Chronic features of allergic asthma are enhanced in the absence of resistin-like molecule-beta

Resistin-like molecules: a marker, mediator and therapeutic target for multiple diseases

Resistin-like molecules (RELMs) are highly cysteine-rich proteins, including RELMα, RELMβ, Resistin, and RELMγ. However, RELMs exhibit significant differences in structure, distribution, and function. The expression of RELMs is regulated by various signaling molecules, such as IL-4, IL-13, and their receptors. In addition, RELMs can mediate numerous signaling pathways, including HMGB1/RAGE, IL-4/IL-4Rα, PI3K/Akt/mTOR signaling pathways, and so on. RELMs proteins are involved in wide range of physiological and pathological processes, including inflammatory response, cell proliferation, glucose metabolism, barrier defense, etc., and participate in the progression of numerous diseases such as lung diseases, intestinal diseases, cardiovascular diseases, and cancers. Meanwhile, RELMs can serve as biomarkers, risk predictors, and therapeutic targets for these diseases. An in-depth understanding of the role of RELMs may provide novel targets or strategies for the treatment and prevention of related diseases. Video abstract.

Effects of human adipose tissue- and bone marrow-derived mesenchymal stem cells on airway inflammation and remodeling in a murine model of chronic asthma

It is challenging to overcome difficult-to-treat asthma, and cell-based therapies are attracting increasing interest. We assessed the effects of mesenchymal stem cell (MSC) treatments using a murine model of chronic ovalbumin (OVA)-challenged asthma. We developed a murine model of chronic allergic asthma using OVA sensitization and challenge. Human adipose-derived MSCs (hADSCs) or human bone marrow-derived MSCs (hBMSCs) were administered. We measured the levels of resistin-like molecule-β (RELM-β). We also measured RELM-β in asthma patients and normal controls. OVA-challenged mice exhibited increased airway hyper-responsiveness, inflammation, and remodeling. hBMSC treatment remarkably decreased airway hyper-responsiveness but hADSC treatment did not. Both MSCs alleviated airway inflammation, but hBMSCs tended to have a more significant effect. hBMSC treatment reduced Th2-cytokine levels but hADSC treatment did not. Both treatments reduced airway remodeling. The RELM-β level decreased in the OVA-challenged control group, but increased in both treatment groups. We found that the serum level of RELM-β was lower in asthma patients than controls. MSC treatments alleviated the airway inflammation, hyper-responsiveness, and remodeling associated with chronic asthma. hBMSCs were more effective than hADSCs. The RELM-β levels increased in both treatment groups; the RELM-β level may serve as a biomarker of MSC treatment efficacy.

Blood Levels of Indicators of Lower Respiratory Tract Damage in Chronic Bronchitis in Patients with Abdominal Obesity

Objective: to study biomolecules associated with pathology in the respiratory system, in particular, with the development of chronic bronchitis in patients with abdominal obesity. Materials and methods: This is a pilot study. The main group consisted of 158 people with chronic bronchitis, divided into two subgroups: one with abdominal obesity, and the other without it. The control group consisted of 68 people without chronic bronchitis. We determined the blood levels of SP-A, SP-D, α1-antitrypsin, CC16, PARC, and RELM-β. Results: In the first subgroup, patients significantly more often complained of coughing, experienced shortness of breath 1.5 times more often with light physical exertion and 2.7 times more often with moderate physical exertion. In these patients, a Tiffeneau–Pinelli index (FEV1/FVC) below 70% was 1.8 times more common, more patients had FEV1 and FVC of less than 80%, and presented a statistically significant decrease in SP-A, α1-antitrypsin, CC16 levels and an increase in PARC levels than in the second subgroup. Conclusion: In patients with chronic bronchitis and abdominal obesity, there is a decrease in the levels of SP-A, α1-antitrypsin, CC16 and an increase in the level of PARC compared with patients without abdominal obesity, which is probably due to the presence of an additional source of chronic inflammation associated with adipose tissue.

Regulatory Peptides in Asthma

Numerous regulatory peptides play a critical role in the pathogenesis of airway inflammation, airflow obstruction and hyperresponsiveness, which are hallmarks of asthma. Some of them exacerbate asthma symptoms, such as neuropeptide Y and tachykinins, while others have ameliorating properties, such as nociception, neurotensin or β-defensin 2. Interacting with peptide receptors located in the lungs or on immune cells opens up new therapeutic possibilities for the treatment of asthma, especially when it is resistant to available therapies. This article provides a concise review of the most important and current findings regarding the involvement of regulatory peptides in asthma pathology.

