Vitamin C intake potentially lowers total cholesterol to improve endothelial function in diabetic patients at increased risk of cardiovascular disease: A systematic review of randomized controlled trials

BACKGROUND

Vitamin C is one of the most consumed dietary compounds and contains abundant antioxidant properties that could be essential in improving metabolic function. Thus, the current systematic review analyzed evidence on the beneficial effects of vitamin C intake on cardiovascular disease (CVD)-related outcomes in patients with diabetes or metabolic syndrome.

METHODS

To identify relevant randomized control trials (RCTs), a systematic search was run using prominent search engines like PubMed and Google Scholar, from beginning up to March 2022. The modified Black and Downs checklist was used to assess the quality of evidence.

RESULTS

Findings summarized in the current review favor the beneficial effects of vitamin C intake on improving basic metabolic parameters and lowering total cholesterol levels to reduce CVD-risk in subjects with type 2 diabetes or related metabolic diseases. Moreover, vitamin C intake could also reduce the predominant markers of inflammation and oxidative stress like C-reactive protein, interleukin-6, and malondialdehyde. Importantly, these positive outcomes were consistent with improved endothelial function or increased blood flow in these subjects. Predominantly effective doses were 1,000 mg/daily for 4 weeks up to 12 months. The included RCTs presented with the high quality of evidence.

CONCLUSION

Clinical evidence on the beneficial effects of vitamin C intake or its impact on improving prominent markers of inflammation and oxidative stress in patients with diabetes is still limited. Thus, more RCTs are required to solidify these findings, which is essential to better manage diabetic patients at increased risk of developing CVD.

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.

Activated monocytes as a therapeutic target to attenuate vascular inflammation and lower cardiovascular disease-risk in patients with type 2 diabetes: A systematic review of preclinical and clinical studies

Low grade inflammation is associated with the progression of atherosclerosis. Patients with type 2 diabetes (T2D) have altered cholesterol levels, which are targeted by free radicals to promote lipid peroxidation. Elevated levels of monocyte-associated cytokines such as interleukin (IL)-6, monocyte chemoattractant protein 1 (MCP-1), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), and tumor necrosis factor-alpha (TNF-α), subsequently drive endothelial tissue injury. In fact, the levels of circulating platelet-monocyte aggregates in patients with T2D is a robust marker for atherosclerosis and a cardiovascular disease (CVD)-risk factor. To identify eligible studies, we searched the major online databases using PubMed and Google Scholar. The cumulative evidence synthesized in the current review suggests that, traditional therapies which include thiazolidinediones, statins and some calcium channel blockers can be useful in the primary prevention of atherosclerosis by inhibiting the formation of monocyte-derived microparticles, and pro-inflammatory cytokines such as IL-6, TNF-α, MCP-1, and NF-κB in patients with T2D. Future studies are needed to ascertain whether the combination of dietary interventions and glucose or lipid lowering agents can provide an enhanced cardioprotection in patients with T2D.

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.

Circulating

Impaired Glc tolerance and hyperinsulinemia are a hallmark of type 2 diabetes (T2D) and are associated with an altered innate and adaptive immune response. In this study, we used a high-fat diet (HFD)-induced model of pre-diabetes to explore the pathological implications of altered innate lymphoid cell (ILC) profiles in a state of impaired Glc tolerance. Sixteen male C57BL/6 mice were randomized to receive two experimental diets (n = 8 per group), low-fat (LFD), and HFD for 8-13 wk. We evaluated the levels of circulating innate lymphoid cells and their respective cytokines following HFD-feeding. The HFD group had impaired Glc tolerance, elevated insulin levels, and increased total cholesterol levels. Notably, the levels of circulating ILC1s were elevated following 13 wk of HFD-feeding. Moreover, the levels of TNF-α were decreased, but there were no changes in IFN-γ levels. Lastly, the levels of circulating ILC2s and ILC3s were comparable between the HFD and LFD group. The findings demonstrated that short-term HFD-feeding increases postprandial blood Glc, total cholesterol and insulin levels. However, the metabolic changes did not alter ILC2 and ILC3 levels and their respective cytokine profiles.

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.

