Association of cyclophilins and cardiovascular risk factors in coronary artery disease

Cyclophilin A and C are the Main Components of Extracellular Vesicles in Response to Hyperglycemia in BV2 Microglial Cells

Cyclophilins (Cyps) and CD147 receptor play a crucial role in the inflammatory responses. Chronic inflammation causes tissue damage and is a common condition of several inflammation-based pathologies as diabetes or Alzheimer´s disease. Under high glucose (HG) conditions, microglia is activated and releases inflammatory mediators. In this process the role of Cyps is unknown, so this study was aimed to investigate the profile of Cyps in microglia and their release through extracellular vesicles (EVs) under hyperglycemia. An increase in reactive oxygen species (ROS) and nitric oxide (NO) levels was observed when BV2 glia cells were incubated with HG concentration. These effects were mitigated by the Cyps inhibitor cyclosporine A (CsA), suggesting the implication of Cyps in BV2 activation. In these conditions the intracellular expression of CypA, B, C and D, as well as the membrane expression of CD147 receptor was increased. In addition, only CypA and CypC were detected in the extracellular medium. Then, the presence of Cyps inside EVs was explored as an alternative secretion route. Interestingly, under HG treatment, an increase in the levels of the four Cyps in EVs was observed. When neurons were treated with EVs derived from HG-treated glia cells, their viability was reduced and EVs were detected in cytosol neurons pointing to an EVs-Cyps neurotoxic effect. These findings provide novel insights into the relationship between Cyps and EVs in neuroinflammation in hyperglycemia conditions. The current results strengthen the role of Cyps in cell communication and its potential role in brain function under pathological conditions.

The effects of CypA on apoptosis: potential target for the treatment of diseases

Cyclophilin A (CypA), the first member of cyclophilins, is distributed extensively in eukaryotic and prokaryotic cells, primarily localized in the cytoplasm. In addition to acting as an intracellular receptor for cyclosporin A (CSA), CypA plays a crucial role in diseases such as aging and tumorigenesis. Apoptosis, a form of programmed cell death, is able to balance the rate of cell viability and death. In this review, we focus on the effects of CypA on apoptosis and the relationship between specific mechanisms of CypA promoting or inhibiting apoptosis and diseases, including tumorigenesis, cardiovascular diseases, organ injury, and microbial infections. Notably, the process of CypA promoting or inhibiting apoptosis is closely related to disease development. Finally, future prospects for the association of CypA and apoptosis are discussed, and a comprehensive understanding of the effects of CypA on apoptosis in relation to diseases is expected to provide new insights into the design of CypA as a therapeutic target for diseases. KEY POINTS: • Understand the effect of CypA on apoptosis. • CypA affects apoptosis through specific pathways. • The effect of CypA on apoptosis is associated with a variety of disease processes.

N-acetylneuraminic acid modulates SQSTM1/p62 sialyation-mediated ubiquitination degradation contributing to vascular endothelium dysfunction in experimental atherosclerosis mice

Sialic acid (SIA) has been reported to be a risk factor for atherosclerosis (AS) due to its high plasma levels in such patients. However, the effect of increasing SIA in circulation on endothelial function during AS progression remains unclear. In the present study, ApoE-/- mice and endothelial cells line (HUVEC cells) were applied to investigate the effect of SIA on AS progression and its potential molecular mechanism. In vivo, mice were injected intraperitoneally with Neu5Ac (main form of SIA) to keep high-level SIA in circulation. ORO, H&E, and Masson staining were applied to detect the plaque progression. In vitro, HUVECs were treated with Neu5Ac at different times, CCK-8, RT-PCR, western blot, and immunoprecipitation methods were used to analyze its effects on endothelial function and the potential involved mechanism. Results from the present study showed that high plasma levels of Neu5Ac in ApoE-/- mice could aggravate the plaque areas as well as increase necrotic core areas and collagen fiber contents. Remarkably, Neu5Ac levels in circulation displayed a positive correlation with AS plaque areas. Furthermore, results from HUVECs showed that Neu5Ac inhibited cells viability in a time/dose-dependent manner, by then induced the activation of inflammation makers such as ICAM-1 and IL-1β. Mechanism study showed that the activation of excessive autophagy medicated by SQSTM1/p62 displayed an important role in endothelium inflammatory injury. Neu5Ac could modify SQSTM1/p62 as a sialylation protein, and then increase its level with ubiquitin binding, further inducing ubiquitination degradation and being involved in the excessive autophagy pathway. Inhibition of sialylation by P-3Fax-Neu5Ac, a sialyltransferase inhibitor, reduced the binding of SQSTM1/p62 to ubiquitin. Together, these findings indicated that Neu5Ac increased SQSTM1/p62-ubiquitin binding through sialylation modification, thereby inducing excessive autophagy and subsequent endothelial injury. Inhibition of SQSTM1/p62 sialylation might be a potential strategy for preventing such disease with high levels of Neu5Ac in circulation.

