Endothelial dysfunction: a unifying hypothesis for the burden of cardiovascular diseases in sub-Saharan Africa

rhBMP‑7 suppresses TGF‑β1‑induced endothelial to mesenchymal transition in circulating endothelial cells by regulating Smad5

Endothelial to mesenchymal transition (EndMT) has been confirmed to participate in several cardiovascular diseases. In addition, EndMT of circulating endothelial cells (CECs) contributes to the pathology of musculoskeletal injury. However, little is known about the molecular mechanism of CECs undergoing EndMT. In the present study, human CECs were isolated and identified using anti‑CD146‑coupled magnetic beads. CECs were exposed to transforming growth factor (TGF)‑β1 or TGF‑β1 + recombinant human bone morphogenetic protein 7 (rhBMP‑7) or TGF‑β1 + rhBMP‑7 + Smad5 antagonist Jun activation domain‑binding protein 1. Vascular endothelial (VE)‑cadherin and vimentin expression were detected by immunofluorescence staining in TGF‑β1‑treated CECs. The expression levels of von Willebrand factor (vWF), E‑selectin, VE‑cadherin, vimentin, fibronectin, α smooth muscle actin (α‑SMA) and Smad2/3 were detected by reverse transcription‑quantitative PCR or western blot analysis. It was identified that rhBMP‑7 attenuated TGF‑β1‑induced endothelial cell injury. TGF‑β1 could induce the EndMT process in CECs, as confirmed by the co‑expression of VE‑cadherin and vimentin. TGF‑β1 significantly reduced the expression of VE‑cadherin, and induced the expression of vimentin, fibronectin and α‑SMA. rhBMP‑7 reversed the effects of TGF‑β1 on the expression of these genes. Additionally, Smad5 antagonist reversed the effects of rhBMP‑7 on TGF‑β1‑induced EndMT, and upregulated rhBMP‑7‑inhibited Smad2/3 expression. In conclusion, TGF‑β1 could induce EndMT in CECs and rhBMP‑7 may suppress this process by regulating Smad5.

Burden of Peripheral Artery Disease in Sub-Saharan Africa and the Caribbean 1990 to 2015

Background:

The estimated global prevalence of Peripheral artery disease (PAD) increased by 24% in span of 10 years (2000-2010) from 164 to 202 million. Despite scarcity of data on PAD in sub-Saharan Africa (SSA) and the Caribbean, estimates for PAD from these regions may be helpful for health-care providers.

Methods:

The Global Burden of Disease Study 2015 quantified health loss from hundreds of diseases using systematic reviews and multilevel computer modeling. Estimated rates with 95% uncertainty intervals (UI) for PAD (ICD-10 I70.2) were examined for SSA and the Caribbean and compared to high-income North America (HINA). Disability-adjusted life years (DALYs) are years of healthy life lost representing total disease burden by combining years of life lost and years lived disabled.

Results:

In 2015, estimated age-standardized DALYs per 100,000 due to PAD for males were as follows: Caribbean (34, UI: 29-39), HINA (36, UI: 30-42), and SSA (20, UI: 14-30). In contrast, DALYs in females were as follows: Caribbean (25, UI: 20-30), HINA (28, UI: 22-36), and SSA (17, UI: 11-26). For both sexes combined, the rate in Southern SSA was 55 (46-67). This reflects the extremely high rates in South Africa (males 90, UI: 77-107; females 63, UI: 53-75).

Conclusion:

Estimated rate of DALYs per 100,000 was lowest in SSA. Within SSA, the rate in South Africa was highest, exceeding even HINA. Caribbean rates were intermediate.

Recent advances in understanding hypertension development in sub-Saharan Africa

Consistent reports indicate that hypertension is a particularly common finding in black populations. Hypertension occurs at younger ages and is often more severe in terms of blood pressure levels and organ damage than in whites, resulting in a higher incidence of cardiovascular disease and mortality. This review provides an outline of recent advances in the pathophysiological understanding of blood pressure elevation and the consequences thereof in black populations in Africa. This is set against the backdrop of populations undergoing demanding and rapid demographic transition, where infection with the human immunodeficiency virus predominates, and where under and over-nutrition coexist. Collectively, recent findings from Africa illustrate an increased lifetime risk to hypertension from foetal life onwards. From young ages black populations display early endothelial dysfunction, increased vascular tone and reactivity, microvascular structural adaptions as well as increased aortic stiffness resulting in elevated central and brachial blood pressures during the day and night, when compared to whites. Together with knowledge on the contributions of sympathetic activation and abnormal renal sodium handling, these pathophysiological adaptations result in subclinical and clinical organ damage at younger ages. This overall enhanced understanding on the determinants of blood pressure elevation in blacks encourages (a) novel approaches to assess and manage hypertension in Africa better, (b) further scientific discovery to develop more effective prevention and treatment strategies and

