Glutamine deficiency shifts the asthmatic state toward neutrophilic airway inflammation

Chronic PM2.5 Exposure Disrupts Intestinal Barrier Integrity via Microbial Dysbiosis-Triggered TLR2/5-MyD88-NLRP3 Inflammasome Activation

BACKGROUND

PM2.5, a known public health risk, is increasingly linked to intestinal disorders, however, the mechanisms of its impact are not fully understood.

PURPOSE

This study aimed to explore the impact of chronic PM2.5 exposure on intestinal barrier integrity and to uncover the underlying molecular mechanisms.

METHODS

C57BL/6J mice were exposure to either concentrated ambient PM2.5 (CPM) or filtered air (FA) for six months to simulate urban pollution conditions. We evaluated intestinal barrier damage, microbial shifts, and metabolic changes using histopathology, metagenomics, and metabolomics. Analysis of the TLR signaling pathway was also conducted.

RESULTS

The mean concentration of PM2.5 in the CPM exposure chamber was consistently measured at 70.9 ± 26.8 μg/m³ throughout the study period. Our findings show that chronic CPM exposure significantly compromises intestinal barrier integrity, as indicated by reduced expression of the key tight junction proteins Occludin and Tjp1/Zo-1. Metagenomic sequencing revealed significant shifts in the microbial landscape, identifying 35 differentially abundant species. Notably, there was an increase in pro-inflammatory nongastric Helicobacter species and a decrease in beneficial bacteria, such as Lactobacillus intestinalis, Lactobacillus sp. ASF360, and Eubacterium rectale. Metabolomic analysis further identified 26 significantly altered metabolites commonly associated with intestinal diseases. A strong correlation between altered bacterial species and metabolites was also observed. For example, 4 Helicobacter species all showed positive correlations with 13 metabolites, including Lactate, Bile acids, Pyruvate and Glutamate. Additionally, increased expression levels of TLR2, TLR5, Myd88, and NLRP3 proteins were noted, and their expression patterns showed a strong correlation, suggesting a possible involvement of the TLR2/5-MyD88-NLRP3 signaling pathway.

CONCLUSIONS

Chronic CPM exposure induces intestinal barrier dysfunction, microbial dysbiosis, metabolic imbalance, and activation of the TLR2/5-MyD88-NLRP3 inflammasome. These findings highlight the urgent need for intervention strategies to mitigate the detrimental effects of air pollution on intestinal health and identify potential therapeutic targets.

Interleukin-13 Treatment of Living Lung Tissue Model Alters the Metabolome and Proteome-A Nano-DESI MS Metabolomics and Shotgun Proteomics Study

Asthma is a chronic respiratory disease with one of the largest numbers of cases in the world; thus, constant investigation and technical development are needed to unravel the underlying biochemical mechanisms. In this study, we aimed to develop a nano-DESI MS method for the in vivo characterization of the cellular metabolome. Using air-liquid interface (ALI) cell layers, we studied the role of Interleukin-13 (IL-13) on differentiated lung epithelial cells acting as a lung tissue model. We demonstrate the feasibility of nano-DESI MS for the in vivo monitoring of basal-apical molecular transport, and the subsequent endogenous metabolic response, for the first time. Conserving the integrity of the ALI lung-cell layer enabled us to perform temporally resolved metabolomic characterization followed by "bottom-up" proteomics on the same population of cells. Metabolic remodeling was observed upon histamine and corticosteroid treatment of the IL-13-exposed lung cell monolayers, in correlation with alterations in the proteomic profile. This proof of principle study demonstrates the utility of in vivo nano-DESI MS for characterizing ALI tissue layers, and the new markers identified in our study provide a good starting point for future, larger-scale studies.

Pathological and pharmacological functions of the metabolites of polyunsaturated fatty acids mediated by cyclooxygenases, lipoxygenases, and cytochrome P450s in cancers

Oxylipins have garnered increasing attention because they were consistently shown to play pathological and/or pharmacological roles in the development of multiple cancers. Oxylipins are the metabolites of polyunsaturated fatty acids via both enzymatic and nonenzymatic pathways. The enzymes mediating the metabolism of PUFAs include but not limited to lipoxygenases (LOXs), cyclooxygenases (COXs), and cytochrome P450s (CYPs) pathways, as well as the down-stream enzymes. Here, we systematically summarized the pleiotropic effects of oxylipins in different cancers through pathological and pharmacological aspects, with specific reference to the enzyme-mediated oxylipins. We discussed the specific roles of oxylipins on cancer onset, growth, invasion, and metastasis, as well as the expression changes in the associated metabolic enzymes and the associated underlying mechanisms. In addition, we also discussed the clinical application and potential of oxylipins and related metabolic enzymes as the targets for cancer prevention and treatment. We found the specific function of most oxylipins in cancers, especially the underlying mechanisms and clinic applications, deserves and needs further investigation. We believe that research on oxylipins will provide not only more therapeutic targets for various cancers but also dietary guidance for both cancer patients and healthy humans.

