Causal relationships between circulating inflammatory factors and IgA vasculitis: a bidirectional Mendelian randomization study

Genetic Evidence of Causal Effect between C1q/TNF-Related Protein-1 and Atherosclerosis: a Bidirectional and Multivariate Mendelian Randomization Study

AIMS

To investigate the causal relationship between C1q/TNF-related protein-1 (CTRP1) and atherosclerosis across various vascular sites, informed by studies connecting CTRP1 to coronary artery disease.

METHODS

Summary statistics of CTRP1 from the available genome-wide association studies and atherosclerosis in classic vascular sites (including cerebral, coronary, and other arteries) from the FinnGen biobank were extracted for a primary MR analysis, and the analysis was replicated using Ischemic Stroke cohort (large artery atherosclerosis) for validation. The inverse variance-weighted method was used for primary assessment. Sensitivity analysis was performed by Cochrane's Q test and leave-one-out analysis. Potential pleiotropic effects were assessed by MR-Egger intercept and MR-PRESSO global test. Additionally, multivariable MR (MVMR) analysis was performed to investigate the independent effect of CTRP1 on atherosclerosis after removing confounding factors.

RESULTS

Reliable causal evidence was found for CTRP1 involvement in three atherosclerosis endpoints: causal effects of CTRP1 on cerebral atherosclerosis (OR=1.31, CI:1.04-1.66; FDR_P=0.0222)], coronary atherosclerosis (OR=1.13, CI: 1.08-1.19; FDR_P=2.86e-07), and atherosclerosis at other sites (OR=1.06, CI:1.02-1.11; FDR_P=0.0125). The validation cohort further confirmed its causal effect on large-artery atherosclerosis (OR=1.10, CI:1.03-1.18; FDR_P=0.0115). The reverse MR analysis did not support the causal effect of atherosclerosis on CTRP1. Moreover, the MVMR analysis, adjusting for confounders (CTRP3, CTRP5, and CTRP9A), highlighted a significant independent causal effect of CTRP1 remaining on atherosclerosis.

CONCLUSION

CTRP1 may represent a promising target for preventing and treating systemic atherosclerosis.

Risk factors for gastrointestinal bleeding in children with Henoch-Schönlein purpura

Objective

To analyze the risk factors associated with gastrointestinal bleeding in pediatric patients with Henoch-Schönlein purpura (HSP), with the goal of enhancing early diagnosis and treatment, preventing complications, and improving patient outcomes.

Methods

The study involved 23 pediatric patients with HSP who experienced gastrointestinal bleeding, forming the study group. They were admitted to our hospital from June 2023 to June 2024. For comparison, a control group composed of 44 children with HSP but without gastrointestinal bleeding, admitted during the same timeframe, was established. Data on clinical characteristics, laboratory results, and imaging findings were collected. Both univariate and multivariate analyses were conducted to identify potential risk factors.

Results

A total of 67 children with HSP were divided into two groups: those with gastrointestinal bleeding (23 cases) and those without (44 cases). The occurrence of abdominal pain and incidence of intestinal wall thickening detected by gastrointestinal ultrasonography were significantly higher in the group with gastrointestinal bleeding compared to the group without bleeding (P < 0.05). Univariate analysis revealed significant differences in eight laboratory parameters (WBC, NE, NLR, PCT, CRP, D-dimer, Fib, TT), all statistically significant (P < 0.05). Multivariate analysis identified three independent risk factors for gastrointestinal bleeding in children with HSP: abdominal pain (OR = 2.334, 95% CI: 0.458-11.886, P = 0.010), a PCT level above 0.12 ng/ml (OR = 10.010, 95% CI: 1.208-82.929, P = 0.033), and a D-dimer level exceeding 1.87 mg/L (OR = 3.407, 95% CI: 1.022-17.473, P < 0.001).

Conclusion

The findings confirmed that abdominal pain, elevated PCT levels, and increased D-dimer are significant independent risk factors for gastrointestinal bleeding in pediatric patients with Henoch-Schönlein purpura. Clinicians should monitor these indicators attentively to enhance patient management and outcomes.

