Prolyl carboxypeptidase activity in the circulation and its correlation with body weight and adipose tissue in lean and obese subjects

Population-specific thermal responses contribute to regional variability in arbovirus transmission with changing climates

Temperature is increasing globally, and vector-borne diseases are particularly responsive to such increases. While it is known that temperature influences mosquito life history traits, transmission models have not historically considered population-specific effects of temperature. We assessed the interaction between Culex pipiens population and temperature in New York State (NYS) and utilized novel empirical data to inform predictive models of West Nile virus (WNV) transmission. Genetically and regionally distinct populations from NYS were reared at various temperatures, and life history traits were monitored and used to inform trait-based models. Variation in Cx. pipiens life history traits and population-dependent thermal responses account for a predicted 2.9°C difference in peak transmission that is reflected in regional differences in WNV prevalence. We additionally identified genetic signatures that may contribute to distinct thermal responses. Together, these data demonstrate how population variation contributes to significant geographic variability in arbovirus transmission with changing climates.

The spike effect of acute respiratory syndrome coronavirus 2 and coronavirus disease 2019 vaccines on blood pressure

Among the various comorbidities potentially worsening the clinical outcome in patients hospitalized for the acute respiratory syndrome coronavirus-2 (SARS-CoV-2), hypertension is one of the most prevalent. However, the basic mechanisms underlying the development of severe forms of coronavirus disease 2019 (COVID-19) among hypertensive patients remain undefined and the direct association of hypertension with outcome in COVID-19 is still a field of debate. Experimental and clinical data suggest that SARS-CoV-2 infection promotes a rise in blood pressure (BP) during the acute phase of infection. Acute increase in BP and high in-hospital BP variability may be tied with acute organ damage and a worse outcome in patients hospitalized for COVID-19. In this context, the failure of the counter-regulatory renin-angiotensin-system (RAS) axis is a potentially relevant mechanism involved in the raise in BP. It is well recognized that the efficient binding of the Spike (S) protein to angiotensin converting enzyme 2 (ACE2) receptors mediates the virus entry into cells. Internalization of ACE2, downregulation and malfunction predominantly due to viral occupation, dysregulates the protective RAS axis with increased generation and activity of angiotensin (Ang) II and reduced formation of Ang1,7. Thus, the imbalance between Ang II and Ang1-7 can directly contribute to excessively rise BP in the acute phase of SARS-CoV-2 infection. A similar mechanism has been postulated to explain the raise in BP following COVID-19 vaccination ("Spike Effect" similar to that observed during the infection of SARS-CoV-2). S proteins produced upon vaccination have the native-like mimicry of SARS-CoV-2 S protein's receptor binding functionality and prefusion structure and free-floating S proteins released by the destroyed cells previously targeted by vaccines may interact with ACE2 of other cells, thereby promoting ACE2 internalization and degradation, and loss of ACE2 activities.

Transcriptome-wide association study identifies novel genes associated with bone mineral density and lean body mass in children

OBJECTIVE

To identify novel candidate genes whose expression is associated with bone mineral density (BMD) and body lean mass (LM) in children.

METHODS

A tissue-specific transcriptome-wide association study (TWAS) was conducted utilizing a large-scale genome-wide association study (GWAS) dataset associated with BMD and LM and involving 10,414 participants. The measurement of BMD and LM phenotypes was made based on total-body dual-energy X-ray absorptiometry (TB-DXA) scans. TWAS was conducted by using FUSION software. Reference panels for muscle skeleton (MS), peripheral blood (NBL) and whole blood (YBL) were used for TWAS analysis. Functional enrichment and protein-protein interaction (PPI) analyses of the genes identified by TWAS were performed by using the online tool Metascape ( http://metascape.org ).

RESULTS

For BMD, we identified 174 genes with P < 0.05, such as IKZF1 (P = 1.46 × 10^-9) and CHKB (P = 8.31 × 10^-7). For LM, we identified 208 genes with P < 0.05, such as COPS5 (P = 3.03 × 10^-12) and MRPS33 (P = 5.45 × 10^-10). Gene ontology (GO) enrichment analysis of the BMD-associated genes revealed 200 GO terms, such as protein catabolic process (Log P = -5.09) and steroid hormone-mediated signaling pathway (Log P = -3.13). GO enrichment analysis of the LM-associated genes detected 287 GO terms, such as the apoptotic signaling pathway (Log P = -8.08) and lipid storage (Log P = -3.55).

