CXCR3-Dependent Immune Pathology in Mice following Infection with Toxoplasma gondii during Early Pregnancy

Transcriptomic analysis of reproductive organs of pregnant mice post toxoplasma gondii infection reveals the potential factors that contribute to poor prognosis

Toxoplasma gondii is an obligate intracellular parasite of phylum Apicomplexa that poses a huge threat to pregnant hosts, and induces tragic outcomes for pregnant hosts, fetuses and newborns. However, the molecular mechanism underlying the tragic consequences caused by T. gondii remains to be revealed. In the present study, we applied RNA-seq to study the transcriptomic landscape of the whole reproductive organ of pregnant mice post T. gondii infection, aiming to reveal the key altered biological characters of reproductive organs of pregnant mice that could contribute to the tragic outcomes caused by T. gondii infection. The results of the present study showed that the transcriptome of reproductive organs of pregnant mice was significantly altered by T. gondii infection. A total of 2,598 differentially expressed genes (DEGs) were identified, including 1,449 upregulated genes and 1,149 downregulated genes. Enrichment analysis of the DEGs showed that the significantly altered features of reproductive organs of pregnant mice were excessive inflammatory responses, downregulated metabolism processes, and congenital diseases. The chemotaxis of immune cells in the reproductive organs of infected pregnant mice could also be reshaped by 19 differentially expressed chemokines and 6 differentially expressed chemokine receptors that could contribute to the damages of reproductive organ in pregnant mice. Overall, the findings of present study may help to understand the pathogenic mechanism of the acute T. gondii infection in reproductive organs of pregnant mice, and it could also help to improve toxoplasmosis therapeutics for pregnant individuals.

CCR5 contributes to adverse outcomes during malaria in pregnancy

CCR5 is a chemokine receptor that mediates cell recruitment to sites of inflammation. It has been previously reported that the expression of CCR5 is increased in the placentas of women with malaria, a disease characterized by causing deliveries with low birth weight among other complications. CCR5 has been associated with pathology of protozoan infections during pregnancy but its role during malaria in pregnancy has not been elucidated. In the present work, we assessed the pregnancy outcome, placental structure, and levels of inflammatory markers of pregnant C57BL/6 and CCR5-/- mice infected or not with Plasmodium berghei NK65, with the purpose of determine the role of CCR5 in pregnancy associated malaria complications. We demonstrated that the expression of CCR5 mRNA increases in late pregnancy placentas of C57BL/6 when compared to uninfected controls. Infected pregnant C57BL/6 mice showed preterm birth, decreased fetal weight, placental inefficiency, and reduced placental vascular space. On the other hand, CCR5 deficiency led to increased levels of maternal parasitemia, reduced fetal weight and placental inefficiency compared to C57BL/6 mice. However, the infection did not cause additional changes in these parameters or in the incidence of preterm delivery in infected CCR5-/- mice in relation to C57BL/6 mice, showing that CCR5 may contribute to the adverse effects caused by infection during pregnancy. This improvement in pregnancy outcome, observed in infected CCR5-/- mice, was accompanied by lower placental levels of the inflammatory markers, such as TNF and NAG. Furthermore, it was observed that the placentas of CCR5-/- animals showed structural differences in relation to C57BL/6 mice, which could improve the efficiency of maternal-fetal exchanges, reflecting on fetal weight. Taken together, these results indicate that CCR5 expression contributes to the adverse outcomes caused by malaria in late pregnancy.

Involvement of chemokine receptor CXCR3 in the defense mechanism against Neospora caninum infection in C57BL/6 mice

C-X-C motif chemokine receptor 3 (CXCR3) is an important receptor controlling the migration of leukocytes, although there is no report regarding its role in Neospora caninum infection. Herein, we investigated the relevance of CXCR3 in the resistance mechanism to N. caninum infection in mice. Wild-type (WT) C57BL/6 mice and CXCR3-knockout (CXCR3KO) mice were used in all experiments. WT mice displayed a high survival rate (100%), while 80% of CXCR3KO mice succumbed to N. caninum infection within 50 days. Compared with WT mice, CXCR3KO mice exhibited significantly lower body weights and higher clinical scores at the subacute stage of infection. Flow cytometric analysis revealed CXCR3KO mice as having significantly increased proportions and numbers of CD11c-positive cells compared with WT mice at 5 days post infection (dpi). However, levels of interleukin-6 and interferon-γ in serum and ascites were similar in all groups at 5 dpi. Furthermore, no differences in parasite load were detected in brain, spleen, lungs or liver tissue of CXCR3KO and WT mice at 5 and 21 dpi. mRNA analysis of brain tissue collected from infected mice at 30 dpi revealed no changes in expression levels of inflammatory response genes. Nevertheless, the brain tissue of infected CXCR3KO mice displayed significant necrosis and microglial activation compared with that of WT mice at 21 dpi. Interestingly, the brain tissue of CXCR3KO mice displayed significantly lower numbers of FoxP3⁺ cells compared with the brain tissue of WT mice at 30 dpi. Accordingly, our study suggests that the lack of active regulatory T cells in brain tissue of infected CXCR3KO mice is the main cause of these mice having severe necrosis and lower survival compared with WT mice. Thus, CXCR3⁺ regulatory T cells may play a crucial role in control of neosporosis.

