Chronic Toxoplasma gondii Infection Alleviates Experimental Autoimmune Encephalomyelitis by the Immune Regulation Inducing Reduction in IL-17A/Th17 Via Upregulation of SOCS3

Seroprevalence of Toxoplasma gondii and Borrelia burgdorferi infections in patients with multiple sclerosis in Poland

Multiple sclerosis (MS) is a chronic, demyelinating disease of the central nervous system that affects mainly young people. It is believed that the autoimmune process observed in the pathogenesis of MS is influenced by a complex interaction between genetic and environmental factors, including infectious agents. The results of this study suggest the protective role of Toxoplasma gondii infections in MS. Interestingly, high Toxoplasma IgM seropositivity in MS patients receiving immunomodulatory drugs (IMDs) was identified. On the other hand, Borrelia infections seem to be positively associated with MS. Although the interpretation of our results is limited by the retrospective nature of the studies, the results strongly indicate that further experimental and clinical studies are needed to explain the role of infectious agents in the development and pathophysiological mechanisms of MS.

Cognitive Effects of Toxoplasma and CMV Infections: A Cross-Sectional Study of 557 Young Adults Considering Modulation by Sex and Rh Factor

One-third of humanity harbors a lifelong infection with Toxoplasma gondii, and probably about 80% are infected with human cytomegalovirus (CMV). This study aims to delineate the associations between toxoplasmosis and cognitive abilities and compare these to the associations with CMV. We evaluated the cognitive performance of 557 students, who had been examined for Toxoplasma and CMV infections, using intelligence, memory, and psychomotor tests. The results indicated cognitive impairments in seropositive individuals for both pathogens, with variations in cognitive impact related to sex and the Rh factor. Specifically, Toxoplasma infection was associated with lower IQ in men, whereas CMV was predominantly associated with worse performance by women when testing memory and reaction speeds. Analysis of the antibody concentrations indicated that certain Toxoplasma-associated cognitive detrimental effects may wane (impaired intelligence) or worsen (impaired reaction times) over time following infection. The findings imply that the cognitive impairments caused by both neurotropic pathogens are likely due to pathological changes in the brain rather than from direct manipulative action by the parasites.

The neurotropic schistosome vs experimental autoimmune encephalomyelitis: are there any winners?

The incidences of multiple sclerosis have risen worldwide, yet neither the trigger nor efficient treatment is known. Some research is dedicated to looking for treatment by parasites, mainly by helminths. However, little is known about the effect of helminths that infect the nervous system. Therefore, we chose the neurotropic avian schistosome Trichobilharzia regenti, which strongly promotes M2 polarization and tissue repair in the central nervous system, and we tested its effect on the course of experimental autoimmune encephalomyelitis (EAE) in mice. Surprisingly, the symptoms of EAE tended to worsen after the infection with T. regenti. The infection did not stimulate tissue repair, as indicated by the similar level of demyelination. Eosinophils heavily infiltrated the infected tissue, and the microglia number increased as well. Furthermore, splenocytes from T. regenti-infected EAE mice produced more interferon (IFN)-γ than splenocytes from EAE mice after stimulation with myelin oligodendrocyte glycoprotein. Our research indicates that the combination of increased eosinophil numbers and production of IFN-γ tends to worsen the EAE symptoms. Moreover, the data highlight the importance of considering the direct effect of the parasite on the tissue, as the migrating parasite may further tissue damage and make tissue repair even more difficult.

A review on nonviral, nonbacterial infectious agents toxicity involved in neurodegenerative diseases

Neuronal death, decreased activity or dysfunction of neurotransmitters are some of the pathophysiological reasons for neurodegenerative diseases like Alzheimer's, Parkinson's and multiple sclerosis. Also, there is evidence for the role of infections and infectious agents in neurodegenerative diseases and the effect of some metabolites in microorganisms in the pathophysiology of these diseases. In this study, we intend to evaluate the existing studies on the role of infectious agents and their metabolites on the pathophysiology of neurodegenerative diseases. PubMed, Scopus, Google Scholar and Web of Science search engines were searched. Some infectious agents have been observed in neurodegenerative diseases. Also, isolations of some fungi and microalgae have an improving effect on Parkinson's and Alzheimer's.

