Cardiorespiratory Fitness Is Associated with Decreased Platelet Reactivity.

PURPOSE: Platelets are key mediators in cardiovascular disease (CVD). Low cardiorespiratory fitness (CRF) is a risk factor for CVD. The purpose of our study was to assess if CRF associates with platelet function. METHODS: Platelet assays and cardiopulmonary exercise testing were conducted in the Framingham Heart Study (n = 3,014). Linear mixed effects models estimated associations between CRF (assessed by peak oxygen uptake [VO2]), and multiple platelet reactivity assays. Models were adjusted for multiple medications, risk factors, relatedness and prevalent CVD. RESULTS: Nineteen associations passed the significance threshold in the fully adjusted models, all indicating higher CRF associated with decreased platelet reactivity. Significant traits spanned multiple platelet agonists. Strongest associations were observed in Multiplate whole blood testing after TRAP-6 (e.g., velocity, beta = -0.563, 95% CI [-0.735,-0.391], p = 1.38E-10), ADP (e.g., velocity, beta = -0.514, 95% CI [-0.681,-0348], p = 1.41E-09), collagen (e.g., velocity, beta = -0.387, 95% CI [-0.549,-0.224], p = 3.01E-06), ristocetin (e.g., AUC, beta = -0.365, 95% CI [-0.522,-0.208], p = 5.17E-06) and arachidonic acid stimulation of platelets (e.g., velocity, beta = -0.298, 95% CI [-0.435,-0.162], p = 3.39E-04), and light transmission aggregometry (LTA) after ristocetin stimulation (e.g., max aggregation, beta = -0.362, 95% CI [-0.540,-0.184], p = 6.64E-05). One trait passed significance threshold in the aspirin sub-sample (LTA ristocetin primary slope, beta = -0.733, 95% CI [-1.134,-0.333], p = 3.30E-04), and another in a model including von Willebrand Factor levels as a covariate (U46619, a thromboxane receptor mimetic, AUC in the Optimul assay, beta = -0.36, 95%CI [-0.551,-0.168], p = 2.35E-04). No strong interactions were observed between the associations and sex, age or body mass index in formal interaction analyses. CONCLUSIONS: Our findings build on past work that shows CRF to be associated with reduced CVD by suggesting decreased platelet reactivity may play a mechanistic role. We found significant associations with multiple platelet agonists, indicating higher CRF may globally inhibit platelets; however, given multiple strong associations after TRAP-6 and ADP stimulation, PAR-1 and purinergic signaling may be most heavily involved. This is notable since each of these receptor pathways are tied to anti-coagulant (DOACs/thrombin inhibitors) and anti-platelet therapies (P2Y12/PAR1/PAR4 inhibitors) for CVD prevention.

B Cell Subsets and Immune Checkpoint Expression in Patients with Chronic Lymphocytic Leukemia.

Chronic lymphocytic leukemia (CLL) is characterized by dysfunctional B cells. Immune checkpoint molecules such as cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) and programmed death-1 (PD-1) are upregulated in patients with CLL and may correlate with prognostic markers such as beta-2 microglobulin (B2M). The aim of this study was to evaluate the levels of immune checkpoints on B cell subsets and to further correlate them with B2M levels in patients with CLL. We recruited 21 patients with CLL and 12 controls. B cell subsets and the levels of immune checkpoint expression were determined using conventional multi-color flow cytometry. Basal levels of B2M in patients with CLL were measured using an enzyme-linked immunosorbent assay. Patients with CLL had increased levels of activated B cells when compared to the control group, p < 0.001. The expression of PD-1 and CTLA-4 were increased on activated B cells and memory B cells, p < 0.05. There were no associations between B2M levels and the measured immune checkpoints on B cell subsets, after adjusting for sex and age. In our cohort, the patients with CLL expressed elevated levels of PD-1 and CTLA-4 immune checkpoints on activated and memory B cell subsets. However, there was no correlation between these immune checkpoint expressions and B2M levels.

The association between platelet reactivity and lipoprotein levels in Framingham Heart Study participants.

