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Assessment of causal association between thyroid function and lipid metabolism: a Mendelian randomization study.
Wang, JJ, Zhuang, ZH, Shao, CL, Yu, CQ, Wang, WY, Zhang, K, Meng, XB, Gao, J, Tian, J, Zheng, JL, et al
Chinese medical journal. 2021;134(9):1064-1069
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Obesity, dyslipidaemia, and metabolic syndrome are major risk factors for cardiovascular disease, however, effect of thyroid dysfunction on dyslipidaemia and cardiovascular disease is largely unknown. This study used mendelian randomisation (MR), where a genetic variant is used as an instrumental variable to detect the causal effects of exposure to disease. This study used two sample MR analyses to find out whether clinical thyroid function measures show a causal relationship with the changes in lipid levels. The results showed a significant association between the elevated thyrotropin (TSH) level and increased total cholesterol. Also, there was a significant correlation between the free triiodothyronine (FT3): free thyroxine (FT4) ratio and total cholesterol and low-density lipoprotein (LDL). Further robust studies are required to confirm the results and investigate the causal effect of thyroid hormone dysregulation and cardiometabolic diseases due to the limitations of this study. However, healthcare professionals can use the results of this study to understand the importance of the pituitary-thyroid-cardiac axis in lipid metabolism and its impact on cardiometabolic health.
Abstract
BACKGROUND Thyroid dysfunction is associated with cardiovascular diseases. However, the role of thyroid function in lipid metabolism remains partly unknown. The present study aimed to investigate the causal association between thyroid function and serum lipid metabolism via a genetic analysis termed Mendelian randomization (MR). METHODS The MR approach uses a genetic variant as the instrumental variable in epidemiological studies to mimic a randomized controlled trial. A two-sample MR was performed to assess the causal association, using summary statistics from the Atrial Fibrillation Genetics Consortium (n = 537,409) and the Global Lipids Genetics Consortium (n = 188,577). The clinical measures of thyroid function include thyrotropin (TSH), free triiodothyronine (FT3) and free thyroxine (FT4) levels, FT3:FT4 ratio and concentration of thyroid peroxidase antibodies (TPOAb). The serum lipid metabolism traits include total cholesterol (TC) and triglycerides, high-density lipoprotein, and low-density lipoprotein (LDL) levels. The MR estimate and MR inverse variance-weighted method were used to assess the association between thyroid function and serum lipid metabolism. RESULTS The results demonstrated that increased TSH levels were significantly associated with higher TC (β = 0.052, P = 0.002) and LDL (β = 0.041, P = 0.018) levels. In addition, the FT3:FT4 ratio was significantly associated with TC (β = 0.240, P = 0.033) and LDL (β = 0.025, P = 0.027) levels. However, no significant differences were observed between genetically predicted FT4 and TPOAb and serum lipids. CONCLUSION Taken together, the results of the present study suggest an association between thyroid function and serum lipid metabolism, highlighting the importance of the pituitary-thyroid-cardiac axis in dyslipidemia susceptibility.
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Association between plasma fatty acids and inflammatory markers in patients with and without insulin resistance and in secondary prevention of cardiovascular disease, a cross-sectional study.
Bersch-Ferreira, ÂC, Sampaio, GR, Gehringer, MO, Torres, EAFDS, Ross-Fernandes, MB, da Silva, JT, Torreglosa, CR, Kovacs, C, Alves, R, Magnoni, CD, et al
Nutrition journal. 2018;17(1):26
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It is known that people with cardiovascular disease (CVD) have increased inflammation and raised levels of circulating inflammatory molecules. The presence of insulin resistance is thought to increase these levels, as are certain fatty acids coming from dietary fats. The aims of this cross-sectional study were to compare the levels of inflammatory biomarkers in patients with CVD with and without insulin resistance, and to evaluate the possible link between the blood levels of fatty acids and inflammatory biomarkers among these patients. The authors concluded that the CVD patients with insulin resistance had a higher concentration of some inflammatory molecules in the blood than those without insulin resistance. They also observed that saturated fatty acids were linked to higher levels of inflammatory molecules in the blood, while unsaturated fatty acids correlated with lower levels.