Toxoplasma gondii attenuates the ethidium bromide induced demyelination lesions in multiple sclerosis model rats

Multiple sclerosis (MS) is an autoimmune neurodegenerative disease. Since the modulation of the immune system by parasites has been proven, and there have been reports of a reduction in the clinical symptoms of MS in people with toxoplasmosis, this study aimed to investigate the effect of toxoplasmosis on MS in an animal model. MS model was induced by the ethidium bromide injection in the areas specified in the Rat's brain in the stereotaxic device and Toxoplasma gondii RH strain injection of the rat's peritoneal for creation of toxoplasmosis. The effect of acute and chronic toxoplasmosis on the MS model was evaluated by examining the development of clinical symptoms of MS, body weight, changes in the levels of inflammatory cytokines, inflammatory cell infiltration, cell density, and spongy tissue in the brain. The body weight in the acute toxoplasmosis with MS was the same as the MS group, and a significant decrease was observed, but no weight loss was observed in the chronic toxoplasmosis with MS. In the chronic toxoplasmosis, the progress of clinical signs such as Immobility of limbs, including tail, hands, and feet, was observed less compared to other groups. The histology results in the group of chronic toxoplasmosis showed high cell density and inhibition of spongy tissue formation, and the infiltration of inflammatory cells in this group was less. TNF-α and INF-γ decreased in MS with chronic toxoplasmosis compared to the MS group. Our findings showed that chronic toxoplasmosis with inhibition of spongy tissue formation and prevention of cell infiltration and. As a result, the reduction of inflammatory cytokines could reduce clinical symptoms in MS in the animal model.

MS4A4A modifies the risk of Alzheimer disease by regulating lipid metabolism and immune response in a unique microglia state

Genome-wide association studies (GWAS) have identified many modifiers of Alzheimer disease (AD) risk enriched in microglia. Two of these modifiers are common variants in the MS4A locus (rs1582763: protective and rs6591561: risk) and serve as major regulators of CSF sTREM2 levels. To understand their functional impact on AD, we used single nucleus transcriptomics to profile brains from carriers of these variants. We discovered a "chemokine" microglial subpopulation that is altered in MS4A variant carriers and for which MS4A4A is the major regulator. The protective variant increases MS4A4A expression and shifts the chemokine microglia subpopulation to an interferon state, while the risk variant suppresses MS4A4A expression and reduces this subpopulation of microglia. Our findings provide a mechanistic explanation for the AD variants in the MS4A locus. Further, they pave the way for future mechanistic studies of AD variants and potential therapeutic strategies for enhancing microglia resilience in AD pathogenesis.

Does latent Toxoplasma infection have a protective effect against developing multiple sclerosis? Evidence from an updated meta-analysis

Previous epidemiologic evidence suggests a protective effect of Toxoplasma gondii infection against multiple sclerosis (MS) development; however, inconsistent findings have been reported in this regard. Therefore, we performed an updated meta-analysis of observational studies to investigate the association of To. gondii infection with MS development. We searched all articles published in PubMed, Scopus, Embase and Web of Science databases as of 20 December 2021. A random effects meta-analysis model was used to generate the pooled OR at 95% CIs. The heterogeneity between studies was assessed using I2 and Cochran's Q statistics. Moreover, the likelihood of publication bias was determined by Egger's regression test. A total of 11 studies were eligible for meta-analysis, including 1172 MS cases and 1802 controls. Our findings indicated that 29.8% (95% CI 22.8 to 37.2%) of MS patients were seropositive for To. gondii infection, compared with 34.2% (95% CI 21.9 to 47.6%) of control subjects. The estimated pooled OR was 0.79 (95% CI 0.49 to 1.26), suggesting a non-significant negative association between To. gondii infection and MS development (p>0.05). The current study does not support the significant protective role of To. gondii infection on MS development. Our findings imply that further well-designed epidemiological and mechanistic studies are warranted to ascertain the possible association between To. gondii infection and MS and to exclude the potential confounders.

Low SOCS3 expression in CD4+ T cells from pemphigus vulgaris patients enhanced Th1- and Th17-cell differentiation and exacerbated acantholysis via STAT activation

OBJECTIVE

Pemphigus vulgaris (PV) is a chronic inflammatory autoimmune blistering disease. Aberrant SOCS3/STAT pathway activation is associated with many autoimmune diseases. This study explored the relationship between activation of the SOCS3/STAT pathway and abnormally increased proportions of Th1 and Th17 cells in the peripheral blood of PV patients as well as the effect of CD4⁺ T cells with abnormal SOCS3/STAT pathway activation on acantholysis.

METHODS

In PV patients, the proportions of Th1 and Th17 cells in peripheral blood, the levels of IFN-γ and IL-17 in serum and the mRNA levels of SOCS3 and STAT1/3 in CD4⁺ T cells were detected. Then, SOCS3-knockdown primary CD4⁺ T cells were prepared, and cocultured with HaCaT cells. Finally, after SOCS3 knockdown and coculture, CD4⁺ T cells were collected, and the proportions of Th1 and Th17 cells, the protein levels of STAT1/3 and p-STAT1/3, and the levels of IFN-γ and IL-17 were measured. After 2 days of coculture, HaCaT cells were collected, inflammatory factors mRNA expression and acantholysis were assessed.

