Allergic asthma: RIPK2 takes the lead

Investigation of the shared gene signatures and molecular mechanisms between obstructive sleep apnea syndrome and asthma

BACKGROUND

Obstructive sleep apnea syndrome (OSAS) is highly related with asthma from the epidemiology to pathogenesis, while the underlying mechanism is still unclear. Herein, we aimed to reveal the shared gene signatures and molecular mechanisms underlying the coexistence of OSAS and asthma and verified relating pathway in mouse models. We downloaded GSE75097 of OSAS and GSE165934 of asthma from GEO database and performed differential expression analysis and functional enrichment analysis to screen differentially expressed genes (DEGs) and potential pathogenic pathway. PPI network was constructed with the STRING database. Hub genes were identified with cytoHubba and immune infiltration analysis was performed with cibersort for further verification. Potential drugs were screened with Comparative Toxicogenomics Database and miRNA-gene network was constructed. Besides, to test the pulmonary function and inflammatory cytokine, mouse models with OSAS and asthma were constructed, followed by validating the involvement of NOD1/NOD2-RIPK2-NF-κB-MCPIP-1 pathway in associated diseases.

RESULTS

In total, 104 DEGs were identified, in which PLAUR, RIPK2, PELI1, ZC3H12A, and TNFAIP8 are the hub genes, while NOD-like receptor signaling pathway and apoptosis signaling pathway were the potential influential pathways. Increased γδT cells and neutrophils were detected in asthma patients through immune infiltration analysis. Significant difference was detected among genders in OSAS, and acetaminophen is a potential drug in the comorbidity by screening the drugs in the Comparative Toxicogenomics Database. Mice with OSAS and asthma presented with worse pulmonary function and higher levels of inflammatory cytokines. The relative proteins, including NOD1, NOD2, RIPK2, NF-κB, and MCPIP-1, were up-regulated in mice with the OSAS and asthma.

CONCLUSIONS

This research firstly elucidates NOD1/NOD2-RIPK2-NF-κB-MCPIP-1 pathway as the shared pathway in the development of OSAS and asthma through bioinformatics and experimental methods. There is an interactive deterioration model between OSAS and asthma. This study may provide some potential biomarkers in the future research of the underlying pathogenesis and treatment of comorbidity of OSAS and asthma.

Analysis of alternative splicing in chicken macrophages transfected with overexpression/knockdown of RIP2 gene

Receptor-interacting protein 2 (RIP2) plays a critical role in the transduction of many signaling pathways and is associated with many diseases. Alternative splicing (AS) is an essential and ubiquitous regulatory mechanism of gene expression that contributes to distinct transcript variants and many different kinds of proteins. In this present study, we characterized genome-wide AS events in wild-type chicken macrophages (WT) and RIP2 overexpression/knockdown chicken macrophages (oeRIP2/shRIP2) by high-throughput RNA sequencing technology. A total of 1901, 2061, and 817 differentially expressed (DE) AS genes were identified in the comparison of oeRIP2 vs. WT, oeRIP2 vs. shRIP2, and shRIP2 vs. WT, respectively. These DE AS genes participated in many important KEGG pathways, including regulation of autophagy, Wnt signaling pathway, Ubiquitin mediated proteolysis, MAPK signaling pathway, and Focal adhesion, etc. In conclusion, this research provided a broad atlas of the genome-wide scale of the AS event landscape in RIP2 overexpression/knockdown and wild-type chicken macrophages. This research also provides the theoretical basis of the gene network related to RIP2.

Receptor Interacting Ser/Thr-Protein Kinase 2 as a New Therapeutic Target

Receptor interacting serine/threonine protein kinase 2 (RIPK2) is a downstream signaling molecule essential for the activation of several innate immune receptors, including the NOD-like receptors (NOD1 and NOD2). Recognition of pathogen-associated molecular pattern proteins by NOD1/2 leads to their interaction with RIPK2, which induces release of pro-inflammatory cytokines through the activation of NF-κB and MAPK pathways, among others. Thus, RIPK2 has emerged as a key mediator of intracellular signal transduction and represents a new potential therapeutic target for the treatment of various conditions, including inflammatory diseases and cancer. In this Perspective, first, an overview of the mechanisms that underlie RIPK2 function will be presented along with its role in several diseases. Then, the existing inhibitors that target RIPK2 and different therapeutic strategies will be reviewed, followed by a discussion on current challenges and outlook.