Targeting reprogrammed metabolism as a therapeutic approach for respiratory diseases

Metabolic reprogramming underlies the etiology and pathophysiology of respiratory diseases such as asthma, idiopathic pulmonary fibrosis (IPF), and chronic obstructive pulmonary disease (COPD). The dysregulated cellular activities driving airway inflammation and remodelling in these diseases have reportedly been linked to aberrant shifts in energy-producing metabolic pathways: glycolysis and oxidative phosphorylation (OXPHOS). The rewiring of glycolysis and OXPHOS accompanying the therapeutic effects of many clinical compounds and natural products in asthma, IPF, and COPD, supports targeting metabolism as a therapeutic approach for respiratory diseases. Correspondingly, inhibiting glycolysis has largely attested effective against experimental asthma, IPF, and COPD. However, modulating OXPHOS and its supporting catabolic pathways like mitochondrial pyruvate catabolism, fatty acid β-oxidation (FAO), and glutaminolysis for these respiratory diseases remain inconclusive. An emerging repertoire of metabolic enzymes are also interconnected to these canonical metabolic pathways that similarly possess therapeutic potential for respiratory diseases. Taken together, this review highlights the urgent demand for future studies to ascertain the role of OXPHOS in different respiratory diseases, under different stimulatory conditions, and in different cell types. While this review provides strong experimental evidence in support of the inhibition of glycolysis for asthma, IPF, and COPD, further verification by clinical trials is definitely required.

Down-regulation of MKP-1 in hippocampus protects against stress-induced depression-like behaviors and neuroinflammation

Chronic stress is the primary environmental risk factor for major depressive disorder (MDD), and there is compelling evidence that neuroinflammation is the major pathomechanism linking chronic stress to MDD. Mitogen-activated protein kinase (MAPK) phosphatase-1 (MKP-1) is a negative regulator of MAPK signaling pathways involved in cellular stress responses, survival, and neuroinflammation. We examined the possible contributions of MKP-1 to stress-induced MDD by comparing depression-like behaviors (anhedonia, motor retardation, behavioral despair), neuroinflammatory marker expression, and MAPK signaling pathways among rats exposed to chronic unpredictable mild stress (CUMS), overexpressing MKP-1 in the hippocampus, and CUMS-exposed rats underexpressing MKP-1 in the hippocampus. Rats exposed to CUMS exhibited MKP-1 overexpression, greater numbers of activated microglia, and enhanced expressions of neuroinflammatory markers (interleukin [IL]-6, [IL]-1β, tumor necrosis factor [TNF]-ɑ, and decreased phosphorylation levels of ERK and p38 in the hippocampus as well as anhedonia in the sucrose preference test, motor retardation in the open field, and greater immobility (despair) in the forced swimming tests. These signs of neuroinflammation and depression-like behaviors and phosphorylation levels of ERK and p38 were also observed in rats overexpressing MKP-1 without CUMS exposure, while CUMS-induced neuroinflammation, microglial activation, phosphorylation levels of ERK and p38, and depression-like behaviors were significantly reversed by MKP-1 knockdown. Moreover, MKP-1 knockdown promoted the activation of the MAPK isoform ERK, implying that the antidepressant-like effects of MKP-1 knockdown may be mediated by the ERK pathway disinhibition. These findings suggested that hippocampal MKP-1 is an essential regulator of stress-induced neuroinflammation and a promising target for antidepressant development.

Glutaminolysis and peripheral CD4+ T cell differentiation: from mechanism to intervention strategy

To maintain the body's regular immune system, CD4+ T cell homeostasis is crucial, particularly T helper (Th1, Th17) cells and T regulatory (Treg) cells. Abnormally differentiated peripheral CD4+ T cells are responsible for the occurrence and development of numerous diseases, including autoimmune diseases, transplantation rejection, and irritability. Searching for an effective interventional approach to control this abnormal differentiation is therefore especially important. As immunometabolism progressed, the inherent metabolic factors underlying the immune cell differentiation have gradually come to light. Mounting number of studies have revealed that glutaminolysis plays an indelible role in the differentiation of CD4+ T cells. Besides, alterations in the glutaminolysis can also lead to changes in the fate of peripheral CD4+ T cells. All of this indicate that the glutaminolysis pathway has excellent potential for interventional regulation of CD4+ T cells differentiation. Here, we summarized the process by which glutaminolysis regulates the fate of CD4+ T cells during differentiation and further investigated how to reshape abnormal CD4+ T cell differentiation by targeting glutaminolysis.

