Serum Bilirubin Is Correlated With the Progression of IgA Vasculitis With Nephritis

The Association between Serum Total Bilirubin and Severe Headaches or Migraine in American Adults

BACKGROUND

Studies about the association between bilirubin and migraine were few. Therefore, the purpose of this study was to investigate the association between serum total bilirubin and the prevalence of severe headaches or migraine.

METHODS

A multivariable logistic regression was used to assess the association between serum total bilirubin concentration and severe headaches or migraine. We also performed stratified analyses, interaction analyses and multiple interpolations in the sensitivity analysis.

RESULTS

This cross-sectional study included 12,552 adults from the National Health and Nutrition Examination Survey (NHANES) from 1999 to 2004. The overall incidence of migraine was 19.99% (2,509/12,552). With every 1 mg/dl increase in bilirubin, the prevalence of migraine decreased by 23% (95% CI: 0.64, 0.93) after adjustment of all related covariates. Similarly, the risk of migraine was reduced by 17% (95% CI: 0.72, 0.97) in the Q4 group (the fourth quartile, highest serum total bilirubin level) compared with the Q1 group (the lowest level). Furthermore, interaction effects by age groups were significant in this relationship (P for interaction = 0.0004). In the Q4 group compared with Q1, inverse associations were observed in those aged ≥40 years (OR: 0.71,95% CI: 0.59, 0.85) in the stratified analysis.

CONCLUSION

These findings support an association between serum total bilirubin and severe headaches or migraine, revealing an inverse association between serum total bilirubin quartiles and severe headaches or migraine in American adults. Age could play an important role in this association.

IgA vasculitis update: Epidemiology, pathogenesis, and biomarkers

Immunoglobulin A vasculitis (IgAV), formerly known as Henoch-Schönlein purpura, is the most common systemic vasculitis in children, characterized by diverse clinical manifestations with a wide spectrum ranging from isolated cutaneous vasculitis to systemic involvement. The incidence of IgAV is geographically and ethnically variable, with a prevalence in autumn and winter, suggesting a driving role that genetic and environmental factors play in the disease. Although IgAV has a certain degree of natural remission, it varies widely among individuals. Some patients can suffer from severe renal involvement and even progress to end-stage renal disease. Its pathogenesis is complex and has not been fully elucidated. The formation of galactose-deficient IgA1 (Gd-IgA1) and related immune complexes plays a vital role in promoting the occurrence and development of IgAV nephritis. In addition, neutrophil activation is stimulated through the binding of IgA to the Fc alpha receptor I expressed on its surface, resulting in systemic vascular inflammation and tissue damage. Starting from the epidemiological characteristics, this article will review the role of immunological factors such as Gd-IgA1, autoantibodies, circulating immune complexes, complement system, cellular immunization, and the contributions of environmental and genetic factors in the pathogenesis of IgAV, and conclude with the major biomarkers for IgAV.

Platelet-to-Albumin Ratio: A Novel IgA Nephropathy Prognosis Predictor

Background

Chronic inflammation is related to the development of IgA nephropathy (IgAN). Emerging studies have reported that platelet-related parameters including platelet (PLT), platelet-to-albumin ratio (PAR), and platelet-to-lymphocyte ratio (PLR) are proved to be novel prognostic indicators for several inflammatory diseases. Whether platelet-related parameters could serve as predictors for IgAN remains unknown.

Methods

A total of 966 IgAN patients were enrolled in this retrospective study and were divided into several groups based on the optimal cut-off value of the platelet-related parameters. End-stage renal disease was used as the renal endpoint. A 1:2 propensity score (PS) match was then carried out to eliminate significant differences at baseline. The area under the receiver operating characteristic curve (AUROC), Kaplan–Meier (K-M) curve, and Cox proportional hazards analyses were performed to evaluate their predictive effect.

Results

Without considering the effect of covariates, the K-M curve showed that PLT, PLR, and PAR were strongly correlated with the renal outcomes of IgAN. However, the AUROC revealed that the PAR and PLR had better predictive power than the PLT. Multivariate Cox regression adjusting for demographic data, pathological findings, treatment, and laboratory results indicated that compared with PLR, albumin and PLT, PAR seemed to be a better marker of adverse renal outcome, implying that PAR was the only platelet-related parameter that could be used as an independent risk factor. Notably, high PAR patients seemed to have more severe clinical manifestations and pathological lesions. However, after eliminating the influence of different baselines on outcome variables, the PAR could still predict the poor prognosis of IgAN. To more accurately evaluate the predictive power of the PAR, we analyzed the predictive effect of the PAR on patients with different clinicopathological characteristics through subgroup analysis. It was indicated that the PAR might better predict the prognosis and outcome of patients whose disease was already very severe.

Conclusion

PAR might be used as an independent risk factor for IgAN progression.

Novel Function for Bilirubin as a Metabolic Signaling Molecule: Implications for Kidney Diseases

Bilirubin is the end product of the catabolism of heme via the heme oxygenase pathway. Heme oxygenase generates carbon monoxide (CO) and biliverdin from the breakdown of heme, and biliverdin is rapidly reduced to bilirubin by the enzyme biliverdin reductase (BVR). Bilirubin has long been thought of as a toxic product that is only relevant to health when blood levels are severely elevated, such as in clinical jaundice. The physiologic functions of bilirubin correlate with the growing body of evidence demonstrating the protective effects of serum bilirubin against cardiovascular and metabolic diseases. Although the correlative evidence suggests a protective effect of serum bilirubin against many diseases, the mechanism by which bilirubin offers protection against cardiovascular and metabolic diseases remains unanswered. We recently discovered a novel function for bilirubin as a signaling molecule capable of activating the peroxisome proliferator-activated receptor α (PPARα) transcription factor. This review summarizes the new finding of bilirubin as a signaling molecule and proposes several mechanisms by which this novel action of bilirubin may protect against cardiovascular and kidney diseases.