BACKGROUND: Hypertriglyceridemia is an independent risk factor for major adverse cardiovascular events, though the mechanisms linking triglycerides and platelet function with thrombosis, remain elusive. The aim of this study was to assess the association between platelet function and triglyceride levels. METHODS: We included participants from the Framingham Heart Study Third Generation cohort, OMNI, and New Offspring Spouse cohort who attended the third examination cycle (2016-2019). Eligible participants were categorized into four triglyceride subgroups. RESULTS: The study comprised a total of 1897 (55.53 %) participants with normal TG levels; 883 (25.85 %) participants with high-normal TGs; 378 (11.07 %) with borderline high TGs; and 258 (7.55 %) participants with hypertriglyceridemia. After adjusting for age, sex, alcohol consumption, aspirin, statin and P2Y12 inhibitors, the levels of ADP-induced platelet aggregation were inversely associated with total cholesterol levels (P < 0.0001). Platelet disaggregation was associated with low-density lipoprotein and high-density lipoprotein cholesterol levels (P < 0.0001). Lastly, in a shear-stress chamber assay mimicking arterial flow velocities, TG levels in the normal-high group were associated with increased levels of collagen-dependent thrombogenicity (ß = 24.16, SE = 6.65, P < 0.0001). CONCLUSION: Triglyceride levels are associated with altered platelet activation and aggregation. Furthermore, increased platelet-driven thrombogenicity is directly associated with triglyceride levels after adjusting for medications and other covariates.

The mean platelet volume and atherosclerotic cardiovascular-risk factors in adults with obesity: a systematic review and meta-analysis of observational studies.

BACKGROUND: Obesity is a major risk factor for atherosclerotic cardiovascular disease (ASCVD) and is associated with altered platelet function. The mean platelet volume (MPV) is a rapid measure of platelet activation and a prognostic marker in patients with cardiovascular disease. However, no meta-analysis on the association between MPV and obesity has been conducted, and the value of monitoring the MPV in patients with obesity remains unclear. OBJECTIVE: To provide cumulative evidence on whether the mean platelet volume (MPV) is increased in individuals with obesity and to describe associations between the ASCVD-risk factors and the MPV in individuals with obesity. METHODS: This meta-analysis was prepared following the Meta-analysis Of Observational Studies (MOOSE) guidelines. We searched the PubMed and Embase database from inception until the 31st of March 2021. Studies were included when they reported the mean platelet volume in individuals with obesity and provided a suitable non-obese comparator group. The risk of bias was independently assessed by two reviewers using the Newcastle-Ottawa scale. The primary outcome of the meta-analysis was the MPV, while we considered the atherosclerotic risk profiles as a secondary outcome. RESULTS: We identified 178 citations through the PUBMED and 255 citations through EMBASE database search. In all, 13 studies met the inclusion criteria. Firstly, we report an increased mean platelet volume in individuals with obesity compared to non-obese individuals (MD 0.79; [95%CI: 0.42 to 1.16], I2 = 93.4%). Moreover, the reported increase in the MPV was inversely associated with the body mass index (Coefficient: -0.57, standard error (SE): 0.18, p < 0.001) and directly related to changes in triglyceride levels (Coefficient: 4.99, standard error (SE): 1.14, p < 0.001). CONCLUSION: This meta-analysis and meta-regression showed an increased MPV in nondiabetic individuals living with obesity. Moreover, the MPV was associated with hypertriglyceridemia, an independent predictor of atherosclerotic cardiovascular disease. Overall, the findings suggest that MPV may be a valuable rapid marker for the monitoring and risk-stratification of individuals with obesity who may be at risk of developing cardiovascular disease.

Serotonin-Affecting Antidepressant Use in Relation to Platelet Reactivity.

