Interaction Of Smoking And Diabetes With Subsequent Risk Of Cardiovascular Events And The Mechanism Of Smoking On Pancreatic β-cell Damage

Objective:Smoking is the leading preventable cause of death and disability in the global population.Smoking substantially increases the risk of cardiovascular disease(CVD)in both the general population and patients with type 2 diabetes.Meanwhile CVD remains the most common cause of mortality among patients with diabetes.Evaluating the interplay between cigarette smoking and diabetes status in relation to CVD risk is of the essence for prioritizing precise clinical and public health strategies to reduce the burden of CVD among patients with diabetes.Thus far,whether current smoking or smoking cessation modifies the associations of diabetes and risk factor management with the incidence of CVD,and whether the smoking-related CVD risk differs among people with and without diabetes are still unknown.This study aims to explore the relationship and interaction between smoking,diabetes and risk factor management in relation to subsequent risk of cardiovascular events.Smoking is closely related to diabetes.In addition,passive smoking can also increase the incidence of diabetes compared with the normal population,and there is a dose-response relationship.The main function of pancreatic β-cells is to secrete insulin,and the main role of insulin is to lower blood sugar.Once the pancreaticβ-cells are damaged and their secretory function is weakened,it is easy to induce hyperglycemia,and hyperglycemia is the main pathological change of diabetes.Clinical studies have found that smoking is harmful to pancreatic β-cells which can lead to hyperglycemia.Therefore,finding out its specific mechanism is particularly important for the follow-up clinical treatment of diabetes.To date,the mechanism on how smoking impacts the function of pancreatic β-cells is still unclear.The first part of the study aims to explore interaction between smoking and diabetes in relation to subsequent risk of cardiovascular events.On this basis,the second part aims to explore cigarette smoke extract promotes pancreatic β-cell pyroptosis via NLRP3 and PDHA1 deacetylation by regulating SIRT3.Methods:The first part of this study is from the China Cardiometabolic Disease and Cancer Cohort Study.The baseline survey was conducted from 2011 to 2012 and included 20 communities from various geographic regions in China.Using a cluster sampling method,and 193,846 men and women aged 40 years or older were recruited to represent the general population.The follow-up survey was conducted between2014 and 2016;all participants were invited to attend an in-person visit,and 170,240 participants were followed up.The participant of the baseline and follow-up survey completed the questionnaire survey,physical examination,blood pressure and laboratory measurements,and the hospitalization or emergency visits of the participants during the study period were collected during the follow-up.The analysis included 126,181 participants who had complete baseline data on cigarette smoking,diabetes status,and covariates;were free from CVD at baseline;and had complete ascertainment of CVD events at the follow-up visit.The second part of this study used cigarette smoke extract(CSE)to construct a pancreatic β-cell CSE model.m RNA expression changes of SIRT3,caspase-1 and IL-18 were detected by q PCR.The SIRT3 overexpression lentiviral vector and the blank control vector were constructed and transfected into pancreatic β-cells.SIRT3 expression and activity was detected after the inhibitor SIRT-IN-3 treatment.The protein level changes of SIRT3,PDHA1,IL-1β,IL-18,NLRP3 and caspase-1 within pancreatic β-cells were detected by Western Blot at 24 h after transfection of SIRT3 overexpression lentivirus.Then,intracellular lactic acid content was detected using the lactic acid kit.Meanwhile,cell cycle changes of each group were analyzed by flow cytometry.GSDMD expression and PDHA1 acetylation level was evaluated using immunofluorescence and IP respectively.The pancreatic β-cell pyroptosis was observed under a transmission electron microscope.Results:In the first part of study,study participants included 19,397 current smokers(15.4%),6,049 former smokers(4.8%),and 100,735 never smokers(79.8%).Mean(SD)age ranged from 55.8(8.6)years to 60.7(9.1)years.Compared with never smokers,heavy smokers exhibited a greater risk of CVD events among participants with diabetes(multivariable-adjusted hazard ratio [HR],1.45;95% CI,1.17-1.78)than among participants without diabetes(HR,1.20;95% CI,1.01-1.42;P for interaction = 0.006).Compared with participants without diabetes,participants with diabetes who were never smokers and had 5 or more controlled risk factors showed no significantly excess CVD risk(HR,0.93;95% CI,0.71-1.22),but the cardiovascular benefits from risk factor management were counteracted among participants with diabetes who were current smokers(HR,1.28;95% CI,0.77-2.14)or former smokers(HR,1.22;95% CI,0.66-2.28).In the second part of this study,the SIRT3 m RNA level in pancreatic β-cells of CSE injury group was decreased(P<0.05),whereas the m RNA levels of caspase-1(P<0.05)and IL-18(P>0.05)were increased.Moreover,CSE modeling decreased SIRT3 and PDHA1 protein levels(P<0.05),but increased IL-1β,IL-18,NLRP3 and caspase-1 protein expression(P<0.05).Intracellular lactic acid content was significantly increased accompanied with the increased GSDMD(P<0.001).Pyroptotic bodies could be observed via TEM.The IP results showed that PDHA1 acetylation level was significantly increased by CSE treatment(P<0.01).Conclusions:1.Smoking and diabetes interacted with each other in relation to increased risk of CVD events,and the beneficial effect of risk factor management on CVD risk among participants with diabetes was attenuated by current or former smoking.2.Smoking can lead to the suppression of SIRT3 in pancreatic β-cells.The suppressed SIRT3 attenuates the deacetylation level of downstream PDHA1 and down-regulates its expression,further inducing subsequent accumulation of intracellular lactic acid.Then,the NLRP3 expression was up-regulated and pancreaticβ-cells pyroptosis was triggered,which may finally lead to hyperglycemia.