Elevated platelet expression of CD36 may contribute to increased risk of thrombo-embolism in active inflammatory bowel disease

The polymorphism analysis for CD36 among platelet donors

CD36 may defect on platelets and/or monocytes in healthy individuals, which was defined as CD36 deficiency. However, we did not know the correlation between the molecular and protein levels completely. Here, we aim to determine the polymorphisms of the CD36 gene, RNA level, and CD36 on platelets and in plasma. The individuals were sequenced by Sanger sequencing. Bioinformational analysis was used by the HotMuSiC, CUPSAT, SAAFEC-SEQ, and FoldX. RNA analysis and CD36 protein detection were performed by qPCR, flow cytometry, and ELISA. In this study, we found c.1228_1239delATTGTGCCTATT (allele frequency = 0.0072) with the highest frequency among our cohort, and one mutation (c.1329_1354dupGATAGAAATGATCTTACTCAGTGTTG) was not present in the dbSNP database. 5 mutations located in the extracellular domain sequencing region with confirmation in deficient individuals, of which c.284T>C, c.512A>G, c.572C>T, and c.869T>C were found to have a deleterious impact on CD36 protein stability. Furthermore, the MFI of CD36 expression on platelets in the mutation-carry, deleterious-effect, and deficiency group was significantly lower than the no-mutation group (P < 0.0500). In addition, sCD36 levels in type II individuals were significantly lower compared with positive controls (P = 0.0060). Nevertheless, we found the presence of sCD36 in a type I individual. RNA analysis showed CD36 RNA levels in platelets of type II individuals were significantly lower than the positive individuals (P = 0.0065). However, no significant difference was observed in monocytes (P = 0.7500). We identified the most prevalent mutation (c.1228_1239delATTGTGCCTATT) among Kunming donors. Besides, our results suggested RNA level alterations could potentially underlie type II deficiency. Furthermore, sCD36 may hold promise for assessing immune reaction risk in CD36-deficient individuals, but more studies should be conducted to validate this hypothesis.

Is the suppression of CD36 a promising way for atherosclerosis therapy?

Atherosclerosis is the main underlying pathology of many cardiovascular diseases and is marked by plaque formation in the artery wall. It has posed a serious threat to the health of people all over the world. CD36 acts as a significant regulator of lipid homeostasis, which is closely associated with the onset and progression of atherosclerosis and may be a new therapeutic target. The abnormal overexpression of CD36 facilitates lipid accumulation, foam cell formation, inflammation, endothelial apoptosis, and thrombosis. Numerous natural products and lipid-lowering agents are found to target the suppression of CD36 or inhibit the upregulation of CD36 to prevent and treat atherosclerosis. Here, the structure, expression regulation and function of CD36 in atherosclerosis and its related pharmacological therapies are reviewed. This review highlights the importance of drugs targeting CD36 suppression in the treatment and prevention of atherosclerosis, in order to develop new therapeutic strategies and potential anti-atherosclerotic drugs both preclinically and clinically.

Bioinformatics Analysis Reveals Crosstalk Among Platelets, Immune Cells, and the Glomerulus That May Play an Important Role in the Development of Diabetic Nephropathy

Diabetic nephropathy (DN) is the main cause of end stage renal disease (ESRD). Glomerulus damage is one of the primary pathological changes in DN. To reveal the gene expression alteration in the glomerulus involved in DN development, we screened the Gene Expression Omnibus (GEO) database up to December 2020. Eleven gene expression datasets about gene expression of the human DN glomerulus and its control were downloaded for further bioinformatics analysis. By using R language, all expression data were extracted and were further cross-platform normalized by Shambhala. Differentially expressed genes (DEGs) were identified by Student's t-test coupled with false discovery rate (FDR) (P < 0.05) and fold change (FC) ≥1.5. DEGs were further analyzed by the Database for Annotation, Visualization, and Integrated Discovery (DAVID) to enrich the Gene Ontology (GO) terms and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway. We further constructed a protein-protein interaction (PPI) network of DEGs to identify the core genes. We used digital cytometry software CIBERSORTx to analyze the infiltration of immune cells in DN. A total of 578 genes were identified as DEGs in this study. Thirteen were identified as core genes, in which LYZ, LUM, and THBS2 were seldom linked with DN. Based on the result of GO, KEGG enrichment, and CIBERSORTx immune cells infiltration analysis, we hypothesize that positive feedback may form among the glomerulus, platelets, and immune cells. This vicious cycle may damage the glomerulus persistently even after the initial high glucose damage was removed. Studying the genes and pathway reported in this study may shed light on new knowledge of DN pathogenesis.

CD36+/CD61+ Microparticles Correlate with the Risk of Percutaneous Cardiac Interventions in Coronary Artery Disease Patients and the Effects of Ticagrelor

PURPOSE

The CD36 scavenger receptor is a mediator of both atherogenesis and thrombosis. We aimed to investigate the prognostic value of CD36+ microparticles (MPs) released from platelets for cardiovascular event presentation in coronary artery disease (CAD) patients and the effects of different antiplatelet drugs on MPs.

