HIV Tat Protein Induces Myocardial Fibrosis Through TGF-β1-CTGF Signaling Cascade: A Potential Mechanism of HIV Infection-Related Cardiac Manifestations

HIV-Associated Cardiovascular Disease Pathogenesis: An Emerging Understanding Through Imaging and Immunology

Cardiac abnormalities were identified early in the epidemic of AIDS, predating the isolation and characterization of the etiologic agent, HIV. Several decades later, the causation and pathogenesis of cardiovascular disease (CVD) linked to HIV infection continue to be the focus of intense speculation. Before the widespread use of antiretroviral therapy, HIV-associated CVD was primarily characterized by HIV-associated cardiomyopathy linked to profound immunodeficiency. With increasing antiretroviral therapy use, viral load suppression, and establishment of immune competency, the effects of HIV on the cardiovascular system are more subtle. Yet, people living with HIV still face an increased incidence of cardiovascular pathology. Advances in cardiac imaging modalities and immunology have deepened our understanding of the pathogenesis of HIV-associated CVD. This review provides an overview of the pathogenesis of HIV-associated CVD integrating data from imaging and immunologic studies with particular relevance to the HIV population originating from high-endemic regions, such as sub-Saharan Africa. The review highlights key evidence gaps in the field and suggests future directions for research to better understand the complex HIV-CVD interactions.

SMAD2/3 Phosphorylation Is Downregulated in T Cells in HIV-Infected Patients

Persistent inflammation contributes to the exhaustion of immune system and non-AIDS-defining events in HIV-infected patients. Transforming growth factor β (TGF-β) is generally considered an anti-inflammatory cytokine. It is unclear that why high-level TGF-β coexists with chronic inflammation during HIV infection. In this study, it was found that HIV-infected patients had lower proportion of phosphorylated SMAD2/3-positive cells among total CD3⁺ T cells and subsets of CD3⁺CD8⁺ and CD3⁺CD8^- T cells when compared with health subjects. The findings implied that phosphorylation of SMAD2/3 is inhibited in HIV-infected patients, and that disturbance of TGF-β/SMAD2/3 signaling pathway may be involved in HIV-related chronic inflammation.

Puerarin ameliorates myocardial remodeling of spontaneously hypertensive rats through inhibiting TRPC6-CaN-NFATc3 pathway

Puerarin (Pue) has been widely used in the treatment of hypertension and cardiovascular diseases, but the basic mechanism of Pue on myocardial remodeling (MR) of hypertension is not clear. The purpose of this study was to investigate the effect and mechanism of Pue on MR and provide the basis for the clinical application. Thirty male spontaneously hypertensive rats (SHR) and six male Wistar Kyoto rats (WKY) aged 3 months were used in this study, SHR rats were randomly divided into 5 groups, Pue (40 or 80 mg/kg/d, ip) and telmisartan (TELMI) (30 mg/kg/d, ig) were administrated for 12 weeks. We used Echocardiography to detect the cardiac function. Morphology and structure of myocardium were observed. H9C2 cells were subjected to 1 μM Ang Ⅱ in vitro, 100 μM Pue, 0.5 μM Calmodulin-dependent calcineurin (CaN) inhibitor Cyclosporin A (CsA) and 1 μM specific transient receptor potential channel 6 (TRPC6) inhibitor SAR7334 were used in H9C2 cells. Long-term administration of Pue could significantly improve cardiac function, improve morphology and structure of myocardium in vivo. Pue could reduce MR related proteins expression (ACTC1, TGF-β1, CTGF, β-MHC and BNP), attenuate ROS, restore MMP and decrease Ca²⁺-overload in vitro. Further study indicated that Pue could decrease TRPC6 expression and inhibit nuclear factor of activated T cells 3 (NFATc3) nuclear translocation in vitro. These results suggested that puerarin could ameliorate myocardial remodeling through inhibiting TRPC6-CaN-NFATc3 in spontaneously hypertensive rats.

The Search for Biomarkers and Treatments in Chagas Disease: Insights From TGF-Beta Studies and Immunogenetics

The anti-inflammatory cytokine transforming growth factor beta (TGF-β) plays an important role in Chagas disease (CD), a potentially life-threatening illness caused by Trypanosoma cruzi. In this review we revisited clinical studies in CD patients combined with in vitro and in vivo experiments, presenting three main sections: an overview of epidemiological, economic, and clinical aspects of CD and the need for new biomarkers and treatment; a brief panorama of TGF-β roles and its intracellular signaling pathways, and an update of what is known about TGF-β and Chagas disease. In in vitro assays, TGF-β increases during T. cruzi infection and modulates heart cells invasion by the parasite fostering its intracellular parasite cycle. TGF-β modulates host immune response and inflammation, increases heart fibrosis, stimulates remodeling, and slows heart conduction via gap junction modulation. TGF-β signaling inhibitors reverts these effects opening a promising therapeutic approach in pre-clinical studies. CD patients with higher TGF-β1 serum level show a worse clinical outcome, implicating a predictive value of serum TGF-β as a surrogate biomarker of clinical relevance. Moreover, pre-clinical studies in chronic T. cruzi infected mice proved that inhibition of TGF-β pathway improved several cardiac electric parameters, reversed the loss of connexin-43 enriched intercellular plaques, reduced fibrosis of the cardiac tissue, restored GATA-6 and Tbox-5 transcription, supporting cardiac recovery. Finally, TGF-β polymorphisms indicate that CD immunogenetics is at the base of this phenomenon. We searched in a Brazilian population five single-nucleotide polymorphisms (-800 G>A rs1800468, -509 C>T rs1800469, +10 T>C rs1800470, +25 G>C rs1800471, and +263 C>T rs1800472), showing that CD patients frequently express the TGF-β1 gene genotypes CT and TT at position -509, as compared to noninfected persons; similar results were observed with genotypes TC and CC at codon +10 of the TGF-β1 gene, leading to the conclusion that 509 C>T and +10 T>C TGF-β1 polymorphisms are associated with Chagas disease susceptibility. Studies in genetically different populations susceptible to CD will help to gather new insights and encourage the use of TGF-β as a CD biomarker.