Depression is an independent risk factor of cardiovascular disease morbidity. Serotonin is a key neurotransmitter in depressive pathology, contained within platelets, and is a weak activator of platelets. Our study assessed the link between platelet reactivity traits, depression, and antidepressant (AD) use in a large population sample. Our study was conducted in the Framingham Heart Study (n = 3,140), and AD use (n = 563) and aspirin use (n = 681) were noted. Depression was measured using the Center for Epidemiological Studies-Depression (CES-D) survey. Platelet reactivity traits were measured across multiple agonists using five distinct assays. We utilized a linear mixed effects model to test associations between platelet traits and depression, adjusting for age, sex, aspirin use, and AD use. Similarly, we analyzed trait associations with any AD use, serotonin-affecting ADs, and norepinephrine-affecting ADs, respectively. There were strong associations with reduced platelet function and AD use, particularly with serotonin-affecting medications. This included lower Optimul epinephrine maximal aggregation (P = 4.87E-13), higher U46619 half maximal effective concentration (P = 9.09E-11), lower light transmission aggregometry (LTA) adenosine diphosphate (ADP) final aggregation (P = 1.03E-05), and higher LTA ADP disaggregation (P = 2.28E-05). We found similar associations with serotonin-affecting ADs in an aspirin-taking subset of our sample. There were no significant associations between platelet traits and depression. In the largest study yet of AD use and platelet function we show that antidepressants, particularly serotonin-affecting ADs, inhibit platelets. We did not find evidence that depressive symptomatology in the absence of medication is associated with altered platelet function. Our results are consistent with AD use leading to platelet serotonin depletions, decreased stability of platelet aggregates, and overall decreased aggregation to multiple agonists, which may be a mechanism by which ADs increase risk of bleeding and decrease risk of thrombosis.

The pleotropic effects of fluvastatin on complement-mediated T-cell activation in hypercholesterolemia.

T-cells orchestrate the inflammatory responses in atherosclerosis, and their function is modified by the lipoprotein milieu and complement activity. We investigated the effects of fluvastatin on the expression of complement decay-accelerating factor (DAF/CD55) antigen, and the levels of transcription factors in circulating T-cells in hypercholesterolemia. The hypercholesterolemic state was associated with the upregulation of DAF expression on circulating T-cells and increased levels nuclear factor kappa B (NF-kB) and interferon regulatory factor 4 (IRF4). Notably, the elevated levels of DAF and NF-kB expression persisted following treatment with fluvastatin. Therefore, the pleiotropic effects of fluvastatin are partially ascribed to its ability to mediate T-cell activation and regulate complement activity. Consequently, enhanced therapeutic interventions that targets complement-induced T-cell activation may be important in mitigating the development of atherosclerosis and major cardiovascular events in individuals with hypercholesterolemia.

Diet-Induced Obesity Promotes the Upregulation of Fas Expression on T-cells.

This study was conducted to assess the expression of Fas (CD95) and programmed cell death-1 (PD-1) on circulating T-cells in obesity using a diet-induced obesity mouse model. Furthermore, we aimed to determine if there are any associations between metabolic disorders and the expression of T-cell regulatory markers. A total of 12 male C57BL/6 mice were randomized into either a high-fat diet (HFD) or low-fat diet (LFD) group for 8 weeks (n = 6/group). Changes in body weights were monitored on a weekly basis. The lipid, glucose, and hematological profiles, as well as Fas and PD1 expression on the T-cell immunophenotype, were measured after 8 weeks of feeding. The HFD-fed group had a higher percentage weight gain (29.17%) in comparison with the LFD-fed group (21.74%) after the 8-week period. In addition, the HFD group had increased fasting glucose and glucose excursion following a 2-h postprandial period. The levels of total cholesterol were elevated in the HFD group when compared with the LFD group (p < 0.05). Notably, the absolute white cell count (p = 0.0096), neutrophil count (p = 0.0022, lymphocytes (p = 0.0155), and monocyte count (p = 0.0015) were elevated in the HFD group when compared with the LFD-fed group. However, the platelets (0.0680), red cell counts (0.3575), and their indices (p > 0.05) were comparable between the two groups. Interestingly, HFD feeding was associated with elevated expression of Fas on T-cells (p < 0.0001), which positively correlated with body weights (r = 0.93, p = 0.0333). No associations were found between Fas expression and dyslipidemia or fasting blood glucose levels (p > 0.05). The multivariant regression analysis showed that the association between the levels of Fas on T-cells and body weights (coefficient: -1.00, t-value: 19.27, p = 0.0330) was independent of fasting blood glucose, total cholesterol, and lymphocyte count. Lastly, the expression of PD-1 on T-cells was comparable between the two diet groups (p = 0.1822). In all, immune activation, dyslipidemia, and poor glucose control in the early stages of obesity may drive the pathogenesis of metabolic T-cell disorders. Importantly, T-cell dysfunction in obesity is partially mediated by an upregulation of Fas which is independent of dyslipidemia and hyperglycemia.