A Meta-Analysis of the Impact of Resveratrol Supplementation on Markers of Renal Function and Blood Pressure in Type 2 Diabetic Patients on Hypoglycemic Therapy

Evidence on the beneficial effects of resveratrol supplementation on cardiovascular disease-related profiles in patients with type 2 diabetes (T2D) is conflicting, while its impact on renal function and blood pressure measurements remains to be established in these patients. The current meta-analysis included randomized controlled trials (RCTs) reporting on the impact of resveratrol supplementation on markers of renal function and blood pressure in patients with T2D on hypoglycemic medication. Electronic databases such as MEDLINE, Cochrane Library, Scopus, and EMBASE were searched for eligible studies from inception up to June 2020. The random and fixed effects model was used in the meta-analysis. A total of five RCTs met the inclusion criteria and involved 388 participants with T2D. Notably, most of the participants were on metformin therapy, or metformin in combination with other hypoglycemic drugs such as insulin and glibenclamide. Pooled estimates showed that resveratrol supplementation in patients with T2D lowered the levels of fasting glucose (SMD: -0.06 [95% CI: -0.24, 0.12]; I2 = 4%, p = 0.39) and insulin (SMD: -0.08 [95% CI: -0.50, 0.34], I2 = 73%, p = 0.002) when compared to those on placebo. In addition, supplementation significantly lowered systolic blood pressure (SMD: -5.77 [95% CI: -8.61, -2.93], I2 = 66%, p = 0.02) in these patients. Although resveratrol supplementation did not affect creatinine or urea levels, it reduced the total protein content (SMD: -0.19 [95% CI: -0.36, -0.02]; I2 = 91%, p = 0.001). In all, resveratrol supplementation in hypoglycemic therapy improves glucose control and lowers blood pressure; however, additional evidence is necessary to confirm its effect on renal function in patients with T2D.

Platelet activation in adult HIV-infected patients on antiretroviral therapy: a systematic review and meta-analysis

BACKGROUND

Antiretroviral therapy (ART) alters platelet reactivity, and as a consequence, patients living with HIV may be at an increased risk of cardiovascular disease (CVD). The current evidence on platelet activation levels in patients with HIV remains inconclusive. We therefore aimed to systematically synthesise evidence on the association of platelet activation in HIV-infected patients on successful treatment.

METHODS

Electronic databases were searched from inception until November 2019. Studies were included if the primary or secondary outcome of the study was to assess platelet activation in HIV-infected patients on ART. The primary outcome of this review included the levels of platelet activation. The pooled effect estimates were calculated using a random-effects meta-analysis model.

RESULTS

We identified 30 studies comprising of 2325 participants. The pooled estimates showed elevated levels of platelet activation in treatment-naïve HIV-infected patients compared to uninfected controls (Hedges' g 2.00 [95%CI 1.05, 2.94]; z = 4.12, p < 0.0001). These remained elevated despite successful ART (Hedges' g 2.05 [95%CI 0.58, 3.52]; z = 2.71, p = 0.0067).

CONCLUSION

The levels of platelet activation are elevated in treatment-naïve HIV-infected patients, and these persist during successful ART. Further studies should assess the clinical relevance of monitoring the levels of platelet activation in HIV-infected patients on ART.

The Effect of Successful Antiretroviral Therapy on Immune Activation and Reconstitution in HIV Infected Adults: A Systematic Review and Meta-Analysis

We performed a systematic review and meta-analysis to investigate the impact of antiretroviral therapy (ART) on immune activation and reconstitution in people living with human immunodeficiency virus (PLWH). The PubMed electronic database and gray literature were searched from inception until March 2020. Studies were included if they reported the levels of immune activation and reconstitution at baseline and post-treatment. The random-effect model was used to calculate effect sizes. We included a total of ten studies comprising of 1 553 PLWH with an average age of 38.02 ± 10.10 years and a male/female ratio of 3.76. Pooled estimates showed a modest increase in the level of immune activation post-treatment (SMD: 0.64 [95% CI: -1.34, 2.63]; I2 = 98%, pH < 0.00001). In addition, treatment with ART significantly reconstituted the immune system (SMD: 0.70 [95% CI: 0.27, 1.44]; I2 = 68%, pH = 0.009). Notably, the level of immune reconstitution was independent of viral load or the treatment duration but dependent on the class of ARV drugs. Consequently, protease inhibitors were associated with the highest degree of immune restoration, followed by chemokine antagonists and lastly integrase inhibitors. In conclusion, immune activation persists in PLWH despite viral suppression and the degree of immune reconstitution is dependent on the drug class. Therefore, inclusion of protease inhibitors in ART may be of great benefit in immune restoration in patients with very low CD4 count.

