No Casual Relationship Between T2DM and the Risk of Infectious Diseases: A Two-Sample Mendelian Randomization Study

Type 2 diabetes and cause-specific mortality in Mexico City: a Mendelian randomisation analysis

Background

Observational epidemiological studies in Mexico have shown high mortality risks associated with type 2 diabetes (T2D). However, it is unclear whether these relationships are wholly causal. We aimed to assess the association of genetically-predicted T2D liability with risk of death in Mexico.

Methods

Between 1998 and 2004, 150,000 men and women were recruited from Mexico City and followed-up until September 2022 for cause-specific mortality. Mendelian randomisation analyses, using a genetic risk score (GRS) comprising 1055 established T2D-associated risk variants, estimated associations with risk of all-cause and cause-specific mortality at ages 35-74.

Findings

Among 121,433 included participants with a mean (standard deviation) age of 51 (11), 68% (n = 82,249) were women and 18% (n = 21,371) had T2D. The GRS explained 6.3% of T2D liability and was not associated with major potential confounders of the T2D-mortality relationship. During a median (interquartile range) of 20.2 (19.4-21.4) years' follow-up, 12,293 participants died. Genetically-predicted T2D liability was associated with a death rate ratio (RR) of 1.29 (95% confidence interval [CI] 1.23-1.36) per trebling in genetically-predicted odds of T2D. There were particularly strong associations with death from renal disease (n = 1696; RR 2.29 [95% CI 1.99-2.64]) and acute diabetic crises (n = 509; RR 2.27 [1.75-2.93]) and weaker, but still strong, associations with death from vascular disease (n = 3226; RR 1.31 [1.19-1.46]) and infection (n = 2437; RR 1.21 [1.07-1.36]). Genetically-predicted T2D liability was not clearly associated with death from cancer (n = 2016; RR 1.00 [95% CI 0.88-1.14]) or cirrhosis (n = 895; RR 0.90 [0.74-1.10]).

Interpretation

T2D is causally associated with death from vascular, renal and infectious diseases. Its prevention and effective management could substantially reduce premature deaths in Mexico, where T2D is common.

Funding

Wellcome Trust, the Mexican Health Ministry, the National Council for Science and Technology (CONACyT) for Mexico, Cancer Research UK, British Heart Foundation, Kidney Research UK, UK Medical Research Council, AstraZeneca, Regeneron.

THE CAUSAL ASSOCIATION OF CARDIOMETABOLIC DISEASES AND SEPSIS-RELATED OUTCOMES: A MENDELIAN RANDOMIZATION AND POPULATION STUDY

ABSTRACT

Objective: The causality between cardiometabolic disease (CMD) and sepsis has remained largely unknown. To elucidate this, we conducted a Mendelian randomization (MR) and population study. Methods: First, we used univariable and multivariable MR analyses to investigate causal associations between CMD and sepsis-related outcomes. We obtained genome-wide association study summary from both the MRC Integrative Epidemiology Unit and the FinnGen consortium. Subsequently, a two-step mediation MR analysis was performed to explore mediators. Afterward, we conducted an observational study using the Medical Information Mart for Intensive Care IV database, in which multivariable logistic regression models were utilized to examine the relationship between CMD and sepsis-related outcomes. Results: In the MR study, type 2 diabetes mellitus (OR = 1.058, 95% CI = 1.017-1.100, P = 0.005), obesity (OR = 1.113, 95% CI = 1.057-1.172, P < 0.001), and heart failure (HF) (OR = 1.178, 95% CI = 1.063-1.305, P = 0.002) were independently causally related to sepsis. Obesity (OR = 1.215, 95% CI = 1.027-1.437, P = 0.023) and HF (OR = 1.494, 95% CI = 1.080-2.065, P = 0.015) also showed independent causal associations with sepsis critical care admission. Mediation MR analysis identified 23 blood metabolites potentially causally linked to sepsis ( P < 0.05), yet none mediated the relationship between CMD and sepsis. In the observational study, we found associations between sepsis and several conditions including type 2 diabetes mellitus, obesity, hypertension, stroke, HF, and hyperlipidemia after adjusting for confounding factors. Moreover, hypertension, stroke, HF, coronary artery disease, and hyperlipidemia were linked to sepsis critical care admission. Conclusion: This study has, for the first time, revealed indicative evidence of a causal relationship between CMD and sepsis through observational and genetic evidence. Taken together, clinical attention to sepsis may be warranted among patients with CMD.