Haptoglobin as a novel predictor of visceral involvement and relapse in adult IgAV patients

INTRODUCTION

IgA vasculitis (IgAV) can present as skin-limited or systemic disease, which can be severe in adults. Predictive markers for visceral involvement are suboptimal. Considering haptoglobin's role as an acute phase reactant, we evaluated whether its differential expression in IgAV patients' skin and leukocytes is also reflected systemically in a larger cohort of adult IgAV patients. Additionally, soluble form of haptoglobin scavenger receptor CD163 was measured in IgAV patient serum.

METHODS

We re-analyzed RNA sequencing data from leukocytes and skin biopsies of treatment-naïve adult IgAV patients: (1) IgAV nephritis (n = 3), (2) skin-limited IgAV (n = 3), and healthy controls (n = 3). Haptoglobin serum level was measured in 178, and haptoglobin genotyping was performed in 91 treatment-naïve adult IgAV patients. Serum sCD163 was measured in 60 IgAV patients and 22 HC.

RESULTS

Transcriptomic data of leukocytes and skin of IgAV nephritis patients identified haptoglobin as a hub gene, based on protein-protein interaction network. Haptoglobin serum level was elevated in IgAV patients with nephritis or gastrointestinal involvement compared to other IgAV patients. Patients who relapsed during follow-up had decreased haptoglobin serum level at disease presentation compared to non-relapsing patients. Haptoglobin genotyping did not show differences between genotype groups regarding clinical presentation and laboratory parameters. Serum sCD163 was significantly higher in IgAV nephritis patients compared to HC.

CONCLUSION

We identified haptoglobin as a novel marker of visceral involvement and relapse in adult IgAV, while sCD163 is linked to renal involvement. Further studies will confirm the clinical utility of haptoglobin as biomarker in IgAV. Key Points • Haptoglobin expression is upregulated in leukocytes and skin of adult IgAV with renal involvement. • Haptoglobin serum level is elevated in IgAV patients with visceral involvement. • Patients with IgAV relapse have lower haptoglobin at disease presentation.

Circulating Inflammatory Factors and Bidirectional Mendelian Randomization Analysis in Patients with Kawasaki Disease

Background

Kawasaki disease (KD), also known as mucocutaneous lymph node syndrome, is a systemic immune vasculitis with an unclear etiology. It is often complicated by coronary artery disease. This study uses bidirectional Mendelian randomization (MR) to investigate the interaction between KD and circulating inflammatory factors, providing insights into their causal relationships.

Methods

We conducted a two-way pooled MR analysis to examine the causal links between 41 circulating inflammatory regulators and the risk of KD. Genetic data related to inflammation were sourced from three genome-wide association studies (GWASs) involving CRP, PCT, and cytokines, while KD data were derived from other studies. Inverse-variance weighting (IVW) was the primary MR method, with sensitivity analyses performed using MR‒Egger, weighted median, weighted mode, and MR-PRESSO to ensure robustness.

Results

Forward MR analyses showed no significant relationship between inflammatory factors and KD outcomes. In contrast, reverse MR, with KD as the exposure factor, revealed that interleukin-2 (IL-2) and interleukin-8 (IL-8) were significantly associated with KD (IL-2: OR=1.0085, P=0.037; IL-8: OR=1.0099, P=0.014). Borderline significant associations were observed for factors such as B_NGF, EOTAXIN, HGF, and IL_12_P70 in MR‒Egger and weighted median analyses.

Conclusion

This bidirectional MR study highlights the role of circulating inflammatory modulators in KD risk, offering insights into KD pathogenesis and potential therapeutic targets.

Exploring potential causal relationships between gut microbiota, inflammatory factors, and postpartum depression: a Mendelian randomization analysis

BACKGROUND

Recent studies have suggested a potential correlation between ecological dysregulation of the gut microbiota (GM) and the onset and development of postpartum depression (PPD). In addition, inflammatory factors (IFs) have been reported to play an important role in the development of PPD. However, the causal connections among GM, IFs, and PPD remain to be understood.