RESULTS

In PV patients, the proportions of Th1 (P = 0.016) and Th17 (P = 0.045) cells and the levels of IFN-γ (P = 0.010) were significantly increased. SOCS3 mRNA in CD4⁺ T cells was significantly decreased (P = 0.008), whereas STAT1 (P = 0.043) and STAT3 (P = 0.004) mRNA were significantly increased. After SOCS3 knockdown, the proportions of Th1 (P < 0.001) and Th17 (P = 0.006) cells, the levels of IFN-γ (P < 0.001) and IL-17 (P = 0.001), and the protein levels of p-STAT1 (P = 0.001) and p-STAT3 (P = 0.003) were significantly increased in the CD4⁺ T-shSOCS3-1 group. In the coculture system, the proportions of Th1 (P < 0.001) and Th17 (P < 0.001) cells, the levels of IFN-γ (P < 0.001) and IL-17 (P < 0.001), and the number of cell fragments (P < 0.001) were significantly increased in the CD4⁺ T-shSOCS3-1+HaCaT-PV-IgG group, whereas the protein level of desmoglein3 (Dsg3) was significantly decreased. In addition, PV-IgG significantly increased IFN-γ and IL-6 mRNA in HaCaT cells.

CONCLUSION

Low SOCS3 expression in CD4⁺ T cells from PV patients leads to overactivation of STAT, which causes CD4⁺ T cells to overdifferentiate into Th1 and Th17 cells. Additionally, PV-IgG-induced local inflammation in skin lesions, which is mediated by IFN-γ and IL-6, can aggravate this phenomenon. Furthermore, low SOCS3 expression in CD4⁺ T cells further exacerbates PV-IgG-induced acantholysis. Therefore, upregulating the expression of SOCS3 in CD4⁺ T cells of PV patients and maintaining the balance of the IFN-γ/STAT1/SOCS3 and IL-6/STAT3/SOCS3 pathways can alleviate acantholysis in patients with PV.

Histopathological, Immunohistochemical and Biochemical Studies of Murine Hepatosplenic Tissues Affected by Chronic Toxoplasmosis

Toxoplasmosis is a serious health problem in humans and animals resulting from obligatory intracellular invasion of reticuloendothelial tissue by Toxoplasma gondii. The profound pathologic effect of toxoplasmosis is confined to nervous tissue, but many other organs, including the liver and spleen, are insulted. Many molecules like caspase-3, CD3, and CD138 are implicated in the tissue immune response in a trial to alleviate hazardous toxoplasmosis impact. This study aimed to investigate the effect of chronic toxoplasmosis on the liver and spleen tissues of mice using biochemical and histopathological techniques and to detect the activity and level of expression of caspase-3, CD3, and CD138 in these tissues using immunohistochemical labeling. Compared with normal control, altered normal histological features accompanied by inflammatory reaction were recorded in hepatosplenic reticuloendothelial tissues in chronically infected mice. The biochemical profile of the liver has been changed in the form of increased liver enzymes, and oxidative stress has been evidenced by elevated nitric oxide (NO) concentration in liver homogenate. The levels of caspase3, CD3, and CD138 were markedly expressed in the liver and spleen of infected mice. Our findings revealed the persistent effect of latent toxoplasmosis on the host's histological architecture, metabolic, and immunological profile, creating a continued challenging host-parasite relationship.

Quercetin Impedes Th17 Cell Differentiation to Mitigate Arthritis Involving PPARγ-Driven Transactivation of SOCS3 and Redistribution Corepressor SMRT from PPARγ to STAT3

SCOPE

Quercetin (QU) is one of the most abundant flavonoids in plants and has attracted the attention of researchers because of its remarkable antirheumatoid arthritis (RA) effects and extremely low adverse reactions. However, the underlying mechanism needs further study.

METHODS AND RESULTS

Flow cytometry, immunofluorescence, enzyme linked immunosorbent assay （ELISA）, and quantitative real-time polymerase chain reaction （qRT-PCR） reveal the obvious inhibitory effects of QU on Th17 cell differentiation in arthritic mice. More importantly, QU markedly limits the development of Th17 cell polarization, which is virtually compromised by the treatment with peroxisome proliferator activated receptor γ (PPARγ) inhibitor GW9662 and knockdown of PPARγ. Additionally, molecular dynamics simulation and immunofluorescence exhibit QU directly binds to PPARγ and increases PPARγ nuclear translocation. Besides, QU confers its moderation effect on suppressor of cytokine signaling protein (SOCS3)/signal transducer and activator of transcription 3 (STAT3) axis partially depending on PPARγ. Furthermore, coimmunoprecipitation shows QU redistributes the corepressor silencing mediator for retinoid and thyroid-hormone receptors (SMRT) from PPARγ to STAT3. Finally, the inhibition of Th17 response and the antiarthritic effect of QU are nullified by GW9662 treatment in arthritic mice.