Adipokines as a therapeutic target by metformin to improve metabolic function: A systematic review of randomized controlled trials

Metformin is a widely used glucose-lowering drug, although its impact on adipose tissue function remains elusive. Adipose tissue-derived molecules regulate diverse physiological mechanisms, including energy metabolism, insulin sensitization, and inflammatory response. Alternatively, it has remained relevant to understand the therapeutic regulation of adipokines in efforts to alleviate inflammation in conditions associated with the metabolic syndrome. The current qualitative analysis of available literature focused on randomized clinical trials (RCTs) assessing the association between administration of metformin and adipokine regulation in individuals with metabolic syndrome. The major electronic databases such as MEDLINE, Cochrane Library, Scopus, and EMBASE were searched for eligible RCTs. Overall, 13 RCTs met the inclusion criteria, with a total of 4605 participants. Patients with metabolic syndrome were characterized by a state of obesity, impaired glucose tolerance, insulin resistance, and type 2 diabetes. Cumulative evidence from these RCTs supported the blood glucose lowering effects of metformin, in addition to promoting weight loss, ameliorating insulin resistance, and reducing pro-inflammatory markers such as interleukin-6 and tumor necrosis factor-α in patients with metabolic syndrome. Importantly, these therapeutic effects are associated with the upregulation of adiponectin and suppression of leptin and resistin.

Natural killer cell levels in adults living with type 2 diabetes: a systematic review and meta-analysis of clinical studies

Background

Chronic immune activation and hyperglycaemia are a hallmark of type 2 diabetes mellitus (T2D) while natural killer (NK) cells are involved in the pathogenesis of T2D. Dysregulated NK cell responses are associated with an increased risk of cardiovascular disease in patients living with T2D.

Objective

To provide a comprehensive and systematic evidence-based estimate on the levels of NK cells in patients living with T2D.

Results

This systematic review and meta-analysis included 13 studies reporting on 491 adult patients with T2D and 1064 nondiabetic controls. The pooled effect estimates showed increased levels of NK cells in adult patients with T2D compared to controls (MD: 0.03 [− 3.20, 3.26], I² = 97%, p < 0.00001).

Conclusion

Overall, the evidence presented in this systematic review shows that the changes in NK cells in patients living with T2D are still unclear and further studies are needed.

Differential expression of glycoprotein IV on monocyte subsets following high-fat diet feeding and the impact of short-term low-dose aspirin treatment

OBJECTIVE

To assess the levels of glycoprotein GPIV (CD36) expression on peripheral blood monocyte subsets, in a mouse model of glucose intolerance. Moreover, to determine the effect of; low-dose aspirin (LDA) alone, LDA combined with metformin, or clopidogrel alone, on the expression of CD36 on subsets of circulating monocytes.

METHOD

The study consisted of two experimental phases. In experiment one, the mice (n = 14) were randomised to receive a low-fat diet (LFD) or a high-fat diet (HFD) for eight weeks. Whereas the secondary phase of the experiment, comprised of twenty-four HFD-fed mice treated with LDA alone (3 mg/kg), or in combination with metformin (150 mg/kg), or clopidogrel alone (10 mg/kg) for six weeks. The surface expression of CD36 on monocytes was measured using flow cytometry.

RESULT

The levels of CD36 expression on monocytes were upregulated in the HFD-fed compared to LFD-fed group (p < 0.05). In addition, HFD group showed; no significant changes in body weight (p = 0.3848), however, blood glucose (p = 0.0002) and insulin (p = 0.0360) levels were markedly increased following HFD-feeding. Interestingly, all treatments reduced the expression of CD36 on monocytes, decreased fasting blood glucose levels (p = 0.0024) and increased circulating monocyte levels (p = 0.0217) when compared to the untreated HFD group. Moreover, treatment with LDA alone increased basophils levels (p = 0.0272), while when combined with metformin showed an improved effect in enhancing eosinophil levels (p = 0.0302).

CONCLUSION

HFD-feeding increased the expression of CD36 on monocyte subsets. LDA as a monotherapy or combined with metformin was as effective as clopidogrel monotherapy, in downregulating the expression of CD36 on monocyte subsets. These treatments may be of relevance in preventing cardiovascular complications associated with impaired glucose tolerance.

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 (T_H) 2 polarization. In children, the prevalence of obesity is associated with an increased incidence of asthma. Notably, obesity is linked with T_H1-mediated inflammation and has been identified as a major risk factor for asthma.

OBJECTIVE

To investigate the impact of obesity on T_H1 (tumor necrosis factor α, interferon gamma, interleukin (IL)-6, IL-8) and T_H2 (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 T_H2-mediated immune response in lean people with asthma compared with controls without asthma (SMD: -1.15 [95% CI: -1.93, 0.36]; I² = 93%; p^H < .001). However, in obese people with asthma, there was polarization toward T_H1 immune response compared with lean people with asthma (SMD: -0.43 [95% CI: -0.79, -0.08]; I² = 88%, p^H < .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 T_H1 rather than the classical T_H2. 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.