CONCLUSION

This study identified several candidate genes for BMD and LM in children, providing novel clues to the genetic mechanisms underlying the development of childhood BMD and LM.

Prolyl Carboxypeptidase Activity Is Present in Human Adipose Tissue and Is Elevated in Serum of Obese Men with Type 2 Diabetes

Prolyl carboxypeptidase (PRCP) is involved in metabolic disorders by hydrolyzing anorexigenic peptides. A link between serum PRCP activity and obesity has been reported, but its origin/source is still unclear. Previously proven correlations between human serum PRCP activity and the amount of adipose tissue may suggest that adipose tissue is an important source of circulating PRCP. We investigated PRCP activity in visceral, subcutaneous adipose tissue (VAT and SCAT), skeletal muscle tissue and serum of lean and obese men with or without type 2 diabetes (T2D). Correlations between PRCP activity, metabolic and biochemical parameters and immune cell populations were assessed. PRCP activity was the highest in VAT, compared to SCAT, and was very low in skeletal muscle tissue in the overall group. Serum PRCP activity was significantly higher in T2-diabetic obese men, compared to lean and obese non-diabetic men, and was positively correlated with glycemic control. A positive correlation was observed between serum PRCP activity and VAT immune cell populations, which might indicate that circulating PRCP activity is deriving rather from the immune fraction than from adipocytes. In conclusion, PRCP activity was observed in human adipose tissue for the first time and serum PRCP activity is correlated with T2D in obese men.

COVID-19, vaccines and deficiency of ACE2 and other angiotensinases. Closing the loop on the "Spike effect"

The role of a dysregulated renin-angiotensin system (RAS) in the pathogenesis of COVID-19 is well recognized. The imbalance between angiotensin II (Ang II) and Angiotensin_1-7 (Ang_1,7) caused by the interaction between SARS-CoV-2 and the angiotensin converting enzyme 2 (ACE₂) receptors exerts a pivotal role on the clinical picture and outcome of COVID-19. ACE₂ receptors are not the exclusive angiotensinases in nature. Other angiotensinases (PRCP, and POP) have the potential to limit the detrimental effects of the interactions between ACE₂ and the Spike proteins. In the cardiovascular disease continuum, ACE₂ activity tends to decrease, and POP/PRCP activity to increase, from the health status to advanced deterioration of the cardiovascular system. The failure of the counter-regulatory RAS axis during the acute phase of COVID-19 is characterized by a decrease of ACE₂ expression coupled to unchanged activity of other angiotensinases, therefore failing to limit the accumulation of Ang II. COVID-19 vaccines increase the endogenous synthesis of SARS-CoV-2 spike proteins. Once synthetized, the free-floating spike proteins circulate in the blood, interact with ACE₂ receptors and resemble the pathological features of SARS-CoV-2 ("Spike effect" of COVID-19 vaccines). It has been noted that an increased catalytic activity of POP/PRCP is typical in elderly individuals with comorbidities or previous cardiovascular events, but not in younger people. Thus, the adverse reactions to COVID-19 vaccination associated with Ang II accumulation are generally more common in younger and healthy subjects. Understanding the relationships between different mechanisms of Ang II cleavage and accumulation offers the opportunity to close the pathophysiological loop between the risk of progression to severe forms of COVID-19 and the potential adverse events of vaccination.

Proline-specific peptidase activities (DPP4, PRCP, FAP and PREP) in plasma of hospitalized COVID-19 patients

BACKGROUND

COVID-19 patients experience several features of dysregulated immune system observed in sepsis. We previously showed a dysregulation of several proline-selective peptidases such as dipeptidyl peptidase 4 (DPP4), fibroblast activation protein alpha (FAP), prolyl oligopeptidase (PREP) and prolylcarboxypeptidase (PRCP) in sepsis. In this study, we investigated whether these peptidases are similarly dysregulated in hospitalized COVID-19 patients.