Obstructive sleep apnea's causal links to depression, well-being, and negative moods: a bidirectional mendelian randomized study

Previous observational studies showed associations between obstructive sleep apnea (OSA) and depression and other negative moods. However, the causality has not been determined. Single nucleotide polymorphisms were identified as instrumental variables by screening from genome-wide association studies. Bidirectional two-sample mendelian randomization (MR) was applied to assess the potential causal relationship between OSA and depression, subjective well-being, negative moods. Inverse variance weighting (IVW) method and weight median were chosen as the main methods to estimate possible causal effects. MR-Egger, MR pleiotropy residual sum and outlier and leave-one-out analysis methods, were used as sensitivity analysis methods to ensure robust results. MR analyses indicated significantly causal association of OSA on depression (OR = 1.22, P = .010) and major depressive disorder (OR = 1.02, P = .006). Furthermore, genetically predicted OSA was negatively associated with subjective well-being (βIVW = -0.06, P = .009), and was positively associated with negative moods including depressed affect (OR = 1.04, P = .012), irritable mood (P = .006), feeling lonely (P = .011), feeling fed-up (P = .005) and mood swings (P = .017). There is no reverse effect of the above psychiatric traits on OSA. Genetic predisposition to OSA causally increased depression and major depressive disorder. Consistently, OSA has causal impacts on both subjective well-being, representing positive emotions, and negative moods.

Exploring and validating associations between six systemic inflammatory indices and ischemic stroke in a middle-aged and old Chinese population

BACKGROUND

Inflammation and maladaptive immune mechanisms have been substantiated as integral components in the critical pathological processes of the injury cascade in ischemic stroke (IS). This study aimed to explore the associations between six systemic inflammatory indices and IS in a Chinese population.

METHODS

This was a case-control study based on the retrospective review of electronic medical records from two hospitals in Shandong Province, China. Systemic inflammatory indices, including the systemic inflammation response index (SIRI), systemic immune inflammation index (SII), pan-immune-inflammation value (PIV), neutrophil lymphocyte ratio (NLR), platelet lymphocyte ratio (PLR), and lymphocyte monocyte ratio (LMR), were calculated. Logistic regression models and classification analyses were employed to evaluate associations and discriminatory abilities.

RESULTS

In total, 9392 participants aged 40-83 years old were included in the discovery (3620 pairs of IS-present cases and healthy controls) and validation (1076 pairs of IS-present cases and IS-absent controls with IS mimics) datasets. After adjusting for potential confounding factors, IS was found to be associated with all six systemic indices in the discovery dataset, including SIRI (odd ratio [OR] 8.77, 95% confidence interval [CI] 7.48-10.33), SII (1.03, 1.01-1.04), PIV (1.01, 1.01-1.01), NLR (2.23, 2.08-2.39), PLR (1.01, 1.01-1.01), and LMR (0.77, 0.75-0.78). Notably, only LMR exhibited significant associations with IS in both discovery and validation datasets (0.88, 0.83-0.93), suggesting an independent protective role of this index. SIRI, SII, PIV, NLR, and LMR showed good discriminative ability between IS patients and healthy controls in the discovery dataset (AUCs > 0.70). However, they performed poorly in distinguishing IS patients from IS mimics in the validation dataset (AUCs < 0.60).

CONCLUSION

This study provides valuable insights into the associations between systemic inflammatory indices and IS, offering potential implications for risk stratification. While these inflammatory indices are potential indicators for distinguishing IS from healthy conditions, additional biomarkers may be needed when differentiating IS from other chronic inflammatory conditions in clinical practice.

A Genome-wide Association Study of Susceptibility to Upper Urinary Tract Infections

BACKGROUND

Our goal was to identify genetic and modifiable risk factors for upper urinary tract infections (UTIs).

METHODS

We used data from UK Biobank, the Trøndelag Health Study, and the Michigan Genomics Initiative to conduct genome-wide association studies and sex-stratified analyses on upper UTI. Mendelian randomization (MR) analyses were conducted to examine potential causal relationships between cardiometabolic risk factors and upper UTIs.

RESULTS

One genome-wide significant (P ≤ 5E-08) locus was associated with the susceptibility to upper UTI, located near TSN in the female-only analysis. Additionally, we identified suggestive (P ≤ 5E-06) loci near DNAI3 for females, SCAMP1-AS1 for males, and near TSN, LINC00603, and HLA-DQA2 for both sexes. In MR analyses, higher genetically predicted lifetime smoking scores were associated with an increased risk of developing upper UTI for females and both sexes (odds ratio [OR], 4.84, P = 4.50E-06 and OR, 2.79, P = 3.02E-05, respectively).

CONCLUSIONS

We found that genetic variants near TSN was associated with the risk of upper UTIs among females. In addition, we found several genetic loci with suggestive associations with the risk of upper UTIs. Finally, MR analyses found smoking to be a potential causal risk factor for upper UTIs.