OBJECTIVE

This study sought to determine if genetically predicted GM and IFs exert a causal effect on PPD and to study whether IFs mediate the causal effect of GM on PPD.

METHODS

Two-step and two-sample Mendelian randomization (MR) analyses, primarily employing the inverse variance weighted (IVW) method, were conducted to evaluate the causal relationship between GM, IFs, and PPD, and to assess potential mediating effects. Heterogeneity and horizontal pleiotropy tests were performed to evaluate the robustness of the findings and the strength of the causal associations.

RESULTS

Class Alphaproteobacteria, genus Family XIII AD3011 group exhibited a positive association with PPD risk; whereas, the family Clostridiales vadin BB60 group, family Veillonellaceae, genus Ruminococcaceae UCG011, and the inflammatory factors C-C motif chemokine ligand 5 (CCL5) and C-C motif chemokine ligand 3 (CCL3) demonstrated negative correlations with PPD risk. IFs did not exhibit a mediating role. No heterogeneity or horizontal pleiotropy was observed.

CONCLUSIONS

Our MR study offered genetic evidence that GM and IFs contribute to the pathogenesis of PPD, with no mediating effect of IFs. This enhances our understanding of PPD's pathological mechanisms and offers new perspectives for developing novel preventative and therapeutic strategies.

Immune traits in combination with inflammatory proteins revealing the pathogenesis of autoimmune liver diseases: A Mendelian randomization study

BACKGROUND

Prior observational research has shown relationships between immune cells, inflammatory proteins, and autoimmune liver diseases (AILD), but their causal associations remain controversial. Therefore, we aimed to clarify the causal association between them.

METHODS

We carried out a comprehensive Mendelian randomization (MR) analysis to clarify causal associations between 731 immune traits, 91 circulating inflammatory proteins, and AILD, including primary biliary cholangitis (PBC), primary sclerosing cholangitis (PSC), and autoimmune hepatitis (AIH). A two-step MR analysis was used to explore the mediating role of circulating inflammatory proteins. Additionally, we performed sensitivity analyses to evaluate the robustness of the results.

RESULTS

CD27 on IgD+CD24+B cell, CD27 on IgD-CD38dimB cell, CD27 on unswitched memory B cell, CD27 on switched memory B cell, and CD27 on CD24+CD27+B cell were risk factors for PBC. However, we detected protective effects of CD25 on IgD-CD27-B cell against PBC and CD28 on resting CD4+Treg cell against PSC. Circulating CD40, Interleukin-33, and Delta and Notch-like epidermal growth factor-related receptor were protective factors for PBC. Furthermore, CD40 mediated the association between immune traits and PBC, with the mediated proportions ranging from 18.3 % to 35.4 %. Tumor necrosis factor superfamily member 12 was identified as a risk factor for PSC, and monocyte chemotactic protein 3 was identified as a protective factor for PSC. Additionally, PBC and PSC had effects on eleven immune traits, which are suggested to be the consequences of them. We found no causal association between immune traits, circulating inflammatory proteins, and AIH. Sensitivity analyses demonstrated our results were robust.

CONCLUSIONS

Our results demonstrate the causal roles of immune traits and inflammatory proteins in PBC and PSC, which reveals their pathogenesis. It is necessary to investigate the specific mechanism by which immune cells and inflammatory proteins affecting the occurrence of AILD.

Causal relationship between systemic circulatory inflammatory regulators and intervertebral disc degeneration: A bidirectional 2-sample Mendelian randomization study

