In vivo effect of anti-TNF agent (etanercept) in reactivation of latent toxoplasmosis

Association Between Ocular Trauma and Activation of Ocular Toxoplasmosis

PURPOSE

To evaluate the association between ocular trauma and activation of ocular toxoplasmosis.

METHODS

Retrospective review of 686 patients with ocular toxoplasmosis and its association with trauma to the eye or the head within 1 week of activation.

RESULTS

Ten patients with a history of trauma and activation of ocular toxoplasmosis were detected (10/686; 1.45%). Nine patients showed a primary focus of retinitis without a previous scar and one patient had a recurrent form of ocular toxoplasmosis. From these 10 patients, Toxoplasma IgG was positive in eight of them. The median age of the patients was 35.8 years-old (range 17 to 65).

CONCLUSIONS

These cases suggest that trauma can be associated with activation of retinal bradyzoite cysts in ocular toxoplasmosis.

Effect of SARS-CoV-2 and Toxoplasma gondii co-infection on IFN-γ and TNF-α expression and its impact on disease severity

The symptomatology of COVID-19 is dependent on the immune status and the cytokine response of the host. The cytokine level of the host is influenced by the presence of chronic persistent or latent infections with co-pathogens. Parasitic diseases are known to induce host immune-modulation which may impact the response to co-infection. Toxoplasmosis is a widespread protozoal infection that remains quiescent in its latent form to be re-activated during states of immune depression. Clinical data on the relation between toxoplasmosis and COVID-19 cytokine profile and symptomatology are still insufficient. Seventy-nine subjects were included in this study. Patients were diagnosed with COVID-19 by PCR. Serological testing for toxoplasmosis was performed by the detection of anti-Toxoplasma IgG antibodies, in addition to IgG avidity testing. IFN-γ and TNF-α levels were determined by RT-PCR. Among patients diagnosed with COVID-19, 67.1% were seronegative for anti-Toxoplasma IgG, while 32.9% were seropositive. High avidity was found in 10 cases (40% of seropositive cases), 4 of whom required ICU administration, while low avidity was found in 15 cases (60%), 7 of which were administered to the ICU. TNF-α and INF-γ levels were significantly higher in COVID-19 patients than in healthy control subjects. No significant association was found between the seroprevalence of toxoplasmosis and the presence of COVID-19 and its severity. Cytokines were significantly higher in both seropositive and seronegative COVID-19 patients than in their control counterparts. The high prevalence of toxoplasmosis merits further exploration of its relation to COVID-19 by mass studies.

Toxoplasma gondii Infection in Humans: A Comprehensive Approach Involving the General Population, HIV-Infected Patients and Intermediate-Duration Fever in the Canary Islands, Spain

A prior investigation in 1993 identified a high seroprevalence of toxoplasmosis (63%) in the Canary Islands. This study aims to assess the current prevalence of the disease in diverse population groups. The study was based on a population-scale screening involving 273 residents utilizing T. gondii IgG ELISA and a 20 year retrospective study (1998-2018). This included AIDS/HIV outpatients (1357, of which 324 were residents), AIDS/HIV hospitalized patients (741) and patients with fever of intermediate duration (158). The seroprevalence in the resident population was 37%, with significant differences between islands. Among resident outpatients with AIDS/HIV, 14.2% had specific anti-T. gondii IgG, and three had anti-T. gondii IgM; however, IgG avidity testing indicated non-active infection. In patients hospitalized for AIDS/HIV, T. gondii causing encephalitis was detected in 2%. Among patients with fever of intermediate duration, 28.5% were positive for T. gondii IgG, and four also showed IgM positivity, although the infection was non-active. The study reveals a decrease in human toxoplasmosis over the past 30 years. However, the current seroprevalence, which stands at 37%, together with the substantial risk that T. gondii represents for immunocompromised individuals, highlights the need to implement preventive and control strategies to control the threat that this infection can pose to public health in the Canary Islands population.