Kidney damage on fertility and pregnancy: A Mendelian randomization

BACKGROUND

Low fertility and adverse pregnancy outcomes are commonly observed in women with chronic kidney disease (CKD). However, a causal relationship between low fertility and adverse pregnancy outcomes with CKD remains unclear. Besides, whether mild kidney dysfunction can affect fertility and pregnancy still needs exploration. Hence, this study aimed to investigate the causal effect of kidney damage on fertility and pregnancy using Mendelian randomization (MR).

METHODS

We first used two-sample MR to examine the effects of kidney damage on fertility and pregnancy. Next, we introduced the Bayesian model averaging MR analysis to detect major causal relationships and render the results robust. The genetic instruments and outcome data were derived from various large genome-wide association studies.

RESULTS

Adverse pregnancy outcomes: Our analyses supported a suggestive causal effect of CKD and estimated glomerular filtration rate (eGFR) rapid on stillbirth, with CKD having an odds ratio (OR) of 1.020 [95% confidence interval (CI) 1.002 to 1.038] and eGFR rapid having an OR of 1.026 (95% CI 1.004-1.048). We also discovered a suggestive causal effect of eGFR on spontaneous abortion, with an OR of 2.63 (95% CI 1.269 to 5.450). Moreover, increased urinary albumin-to-creatinine ratio (UACR) was regarded as a potential risk factor for pre-eclampsia (OR = 1.936; 95% CI 1.065 to 3.517) and gestational hypertension (OR = 1.700; 95% CI 1.002 to 2.886). Fertility assessment: The results indicated that eGFR and UACR had a suggestive causal relationship with the anti-Müllerian hormone level (eGFR beta: 1.004; UACR beta: 0.405).

CONCLUSIONS

Our study used MR to demonstrate a suggestive causal relationship between kidney damage and fertility and pregnancy. We reported that mild kidney dysfunction might be a risk factor for reduced fertility and adverse pregnancy outcomes. Dynamic renal detection may help preserve fertility and reduce the risk of pregnancy loss.

Exploring the causal role of the immune response to varicella-zoster virus on multiple traits: a phenome-wide Mendelian randomization study

BACKGROUND

The immune response to infections could be largely driven by the individual's genes, especially in the major histocompatibility complex (MHC) region. Varicella-zoster virus (VZV) is a highly communicable pathogen. In addition to infection, the reactivations of VZV can be a potential causal factor for multiple traits. Identification of VZV immune response-related health conditions can therefore help elucidate the aetiology of certain diseases.

METHODS

A phenome-wide Mendelian randomization (MR) study of anti-VZV immunoglobulin G (IgG) levels with 1370 traits was conducted to explore the potential causal role of VZV-specific immune response on multiple traits using the UK Biobank cohort. For the robustness of the results, we performed MR analyses using five different methods. To investigate the impact of the MHC region on MR results, the analyses were conducted using instrumental variables (IVs) inside (IV_mhc) and outside (IV_no.mhc) the MHC region or all together (IV_full).

RESULTS

Forty-nine single nucleotide polymorphisms (IV_full) were associated with anti-VZV IgG levels, of which five (IV_mhc) were located in the MHC region and 44 (IV_no.mhc) were not. Statistical evidence (false discovery rate < 0.05 in at least three of the five MR methods) for a causal effect of anti-VZV IgG levels was found on 22 traits using IV_mhc, while no evidence was found when using IV_no.mhc or IV_full. The reactivations of VZV increased the risk of Dupuytren disease, mononeuropathies of the upper limb, sarcoidosis, coeliac disease, teeth problems and earlier onset of allergic rhinitis, which evidence was concordant with the literature. Suggestive causal evidence (P < 0.05 in at least three of five MR methods) using IV_full, IV_mhc and IV_no.mhc was detected in 92, 194 and 56 traits, respectively. MR results from IV_full correlated with those from IV_mhc or IV_no.mhc. However, the results between IV_mhc and IV_no.mhc were noticeably different, as evidenced by causal associations in opposite directions between anti-VZV IgG and ten traits.

CONCLUSIONS

In this exploratory study, anti-VZV IgG was causally associated with multiple traits. IVs in the MHC region might have a substantial impact on MR, and therefore, could be potentially considered in future MR studies.

Causal relationship between type 1 diabetes mellitus and six high-frequency infectious diseases: A two-sample mendelian randomization study

Purpose

Type 1 diabetes mellitus (T1DM) is associated with different types of infections; however, studies on the causal relationship between T1DM and infectious diseases are lacking. Therefore, our study aimed to explore the causalities between T1DM and six high-frequency infections using a Mendelian randomization (MR) approach.