The impact of coenzyme Q10 on metabolic and cardiovascular disease profiles in diabetic patients: A systematic review and meta-analysis of randomized controlled trials

AIMS

Coenzyme Q10 (CoQ10) is well known for its beneficial effects in cardiovascular disease (CVD); however, reported evidence has not been precisely synthesized to better inform on its impact in protecting against cardiovascular-related complications in diabetic patients.

MATERIALS AND METHODOLOGY

The current meta-analysis included randomized controlled trials published in the past 5 years reporting on the effect of CoQ10 on metabolic and CVD-related risk profiles in individuals with diabetes or metabolic syndrome. We searched electronic databases such as MEDLINE, Cochrane Library, Scopus and EMBASE for eligible studies. In addition to assessing the risk of bias and quality of evidence, the random and fixed-effect models were used to calculate the standardized mean difference and 95% confidence intervals for metabolic parameters and CVD outcomes.

RESULTS

Overall, 12 studies met the inclusion criteria, enrolling a total of 650 patients. Although CoQ10 supplementation did not statistically affect all metabolic profiles measured, it significantly reduced CVD-risk-related indexes such as total cholesterol and low-density lipoprotein (LDL) levels in diabetic patients when compared to those on placebo [SMD = 0.13, 95% CI (0.03; 0.23), Chi2 = 43.62 and I 2 = 29%, P = .07].

CONCLUSIONS

The overall results demonstrated that supplementation with CoQ10 shows an enhanced potential to lower CVD risk in diabetic patients by reducing total cholesterol and LDL. Moreover, the beneficial effects of CoQ10 in lowering the CVD risk are associated with its ameliorative properties against oxidative stress and improving endothelial health.

Elevated T-helper 2 cytokine levels in high fat diet-fed C57BL/6 mice are attenuated by short-term 6-week treatment with a combination of low-dose aspirin and metformin

OBJECTIVE

To evaluate T-helper cytokine responses in a short-term high fat diet (HFD) induced impaired glucose metabolism. To further evaluate the modulation of T-helper 1 (Th₁) and T-helper 2 (Th₂) cytokines using short-term low-dose aspirin in combination with metformin.

DESIGN

Two experiments were carried out in this study in order to evaluate the T-helper cytokine profiles in a state of impaired glucose metabolism. A total of 28 six-week-old male C57BL/6 mice were used in this study. In the first experiment, mice were fed either a high fat diet or low fat diet for a duration of 10 weeks. We then determined the Th₁, Th₂ and T-helper 17 (Th₁₇) cytokine profiles. In the second experiment, we evaluated whether the short term 6-week treatment with low-dose aspirin in combination with metformin modulates T-helper cytokine profiles of the HFD-fed mice.

MEASUREMENTS

In the first experiment, we measured the body weights, blood glucose levels, insulin levels, lipid profiles and haematological parameters. We further performed oral glucose tolerance testing following an 8-hour fast and serum Th₁, Th₂ and Th₁₇ cytokine levels were also determined following short-term 8-week diet-feeding and 6-week low-dose aspirin and combined metformin with low-dose aspirin treatment.

RESULTS

High fat diet-feeding caused a marked increase in circulating peripheral blood lymphocytes, which was attenuated by short-term low-dose aspirin treatment. Moreover, the HFD feeding resulted in 2-fold increase in total cholesterol and a 4-fold increase in low-density lipoprotein cholesterol when compared to the low-fat diet-fed group (p < 0.05). In the high fat diet group, impaired glucose metabolism was associated with skewed Th₂ responses without alterations in the Th₁ and Th₁₇ cytokine profiles. Interestingly the short-term treatment with low-dose aspirin showed no effect on the selected T-helper 1 cytokine IFN-Ƴ (P > 0.05). While the combination of low-dose aspirin with metformin considerably reduced the levels of serum IFN-Ƴ (P < 0.05). Furthermore low-dose aspirin treatment showed the modest attenuation of the selected Th₂ cytokines, IL-10 and IL-13 when compared to low-dose aspirin with metformin (P < 0.01).

CONCLUSION

The early immunological and metabolic changes that occur in a state impaired glucose tolerance are accompanied by the increased production of Th₂ cell cytokines. The short-term treatment using low-dose aspirin combined with metformin may provide therapeutic benefits in preventing complications associated with dysregulated Th₂ cell responses.