Glutamine ameliorates hyperoxia-induced hippocampal damage by attenuating inflammation and apoptosis via the MKP-1/MAPK signaling pathway in neonatal rats

Glutamine (Gln) is an immunomodulatory protein that mediates oxidative stress, inflammation, and apoptosis, but has not been reported in the treatment of hyperoxia (Hyp)-induced brain injury. The aim of this study was to determine whether Gln could improve hyp-induced brain injury in neonatal rats to and later learning and memory dysfunction, and to explore its possible mechanisms. We prepared a model of neonatal rat brain injury caused by normobaric hyperoxia while administered with Gln for 7 days for evaluation. Learning memory function was assessed with the Morris water maze test. Histological analysis, protein expression analysis, oxidative stress and inflammation level analysis were performed using hippocampal tissue. Gln treatment significantly reduced brain tissue water content, oxidative stress levels, microglia activation and inflammatory factor expression, and attenuated tissue damage and apoptosis in the hippocampal region. Gln ameliorates hyp-induced learning, memory impairment in neonatal rats in water maze test. It also increased MKP-1 protein expression and decreased p-p38, p-ERK and p-JNK. Therefore, it is hypothesized that Gln may exert neuroprotective effects by increasing MKP-1 expression to negatively regulate MAPK signaling, with potential cognitive improvement in hyp-induced brain injury.

Immune Metabolism in TH2 Responses: New Opportunities to Improve Allergy Treatment - Cell Type-Specific Findings (Part 2)

PURPOSE OF REVIEW

Over the last years, we have learned that the metabolic phenotype of immune cells is closely connected to the cell's effector function. Understanding these changes will allow us to better understand allergic disease pathology and improve allergy treatment by modulating immune metabolic pathways. As part two of a two-article series, this review reports on the recent studies investigating the metabolism of the cell types involved in allergies and discusses the initial application of these discoveries in allergy treatment.

RECENT FINDINGS

The cell types involved in allergic reactions display pronounced and highly specific metabolic changes (here discussed for epithelial cells, APCs, ILC2s, mast cells, eosinophils, and Th2 cells). Currently, the first drugs targeting metabolic pathways are tested for their potential to improve allergy treatment. Immune-metabolic changes observed in allergy so far are complex and depend on the investigated disease and cell type. However, our increased understanding of the underlying principles has pointed to several promising target molecules that are now being investigated to improve allergy treatment.

Guominkang formula alleviate inflammation in eosinophilic asthma by regulating immune balance of Th1/2 and Treg/Th17 cells

The number of patients with allergic asthma is rising yearly, and hormonal drugs, such as dexamethasone, have unique advantages and certain limitations. In the treatment of allergic diseases especially allergic asthma, increasing the percentage or the function of immunosuppressive cells, such as Treg cells, may achieve a good effect. On the basis of good clinical results, we found that Guominkang (GMK) especially high-concentration GMK can achieve a similar effect with dexamethasone in controlling the symptoms of allergic asthma and inhibiting inflammation of allergic asthma. In our study, GMK can inhibit the recruitment of inflammatory cells, decrease mucus production, and reduce airway resistance. Besides, GMK can reconstruct the cellular immune balance of Th1/2 and Treg/Th17 cells. Metabolome results show that DL-glutamine, L-pyroglutamic acid, prostaglandin b1, prostaglandin e2, and 3,4-dihydroxyhydrocinnamic acid are the metabolic biomarkers and are associated with Th1/2 and Treg/Th17 cell balance. GMK can also change the gut microbiota in the allergic asthma mouse model. The genus_Muriculum, genus_(Clostridium) GCA900066575, genus_klebsiella, genus_Desulfovibrio, genus_Rikenellaceae RC9 gut group, family_Chitinophagaceae, family_Nocardioidaceae, and genus_Corynebacterium are gut microbiota biomarkers treated by GMK. Among these biomarkers, genus_Muriculum is the gut microbiota biomarker associated with Th1/2 and Treg/Th17 cell balance. Interestingly, we first found that DL-glutamine, L-pyroglutamic acid, prostaglandin b1, prostaglandin e2, and 3,4-dihydroxyhydrocinnamic acid are all associated with genus_Muriculum. GMK will be a new strategy for the treatment of eosinophilic asthma, and biomarkers will also be a new research direction.