FIZZ2 as a Biomarker for Acute Exacerbation of Chronic Obstructive Pulmonary Disease

PURPOSE

Found in inflammatory zone 2 (FIZZ2) is associated with lung inflammation. The aim of the study was to investigate the expression and utility of FIZZ2 as a marker for chronic obstructive pulmonary disease (COPD).

METHODS

Immunohistochemistry was used to detect the expression of FIZZ2 in COPD. The serum concentration of FIZZ2 was measured by enzyme-linked immunosorbent assay and the episodes of acute exacerbations of COPD (AECOPD) in the following year were recorded.

RESULTS

FIZZ2 expression was elevated in bronchial epithelial cells (0.217 ± 0.021 vs 0.099 ± 0.010, p < 0.0001) and negatively correlated with the pulmonary function (FEV1/FVC%) (p = 0.0149) and positively correlated with the smoking index (p = 0.0241). Serum level of FIZZ2 in COPD were significantly higher than that in healthy controls (561.6 ± 70.71 vs 52.24 ± 20.52 pg/ml, p < 0.0001) and increased with the COPD severity. Serum levels of FIZZ2 negatively correlated with the pulmonary function [Forced Vital Capacity (FVC), Forced Expiratory Volume (FEV1), FEV1%, FEV1/FVC) (r =  - 0.3086, - 0.3529, - 0.3343, and - 0.2676, respectively, p = 0.0003, p < 0.0001, p < 0.0001, p = 0.0014). The expression of human serum FIZZ2 was positively correlated with the smoking index (r = 0.2749, p = 0.0015). There was a positive correlation between the FIZZ2 concentration and the frequency of AECOPD episodes in the following year (r = 0.7291, p < 0.0001).

CONCLUSION

FIZZ2 expression was elevated in patients with COPD and its serum concentration might be a potential biomarker for AECOPD.

Initiation and Pathogenesis of Severe Asthma with Fungal Sensitization

Fungi represent one of the most diverse and abundant eukaryotes on earth, and their ubiquity and small proteolytically active products make them pervasive allergens that affect humans and other mammals. The immunologic parameters surrounding fungal allergies are still not fully elucidated despite their importance given that a large proportion of severe asthmatics are sensitized to fungal allergens. Herein, we explore fungal allergic asthma with emphasis on mouse models that recapitulate the characteristics of human disease, and the main leukocyte players in the pathogenesis of fungal allergies. The endogenous mycobiome may also contribute to fungal asthma, a phenomenon that we discuss only superficially, as much remains to be discovered.

The Role of Hypoxia-Induced Mitogenic Factor in Organ-Specific Inflammation in the Lung and Liver: Key Concepts and Gaps in Knowledge Regarding Molecular Mechanisms of Acute or Immune-Mediated Liver Injury

Hypoxia-induced mitogenic factor (HIMF), which is also known as resistin-like molecule α (RELM-α), found in inflammatory zone 1 (FIZZ1), or resistin-like alpha (retlna), is a cysteine-rich secretory protein and cytokine. HIMF has been investigated in the lung as a mediator of pulmonary fibrosis, inflammation and as a marker for alternatively activated macrophages. Although these macrophages have been found to have a role in acute liver injury and acetaminophen toxicity, few studies have investigated the role of HIMF in acute or immune-mediated liver injury. The aim of this focused review is to analyze the literature and examine the effects of HIMF and its human homolog in organ-specific inflammation in the lung and liver. We followed the guidelines set by PRISMA in constructing this review. The relevant checklist items from PRISMA were included. Items related to meta-analysis were excluded because there were no randomized controlled clinical trials. We found that HIMF was increased in most models of acute liver injury and reduced damage from acetaminophen-induced liver injury. We also found strong evidence for HIMF as a marker for alternatively activated macrophages. Our overall risk of bias assessment of all studies included revealed that 80% of manuscripts demonstrated some concerns in the randomization process. We also demonstrated some concerns (54.1%) and high risk (45.9%) of bias in the selection of the reported results. The need for randomization and reduction of bias in the reported results was similarly detected in the studies that focused on HIMF and the liver. In conclusion, we propose that HIMF could be utilized as a marker for M2 macrophages in immune-mediated liver injury. However, we also detected the need for randomized clinical trials and additional experimental and human prospective studies in order to fully comprehend the role of HIMF in acute or immune-mediated liver injury.

