Cytokines and T-cell response in malaria

The new ceRNA crosstalk between mRNAs and miRNAs in intervertebral disc degeneration

Degeneration of the intervertebral disc has been linked to lower back pain. To date, pathophysiological mechanisms of intervertebral disc degeneration (IDD) remain unclear; it is meaningful to find effective diagnostic biomarkers and new therapeutic strategies for IDD. This study aimed to reveal the molecular mechanism of IDD pathogenesis from the multidimensional transcriptomics perspective. Here, we acquired IDD bulk omics datasets (GSE67567 and GSE167199) including mRNA, microRNA expression profiles, and single-cell RNA sequencing (GSE199866) from the public Gene Expression Omnibus (GEO) database. Through principal component analysis and Venn analysis, we found different expression patterns in the IDD transcription level and identified 156 common DEGs in both bulk datasets. GO and KEGG functional analyses showed these dysregulators were mostly enriched in the collagen-containing extracellular matrix, cartilage development, chondrocyte differentiation, and immune response pathways. We also constructed a potentially dysregulated competing endogenous RNA (ceRNA) network between mRNAs and miRNAs related to IDD based on microRNA target information and co-expression analysis of RNA profiles and identified 36 ceRNA axes including ZFP36/miR-155-5p/FOS, BTG2/hsa-miR-185-5p/SOCS3, and COL9A2/hsa-miR-664a-5p/IBA57. Finally, in integrating bulk and single-cell transcriptome data analyses, a total of three marker genes, COL2A1, PAX1, and ZFP36L2, were identified. In conclusion, the key genes and the new ceRNA crosstalk we identified in intervertebral disc degeneration may provide new targets for the treatment of IDD.

A comprehensive study of epitopes and immune reactivity among Plasmodium species

Background

Malaria is a life-threatening disease caused by protozoan parasite of genus Plasmodium. Various antigenic proteins of Plasmodium are considered as the major targets for the development of an effective vaccine. The aim of the current study was a comprehensive analysis of the experimentally validated epitopes of Plasmodium obtained from various immunoassays.

Methods

Plasmodium species epitopes were prefetched from Immune Epitope Database (IEDB). Species specific classification of available epitopes was done for both human and murine malaria parasites. Further, these T cell and B cell epitopes along with MHC I/II binders of different Plasmodium species were examined to find out their capability to induce IFN-γ and IL-10 using IFNepitope and IL-10 Pred, respectively.

Results

The species-specific classification of 6874 unique epitopes resulted in the selection of predominant human and murine Plasmodium species. Further, the attempt was made to analyse the immune reactivity of these epitopes for their ability to induce cytokines namely IFN-γ and IL-10. Total, 2775 epitopes were predicted to possess IFN-γ inducing ability, whereas 1275 epitopes were found to be involved in the induction of IL-10.

Conclusions

This study facilitates the assessment of Plasmodium epitopes and associated proteins as a potential approach to design and develop an epitope-based vaccine. Moreover, the results highlight the epitope-based immunization in malaria to induce a protective immune response.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12866-022-02480-7.

Differential role of T regulatory and Th17 in Swiss mice infected with Plasmodium berghei ANKA and Plasmodium yoelii

The outcome of malaria infection is determined, in part, by the balance of pro-inflammatory and regulatory immune responses. Host immune responses in disease including malaria are finely regulated by the opposing effects of Th17 and T regulatory (Treg) cells. Here we have examined the role of Treg cells and Th17 cells during malaria infection and find that low levels of Treg cells possibly influence the outcome of infections with the lethal strain of Plasmodium berghei ANKA (PbA). In contrast, high level of Treg cells may influence the outcome of nonlethal Plasmodium yoelii NXL (P. yoelii) infections. We observed decreased expressions of key regulators of Treg inductions-TGF-β, CD4IL-2 and IL-10 during PbA infection, whereas their expression remains high during P. yoelii infection. On the other hand TNF-α, IL-6, IFN-γ and IL-23 expression is high during PbA infection and lower during P. yoelii infection. Thus, results from this study suggest that the differential expression of Treg and Th17 might have a key role on host pathogenesis during malaria infection. The high level of IL-6 and low level of TGF-β may composite of the advantaged local microenvironment for the production of Th17 cells in the spleen of the PBA infected mice and vice verse during nonlethal P. yoelii.