Monocyte-mediated inflammation and cardiovascular risk factors in type 2 diabetes mellitus: A systematic review and meta-analysis of pre-clinical and clinical studies

BACKGROUND

Monocyte-mediated inflammation increases the risk of developing type 2 diabetes mellitus and cardiovascular disease. This is the first systematic review and meta-analysis of studies reporting on monocyte-mediated inflammation in type 2 diabetes mellitus.

METHODS

This systematic review and meta-analysis was registered in the international prospective register of a systematic review: CRD42019132902. The MEDLINE, EMBASE and Google scholar electronic databases were searched, and a random-effects model was used to generate pooled standardised mean differences between patients with type 2 diabetes mellitus and healthy controls.

RESULTS

The clinical studies (n = 20) comprised of 1065 patients with type 2 diabetes mellitus and 1103 healthy controls. Notably, the levels of monocyte activation were higher in patients with type 2 diabetes mellitus compared to healthy controls (standardised mean difference  = 0.47, 95% confidence interval (0.10, 0.84), p = 0.01) (χ2 = 65.72, I 2 = 83%, p < 0.00001). Patients with type 2 diabetes mellitus had an increased risk of cardiovascular disease compared to healthy controls (standardised mean difference  = 0.37, 95% confidence interval (0.13, 0.61), p = 0.003) (χ2 = 958.77, I 2 = 95%, p < 0.00001). All included pre-clinical studies reported on the C57BL/6 mice strain, with a majority of the studies 57% of reporting on high fat diet-induced C57BL/6 mice model. The overall quality of the studies was good with a median score and range of 16 (13-19).

CONCLUSION

Our meta-analysis suggests that there is increased monocyte activation in patients with type 2 diabetes mellitus.

A systematic review on the functional role of Th1/Th2 cytokines in type 2 diabetes and related metabolic complications

The T-helper (Th1/Th2) paradigm is widely studied for its role in modulating an adaptive immune response, especially in relation to the onset of various autoimmune diseases. In fact, emerging evidence clearly shows an inverse relationship between Th1/Th2 cytokines and the development of type 2 diabetes (T2D) complications, which is accelerated by an exacerbated inflammatory state. Here, relevant studies reporting on any association between the levels of Th1/Th2 cytokines and the development of T2D were retrieved through major electronic databases such as The Cochrane Library, Embase and PubMed. Extracted evidence which mostly involved animal models and human subjects with T2D or metabolic syndrome was assessed for quality and risk of bias using the Downs and Black checklist and Animal Research: Reporting of In Vivo Experiments (ARRIVE) guidelines. Results strongly correlated raised Th1/Th2 cytokines such as interferon-gamma (IFN-γ)/interleukin (IL)-5 and IL-2/IL-5 ratios to T2D, and this was positively linked with the other complications including retinopathy and cardiovascular complications. Further, logistic regression analysis demonstrated that the Th1/Th2 ratios were significantly associated with impaired glucose homeostasis, abnormally enhanced lipid profiles, and insulin resistance. Although more studies making use of a larger sample size are required, current data suggest that optimal modulation of Th1/Th2 cytokines may be an important aspect in the management of T2D and its associated complications.

The role of innate lymphoid cells and T helper cell activation in type 2 diabetic patients: a protocol for a systematic review and meta-analysis

BACKGROUND

Persistent levels of low-grade inflammation and T lymphocyte activation are associated with insulin resistance and type 2 diabetes that eventually lead to the development of cardiovascular diseases. Interestingly, increasing studies report on an emerging role of innate lymphoid cells in the development of both type 2 diabetes and cardiovascular disease. This systematic review will provide a comprehensive synthesis of available studies reporting on the role of innate lymphoid cells and associated T helper cell function in type 2 diabetic patients. It will further provide insight into the association of innate lymphoid cell activation and cardiovascular risk in adults living with type 2 diabetes.

METHODS

This systematic review protocol has been prepared in accordance with Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols 2015 guidelines. The protocol has been registered with PROSPERO (CRD42018106159). This systematic review and meta-analysis will include published randomised clinical trials, observational studies, and case-control studies. We will also include grey literature. A search strategy will be developed with the help of subject librarian using Medical Subject Heading (MeSH) words for MEDLINE. This will then be adapted for the Embase database. Two independent reviewers VM and BBN will screen all studies using prespecified inclusion and exclusion criteria. The Downs and Black checklist will be used to assess the quality of individual studies. Predefined relevant data items will be extracted using sheets, and all study tables will be created using Review Manager V.5.3. The Grading of Recommendations Assessment, Development and Evaluation approach will be used to assess the strength of evidence.

ETHICS AND DISSEMINATION

The review will include publicly available data. The findings of this review will be disseminated through publications.

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.