METHODS

A total of 101 aspirin-treated CAD patients, who were planned to undergo coronary angiography (CAG), were randomized to either a standard clopidogrel regimen or ticagrelor treatment. Total Annexin V-(AV)+ MPs, CD61+/AV+ MPs, and CD36+/CD61+/AV+ MPs were quantified by flow cytometry at baseline, before and immediately after the operation. The ADP-induced platelet inhibition rate was measured by thromboelastogram (TEG) examination 1 h before the operation.

RESULTS

The baseline levels of CD36+/CD61+/AV+ MPs were significantly increased in percutaneous coronary intervention (PCI) patients (n = 52) compared to no-PCI patients (n = 49) (p < 0.05). A ROC-curve clustered model for CD36+/CD61+/AV+ MPs at baseline predicted an increased risk of PCI [p = 0.009, AUC = 0.761 (95%CI: 0.601 to 0.922)]. Moreover, TEG examination showed that the preoperative proportion of CD36+/CD61+/AV+ MPs was significantly negatively correlated with R time and K time (r = - 0.236, p = 00.026; r = - 0.288, p = 0.006), and positively correlated with MA_ADP (r = 0.226, p = 0.045). Subgroup analysis of PCI group showed that the platelet inhibition rate of ticagrelor was significantly higher (66.05% ± 28.76% vs.31.01% ± 27.33%, p < 0.001), and the number of AV+ MPs, CD61+/AV+ MPs, and CD36+/CD61+/AV+ MPs before the operation was significantly lower than clopidogrel (p < 0.05, all).

CONCLUSION

The high levels of CD36+ MPs derived from activated platelets are related to an increased risk of PCI in CAD patients. Ticagrelor significantly reduced the number of CD61+/AV+ MPs and CD36+/CD61+/AV+ MPs. This trial registration number is ChiCTR1800014908 and the date of registration is 2018.05.01.

The role of CD36 in cardiovascular disease

CD36, also known as the scavenger receptor B2, is a multifunctional receptor widely expressed in various organs. CD36 plays a crucial role in the uptake of long-chain fatty acids, the main metabolic substrate in myocardial tissue. The maturation and transportation of CD36 is regulated by post-translational modifications, including phosphorylation, ubiquitination, glycosylation, and palmitoylation. CD36 is decreased in pathological cardiac hypertrophy caused by ischaemia-reperfusion and pressure overload, and increased in diabetic cardiomyopathy and atherosclerosis. Deficiency of CD36 alleviates diabetic cardiomyopathy and atherosclerosis, while overexpression of CD36 eliminates ischaemia-reperfusion damage, together suggesting that CD36 is closely associated with the progression of cardiovascular diseases and may be a new therapeutic target. This review summarizes the regulation and post-translational modifications of CD36 and evaluates its role in cardiovascular diseases and its potential as a therapeutic target.

Protein biomarkers for incident deep venous thrombosis in critically ill adolescents: An exploratory study

BACKGROUND

There are no tests to identify critically ill children at high risk of deep venous thrombosis (DVT). In this exploratory study, we aimed to identify proteins that are associated with incident DVT in critically ill adolescents.

PROCEDURE

Plasma samples were obtained from critically ill adolescents within 24 hours after initiation of cardiopulmonary support. The adolescents were followed with ultrasound to detect the development of DVT of the lower extremity and clinically for bleeding. Thrombin-antithrombin complex and prothrombin fragment 1+2 were measured using immunosorbent assays, whereas procoagulation and anticoagulation factors were measured using multiplex assays. Plasma samples were also analyzed using SOMAscan, an aptamer-based capture assay. The associations between DVT and the log-transformed level of the proteins were assessed using logistic regression adjusting for the presence of femoral venous catheter and severity of illness. Associations were expressed as odds ratio (OR) for every log-fold increase in level of the protein with 95% confidence interval (CI).

RESULTS

Plasma from 59 critically ill adolescents, of whom 9 developed incident DVT, was analyzed. The median age of the adolescents was 15.1 years (interquartile range, 14.0-16.7 years). Higher levels of thrombin-antithrombin complex (OR: 31.54; 95% CI: 2.09-475.92) and lower levels of factor XIII (OR: 0.03; 95% CI: 0.002-0.44) were associated with DVT. CD36, MIC-1, and EpoR were marginally associated with DVT. Only factor XIII was associated with clinically relevant bleeding (OR: 0.27; 95% CI: 0.08-0.97).

CONCLUSIONS

We identified candidate protein biomarkers for incident DVT. We plan to validate our findings in adequately powered studies.

Thrombosis in inflammatory bowel disease: are we tailoring prophylaxis to those most at risk?

Inflammatory bowel disease (IBD) is a disease-specific risk factor for incident and recurrent venous thromboembolism (VTE). The reasons are acquired, multifactorial, and related to prothrombotic aberrations during active disease, although the mechanisms remain incompletely elucidated. VTE represents a potentially life-threatening extraintestinal manifestation of IBD, but the associated morbidity and mortality can be reduced by appropriate use of thromboprophylaxis. Nevertheless, despite international guidelines advocating thromboprophylaxis in hospitalised patients with IBD, practice is highly variable, since 65% of gastroenterologists may not use pharmacological VTE prophylaxis in hospitalised patients with acute severe colitis. Furthermore, there is no guidance on appropriate prophylaxis for ambulatory outpatients with active disease who are at an appreciable risk of VTE. Thus the question: are we tailoring thromboprophylaxis to those patients with IBD who are most at risk?