Cardiovascular risk and endothelial function in people living with HIV/AIDS: design of the multi-site, longitudinal EndoAfrica study in the Western Cape Province of South Africa

Background

There is growing evidence of an interaction between HIV-infection, anti-retroviral therapy (ART) and cardiovascular diseases (CVD). Epidemiological studies in Europe and North America have been observing a shift towards an increased incidence of coronary heart disease and acute myocardial infarctions in HIV-infected populations compared to the general population even after adjusting for traditional cardiovascular risk factors. Despite South Africa (and sub-Saharan Africa, SSA) being regarded as the epicentre of the global HIV epidemic, very little is known about the prevalence of cardiovascular risk factors and precursors of vascular disease in HIV-infected populations in this region. The knowledge gap is further widened by the paucity of data from prospective studies. We present the rationale, objectives and key methodological features of the EndoAfrica study, which aims to determine whether HIV-infection and ART are associated with altered cardiovascular risk and changes in vascular endothelial structure and function in adults living in the Western Cape Province of South Africa.

Methods

In this longitudinal study, comprehensive cardiovascular assessments of HIV-negative and HIV-positive (with and without ART) study participants are performed by clinical and biochemical screening for traditional cardiovascular risk factors and biomarkers of CVD. Vascular and endothelial function is determined by brachial artery flow-mediated dilatation (FMD), carotid-intima-thickness (IMT) measurements and quantitative retinal blood vessel analyses, complemented by vascular endothelial biomarker assays. Finally, we aim to statistically determine whether HIV-infection and/or ART are associated with increased cardiovascular risk and vascular endothelial dysfunction, and determine whether there is progression/regression in these endpoints 18 months after the baseline assessments.

Discussion

The EndoAfrica study provides a unique opportunity to recruit a cohort of HIV-infected patients and HIV-negative controls who will be comprehensively and longitudinally assessed for cardiovascular risk and disease profile with vascular endothelial function as a potentially important intermediate cardiovascular phenotype. To our knowledge, it is the first time that such a systematic study has been established in the context of SSA and South Africa.

Human induced pluripotent stem cells derived endothelial cells mimicking vascular inflammatory response under flow

Endothelial cells (ECs) have great potential in vascular diseases research and regenerative medicine. Autologous human ECs are difficult to acquire in sufficient numbers in vitro, and human induced pluripotent stem cells (iPSCs) offer unique opportunity to generate ECs for these purposes. In this work, we present a new and efficient method to simply differentiate human iPSCs into functional ECs, which can respond to physiological level of flow and inflammatory stimulation on a fabricated microdevice. The endothelial-like cells were differentiated from human iPSCs within only one week, according to the inducing development principle. The expression of endothelial progenitor and endothelial marker genes (GATA2, RUNX1, CD34, and CD31) increased on the second and fourth days after the initial inducing process. The differentiated ECs exhibited strong expression of cells-specific markers (CD31 and von Willebrand factor antibody), similar to that present in human umbilical vein endothelial cells. In addition, the hiPSC derived ECs were able to form tubular structure and respond to vascular-like flow generated on a microdevice. Furthermore, the human induced pluripotent stem cell-endothelial cells (hiPSC-ECs) pretreated with tumor necrosis factor (TNF-α) were susceptible to adhesion to human monocyte line U937 under flow condition, indicating the feasibility of this hiPSCs derived microsystem for mimicking the inflammatory response of endothelial cells under physiological and pathological process.

Reconciling the IPC and Two-Hit Models: Dissecting the Underlying Cellular and Molecular Mechanisms of Two Seemingly Opposing Frameworks

Inflammatory cascades and mechanisms are ubiquitous during host responses to various types of insult. Biological models and interventional strategies have been devised as an effort to better understand and modulate inflammation-driven injuries. Amongst those the two-hit model stands as a plausible and intuitive framework that explains some of the most frequent clinical outcomes seen in injuries like trauma and sepsis. This model states that a first hit serves as a priming event upon which sequential insults can build on, culminating on maladaptive inflammatory responses. On a different front, ischemic preconditioning (IPC) has risen to light as a readily applicable tool for modulating the inflammatory response to ischemia and reperfusion. The idea is that mild ischemic insults, either remote or local, can cause organs and tissues to be more resilient to further ischemic insults. This seemingly contradictory role that the two models attribute to a first inflammatory hit, as priming in the former and protective in the latter, has set these two theories on opposing corners of the literature. The present review tries to reconcile both models by showing that, rather than debunking each other, each framework offers unique insights in understanding and modulating inflammation-related injuries.