Immune system roles in pathogenesis, prognosis, control, and treatment of Toxoplasma gondii infection

Toxoplasma gondii is the protozoan causative agent of toxoplasmosis in humans and warm-blooded animals. Recent studies have illustrated that the immune system plays a pivotal role in the pathogenesis of toxoplasmosis by triggering immune cytokines like IL-12, TNF-α, and IFN-γ and immune cells like DCs, Th1, and Th17. On the other hand, some immune components can serve as prognosis markers of toxoplasmosis. In healthy people, the disease is often asymptomatic, but immunocompromised people and newborns may suffer severe symptoms and complications. Therefore, the immune prognostic markers may provide tools to measure the disease progress and help patients to avoid further complications. Immunotherapies using monoclonal antibody, cytokines, immune cells, exosomes, novel vaccines, and anti-inflammatory molecules open new horizon for toxoplasmosis treatment. In this review article, we discussed the immunopathogenesis, prognosis, and immunotherapy of Toxoplasma gondii infection.

Evaluation of Specific Cellular and Humoral Immune Response to Toxoplasma gondii in Patients with Autoimmune Rheumatic Diseases Immunomodulated Due to the Use of TNF Blockers

(1) Background: TNF antagonists have been used to treat autoimmune diseases (AD). However, during the chronic phase of toxoplasmosis, TNF-α and TNFR play a significant role in maintaining disease resistance and latency. Several studies have demonstrated the risk of latent infections’ reactivation in patients infected with toxoplasmosis. Our objective was to verify whether patients with autoimmune rheumatic diseases, who use TNF antagonists and/or synthetic drugs and had previous contact with Toxoplasma gondii (IgG+), present any indication of an increased risk of toxoplasmosis reactivation. (2) Methods: Blood samples were collected, and peripheral blood mononuclear cells (PBMCs) were evaluated after stimulation with antigens of Toxoplasma gondii, with anti-CD3/anti-CD28 or without stimulus, at 48 and 96 h. CD69+, CD28+, and PD-1 stains were evaluated, in addition to intracellular expression of IFN-γ, IL-17, and IL-10 by CD4+ and the presence of regulatory CD4+ T cells by labeling CD25+, FOXP3, and LAP. The cytokines IL-2, IL-4, IL-6, IL-10, IFN-γ, TNF-α, and IL-17 were measured in the culture supernatant after 96 h. Serology for IgG and IgG1 was evaluated. (3) Results: There were no differences in the levels of IgG and IgG1 between the groups, but the IgG1 avidity was reduced in the immunobiological group compared to the control group. All groups exhibited a significant correlation between IgG and IgG1 positivity. CD4+ T lymphocytes expressing PD-1 were increased in individuals suffering from autoimmune rheumatic diseases and using disease-modifying antirheumatic drugs. In addition, treatment with TNF blockers did not seem to influence the populations of regulatory T cells and did not interfere with the expression of the cytokines IFN-γ, IL-17, and IL-10 by CD4+ cells or the production of cytokines by PBMCs from patients with AD. (4) Conclusions: This study presents evidence that the use of TNF-α blockers did not promote an immunological imbalance to the extent of impairing the anti-Toxoplasma gondii immune response and predisposing to toxoplasmosis reactivation.

TNF-TNFR1 Signaling Enhances the Protection Against Neospora caninum Infection

Neospora caninum is a protozoan associated with abortions in ruminants and neuromuscular disease in dogs. Classically, the immune response against apicomplexan parasites is characterized by the production of proinflammatory cytokines, such as IL-12, IFN-γ and TNF. TNF is mainly produced during the acute phases of the infections and binds to TNF receptor 1 (CD120a, p55, TNFR1) activating a variety of cells, hence playing an important role in the induction of the inflammatory process against diverse pathogens. Thus, in this study, we aimed to evaluate the role of TNF in cellular and humoral immune responses during N. caninum infection. For this purpose, we used a mouse model of infection based on wildtype (WT) and genetically deficient C57BL/6 mice in TNFR1 (Tnfr1 ^-/-). We observed that Tnfr1 ^-/- mice presented higher mortality associated with inflammatory lesions and increased parasite burden in the brain after the infection with N. caninum tachyzoites. Moreover, Tnfr1 ^-/- mice showed a reduction in nitric oxide (NO) levels in vivo. We also observed that Tnfr1 ^-/- mice showed enhanced serum concentration of antigen-specific IgG2 subclass, while IgG1 production was significantly reduced compared to WT mice, suggesting that TNFR1 is required for regular IgG subclass production and antigen recognition. Based on our results, we conclude that the TNF-TNFR1 complex is crucial for mediating host resistance during the infection by N. caninum.

Can Toxoplasma gondii Pave the Road for Dementia?