The imbalance in the relationship between inflammatory and regulatory cytokines during gestational toxoplasmosis can be harmful to fetuses: A systematic review

Objective

To evaluate the available information on inflammatory and regulatory plasma mediators in pregnant women (PW) diagnosed with toxoplasmosis. Source: The PubMed, Embase, Scopus, and Lilacs databases were evaluated until October 2022. Study eligibility criteria: This review was carried out following the PRISMA and registered on the PROSPERO platform (CRD42020203951). Studies that reported inflammatory mediators in PW with toxoplasmosis were considered.

Evaluation methods

After excluding duplicate articles, two authors independently carried out the process of title and abstract exclusion, and a third resolved disagreements when necessary. The full text was evaluated to detect related articles. The extraction table was built from the following data: Author, year of publication, journal name and impact factors, country, study design, number of gestations and maternal age (years), gestational period, diagnosis of toxoplasmosis, levels of inflammatory markers, laboratory tests, and clinical significance. Methodological quality was assessed using Joanna Briggs Institute tools.

Results

Of the 1,024 studies reported, only eight were included. Of the 868 PW included in this review, 20.2% were IgM+/IgG- and 50.8% were IgM-/IgG+ to T. gondii, and 29.0% uninfected. Infected PW presented higher plasma levels ofIL-5, IL-6, IL-8, IL-17, CCL5, and IL-10. Regarding the methodological quality, four studies obtained high quality. Data from this review pointed out the maintenance of the inflammatory pattern during pregnancy with a closely related to the parasite.

Conclusion

Immune status in PW defined the course of the T. gondii infection, where the equilibrium between inflammatory and regulatory cytokines mitigated the harmful placenta and fetus effects.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, identifier CRD420203951.

CXCR3 Inhibition Blocks the NF-κB Signaling Pathway by Elevating Autophagy to Ameliorate Lipopolysaccharide-Induced Intestinal Dysfunction in Mice

Autophagy is a cellular catabolic process in the evolutionarily conservative turnover of intracellular substances in eukaryotes, which is involved in both immune homeostasis and injury repairment. CXCR3 is an interferon-induced chemokine receptor that participates in immune regulation and inflammatory responses. However, CXCR3 regulating intestine injury via autophagy along with the precise underlying mechanism have yet to be elucidated. In the current study, we employed an LPS-induced inflammatory mouse model and confirmed that CXCR3 knockout significantly attenuates intestinal mucosal structural damage and increases tight junction protein expression. CXCR3 knockout alleviated the LPS-induced increase in the expression of inflammatory factors including TNF-α, IL-6, p-65, and JNK-1 and enhanced autophagy by elevating LC3II, ATG12, and PINK1/Parkin expression. Mechanistically, the function of CXCR3 regarding autophagy and immunity was investigated in IPEC-J2 cells. CXCR3 inhibition by AMG487 enhanced autophagy and reduced the inflammatory response, as well as blocked the NF-κB signaling pathway and elevated the expression of the tight junction protein marker Claudin-1. Correspondingly, these effects were abolished by autophagy inhibition with the selective blocker, 3-MA. Moreover, the immunofluorescence assay results further demonstrated that CXCR3 inhibition-mediated autophagy blocked p65 nuclear translocation, and the majority of Claudin-1 was located at the tight junctions. In conclusion, CXCR3 inhibition reversed LPS-induced intestinal barrier damage and alleviated the NF-κB signaling pathway via enhancing autophagy. These data provided a theoretical basis for elucidating the immunoregulatory mechanism by targeting CXCR3 to prevent intestinal dysfunction.

Toll-Like Receptor 2 is Involved in Abnormal Pregnancy in Mice Infected with Toxoplasma gondii During Late Pregnancy

Infection with Toxoplasma gondii during pregnancy causes failure of pregnancy maintenance, resulting in fetal death, abortion, stillbirth, or premature birth, but the mechanism of disease onset remains unclear. Although Toll-like receptor 2 (TLR2) is expressed on antigen-presenting cells and trophoblasts, the role of TLR2 in T. gondii infection during pregnancy is unknown. In this study, we investigated the role of TLR2 in congenital toxoplasmosis using TLR2-deficient (TLR2^−/−) mice. T. gondii infection on gestational day 12.5 (Gd12.5) induced more abnormal pregnancy, including premature birth and stillbirth, in wild-type mice than in TLR2^−/− mice. Multiple calcifications were observed in the placentas of the infected wild-type mice. At Gd18.5 (6days postinfection), the parasite numbers in the placenta and uterus and the histological changes did not differ significantly between the wild-type and TLR2^−/− mice. However, T. gondii infection reduced the mRNA expression of interleukin-12p40 (IL-12p40) and increased IL-4 and IL-10 mRNAs in the placentas of the wild-type mice. In contrast, the placentas of the TLR2^−/− mice showed no changes in the expression of these cytokines, including IL-6 and tumor necrosis factor α, in response to T. gondii infection. Serum interferon-γ levels were significantly lower in the infected TLR2^−/− mice than in the infected wild-type mice on Gd18.5. Thus, the TLR2^−/− mice were less susceptible to the induction of immune responses by T. gondii infection during late pregnancy. Therefore, TLR2 signaling may play a role in the development of disease states during pregnancy, specifically placental hypofunction.