presented 80% and 90% of survival, respectively, higher parasite burden and intestinal eggs. The three mouse lineages displayed distinct patterns in the expression of innate immune receptors, their adaptor molecules and cytokines, at 2 and 7 wpi. MAIN CONCLUSIONS Our results suggest that the pathogenesis of S. mansoni infection is related to a dynamic early activation of innate immunity receptors and cytokines important for the control of developing worms.

Infection rate by TOXOPLASMA GONDII in free-range and broiler chickens in the states of Rio Grande do Norte and Paraíba, Brazil

Toxoplasmosis is a zoonosis caused by Toxoplasma gondii, a protozoan that has a cosmopolitan geographic distribution and low specificity for intermediate hosts. Domestic chickens are among the most important hosts in toxoplasmosis epidemiology, since they are potential sources of infection for humans, in addition to indicating environmental contamination by protozoa. In this work, we studied the prevalence of T. gondii infection in chickens in different breeding systems from distinct mesoregions of Rio Grande do Norte and Paraiba States: broiler chickens from commercial farms and free-range chickens from small farms. Indirect fluorescent antibody test (IFAT) and ELISA techniques were used for detecting specific antibodies in blood samples from the birds. There were no seropositive samples among the broilers tested, indicating that intensive management limited the chances of infection for these animals. Among the free-range chickens, the frequency of IgG anti-T. gondii detected by IFAT and ELISA were 37.9% and 40.4% respectively. Among the seropositive samples by IFAT, 33 (27.1%) were positive at a dilution of 1:16; in 1:32, 31 (25.4%); in 1:64, 24 (19.7%); 15 (12.3%) in 1:128, and 19 presented titers greater than or equal to 1:256 (15.6%). The substantial concordance observed between IFAT and ELISA signifies these methods are effective methodologies for the diagnosis of avian toxoplasmosis. The high prevalence of specific antibodies among poultry in the studied region highlights the potential risk of T. gondii transmission to humans through consumption of infected meat.