The role of plasma arachidonic acid metabolites in the pathogenesis and the prognosis of Henoch-Schönlein purpura

Arachidonic acid metabolism in health and disease

Arachidonic acid (AA), an n-6 essential fatty acid, is a major component of mammalian cells and can be released by phospholipase A2. Accumulating evidence indicates that AA plays essential biochemical roles, as it is the direct precursor of bioactive lipid metabolites of eicosanoids such as prostaglandins, leukotrienes, and epoxyeicosatrienoic acid obtained from three distinct enzymatic metabolic pathways: the cyclooxygenase pathway, lipoxygenase pathway, and cytochrome P450 pathway. AA metabolism is involved not only in cell differentiation, tissue development, and organ function but also in the progression of diseases, such as hepatic fibrosis, neurodegeneration, obesity, diabetes, and cancers. These eicosanoids are generally considered proinflammatory molecules, as they can trigger oxidative stress and stimulate the immune response. Therefore, interventions in AA metabolic pathways are effective ways to manage inflammatory-related diseases in the clinic. Currently, inhibitors targeting enzymes related to AA metabolic pathways are an important area of drug discovery. Moreover, many advances have also been made in clinical studies of AA metabolic inhibitors in combination with chemotherapy and immunotherapy. Herein, we review the discovery of AA and focus on AA metabolism in relation to health and diseases. Furthermore, inhibitors targeting AA metabolism are summarized, and potential clinical applications are discussed.

Predictive biomarkers of IgA vasculitis with nephritis by metabolomic analysis

BACKGROUND

IgA vasculitis (IgAV) is the most common vasculitis of childhood. Renal involvement defines late morbidity of the disease. A better understanding of the pathophysiology of the progression to kidney disease and predictive biomarkers are required for better management of IgAV and its nephritis (IgAVN).

OBJECTIVES

An untargeted metabolomics approach was performed to reveal the underlying molecular mechanism of disease pathogenesis and to define potential biomarkers from plasma samples from IgAV and IgAVN patients.

METHODS

Forty-five active IgAV patients (H) and six healthy controls (C) were enrolled in the study. Plasma samples were collected on the same day of diagnosis and before any immunosuppressive treatment was initiated. At the time of diagnosis and sample collection, none of the patients had renal involvement. We used Quadrupole Time of Flight Mass Spectrometry (Q-TOF LC/MS) to investigate the alterations in plasma metabolomic profiles. Three separate pools were created: healthy controls (group C), active IgAV patients who did not develop renal involvement (group H), and patients who developed IgAVN at follow up (group N). Peak picking, grouping, and comparison parts were performed via XCMS (https://xcmsonline.scripps.edu/) software.

RESULTS

At follow-up, IgAVN developed in 6 out of 45 IgAV patients. The median time of renal involvement development is 23 days (range 5-45 days). Of these, 3 had nephritic proteinuria, one had nephrotic proteinuria, and 2 had microscopic hematuria. There were no significant differences in gender, age, clinical manifestations, and laboratory findings between the six patients who developed renal involvement and those who did not. In multivariate analysis, there was no significant association between any of the defined demographic and clinical characteristics (male sex, gastrointestinal system involvement, joint involvement, CRP, WBC, PLT) and the occurrence of renal involvement. Totally 2618 peaks were detected for group H, N, and C. Among them, 355 peaks were found to be statistically significant and reliable (p<0.05), and 155 of these peaks were found to be changed (fold change >1.5) between the groups C and H, and 66 peaks were found to be changed (fold change >1.5) between the groups H and N. The number of the peaks on the intersection of the peaks found to be different between the groups (C and H) and (H and N) was 39. Based on putative identification results, 15 putatively identified metabolites matched with 11 peaks were presented as biomarker candidates after careful evaluation with a clinical perspective.

CONCLUSION

We suggest that DHAP (18:0), prostaglandin D2/I2, porphobilinogen, 5-methyltetrahydrofolic acid, and N-Acetyl-4-O-acetylneuraminic acid/N-Acetyl-7-O-acetylneuraminic acid may serve as biomarkers for predicting kidney disease. Future studies with larger groups of IgAV patients are needed to validate the identified metabolic profile.

Add-on therapy with montelukast in the treatment of Henoch-Schönlein purpura

BACKGROUND

Previous studies suggested that leukotrienes (LT) were involved in the pathogenesis of Henoch-Schönlein purpura (HSP). This study investigated the efficacy of an add-on therapy with montelukast in the treatment of HSP.

METHODS

In this four-center, double-blind, placebo-controlled, parallel paired comparative study, 130 children with HSP were divided into two large groups: 84 patients without nephritis and 46 patients with nephritis. For each pair of patients with the same severity of disease, one subject was randomly allocated to one subgroup and the other allocated to the other subbroup; one subgroup received routine treatment plus placebo treatment, while the other subgroup received routine treatment plus montelukast treatment for 3 months. The efficacy was determined using Severity Scale Score (SSS). Blood eosinophil count, eosinophil cationic protein (ECP), IgE, interleukin (IL)-4, IL-5, IL-6, IL-8, IL-17, LTB4 , and urinary LTE4 were measured.

RESULTS

Add-on therapy with montelukast alleviated the symptoms of HSP including purpura, abdominal pain, stool occult blood, arthritis, proteinuria and hematuria, and, accordingly, shortened the length of hospital stay, and lowered blood eosinophil count, ECP, IgE, IL-4, IL-5, IL-6, IL-8, IL-17, LTB4 , and urinary LTE4 production, and also lowered the HSP relapse rate during the 3 months of treatment, but did not alter the outcome of nephritis at the end of follow up.

CONCLUSIONS

Add-on therapy with montelukast alleviated the symptoms of HSP. HSP may be improved by add-on therapy with a leukotriene receptor antagonist.

Role of free oxygen radicals and prostanoids in the pathogenesis of Henoch-Schönlein Purpura

The pathogenesis of Henoch-Schonlein Purpura (HSP) is still controversial. The aim of our study was to investigate the role of oxidative stress and cyclooxygenase (CO) pathway products in the pathogenesis of HSP. In order to investigate this, malondialdehyde (MDA) levels, indicating lipid peroxidation, prostaglandin E (PGE)-like activity as inflammatory mediator and vitamin E (vit-E) levels indicating anti-oxidant status were studied in a group of 10 children with HSP (five girls and five boys, aged 6-21 years, mean 10.7 years), both in the acute and recovery phase of the disease and in five age and sex-matched healthy children as a control group. The patients were also grouped into low and high clinical score groups. Plasma levels of MDA and PGE-like activity were significantly elevated in the active phase of HSP compared to the recovery phase. Vit-E levels were significantly reduced in the active phase compared to the recovery phase. The plasma levels of PGE-like activity of the patients obtained in the active phase were significantly higher than the levels of the control group, whereas the levels of the recovery phase were significantly lower than in the control group. No such difference between the controls and MDA and vit-E levels in the patient group was shown. No correlation between the clinical scores and the parameters studied could be found. Our findings indicate that oxidant stress and CO pathway products may play a role in the pathogenesis of HSP.