METHODS

Fifty-six hospitalized COVID-19 patients and 32 healthy controls were included. Enzymatic activities of DPP4, FAP, PREP and PRCP were measured in samples collected shortly after hospital admission and in longitudinal follow-up samples.

RESULTS

Compared to healthy controls, both DPP4 and FAP activities were significantly lower in COVID-19 patients at hospital admission and FAP activity further decreased significantly in the first week of hospitalization. While PRCP activity remained unchanged, PREP activity was significantly increased in COVID-19 patients at hospitalization and further increased during hospital stay and stayed elevated until the day of discharge.

CONCLUSION

The changes in activities of proline-selective peptidases in plasma are very similar in COVID-19 and septic shock patients. The pronounced decrease in FAP activity deserves further investigation, both from a pathophysiological viewpoint and as its utility as a part of a biomarker panel.

Prolyl Carboxypeptidase Mediates the C-Terminal Cleavage of (Pyr)-Apelin-13 in Human Umbilical Vein and Aortic Endothelial Cells

The aim of this study was to investigate the C-terminal cleavage of (pyr)-apelin-13 in human endothelial cells with respect to the role and subcellular location of prolyl carboxypeptidase (PRCP). Human umbilical vein and aortic endothelial cells, pre-treated with prolyl carboxypeptidase-inhibitor compound 8o and/or angiotensin converting enzyme 2 (ACE2)-inhibitor DX600, were incubated with (pyr)-apelin-13 for different time periods. Cleavage products of (pyr)-apelin-13 in the supernatant were identified by mass spectrometry. The subcellular location of PRCP was examined via immunocytochemistry. In addition, PRCP activity was measured in supernatants and cell lysates of LPS-, TNFα-, and IL-1β-stimulated cells. PRCP cleaved (pyr)-apelin-13 in human umbilical vein and aortic endothelial cells, while ACE2 only contributed to this cleavage in aortic endothelial cells. PRCP was found in endothelial cell lysosomes. Pro-inflammatory stimulation induced the secretion of PRCP in the extracellular environment of endothelial cells, while its intracellular level remained intact. In conclusion, PRCP, observed in endothelial lysosomes, is responsible for the C-terminal cleavage of (pyr)-apelin-13 in human umbilical vein endothelial cells, while in aortic endothelial cells ACE2 also contributes to this cleavage. These results pave the way to further elucidate the relevance of the C-terminal Phe of (pyr)-apelin-13.

Prolylcarboxypeptidase Mitigates Myocardial Ischemia/Reperfusion Injury by Stabilizing Mitophagy

The role of prolylcarboxypeptidase (PRCP) in myocardial ischemia/reperfusion (I/R) injury is unclear. Herein, we aimed to evaluate the protective effect of the PRCP-angiotensin-(1-7) [Ang-(1-7)]/bradykinin-(1-9) [BK-(1-9)] axis on myocardial I/R injury and identify the mechanisms involved. Plasma PRCP level and activity, as well as Ang-(1-7) and BK-(1-9) levels, were compared in healthy subjects, patients with unstable angina, and those with ST-segment-elevated acute myocardial infarction (AMI). Thereafter, the effects of PRCP overexpression and knockdown on left ventricular function, mitophagy, and levels of Ang-(1-7) and BK-(1-9) were examined in rats during myocardial I/R. Finally, the effects of Ang-(1-7) and BK-(1-9) on I/R-induced mitophagy and the signaling pathways involved were investigated in vitro in rat cardiomyocytes. AMI patients showed increased plasma level and activity of PRCP and levels of Ang-(1-7) and BK-(1-9) as compared with healthy subjects and those with unstable angina. PRCP protected against myocardial I/R injury in rats by paradoxical regulation of cardiomyocyte mitophagy during the ischemia and reperfusion phases, which was mediated by downstream Ang-(1-7) and BK-(1-9). We further depicted a possible role of activation of AMPK in mitophagy induction during ischemia and activation of Akt in mitophagy inhibition during reperfusion in the beneficial effects of Ang-(1-7) and BK-(1-9). Thus, the PRCP-Ang-(1-7)/BK-(1-9) axis may protect against myocardial I/R injury by paradoxical regulation of cardiomyocyte mitophagy during ischemia and reperfusion phases.