A systematic review and meta-analysis on the regulation of programmed cell death-1 on T-cells in type 2 diabetes.

BACKGROUND: To assess T-cell exhaustion mediated by programmed cell death 1 (PD-1) pathway in patients living with type 2 diabetes (T2D). METHODS: MEDLINE and ProQuest electronic databases were searched for eligible studies from inception up to February 2020. The risk of bias and the quality of evidence were independently assessed by two reviewers using the modified Newcastle-Ottawa Scale adapted for cross-sectional studies and the Grading of Recommendations Assessment, Development and Evaluation (GRADE) tool, respectively. The random effects model was used to calculate effect estimates. RESULTS: We identified 5 studies involving 380 participants which met the inclusion criteria. The pooled estimates showed elevated T helper cell exhaustion in patients with T2D in comparison to controls (mean difference [MD]: 2.57% [95% confidence interval [CI]: -3.84, 8.97]; I2 = 100%, P < .00001). Likewise, T2D patients had increased levels of cytotoxic T-cells exhaustion (MD: 3.09% [95% CI: -12.96, 19.14]; I2 = 100%, P < .00001). Although the upregulation of PD-1 on T-cells did not affect glucose metabolism-related profiles, it was associated with inflammation and the development of cardiovascular disease. CONCLUSION: In patients living with T2D, immune dysfunction is at least in part due to T-cell exhaustion mediated by the upregulation of PD-1 expression. Therefore, the use of immune checkpoint inhibitors as a therapeutic strategy may be beneficial in restoring immune function in patients with T2D.

The aberrant expression of CD69 on peripheral T-helper cells in diet-induced inflammation is ameliorated by low-dose aspirin and metformin treatment.

Chronic inflammation in patients with type 2 diabetes (T2D) is associated with T-cell dysfunction. Using a rodent model, we evaluated changes in metabolic profiles, inflammation status and the expression of T-cell function markers following high-fat diet (HFD)-feeding. In addition, we assessed the modulatory effects of treatment with low-dose aspirin (LDA) and its combination with metformin (LDA + Met) on these parameters. Notably, HFD-feeding induced metabolic disorders and aggravated inflammation. Most importantly, it was associated with decreased expression of CD69 on T-helper cells but had no effect on the expression of programmed cell death 1 (PD-1). Treatment with LDA monotherapy had no effect on metabolic profiles. However, its combination with metformin ameliorated the levels of inflammation and up-regulated the expression of CD69 although it had no therapeutic effect on the levels of PD-1 expression. Therefore, alleviating inflammation and lowering glucose levels in T2D may be an effective strategy to improve T-cell function in these patients.

The impact of immune checkpoint inhibitors in patients with chronic lymphocytic leukemia (CLL): A protocol for a systematic review and meta-analysis of randomized controlled trials.