Anti-malarial IgG subclasses pattern and FcγRIIa (CD32) polymorphism among pregnancy-associated malaria in semi-immune Saudi women

Background

Pregnant women remain are at an increased risk of malaria with primigravidae being at the highest risk. Genetic polymorphism of the Fc receptor IIa for immunologlobulin (Ig) G (FcγRIIa) determines IgG subclass binding. Protection against pregnancy-associated malaria (PAM) is associated with the production of IgG specific for apical membrane antigen-1 (AMA-1). The present study was undertaken to examine the relationship between specific IgG/IgG subclasses and malaria infection. The second aim of the study is to examine the association between FcγRIIa R/H131 polymorphism in correlation with specific anti-malarial IgG antibodies of AMA-1 distribution and asymptomatic malaria infection among Saudi women living in the southern part of Saudi Arabia.

Methods

One hundred and twenty pregnant women living in an area of meso-endemic Plasmodium falciparum malaria infection were consecutively enrolled onto the study. These pregnant women were asymptomatic and attending routine antenatal clinics. The levels of plasma antibodies (IgG and subclasses AMA-1) were measured using indirect enzyme-linked immunosorbent assays (ELISA). Genotyping of FcγRIIa-R/H131 dimorphism was performed using gene-specific polymerase chain reaction (PCR) amplification with allele-specific restriction enzyme digestion (BstU1) of the PCR product.

Results

A total of sixty-two (52%) pregnant women was diagnosed with asymptomatic malarial infection (ASM) compared with 58 (48%) malaria free controls (MFC). In the ASM group, there were high levels of anti-malarial IgG1 and IgG3, when compared to MFC (P value <0.001, respectively). The FcγRIIa-R/R131 genotype and R131 were found to be statistically significantly more prevalent in the ASM group when compared to the MFC group [55% for ASM versus 12% for MFC, odds ratio (OR) 5.62, 95% confidence interval (CI)= (2.03- 15.58), P value= 0.001]. However, the H/H131 genotype showed statistically significant association with MFC [14% for ASM versus 50% for MFC, OR(0.36), 95% CI= (0.14- 0.95), P value= 0.03].

Conclusions

The study revealed that the ASM patients had higher anti-malarial IgG and IgG subclasses antibody levels when compared to the MFC. The FcγRIIa-R/R131 genotype and R131 allele were found to be statistically prevalent in the ASM when compared to the MFC group. The individuals carrying H/H131 were consistently associated with higher levels of anti-malarial IgG subclasses.

Hemozoin from Schistosoma japonicum does not affect murine myeloid dendritic cell function

Hemozoin (Hz) formation is a byproduct of hemoglobin digestion in some hematophagous organisms. Although Hz produced by Plasmodium falciparum (PfHz) has been shown to affect development and activities of human dendritic cells (DCs), the effects of Schistosoma Hz on DCs have not been elucidated. Our data presented in this report demonstrated that native Schistosoma japonica Hz (SjHz) did not affect the differentiation of murine bone marrow cells into immature DCs (imDCs). Maturation and stimulatory activities to T cells by imDCs induced by LPS were not altered in the presence of SjHz; whereas purified PfHz induced a slight increase in CD40 expression and enhanced IL-12p40 secretion. Lastly, SjHz treatment did not significantly affect the phagocytic activities of DCs. These data suggested that SjHz failed to exert any significant effects on the development and activities of murine myeloid DCs. The mechanisms of different effects on DCs by SjHz and PfHz remain to be elucidated.