Abstract
BACKGROUND Proinflammatory biomarkers levels are increased among patients with cardiovascular disease, and it is known that both the presence of insulin resistance and diet may influence those levels. However, these associations are not well studied among patients with established cardiovascular disease. Our objective is to compare inflammatory biomarker levels among cardiovascular disease secondary prevention patients with and without insulin resistance, and to evaluate if there is any association between plasma fatty acid levels and inflammatory biomarker levels among them. METHODS In this cross-sectional sub-study from the BALANCE Program Trial, we collected data from 359 patients with established cardiovascular disease. Plasma fatty acids and inflammatory biomarkers (interleukin (IL)-1β, IL-6, IL-8, IL-10, IL-12, high sensitive C-reactive protein (hs-CRP), adiponectin, and tumor necrosis factor (TNF)-alpha) were measured. Biomarkers and plasma fatty acid levels of subjects across insulin resistant and not insulin resistant groups were compared, and general linear models were used to examine the association between plasma fatty acids and inflammatory biomarkers. RESULTS Subjects with insulin resistance had a higher concentration of hs-CRP (p = 0.002) and IL-6 (p = 0.002) than subjects without insulin resistance. Among subjects without insulin resistance there was a positive association between stearic fatty acid and IL-6 (p = 0.032), and a negative association between alpha-linolenic fatty acid and pro-inflammatory biomarkers (p < 0.05). Among those with insulin resistance there was a positive association between monounsaturated fatty acids and arachidonic fatty acid and adiponectin (p < 0.05), and a negative association between monounsaturated and polyunsaturated fatty acids and pro-inflammatory biomarkers (p < 0.05), as well as a negative association between polyunsaturated fatty acids and adiponectin (p < 0.05). Our study has not found any association between hs-CRP and plasma fatty acids. CONCLUSIONS Subjects in secondary prevention for cardiovascular disease with insulin resistance have a higher concentration of hs-CRP and IL-6 than individuals without insulin resistance, and these inflammatory biomarkers are positively associated with saturated fatty acids and negatively associated with unsaturated fatty acids.
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Randomized placebo control study of insulin sensitizers (Metformin and Pioglitazone) in psoriasis patients with metabolic syndrome (Topical Treatment Cohort).
Singh, S, Bhansali, A
BMC dermatology. 2016;16(1):12
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As an immune-mediated chronic inflammatory skin condition, psoriasis is associated with obesity, metabolic syndrome, diabetes, and cardiovascular disease. Medications capable of sensitising insulin, such as Metformin and Pioglitazone, have also shown benefits in improving factors associated with metabolic syndrome and psoriasis. This single-centre, parallel-group, randomised, open-label with blinded endpoint evaluated the effects of Metformin with Pioglitazone and placebo in psoriatic patients. Patients with mild-to-moderate psoriasis were randomised to a topical treatment cohort to take 1000 mg metformin daily or 30 mg pioglitazone or placebo groups for 12 weeks. Each participant received a topical ointment containing 5% coal tar during the treatment period. The Metformin and Pioglitazone groups showed significant improvements in psoriasis and metabolic syndrome parameters, such as fasting plasma glucose, total cholesterol, and triglyceride levels, after 12 weeks of treatment. The treatment with metformin resulted in significant improvements in weight, BMI, waist circumference, FPG, triglycerides, and total cholesterol, while the treatment with pioglitazone resulted in significant improvements in FPG, triglycerides, systolic and diastolic blood pressure, cholesterol levels, and LDL cholesterol levels. There was no significant improvement in inflammatory cytokine levels in any group. For further evaluation of the beneficial effects of insulin-sensitising drugs in patients suffering from psoriasis and metabolic syndrome, more robust studies are needed. The study results can be used by healthcare professionals to better understand how insulin-sensitising drugs may decrease the risk of diabetes, cardiovascular disease, and psoriasis in psoriasis patients with metabolic syndrome.
Abstract
BACKGROUND Increased prevalence of metabolic syndrome (MS) is observed in psoriasis. Metformin has shown improvement in cardiovascular risk factors while pioglitazone demonstrated anti proliferative, anti-inflammatory and anti angiogenic effects. Study objective is to evaluate the efficacy and safety of Insulin sensitizers (metformin and pioglitazone) in psoriasis patients with metabolic syndrome (MS). METHODS Single centre, parallel group, randomized, study of metformin, pioglitazone and placebo in psoriasis patients with MS. RESULTS Statistically significant improvement was observed in Psoriasis Area and Severity Index (PASI), Erythema, Scaling and Induration (ESI) and Physician global assessment (PGA) scores in pioglitazone (p values - PASI = 0.001, ESI = 0.002, PGA = 0.008) and metformin groups (p values - PASI = 0.001, ESI = 0.016, PGA = 0.012) as compared to placebo. There was statistically significant difference in percentage of patients achieving 75 % reduction in PASI and ESI scores in metformin (p value - PASI = 0.001, ESI = 0.001) and pioglitazone groups (p vaue - PASI = 0.001, ESI = 0.001). Significant improvement was observed in fasting plasma glucose (FPG) and triglycerides levels in metformin and pioglitazone arms. Significant improvement was noted in weight, BMI, waist circumference, FPG, triglycerides and total cholesterol after 12 weeks of treatment with metformin while pioglitazone showed improvement in FPG, triglyceride levels, systolic blood pressure (SBP), diastolic blood pressure (DBP), total cholesterol and LDL cholesterol levels. There was no difference in pattern of adverse drug reaction in three groups. CONCLUSION Insulin sensitizers have shown improvement in the parameters of MS as well as disease severity in psoriasis patients. TRIAL REGISTRATION CTRI Registration Number: CTRI/2011/12/002252 . Registered on 19/12/2011.