INTRODUCTION: The global burden of chronic lymphocytic leukemia (CLL) has constantly increased over the years, with a current incidence of 3.5 cases per 100,000 people. Although the conventional drugs used to treat CLL patients have been effective treatment failure rate in some of the patients is alarming. Therefore, as a result, novel treatment strategies with improved outcomes such as the blockade of immune checkpoints have emerged. However, consensus on the risk-benefit effects of the using these drugs in patients with CLL is controversial and has not been comprehensively evaluated. This systemic review and meta-analysis provide a comprehensive synthesis of available data assessing adverse events associated with the use of immune checkpoint inhibitors in patients with CLL as well as their influence on the overall survival rate. METHODS: This protocol for a systematic review and meta-analysis has been prepared in accordance with Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols 2015 guidelines. A search strategy will be developed using medical subject headings words in PubMed search engine with MEDLINE database. The search terms will also be adapted for gray literature, Embase, and Cochrane Central Register of Controlled Trials electronic databases. Two reviewers (AN and SRN) will independently screen studies, with a third reviewer consulted in cases of disagreements using a defined inclusion and exclusion criteria. Data items will be extracted using a predefined data extraction sheet. Moreover, the risk of bias and quality of the included studies will be appraised using the Downs and Black checklist and the quality and strengths of evidence across selected studies will be assessed using the Grading of Recommendations Assessment Development and Evaluation approach. The Cochran's Q statistic and the I statistics will be used to analyze statistical heterogeneity across studies. If the included studies show substantial level of statistical heterogeneity (I > 50%), a random-effects meta-analysis will be performed using R statistical software. ETHICS AND DISSEMINATION: The review and meta-analysis will not require ethical approval and the findings will be published in peer-reviewed journals and presented at local and international conferences. This review may help provide clarity on the risk-benefit effects of using immune checkpoint inhibitors in patients with CLL. SYSTEMATIC REVIEW REGISTRATION: International prospective Register of Systematic Reviews (PROSERO) number: CRD42020156926.

Obesity-related asthma in children is characterized by T-helper 1 rather than T-helper 2 immune response: A meta-analysis.

BACKGROUND: Asthma is a chronic inflammatory condition characterized by T-helper (TH) 2 polarization. In children, the prevalence of obesity is associated with an increased incidence of asthma. Notably, obesity is linked with TH1-mediated inflammation and has been identified as a major risk factor for asthma. OBJECTIVE: To investigate the impact of obesity on TH1 (tumor necrosis factor α, interferon gamma, interleukin (IL)-6, IL-8) and TH2 (IL-4, IL-5, IL-10, IL-13) immune responses in children with asthma. METHODS: We searched the MEDLINE and gray literature electronic databases for eligible studies from inception up until April 2020. The quality of included studies and evidence was independently assessed by 2 reviewers. The random-effects model was used in this meta-analysis, and outcomes were reported as standardized mean difference (SMD) and 95% confidence interval (CI). RESULTS: Overall, 5 studies comprising 482 participants met the inclusion criteria. The meta-analysis revealed an increased TH2-mediated immune response in lean people with asthma compared with controls without asthma (SMD: -1.15 [95% CI: -1.93, 0.36]; I2 = 93%; pH < .001). However, in obese people with asthma, there was polarization toward TH1 immune response compared with lean people with asthma (SMD: -0.43 [95% CI: -0.79, -0.08]; I2 = 88%, pH < .001). CONCLUSION: This meta-analysis reveals that there are differences in immune responses mediated by T-helper cells in lean and obese children with asthma. Moreover, and not unique to asthma, obesity polarizes the immune response toward TH1 rather than the classical TH2. This could be an important aspect to understand to establish effective therapeutic targets for obese children with asthma.

The impact of metformin and aspirin on T-cell mediated inflammation: A systematic review of in vitro and in vivo findings.

Chronic inflammation and hyperglycaemia are well-established aspects in the pathogenesis of type 2 diabetes mellitus (T2D), including the progression of its associated complications such as cardiovascular diseases (CVDs). In fact, emerging evidence shows that dysfunctional immune responses due to dysregulated T-cell function aggravates CVD-related complications in T2D. However, there is a lack of specific therapeutic interventions that protect patients with diabetes who are at risk of heart failure. Metformin and aspirin are among the leading therapies being used to protect or at the very least slow the progression of CVD-related complications. The current review made use of major electronic databases to identify and systematically synthesise emerging experimental data on the impact of these pharmacological drugs on T-cell responses. The quality and risk of bias of include evidence were independently assessed by two reviewers. Overwhelming evidence showed that both metformin and aspirin can ameliorate T-cell mediated inflammation by inducing regulatory T-cells (Tregs) polarisation, inhibiting T-cell trafficking and activation as well as signal transducer and activator of transcription (STAT)3 signalling. As a plausible mechanism to mediate T-cell function, metformin showed enhanced potential to regulate mechanistic targets of rapamycin (mTOR), STAT5 and adenosine-monophosphate-activated protein kinase (AMPK) signalling pathways. Whilst aspirin modulated nuclear factor kappa-light-chain-enhancer of activated B-cells (NF-kB) and co-stimulatory signalling pathways and induced T-cell anergy. Overall, synthesised data prompt further investigation into the combinational effect of metformin and aspirin for the management of T2D-related cardiovascular complications.