CD4(+) T cell response in early erythrocytic stage malaria: Plasmodium berghei infection in BALB/c and C57BL/6 mice

Plasmodium berghei ANKA causes lethal malaria in mice. It is well established that C57BL/6 mice die early with fulminant symptoms including convulsion, whereas BALB/c mice survive this phase and die later of anemia and prostration. Early death in C57BL/6 mice has been considered to result from the adverse effects of inflammatory cytokines. To elucidate the CD4(+) T cell responses in early death due to severe malaria, the kinetics of CD4(+) T cells were compared by analyzing cell surface markers and the production of cytokines and transcription factors. The results revealed that cytokine production by CD4(+) T cells was induced as early as 5 days after infection and the maintenance of higher levels of IL-4 and IL-10 may be associated with the protection of BALB/c mice from early death. These results suggest that parasite control in the early phase of infection may be important for the development of an effective vaccine.

Toxoplasma gondii infection can regulate the expression of tumour necrosis factor-alpha receptors on human cells in vitro

The in vitro regulation of tumour necrosis factor (TNF)-alpha receptors during Toxoplasma gondii infection of human MRC5 fibroblasts and human myelomonocytic THP-1 cells was investigated. Cells were infected with the virulent RH of T. gondii. TNFR membrane receptors were analysed by flow cytometry with biotinylated TNF-alpha. Shedding of the soluble form of TNFR1 and TNFR2 in cell culture supernatants was measured by enzyme-linked immunosorbent assay, and expression of mRNA production of TNFR1 and TNFR2 was analysed by quantitative real-time polymerase chain reaction, 1 h after infection. In the MRC5 cell line, T. gondii infection did not induce any up- or down-regulation of membrane TNFRs, soluble TNFRs or mRNA of TNFRs. However, THP-1 cell infection with living parasites induced a significant soluble TNFR1 release by THP-1 cells after 1 h. We detected an approximately 50% up-regulation (P < 0.01) of soluble TNFR1 in infected THP-1 cells compared to controls. No change in soluble TNFR2 levels was observed in the same conditions. Moreover, infection decreased the level of TNF membrane receptors, but had no effect on TNFR1 and TNFR2 mRNA levels. TNFR modulation by T. gondii infection, in vitro, depends on the cell type. Furthermore, our data suggest that living parasites control the shedding of the soluble form of TNFR1. This mechanism may influence the role of TNF-alpha in toxoplasmosis.

Molecular aspects of severe malaria

Human infections with Plasmodium falciparum may result in severe forms of malaria. The widespread and rapid development of drug resistance in P. falciparum and the resistance of the disease-transmitting mosquitoes to insecticides make it urgent to understand the molecular background of the pathogenesis of malaria to enable the development of novel approaches to combat the disease. This review focuses on the molecular mechanisms of severe malaria caused by the P. falciparum parasite. The nature of severe malaria and the deleterious effects of parasite-derived toxins and host-induced cytokines are introduced. Sequestration, brought about by cytoadherence and rosetting, is linked to severe malaria and is mediated by multiple receptors on the endothelium and red blood cells. P. falciparum erythrocyte membrane protein 1 (PfEMP1) is the ligand responsible for a majority of binding interactions, and the multiply adhesive features of this sticky molecule are presented. Antigenic variation is also a major feature of PfEMP1 and of the surface of the P. falciparum-infected erythrocyte. Possible mechanisms of P. falciparum antigenic variation in asexual stages are further discussed. We conclude this review with a perspective and suggestions of important aspects for future investigations.