CONCLUSION

QU targets PPARγ and consequently inhibits Th17 cell differentiation by dual inhibitory activity of STAT3 to exert antiarthritic effect. The findings facilitate its development and put forth a stage for uncovering the mechanism of other naturally occurring compounds with chemical structures similar to QU.

Non-lethal rodent malarial infection prevents collagen-induced arthritis in mice via anti-arthritic immunomodulation

AIMS

Immunomodulatory effects of parasitic infections on the outcomes of allergic or autoimmune disorders have been addressed in many experimental studies. We examined the effects of Plasmodium yoelii 17X NL (Py) infection on collagen-induced arthritis (CIA).

METHODS AND RESULTS

Male DBA/1J mice were immunized with bovine type II collagen (IIC). Py inoculation was induced at three different time points (1, 4 weeks after or 4 weeks before the immunization). Only the inoculation at 4 weeks after IIC immunization significantly inhibited arthritis development. Non-malarial anaemia induced by phenylhydrazine hydrochloride (PHZ) did not affect arthritis development. In the infected mice, anti-IIC IgG levels were transiently reduced. In addition, splenic production of pro-arthritic cytokines (IL-17 and TNF-α) and IFN-γ decreased, whereas IL-10 production increased. Flow cytometric analysis clarified that the main IL-10 producers in Py-infected mice had the CD4⁺ CD25^- Foxp3^- phenotype, presumably Tr1 cells.

CONCLUSION

We demonstrated that experimental malarial infection alleviated autoimmune arthritis via immunomodulation, suggesting the importance of malaria in the hygiene hypothesis and the significance of searching for therapeutic immunomodulatory molecules from malarial parasites.

MicroRNA-155 contributes to host immunity against Toxoplasma gondii

Toxoplasma gondii is well known to infect almost all avian and mammalian species including humans, with worldwide distribution. This protozoan parasite can cause serious toxoplasmosis, posing with a risk to public health. The role of microRNAs in the pathogenesis of T. gondii has not been well described. The aim of the present study was to investigate the role of microRNA-155 (miR-155) in mediating innate and adaptive immune responses during T. gondii infection in mice models. The survival and parasite burden in T. gondii-infected miR-155^−/− and wild-type (WT) C57BL6 mice were compared. In these two mouse models, ELISA tests were used for analysis of Th1-associated, Th2-associated, and Th17-associated cytokines, and flow cytometry was used for analysis of the subpopulations of NK, NKT, CD8⁺T, CD4⁺T cells and regulatory T cells (Tregs), as well as Ly6Chi inflammatory monocytes and dendritic cells. The lack of miR-155 led to increased parasite burden and decreased survival of infected mice in contrast to WT mice. Innate and adaptive immune responses were reduced in the absence of miR-155, along with decreased proinflammatory mediators, Th-1-associated and Th-2-associated cytokines and accumulation of lymphocyte subpopulations. Also, CD8⁺ T cell exhaustion was also worsened in the absence of miR-155 via targeting of SHIP-1 and SOCS1, showing as up-regulated recruitment of Tregs and expression of PD-1, and down-regulated expression of IFN-γ and TNF-α in CD8⁺ T cells. Our results show that miR-155 is a critical immune regulator for the control of T. gondii infection, suggesting that miR-155 can be explored as a potential molecular target for boosting immunity against T. gondii.

Reduction of Amyloid Burden by Proliferated Homeostatic Microglia in Toxoplasma gondii-Infected Alzheimer's Disease Model Mice

In this study, we confirmed that the number of resident homeostatic microglia increases during chronic Toxoplasma gondii infection. Given that the progression of Alzheimer’s disease (AD) worsens with the accumulation of amyloid β (Aβ) plaques, which are eliminated through microglial phagocytosis, we hypothesized that T. gondii-induced microglial proliferation would reduce AD progression. Therefore, we investigated the association between microglial proliferation and Aβ plaque burden using brain tissues isolated from 5XFAD AD mice (AD group) and T. gondii-infected AD mice (AD + Toxo group). In the AD + Toxo group, amyloid plaque burden significantly decreased compared with the AD group; conversely, homeostatic microglial proliferation, and number of plaque-associated microglia significantly increased. As most plaque-associated microglia shifted to the disease-associated microglia (DAM) phenotype in both AD and AD + Toxo groups and underwent apoptosis after the lysosomal degradation of phagocytosed Aβ plaques, this indicates that a sustained supply of homeostatic microglia is required for alleviating Aβ plaque burden. Thus, chronic T. gondii infection can induce microglial proliferation in the brains of mice with progressed AD; a sustained supply of homeostatic microglia is a promising prospect for AD treatment.