Dementia is an ominous neurological disease. Scientists proposed a link between its occurrence and the presence of Toxoplasma gondii (T. gondii). The long-term sequels of anti-Toxoplasma premunition, chiefly dominated by TNF-α, on the neurons and their receptors as the insulin-like growth factor-1 receptor (IGF-1R), which is tangled in cognition and synaptic plasticity, are still not clear. IGF-1R mediates its action via IGF-1, and its depletion is incorporated in the pathogenesis of dementia. The activated TNF-α signaling pathway induces NF-κβ that may induce or inhibit neurogenesis. This study speculates the potential impact of anti-Toxoplasma immune response on the expression of IGF-1R in chronic cerebral toxoplasmosis. The distributive pattern of T. gondii cysts was studied in association with TNF-α serum levels, the in situ expression of NF-κβ, and IGF-1R in mice using the low virulent ME-49 T. gondii strain. There was an elevation of the TNF-α serum level (p value ≤ 0.004) and significant upsurge in NF-κβ whereas IGF-1R was of low abundance (p value < 0.05) compared to the controls. TNF-α had a strong positive correlation with the intracerebral expression of NF-κβ (r value ≈ 0.943, p value ≈ 0.005) and a strong negative correlation to IGF-1R (r value -0.584 and -0.725 for area% and O.D., respectively). This activated TNF-α/NF-κβ keeps T. gondii under control at the expense of IGF-1R expression, depriving neurons of the effect of IGF-1, the receptor's ligand. We therefore deduce that T. gondii immunopathological reaction may be a road paver for developing dementia.

In vitro and in vivo evaluation of kojic acid against Toxoplasma gondii in experimental models of acute toxoplasmosis

As current toxoplasmosis chemotherapies have many side effects along with toxicity on patients, we examined the anti-Toxoplasma effect of a biologically important natural antibiotic, kojic acid, in vitro and in vivo. Vero cells were incubated with different concentrations of kojic acid or pyrimethamine (positive control), and the cellular viability was determined. Next, Vero cells were infected with T. gondii (RH strain) and treated with drugs. Then, we calculated the infection index, T. gondii intracellular proliferation and the number and measure of plaque. Moreover, the effect of kojic acid on survival times, serum levels of IFN-γ and TNF-α and histopathological changes in the liver and spleen of Balb/c mice infected with T. gondii were determined. Kojic acid reduced the infection index, intracellular proliferation, the number and measure of plaque in vitro when compared to untreated infected cells. Kojic acid (100 mg/kg/day) also showed a better survival rate than infected untreated control mice (P < 0.05). IFN-γ and TNF-α secretions were significantly increased by kojic acid treatment in comparison to untreated groups (P < 0.05). In addition, its inhibitory effects on inflammatory alterations, apoptosis, and necrosis have been shown in sections of liver and spleen. We conclude that kojic acid exhibit potent anti-Toxoplasma activity with direct and indirect effects on the parasite, although further studies are needed before consideration of clinical trials.

Systematic review and meta-analysis of variation in Toxoplasma gondii cyst burden in the murine model

Toxoplasma gondii is an obligate intracellular protozoan parasite that infects approximately 30% of the population of the United States, with worldwide distribution. The chronic (latent) infection, mediated by the bradyzoite parasite life stage, has attracted attention due to possible links to host behavioral alteration and psychomotor effects. Mice are a common model organism for studying the chronic stage, as they are natural hosts of infection. Notably, published studies demonstrate vast ranges of measured cyst burden within the murine brain tissue. The inconsistency of measured cyst burden within and between experiments makes interpretation of statistical significance difficult, potentially confounding studies of experimental anti-parasitic approaches. This review analyzes variation in measured cyst burden in a wide array of experimental mouse infections across published literature. Factors such as parasite infection strain, mouse strain, mode of infection, and infectious dose were all examined. The lowest variation in measured cyst burden occurred with the commonly available Balb/c and CBA mice undergoing infection by the ME49 strain of T. gondii. A summary of cyst variation and average cyst counts in T. gondii mouse models is presented, which may be useful for designing future experiments.

