Role of genetic variations of chitinase 3-like 1 in bronchial asthmatic patients

LncRNA-AK007111 affects airway inflammation in asthma via the regulation of mast cell function

Long noncoding RNAs (lncRNAs) are involved in gene transcription and pathophysiological processes of human diseases. Multiple lncRNAs have been shown to play important roles in the occurrence and development of asthma. This study aimed to explore the role of a novel lncRNA, lncRNA-AK007111, in asthma. Overexpression of lncRNA-AK007111 was induced in a mouse model of asthma via viral transfection, followed by the collection of alveolar lavage fluid and lung tissue for the detection of relevant inflammatory factors and pathological analysis of lung sections. Pulmonary resistance and respiratory dynamic compliance were measured using an animal pulmonary function analyzer. The number of mast cells sensitized by immunofluorescence was detected at the cellular level. The degree of degranulation of lncRNA-AK007111 after its knockdown was determined by detecting the level of β-hexosaminidase that was released and quantifying IL-6 and TNF-α using ELISA in a model of RBL-2H3 cells activated by immunoglobulin E plus antigen. Finally, we observed the migration ability of mast cells under a microscope. The results showed that in ovalbumin-sensitized mice, the upregulation of lncRNA-AK007111 promoted the infiltration of inflammatory cells in lung tissue, increased the number of total cells, eosinophils, and mast cells, upregulated IL-5 and IL-6 levels, and increased airway hyper-reactivity. Downregulation of lncRNA-AK007111 decreased the degranulation ability of IgE/Ag-activated mast cells and inhibited the expression of IL-6 and TNF-α; moreover, the migration ability of mast cells was significantly weakened. In conclusion, our study revealed that lncRNA-AK007111 plays an important role in asthma by modulating mast cell-related functions.

Chitinases and chitinase-like proteins in asthma

Despite the lack of endogenous chitin synthesis, mammalian genomes encode two enzymatically active true chitinases (chitotriosidase and acidic mammalian chitinase) and a variable number of chitinase-like proteins (CLPs) that have no enzyme activity but bind chitin. Chitinases and CLPs are prominent components of type-2 immune response-mediated respiratory diseases. However, despite extensive research into their role in allergic airway disease, there is still no agreement on whether they are mere biomarkers of disease or actual disease drivers. Functions ascribed to chitinases and CLPs include, but are not limited to host defense against chitin-containing pathogens, directly promoting inflammation, and modulating tissue remodeling and fibrosis. Here, we discuss in detail the chitin-dependent and -independent roles of chitinases and CLPs in the context of allergic airway disease, and recent advances and emerging concepts in the field that might identify opportunities for new therapies.

Chi3L1 is a therapeutic target in bone metabolism and a potential clinical marker in patients with osteoporosis

BMP2 is clinically used as an ectopic bone inducer and plays a significant role in bone development, formation, and diseases. Chitinase 3-like 1 protein (Chi3L1) is found in the skeletal system. However, Chi3L1-mediated bone metabolism and aging-related bone erosion via BMP2 signaling have not yet been demonstrated. Herein, Chi3L1 increased BMP2-induced osteoblast differentiation in mesenchymal precursor cells and human primary osteoblasts. Chi3L1^KO(-/-) showed abnormal bone development, and primary osteoblasts isolated from Chi3L1^KO(-/-) exhibited impaired osteoblast differentiation and maturation. Chi3L1 also potentiated BMP2 signaling and RUNX2 expression in primary osteoblasts. Chi3L1 interacted with BMPRIa, which increased the surface expression of BMPRIa and promoted BMP2 signaling to induce osteoblast differentiation. Chi3L1^KO(-/-) mice showed bone formation reduced with a decrease in RUNX2 expression in calvarial defects. Chi3L1^KO(-/-) mice exhibited aging-related osteoporotic bone loss with decreases in the levels of RUNX2 and OPG, while serum PYD level and osteoclast number increased. Chi3L1 increased OPG via non-canonical BMP2 signaling in osteoblasts, which suppressed osteoclastogenesis in BMMs. Furthermore, ROC analysis showed that serum Chi3L1 level clinically decreased in osteoporosis patients. Our findings demonstrate that Chi3L1 promotes bone formation, suppresses osteoclastogenesis, and prevents aging-related osteoporosis.