Methods

Two-sample MR studies were conducted to explore the causalities between T1DM and six high-frequency infections: sepsis, acute lower respiratory infections (ALRIs), intestinal infections (IIs), infections of the genitourinary tract (GUTIs) in pregnancy, infections of the skin and subcutaneous tissues (SSTIs), and urinary tract infections (UTIs). Data on summary statistics for T1DM and infections were obtained from the European Bioinformatics Institute database, the United Kingdom Biobank, FinnGen biobank, and Medical Research Council Integrative Epidemiology Unit. All data obtained for summary statistics were from European countries. The inverse-variance weighted (IVW) method was employed as the main analysis. Considering the multiple comparisons, statistical significance was set at p< 0.008. If univariate MR analyses found a significant causal association, multivariable MR (MVMR) analyses were performed to adjust body mass index (BMI) and glycated hemoglobin (HbA1c). MVMR-IVW was performed as the primary analysis, and the least absolute shrinkage and selection operator (LASSO) regression and MVMR-Robust were performed as complementary analyses.

Results

MR analysis showed that susceptibility to IIs increased in patients with T1DM by 6.09% using the IVW-fixed method [odds ratio (OR)=1.0609; 95% confidence interval (CI): 1.0281-1.0947, p=0.0002]. Results were still significant after multiple testing. Sensitivity analyses did not show any significant horizontal pleiotropy or heterogeneity. After adjusting for BMI and HbA1c, MVMR-IVW (OR=1.0942; 95% CI: 1.0666-1.1224, p<0.0001) showed significant outcomes that were consistent with those of LASSO regression and MVMR-Robust. However, no significant causal relationship was found between T1DM and sepsis susceptibility, ALRI susceptibility, GUTI susceptibility in pregnancy, SSTI susceptibility, and UTI susceptibility.

Conclusions

Our MR analysis genetically predicted increased susceptibility to IIs in T1DM. However, no causality between T1DM and sepsis, ALRIs, GUTIs in pregnancy, SSTIs, or UTIs was found. Larger epidemiological and metagenomic studies are required to further investigate the observed associations between the susceptibility of certain infectious diseases with T1DM.

Editorial: Advances in genomic and genetic tools, and their applications for understanding embryonic development and human diseases

Significant advances have been recently made in the development of the genetic and genomic platforms. This has greatly contributed to a better understanding of gene expression and regulation machinery. Consequently, this led to considerable progress in unraveling evidence of the genotype-phenotype correlation between normal/abnormal embryonic development and human disease complexity. For example, advanced genomic tools such as next-generation sequencing, and microarray-based CGH have substantially helped in the identification of gene and copy number variants associated with diseases as well as in the discovery of causal gene mutations. In addition, bioinformatic analysis tools of genome annotation and comparison have greatly aided in data analysis for the interpretation of the genetic variants at the individual level. This has unlocked potential possibilities for real advances toward new therapies in personalized medicine for the targeted treatment of human diseases. However, each of these genomic and bioinformatics tools has its limitations and hence further efforts are required to implement novel approaches to overcome these limitations. It could be possible that the use of more than one platform for genotype-phenotype deep analysis is an effective approach to disentangling the cause and treatment of the disease complexities. Our research topic aimed at deciphering these complexities by shedding some light on the recent applications of the basic and advanced genetic/genomic and bioinformatics approaches. These include studying gene-gene, protein-protein, and gene-environment interactions. We, in addition, aimed at a better understanding of the link between normal/abnormal embryonic development and the cause of human disease induction.

Inflammatory bowel disease and risk of coronary heart disease : A Mendelian randomization study

BACKGROUND

Inflammatory bowel disease (IBD), including ulcerative colitis (UC) and Crohn's disease (CD), has been reported to be associated with an increased risk of coronary heart disease (CHD); however, the causal link between IBD and CHD is unclear. We performed Mendelian randomization (MR) analysis to investigate the association between genetically predicted IBD and CHD risk.

METHODS

Exposure summary data were obtained from genome-wide association studies (GWAS) with cohorts of IBD (12,882 cases and 21,770 controls), UC (6968 cases and 20,464 controls), and CD (5956 cases and 14,927 controls) of European descent to identify single nucleotide polymorphisms (SNPs) as instrumental variables. Outcome summary data were obtained from a meta-analysis of 22 GWAS including 22,233 cases and 64,762 controls of European descent. To estimate MR, four methods were used, including inverse variance-weighted (IVW), MR-Egger, simple mode, and weighted median methods. Sensitivity analysis was also performed. The Bonferroni method was used to correct the bias of multiple testing.

RESULTS

Three sets of SNPs (69 SNPs of IBD, 40 SNPs of UC, and 58 SNPs of CD) were used to estimate the causal effect between genetically predicted IBD and CHD. Using the IVW method, we found that no causal relationship between genetically predicted IBD and CHD after Bonferroni correction, and there was no causal relationship between UC/CD and the development of CHD. No evidence of significant heterogeneity and pleiotropy was found.

CONCLUSION

The results of this study suggested that genetically predicted IBD may have no causal effect on CHD risk in a population with European ancestry.