Risk Assessment of Etanercept in Mice Chronically Infected With Toxoplasma gondii

Toxoplasma gondii (T. gondii) is a zoonotic parasite that severely harms the health of the host. The cysts of T. gondii can reactivate from bradyzoites to tachyzoites, if the individual develops low or defective immunity, causing lethal toxoplasmosis. The host resists T. gondii infection by mediating Th1-type cellular immunity to generate pro-inflammatory cytokines. Tumor necrosis factor (TNF) is an important pro-inflammatory cytokine, which can induce lysosomal fusion of parasitophorous vacuole (PV) to kill parasites. Etanercept is a soluble TNF receptor fusion protein, which is widely used clinically to cure autoimmune diseases. The effects and specific molecular mechanisms of etanercept treatment on patients co-infected with autoimmune diseases and chronic toxoplasmosis are rarely reported. In our study, a mouse model of chronic infection with T. gondii and murine macrophages RAW264.7 cells infected with T. gondii were employed to investigate the impact of etanercept on the status of chronic infection. The cytokines levels and a series of phenotypic experiments in vivo and in vitro were measured. In the present study, the expression levels of TNF, IL-1β, and IL-6 were decreased and the brain cysts number was increased in mice chronically infected with T. gondii after being treated with etanercept. In vivo experiments confirmed that etanercept caused a decrease in the immune levels of the mice and activated the brain cysts, which would lead to conversion from chronic infection to acute infection, causing severe clinical and pathological symptoms. Murine macrophages RAW264.7 cells were pretreated with etanercept, and then infected with T. gondii. In vitro experiments, the expression levels of cytokines were decreased, indicating that etanercept could also reduce the cells’ immunity and promote the transformation of bradyzoites to tachyzoites, but did not affect the intracellular replication of tachyzoites. In summary, etanercept treatment could activate the conversion of bradyzoites to tachyzoites through reducing host immunity in vivo and in vitro. The results obtained from this study suggest that the use of etanercept in patients co-infected with autoimmune diseases and chronic toxoplasmosis may lead to the risk of activation of chronic infection, resulting in severe acute toxoplasmosis.

Activities of anti-Toxoplasma drugs and compounds against tissue cysts in the last three decades (1987 to 2017), a systematic review

Currently, there is no approved therapy that can eradicate Toxoplasma gondii tissue cysts, which are responsible for chronic infection. This systematic review was performed to assess drugs or compounds that can be used as anti-T. gondii tissue cysts in vitro and in vivo. English electronic databases (i.e., PubMed, Science Direct, Scopus, Google Scholar, and Web of Science) were systematically searched for articles published up to 2017. A total of 55 papers published from 1987 to 2017 were eligible for inclusion in this systematic review. Among the drugs, atovaquone and azithromycin were found effective after long-term inoculation into mice; however, clinical cases of resistance to these drugs have been reported. Also, FR235222, QUI-11, tanshinone IIA, and hydroxyzine were shown to be effective against Toxoplasma cysts, but their effectiveness in vivo remains unknown. Additionally, compound 32, endochin-like quinolones, miltefosine, and guanabenz can be used as effective antiparasitic with the unique ability to reduce brain tissue cysts in chronically infected mice. Importantly, these antimicrobial agents are significant criteria for drug candidates. Future studies should focus on the biology and drug susceptibility of the cyst form of T. gondii in chronic toxoplasmosis patients to find more effective strategies that have sterilizing activity for eliminating T. gondii tissue cysts from the host, preventing disease relapse and potentially shortening the required duration of drug administration. Graphical abstract.

Transcriptome analysis of ankylosing spondylitis patients before and after TNF-α inhibitor therapy reveals the pathways affected

Tumor necrosis factor-α (TNF-α) inhibitors are highly effective in suppressing inflammation in ankylosing spondylitis (AS) patients, and operate by suppression of TFN-α and downstream immunological pathways. To determine the mechanisms of action of TNF-α inhibitors in AS patients, we used transcriptomic and bioinformatic approaches on peripheral blood mononuclear cells from AS patients pre and post treatment. We found 656 differentially expressed genes, including the genome-wide significant AS-associated genes, IL6R, NOTCH1, IL10, CXCR2 and TNFRSF1A. A distinctive gene expression profile was found between male and female patients, mainly because of sex chromosome-linked genes and interleukin 17 receptor C, potentially accounting for the differences in clinical manifestation and treatment response between the genders. In addition to immune and inflammation regulatory pathways, like intestinal immune network for IgA production, cytokine-cytokine receptor interaction, Ras signaling pathway, allograft rejection and hematopoietic cell lineage, KEGG (Kyoto Encyclopedia of Genes and Genomes) pathway analyses revealed that infection-associated pathways (influenza A and toxoplasmosis) and metabolism-associated pathways were involved in response to TNF-α inhibitor treatment, providing insight into the mechanism of TNF-α inhibitors.