Molecular aspects of severe malaria

Human infections with Plasmodium falciparum may result in severe forms of malaria. The widespread and rapid development of drug resistance in P. falciparum and the resistance of the disease-transmitting mosquitoes to insecticides make it urgent to understand the molecular background of the pathogenesis of malaria to enable the development of novel approaches to combat the disease. This review focuses on the molecular mechanisms of severe malaria caused by the P. falciparum parasite. The nature of severe malaria and the deleterious effects of parasite-derived toxins and host-induced cytokines are introduced. Sequestration, brought about by cytoadherence and rosetting, is linked to severe malaria and is mediated by multiple receptors on the endothelium and red blood cells. P. falciparum erythrocyte membrane protein 1 (PfEMP1) is the ligand responsible for a majority of binding interactions, and the multiply adhesive features of this sticky molecule are presented. Antigenic variation is also a major feature of PfEMP1 and of the surface of the P. falciparum-infected erythrocyte. Possible mechanisms of P. falciparum antigenic variation in asexual stages are further discussed. We conclude this review with a perspective and suggestions of important aspects for future investigations.

Haemophagocytic syndrome associated with plasmodium vivax infection

A 41-year-old woman was admitted with fever, splenomegaly and pancytopenia. High serum ferritin, hypertriglyceridaemia and bone marrow haemophagocytosis were consistent with a haemophagocytic syndrome. Trophozoites and gametocytes of Plasmodium vivax were identified on blood smear. Rapid recovery was observed after treatment with oral chloroquine.

Detection of CD4+CD45RO+ T lymphocytes producing IL-4 in response to antigens on Plasmodium falciparum erythrocytes: an in vitro correlate of protective immunity induced with attenuated Plasmodium falciparum sporozoites

Malaria is caused by Plasmodium spp. and is one of the major infectious diseases leading to morbidity and mortality in tropical areas of the world. The model of protective immunity induced by immunization with radiation-attenuated Plasmodia sporozoites (SPZ) has become the framework for the elucidation of protective immune mechanisms and the prototype for a promising vaccine strategy. We have previously reported that although considered stage specific based on antibody and CD8+ cytolytic T lymphocyte responses directed against preerythrocytic stage antigens, in particular, the circumsporozoite protein and sporozoite surface protein 2, protective immunity induced in humans by attenuated Plasmodium falciparum SPZ may also involve CD4+ T cell responding to antigens present on parasitized red blood cells (pRBC). In this study we examined the functional role of pRBC responding CD4+ T cells by comparing in vitro pRBC-stimulated responses of CD4+ T cells from persons during preimmunity to irradiated SPZ, during induction of protection, and infection induced with SPZ. The results reported herein corroborate previously published observations that antigens associated with pRBC induce proliferative CD4+ lymphocytes responses in subjects exposed to malaria parasite-derived antigens and not malaria-naive persons; however, now we demonstrate that pRBC-proliferative CD4+ T cells did not coincide with protective immunity. Similarly, pRBC-induced IFN-gamma levels did not distinguish malaria protected from susceptible persons, although IFN-gamma was observed only in lymphocyte cultures from malaria parasite-exposed volunteers and not in lymphocyte cultures from malaria-naive persons. In contrast, we noted an increase in the IL-4-producing CD4+ T cells that also exhibited the memory phenotype, CD45RO, and an upregulated expression of CD25 in cultures from malaria protected persons as compared to malaria naive persons and subjects who became parasitemic. Hence, these observations suggest that the induction of memory CD4+ T cell subset distinguished by the expression of CD45RO and CD25 and production of IL-4 coincides with protective immune responses generated by immunization with attenuated SPZ.

Immune Evasion by Babesia bovis and Plasmodium falciparum: Cliff-dwellers of the Parasite World

Erythrocyte-dwelling parasites, such as Babesia bovis and Plasmodium falciparum, are not accessible to the host immune system during most of their asexual reproductive cycle because they are intracellular. While intracellular, the host immune response must be directed toward the surface of the infected erythrocyte. Immune individuals mount protective antibody and cell-mediated responses which eliminate most of the parasites, yet some survive to establish chronic infections. In this review, David Allred discusses some of the mechanisms used by these parasites to evade individual immune mechanisms targeting the infected erythrocyte to survive in the hostile environment of an effective immune response.