In the context of the development of intervertebral disc degeneration (IDD), inflammatory mediators play a pivotal role. Nevertheless, due to the influence of the inflammatory microenvironment, the causal relationship between specific inflammatory mediators and the development of IDD remains uncertain. The understanding of the causal relationship between inflammatory mediators and IDD is of great importance in preventing and delaying disc degeneration in the future. We utilized genetic data concerning systemic circulating inflammatory regulators obtained from a Genome-Wide Association Study (GWAS) analyzing 41 serum cytokines in a cohort of 8293 individuals from Finland. The genetic data for IDD were derived from the most recent GWAS summary statistics conducted within the FinnGen consortium, encompassing 37,636 IDD cases and 270,964 controls. Our analysis employed bidirectional 2-sample Mendelian randomization (MR) techniques, which included several MR methods such as MR Egger, weighted median, inverse variance weighted, weighted mode, and simple mode. Additionally, the MR-PRESSO method was employed to identify horizontal pleiotropy, heterogeneity was quantified using the Cochran Q statistic, and MR-Egger intercept analysis was performed to assess pleiotropy. We established causal relationships between 3 specific inflammatory factors and IDD. Elevated levels of MIP-1β (OR = 0.956, 95% CI: -0.08 to -0.006; P = .02) and IFN-G (OR = 0.915, 95% CI: -0.16 to -0.02; P = .01) expression were associated with a reduced risk of IDD. Conversely, genetic susceptibility to IDD was linked to a decrease in IL-13 levels (OR = 0.967, 95% CI: -0.063 to -0.004; P = .03). In this study, we have identified inflammatory factors that exhibit a causal relationship with the onset and progression of IDD, as supported by genetic predictions.

Causal association between circulating inflammatory proteins and peripheral artery disease: a bidirectional two-sample Mendelian randomization study

Introduction

A growing body of research has shown a strong connection between circulating inflammatory proteins and Peripheral artery disease (PAD). However, the causal relationship between circulating inflammatory proteins and PAD is still not fully understood. To investigate this association, we conducted a bidirectional Mendelian randomization study.

Materials and methods

Our study utilized genetic variation data obtained from genome-wide association studies (GWAS) datasets. Specifically, the GWAS dataset related to PAD (identifier: finn-b-I9_PAD) included 7,098 cases and 206,541 controls. Additionally, we extracted data on 91 inflammatory proteins from another GWAS dataset (identifiers: GCST90274758-GCST90274848), involving 14,824 participants. To assess the causal relationship between circulating inflammatory proteins and PAD development, we employed methodologies such as inverse variance weighting (IVW), MR Egger regression, and the weighted median approach. Furthermore, sensitivity analyses were conducted to ensure the reliability and robustness of our findings.

Results

Two inflammatory proteins were found to be significantly associated with PAD risk: Natural killer cell receptor 2B4 levels (OR, 1.219; 95% CI,1.019~1.457; P=0.03), Fractalkine levels (OR, 0.755; 95% CI=0.591~0.965; P=0.025). PAD had statistically significant effects on 12 inflammatory proteins: C-C motif chemokine 19 levels (OR, 0.714; 95% CI, 0.585 to 0.872; P=0.001), T-cell surface glycoprotein CD5 levels (OR, 0.818; 95% CI, 0.713 to 0.938; P=0.004), CUB domain-containing protein 1 levels (OR, 0.889; 95% CI, 0.809 to 0.977; P=0.015), Fibroblast growth factor 23 levels (OR, 1.129; 95% CI, 1.009 to 1.264; P=0.034), Interferon gamma levels (OR, 1.124; 95% CI, (1.011 to 1.250); P=0.031),Interleukin-15 receptor subunit alpha levels (OR, 1.183; 95% CI,(1.005 to 1.392); P=0.044), Interleukin-17C levels (OR,1.186; 95% CI, (1.048 to 1.342); P=0.007), Interleukin-1-alpha levels (OR, 1.349; 95% CI, (1.032 to 1.765); P=0.029), Interleukin-5 levels (OR, 1.119; 95% CI,(1.003 to 1.248); P=0.043), Latency-associated peptide transforming growth factor beta 1 levels (OR,1.123; 95% CI, (1.020 to 1.236); P=0.018), Matrix metalloproteinase-10 levels (OR, 1.119; 95% CI,(1.015 to 1.233); P=0.024), Signaling lymphocytic activation molecule levels (OR, 0.823; 95% CI, (0.693 to 0.978); P=0.027).

Conclusion

Our research expands on genetic studies exploring the strong association between circulating inflammatory proteins and PAD. This discovery has the potential to inform and shape future clinical and basic research endeavors in this area.