Cyclophilin C as a Novel Diagnostic and Prognostic Biomarker of Coronary Artery Diseases. A Systematic Review and Meta-Analysis

We aimed to perform a meta-analysis to investigate the value of Cyclophilin C as a diagnostic and prognostic biomarker in Coronary Artery Disease. PubMed, Web of Science, Scopus and Cochrane library databases were searched. The inclusion criteria were any randomized control trials or controlled observational studies that measured the levels of Cyclophilin C in Coronary Artery disease patients and healthy controls. We excluded case reports, case series, reviews, editorials and animal studies. After search of the literature, 4 studies were included in the meta-analysis with a total number of 454 individuals included in the study. The pooled analysis showed a significant association between CAD group and increased levels of Cyclophilin C (MD = 28.94, 95% confidence interval (CI) = 19.28-38.60, P-value < 0.00001). Subgroup analysis showed a significant association between acute and chronic CAD group with increased levels of cyclophilin c compared with the control group (MD = 35.98, 95% CI = 19.84-52.11, P-value < 0.0001) and (MD = 26.36, 95% CI = 21.87 to 30.85, P-value < 0.00001), respectively. The pooled effect estimate showed that the ROC area for the cyclophillin c as a diagnostic biomarker of CAD was (ROC= 0.880, 95% CI =0.844-0.917, P-value < 0.001). Our study revealed a significant association between acute and chronic coronary artery disease with increased levels of Cyclophilin C. Cyclophilin C could be used as a novel diagnostic and prognostic biomarker in acute and chronic CAD. More research is warranted to support our results.

Cyclophilin B serum levels present variations across the menstrual cycle

Cyclophilins are a family of chaperones involved in inflammation and cell death. Cyclophilin B is released by inflammatory cells and acts through the receptor CD147, affecting matrix metalloproteases release, whilst cyclophilin D participates in hypoxia-induced apoptosis. Previous studies related hormones like estradiol or prolactin to these proteins, however, their blood concentrations across the menstrual cycle have not been determined. In this work, eleven healthy women (BMI: 21.8 kg/m2) were monitored during a single menstrual cycle, making blood extractions at follicular, periovulatory and mid-luteal phases. Hormone and cyclophilin levels were determined in each phase. Statistical differences were determined by repeated measures ANOVA and estimated marginal means tests, or by Friedman and Dunn-Bonferroni tests for parametric and non-parametric variables, respectively. Bivariate correlations were evaluated with the Spearman coefficient. Cyclophilin B concentrations presented significant differences during the menstrual cycle (p = 0.012). The highest levels of this protein were found at follicular extraction, followed by a decrease at periovulatory phase and a slight increase at mid-luteal phase. Cyclophilin D showed the same profile, although statistical significance was not reached. This immunophilin exhibited a positive correlation with luteinizing hormone at periovulatory phase (r = 0.743, p = 0.009) and with follicle stimulating hormone at mid-luteal phase (r = 0.633, p = 0.036). This is the first study describing the changes in cyclophilin B concentrations across the menstrual cycle, as well as the association of luteinizing and follicle stimulating hormones with cyclophilin D. These results suggest a role of these proteins in the cyclic inflammatory events that affect female reproductive system that should be explored.