T-cell activation and cardiovascular risk in adults with type 2 diabetes mellitus: A systematic review and meta-analysis.

BACKGROUND: Chronic immune activation has been described in the development of cardiovascular diseases (CVDs) and in the pathogenesis of type 2 diabetes mellitus (T2D). However, the precise functional role of T-cells remains controversial. We therefore, assessed T-cell activation and cardiovascular risk in T2D. METHODS: The protocol was registered with PROSPERO [CRD42018099745]. We searched electronic databases and grey literature for eligible studies. The risk of bias and quality of evidence were assessed and the random-effects model was used in the meta-analysis. FINDINGS: Fifteen studies met the inclusion criteria. We report on increased T-cell activation in T2D and nondiabetics with CVD. Comorbidity of T2D and CVD (T2D + CVD) exacerbated T-cell activation. In addition, T2D + CVD comorbidity was associated with an increased CVD risk profile. CONCLUSION: This meta-analysis suggests increased T-cell activation in T2D and nondiabetics with CVD. Moreover, an increased cardiovascular risk in patients with T2D which is exacerbated in T2D and CVD comorbidity.

Obesity-induced inflammation and insulin resistance: A mini-review on T-cells.

Excessive lipid accumulation in an obese state is linked with activation and release of detrimental cytokines and chemokines that promote metabolic dysregulation. In fact, emerging experimental evidence shows that abnormal modulation of T-cells in an obese state correlates with the development and progression of insulin resistance. Importantly, the evolving concept linking insulin resistance with impaired immunological mechanisms such as T-cell responses provides new prospects for understanding the role of inflammation in moderating metabolic complications.

Platelet function and cardiovascular risk in adult HIV-infected patients on HAART: a protocol for a systematic review and meta-analysis.

INTRODUCTION: The incidence of cardiovascular disease (CVD) is now at least threefold higher in HIV-infected patients as compared with the general population. Although platelet activation and reactivity are implicated in the development of CVDs in HIV-infected patients, its precise role remains inconclusive. We aim to assess the association between platelet activation and selected cardiovascular risk factors in HIV-1-infected individuals on highly active antiretroviral treatment (HAART). METHODS: This will be a systematic review and meta-analysis of published studies evaluating the association between platelet activation and CVD risk factors in HAART-treated adults. The search strategy will include medical subject headings words for MEDLINE, and this will be adapted to Embase search headings (Emtree) terms for the EMBASE database. The search will cover literature published between 1 January 1996 to 30 April 2017. Studies will be independently screened by two reviewers using predefined criteria. Relevant eligible full texts will be screened; data will be extracted, and a qualitative synthesis will be conducted. Data extraction will be performed using Review Manager V.5.3. To assess the quality and strengths of evidence across selected studies, the Grading of Recommendations Assessment Development and Evaluation approach will be used. The Cochran's Q statistic and the I2 statistics will be used to analyse statistical heterogeneity between studies. If included studies show high levels of homogeneity, a random effects meta-analysis will be performed using R statistical software. ETHICS AND DISSEMINATION: This will be a review of existing studies and will not require ethical approval. The findings will be disseminated through peer-reviewed publication and presented at local and international conferences. An emerging patient management dilemma is that of the increased incidence of CVD in people living with HIV on HAART. This review may inform treatment and cardiovascular risk stratification of HIV-infected patients at increased risk of developing CVD. PROSPERO REGISTRATION NUMBER: CRD42017062393.