Deregulation in adult IgA vasculitis skin as the basis for the discovery of novel serum biomarkers

INTRODUCTION

Immunoglobulin A vasculitis (IgAV) in adults has a variable disease course, with patients often developing gastrointestinal and renal involvement and thus contributing to higher mortality. Due to understudied molecular mechanisms in IgAV currently used biomarkers for IgAV visceral involvement are largely lacking. Our aim was to search for potential serum biomarkers based on the skin transcriptomic signature.

METHODS

RNA sequencing analysis was conducted on skin biopsies collected from 6 treatment-naïve patients (3 skin only and 3 renal involvement) and 3 healthy controls (HC) to get insight into deregulated processes at the transcriptomic level. 15 analytes were selected and measured based on the transcriptome analysis (adiponectin, lipopolysaccharide binding protein (LBP), matrix metalloproteinase-1 (MMP1), C-C motif chemokine ligand (CCL) 19, kallikrein-5, CCL3, leptin, C-X-C motif chemokine ligand (CXCL) 5, osteopontin, interleukin (IL)-15, CXCL10, angiopoietin-like 4 (ANGPTL4), SERPIN A12/vaspin, IL-18 and fatty acid-binding protein 4 (FABP4)) in sera of 59 IgAV and 22 HC. Machine learning was used to assess the ability of the analytes to predict IgAV and its organ involvement.

RESULTS

Based on the gene expression levels in the skin, we were able to differentiate between IgAV patients and HC using principal component analysis (PCA) and a sample-to-sample distance matrix. Differential expression analysis revealed 49 differentially expressed genes (DEGs) in all IgAV patient's vs. HC. Patients with renal involvement had more DEGs than patients with skin involvement only (507 vs. 46 DEGs) as compared to HC, suggesting different skin signatures. Major dysregulated processes in patients with renal involvement were lipid metabolism, acute inflammatory response, and extracellular matrix (ECM)-related processes. 11 of 15 analytes selected based on affected processes in IgAV skin (osteopontin, LBP, ANGPTL4, IL-15, FABP4, CCL19, kallikrein-5, CCL3, leptin, IL-18 and MMP1) were significantly higher (p-adj < 0.05) in IgAV serum as compared to HC. Prediction models utilizing measured analytes showed high potential for predicting adult IgAV.

CONCLUSION

Skin transcriptomic data revealed deregulations in lipid metabolism and acute inflammatory response, reflected also in serum analyte measurements. LBP, among others, could serve as a potential biomarker of renal complications, while adiponectin and CXCL10 could indicate gastrointestinal involvement.

The Causal Relationship between Genetically Predicted Biological Aging, Alzheimer's Disease and Cognitive Function: A Mendelian Randomisation Study

Aging is one of the most important risk factors for Alzheimer's disease (AD). Biological aging is a better indicator of the body's functional state than age (chronological aging). Leukocyte telomere length (LTL) and epigenetic clocks constructed from DNA methylation patterns have emerged as reliable markers of biological aging. Recent studies have shown that it may be possible to slow down or even reverse biological aging, offering promising prospects for treating AD. Several observational studies have reported an association between biological aging, AD, and cognitive function, but the causality behind this association and the effects of different biological aging markers on AD risk and cognitive function remain unclear. Therefore, we explored the causal relationship between them by Mendelian randomization (MR) study. Inverse-variance weighted (IVW) method is the most dominant analytical method in MR studies, which is a weighted average of estimates from different genotype combinations, and this weighted average provides an overall estimate of the causal effect. The results of the IVW analyses showed that HannumAge acceleration and LTL shortening were able to increase the risk of late-onset AD (LOAD), but not early-onset AD (EOAD). Excellent prospective memory and fluid intelligence are potentially protective against GrimAge acceleration. GrimAge acceleration and HorvathAge acceleration increase the risk of LOAD through effects on LTL. Our findings provide important insights into the role of biological aging in the pathogenesis of AD, while also highlighting the interplay of different biological aging markers and their complexity in different AD subtypes.