Murine heart gene expression during acute Chagasic myocarditis

Expression patterns of Galectin-3 and NLRP3 in Chagas reactivation and graft damage in heart transplants

OBJECTIVE

This study aimed to assess the expression patterns of galectin-3 (Gal-3) and NLRP3 in heart transplant recipients according to the presence of reactivated Trypanosoma cruzi infection or allograft rejection in Chagas and non-Chagas heart transplant recipients.

METHODS

Gal-3 and NLRP3 expression levels were analyzed in endomyocardial biopsies from 31 heart transplant recipients, including 16 patients with chronic Chagas disease (ChD) and 15 without ChD. Samples were evaluated during periods of graft rejection or ChD reactivation, characterized by intense myocardial cellular infiltrate, and after remission of the infiltrate, classified by histopathological severity. The transcriptional levels of genes encoding Gal-3, NLRP3, Asc, caspase-1, and IL-1β were identified using the GEO2T tool across different experimental conditions.

RESULTS

Gal-3 expression was lower in the myocardial infiltrate of ChD patients compared to non-ChD patients (p < 0.0001), whereas NLRP3 positivity was higher in ChD patients (p < 0.05). In a murine model of T. cruzi infection, elevated Gal-3 mRNA and NLRP3 inflammasome levels were observed in myocardial interstitial cells (p < 0.05). Peripheral blood mononuclear cells and cells from rodent cardiac allografts showed increased Gal-3 mRNA and NLRP3 levels compared to non-transplanted and rodent cardiac isografts (p < 0.001).

CONCLUSIONS

Our findings suggest that Gal-3 and NLRP3 may be important biomarkers for differentiating heart transplant recipients with and without ChD regarding the myocardial immunological processes.

Akt inhibitor deguelin aggravates inflammation and fibrosis in myocarditis

OBJECTIVES

Myocarditis is characterized by inflammatory cell infiltration in myocardial stroma. Attenuation of tumor necrosis factor (TNF)-α and interleukin (IL)-1β is a reliable mark for improving the prognosis. Protein kinase B (Akt) plays an important role in the development and progression of myocarditis. The specific role of the natural inhibitor of Akt, Deguelin, on myocarditis has not been reported. In this study, we used deguelin to investigate the effects of natural Akt inhibitor on myocarditis in experimental autoimmune myocarditis (EAM) rats.

MATERIALS AND METHODS

EAM rat models were made by using Lewis rats and Deguelin was injected intraperitoneally on day 3, 6, 9, 12 and 15 after successful modeling. On day 18, rats were sacrificed and the heart weight (HW)/ body weight (BW) ratio were measured. The pathological changes, pathological scores and fibrosis area were evaluated after H.&E. and Masson's trichrome staining. The mRNA levels of TNF-α and IL-1β were measured by RT-qPCR, while the protein expressions of TNF-α and IL-1β were detected by immunohistochemical staining and Western bolt. The protein expressions of Akt, Akt1, phosphorylated (p-) Akt and nuclear factor (NF)-κB were detected by Western bolt.

RESULTS

We found that the TNF-α and IL-1β levels, inflammatory scores and fibrosis areas were markedly increased after 18 days deguelin administration.

CONCLUSION

Akt inhibition with deguelin may aggravate myocarditis of EAM rats.

Using Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes as a Model to Study Trypanosoma cruzi Infection

Chagas disease (ChD) is one of the most neglected tropical diseases, with cardiomyopathy being the main cause of death in Trypanosoma cruzi-infected patients. As the parasite actively replicates in cardiomyocytes (CMs), the heart remains a key target organ in the pathogenesis of ChD. Here we modeled ChD using human induced pluripotent stem cell-derived CMs (iPSC-CMs) to understand the complex interplay between the parasite and host cells. We showed that iPSC-CMs can get infected with the T. cruzi Y strain and that all parasite cycle stages can be identified in our model system. Importantly, characterization of T. cruzi-infected iPSC-CMs showed significant changes in their gene expression profile, cell contractility, and distribution of key cardiac markers. Moreover, these infected iPSC-CMs exhibited a pro-inflammatory profile as indicated by significantly elevated cytokine levels and cell-trafficking regulators. We believe our iPSC-CM model is a valuable platform to explore new treatment strategies for ChD.

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iPSC-CMs can be infected with trypomastigote blood form of the T. cruzi Y strain

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T. cruzi induces significant changes in iPSC-CM gene expression and contractility

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T. cruzi alters the distribution of α-actinin, troponin T, and connexin 43

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iPSC-CMs show a pro-inflammatory profile following T. cruzi infection