Systemic Immune Modulation in Gliomas: Prognostic Value of Plasma IL-6, YKL-40, and Genetic Variation in YKL-40

Background: Complex local and systemic immune dysfunction in glioblastoma (GBM) may affect survival. Interleukin (IL)-6 and YKL-40 are pleiotropic biomarkers present in the tumor microenvironment and involved in immune regulation. We therefore analyzed plasma IL-6, YKL-40, and genetic variation in YKL-40 and explored their ability to distinguish between glioma subtypes and predict survival in GBM. Methods: One hundred fifty-eight patients with glioma WHO grade II-IV were included in the study. Plasma collected at surgery was analyzed for IL-6 and YKL-40 (CHI3L1) by ELISA. CHI3L1 rs4950928 genotyping was analyzed on whole-blood DNA. Results: Neither plasma IL-6 nor YKL-40 corrected for age or rs4950928 genotype could differentiate GBM from lower grade gliomas. GC and GG rs4950928 genotype were associated with lower plasma YKL-40 levels (CC vs. GC, p = 0.0019; CC vs. GG, p = 0.01). Only 10 and 14 out of 94 patients with newly diagnosed GBM had elevated IL-6 or YKL-40, respectively. Most patients received corticosteroid treatment at time of blood-sampling. Higher pretreatment plasma IL-6 was associated with short overall survival (OS) [HR = 1.19 (per 2-fold change), p = 0.042] in univariate analysis. The effect disappeared in multivariate analysis. rs4950928 genotype did not associate with OS [HR = 1.30, p = 0.30]. In recurrent GBM, higher YKL-40 [HR = 2.12 (per 2-fold change), p = 0.0005] but not IL-6 [HR = 0.99 (per 2-fold change), p = 0.92] were associated with short OS in univariate analysis. Conclusion: In recurrent GBM high plasma YKL-40 may hold promise as a prognostic marker. In newly diagnosed GBM perioperative plasma IL-6, YKL-40, and genetic variation in YKL-40 did not associate with survival. Corticosteroid use may complicate interpretation of results.

Chitinase 3 like 1 suppresses the stability and activity of p53 to promote lung tumorigenesis

Background

Chitinase 3 like 1 protein (Chi3L1) is expressed in several cancers, and a few evidences suggest that the secreted Chi3L1 contributes to tumor development. However, the molecular mechanisms of intracellular Chi3L1 are unknown in the lung tumor development. Methods: In the present study, we generated Chi3L1 knockout mice (Chi3L1^KO(−/−)) using CRISPR/Cas9 system to investigate the role of Chi3L1 on lung tumorigenesis.

Results

We established lung metastasis induced by i.v. injections of B16F10 in Chi3L1^KO(−/−). The lung tumor nodules were significantly reduced in Chi3L1^KO(−/−) and protein levels of p53, p21, BAX, and cleaved-caspase 3 were significantly increased in Chi3L1^KO(−/−), while protein levels of cyclin E1, CDK2, and phsphorylation of STAT3 were decreased in Chi3L1^KO(−/−). Allograft mice inoculated with B16F10 also suppressed tumor growth and increased p53 and its target proteins including p21 and BAX. In addition, knockdown of Chi3L1 in lung cancer cells inhibited lung cancer cell growth and upregulated p53 expression with p21 and BAX, and a decrease in phosphorylation of STAT3. Furthermore, we found that intracellular Chi3L1 physically interacted and colocalized with p53 to inhibit its protein stability and transcriptional activity for target genes related with cell cycle arrest and apoptosis. In lung tumor patient, we clinically found that Chi3L1 expression was upregulated with a decrease in p53 expression, as well as we validated that intracellular Chi3L1 was colocalized, reversely expressed, and physically interacted with p53, which results in suppression of the expression and function of p53 in lung tumor patient.

Conclusions

Our studies suggest that intracellular Chi3L1 plays a critical role in the lung tumorigenesis by regulating its novel target protein, p53 in both an in vitro and in vivo system.

Genes and Pathways Regulating Decline in Lung Function and Airway Remodeling in Asthma

Asthma is a common disorder of the airways characterized by airway inflammation and by decline in lung function and airway remodeling in a subset of asthmatics. Airway remodeling is characterized by structural changes which include airway smooth muscle hypertrophy/hyperplasia, subepithelial fibrosis due to thickening of the reticular basement membrane, mucus metaplasia of the epithelium, and angiogenesis. Epidemiologic studies suggest that both genetic and environmental factors may contribute to decline in lung function and airway remodeling in a subset of asthmatics. Environmental factors include respiratory viral infection-triggered asthma exacerbations, and tobacco smoke. There is also evidence that several asthma candidate genes may contribute to decline in lung function, including ADAM33, PLAUR, VEGF, IL13, CHI3L1, TSLP, GSDMB, TGFB1, POSTN, ESR1 and ARG2. In addition, mediators or cytokines, including cysteinyl leukotrienes, matrix metallopeptidase-9, interleukin-33 and eosinophil expression of transforming growth factor-β, may contribute to airway remodeling in asthma. Although increased airway smooth muscle is associated with reduced lung function (i.e. forced expiratory volume in 1 second) in asthma, there have been few long-term studies to determine how individual pathologic features of airway remodeling contribute to decline in lung function in asthma. Clinical studies with inhibitors of individual gene products, cytokines or mediators are needed in asthmatic patients to identify their individual role in decline in lung function and/or airway remodeling.