Predictive and Prognostic Utility of the Serum Level of Resistin-Like Molecule Beta for Risk Stratification in Patients with Community-Acquired Pneumonia

Despite progress in intensive care, the morbidity and mortality of patients with community-acquired pneumonia (CAP) remains high. Furthermore, the predictive and prognostic utility of resistin-like molecule beta (RELM-β) in patients with CAP is uncertain. This study investigated the role of RELM-β in patients with CAP and evaluated its correlation with disease severity and the risk of death. A prospective, multicenter study was conducted in 2017, and admission serum levels of RELM-β were detected using quantitative enzyme-linked immunosorbent assay. A total of 114 and 112 patients with severe CAP (SCAP) and non-severe CAP (NSCAP) were enrolled, respectively, with 15 healthy controls. Patients with SCAP, especially non-survivors, had significantly higher levels of serum RELM-β than patients with NSCAP. RELM-β levels positively correlated with severity scores and consistently predicted SCAP in patients with CAP (area under the curve = 0.794). Increased levels of RELM-β were closely related to the severity and prognosis of patients with CAP. The accuracy of 30-day mortality predictions of CURB-65 (confusion, urea, respiratory rate, blood pressure, and age ≥ 65 years) can be significantly improved when combined with RELM-β levels. The level of RELM-β can assist clinicians in risk stratification of patients with CAP in early stages.

Inhibition of RELM-β prevents hypoxia-induced overproliferation of human pulmonary artery smooth muscle cells by reversing PLC-mediated KCNK3 decline

AIMS

Although resistin-like molecule β (RELM-β) is involved in the pathological processes of various lung diseases, such as pulmonary inflammation, asthma and fibrosis, its potential roles in hypoxic pulmonary arterial hypertension (PAH) remain largely unknown. The study aims to investigate whether RELM-β contributes to hypoxia-induced excessive proliferation of human pulmonary artery smooth muscle cells (PASMCs) and to explore the potential mechanisms of this process.

MAIN METHODS

Human PASMCs were exposed to normoxia or hypoxia (1% O₂) for 24 h. siRNA targeting RELM-β was transfected into cells. Protein levels of KCNK3, RELM-β, pSTAT3 and STAT3 were determined by immunoblotting. The translocation of NFATc2 and expression of KCNK3 were visualized by immunofluorescence. 5-ethynyl-2'-deoxyuridine assays and cell counting kit-8 assays were performed to assess the proliferation of PASMCs.

KEY FINDINGS

(1) Chronic hypoxia significantly decreased KCNK3 protein levels while upregulating RELM-β protein levels in human PASMCs, which was accompanied by excessive proliferation of cells. (2) RELM-β could promote human PASMCs proliferation and activate the STAT3/NFAT axis by downregulating KCNK3 protein under normoxia. (3) Inhibition of RELM-β expression effectively prevented KCNK3-mediated cell proliferation under hypoxia. (4) Phospholipase C (PLC) inhibitor U-73122 could not only prevent the hypoxia/RELM-β-induced decrease in KCNK3 protein, but also inhibit the enhanced cell viability caused by hypoxia/RELM-β. (5) Both hypoxia and RELM-β could downregulate membrane KCNK3 protein levels by enhancing endocytosis.

SIGNIFICANCE

RELM-β activation is responsible for hypoxia-induced excessive proliferation of human PASMCs. Interfering with RELM-β may alleviate the progression of hypoxic PAH by upregulating PLC-dependent KCNK3 expression.

Macrophage CD14 impacts immune defenses against influenza virus in allergic hosts

Asthma and influenza are leading causes of worldwide morbidity and mortality. Although these two conditions can co-exist in the same patient, the immune parameters that impact disease outcomes are not fully elucidated. The importance of macrophages to both conditions suggested a role for CD14, a co-receptor for endotoxin, as a regulatory mechanism for innate immune responses during asthma and influenza co-morbidity. Herein, we hypothesized that parameters of influenza morbidity will be reduced in the absence of CD14. Age and gender matched wild-type (WT) and CD14 knock-out (KO) mice were subjected to our validated model of Aspergillus-induced model of asthma and/or influenza. Characteristics of disease pathogenesis were investigated using standard methods in weight loss, flow cytometry, airway resistance, histology, quantitative real-time PCR, and viral titer quantification. The absence of CD14 did not have an impact on morbidity as these mice were equally susceptible to disease with similar airway resistance. Peribronchovascular inflammation and goblet cell content were equivalent between WT and KO mice in asthma alone and asthma and influenza co-morbidity. Co-morbid KO mice had less lymphocytes and eosinophils in the airways although their lung viral burden was equivalent to WT. Inflammatory gene signatures were altered in co-morbid mice in each genotype. CD14 expression on macrophages is necessary for airway inflammation but not for viral pathogenesis in allergic hosts.