The ubiquitination of RIPK2 is mediated by Peli3 and negatively regulates the onset of infectious osteomyelitis

Osteomyelitis is the infection and destruction of bone. Until now, there is no universal protocol for its treatment. Receptor-interacting serine/threonine-protein kinase 2 (RIPK2) was implicated in the development of osteomyelitis. However, its detailed mechanism remains unknown. 6-8 weeks old wild-type or Pellino E3 Ubiquitin Protein Ligase Family Member 3 (Peli3) deficiency mice were injected with S. aureus to induce osteomyelitis. RAW264.7 cells or bone marrow-derived macrophages (BMDMs) isolated from mice, were treated with lipopolysaccharides (LPS). Knocking down Peli3 in RAW264.7 cells increased the expressions of inflammatory cytokines after the stimulation of LPS, including interleukin-1β, interleukin-6 and tumor necrosis factor-α. Inflammation was also activated in S. aureus-induced Peli3 deficiency mice. Moreover, Peli3 deficiency mice also displayed more severe symptoms of osteomyelitis in S. aureus-infected mice. Moreover, Peli3 targeted and degraded RIPK2 through K48-linked ubiquitination. Peli3 negatively modulates osteomyelitis by degrading RIPK2. Our data further expand current understanding of RIPK2 on osteomyelitis, which suggests that RIPK2 might serve as novel therapeutic target for treating osteomyelitis.

Role of Ezrin in Asthma-Related Airway Inflammation and Remodeling

Ezrin is an actin binding protein connecting the cell membrane and the cytoskeleton, which is crucial to maintaining cell morphology, intercellular adhesion, and cytoskeleton remodeling. Asthma involves dysfunction of inflammatory cells, cytokines, and airway structural cells. Recent studies have shown that ezrin, whose function is affected by extensive phosphorylation and protein interactions, is closely associated with asthma, may be a therapeutic target for asthma treatment. In this review, we summarize studies on ezrin and discuss its role in asthma-related airway inflammation and remodeling.

The RIPK family: expression profile and prognostic value in lung adenocarcinoma

Receptor interacting protein kinases (RIPKs) are a family of serine/threonine kinases which are supposed to regulate tumor generation and progression. Rare study illustrates the roles and functions of RIPKs family in lung adenocarcinoma (LUAD) comprehensively. Our results indicated that the expression of RIPK2 higher in LUAD patients while RIPK5 (encoded by gene DSTYK) expression was lower. Only RIPK2 had a strong correlation with pathological stage in LUAD patients. Kaplan-Meier plotter revealed that LUAD patients with low RIPK2 or RIPK3 level showed better overall survival (OS), but worse when LUAD patients with high RIPK5. Further, lower expression of RIPK2 and higher expression of RIPK1, RIPK4 and RIPK5 prompted a longer disease free survival (DFS). Genetic alterations based on cBioPortal revealing 16% alteration rates of RIPK2, as well as RIPK5. We also found that the functions of RIPKs family were linked to cellular senescence, protein serine/threonine kinase activity, apoptosis process et al. TIMER database indicated that the RIPKs family members had distinct relationships with the infiltration of six types of immune cells (macrophages, neutrophils, CD8+ T-cells, B-cells, CD4+ T-cells and dendritic cells). Moreover, RIPK2 could be observed as an independent prognostic factor with Cox proportional hazard model analysis. DiseaseMeth databases revealed that the global methylation levels of RIPK2 increased in LUAD patients. Thus, the findings above will enhance the understanding of RIPKs family in LUAD pathology and progression, providing novel insights into RIPKs-core therapy for LUAD patients.

A risk signature of three autophagy-related genes for predicting lower grade glioma survival is associated with tumor immune microenvironment

Treatment for lower-grade gliomas (LGG) has been challenging. Though emerging approaches such as immunotherapy is promising, it is still faced with immune tolerance, an obstacle that may be overcome by targeting autophagy-related (ATG) genes. After identifying three differentially expressed ATG genes (RIPK2, MUL1 and CXCR4), we constructed an ATG gene risk signature by Kaplan-Meier, univariate Cox regression, least absolute shrinkage and selection operator regression and multivariate Cox regression, followed by internal and external validation using K-M and ROC analysis. Since gene set enrichment analysis (GSEA) suggested that the signature was strongly associated with immune cell functions, CIBERSORT, LM22 matrix and Pearson correlation were further performed, showing that the risk signature was significantly correlated with immune cell infiltration and immune checkpoint genes. In conclusion, we identified and independently validated an ATG gene risk signature for LGG patients, as well as discovering its significant association with LGG immune microenvironment.

Repeated Herbal Acupoint Sticking Relieved the Recurrence of Allergic Asthma by Regulating the Th1/Th2 Cell Balance in the Peripheral Blood

Allergic asthma is an inflammatory disease involving the Th1/Th2 cell imbalance in the peripheral blood. Repeated herbal acupoint sticking (RHAS) has been used for hundreds of years in China to relieve the recurrence of allergic asthma, and it is still practiced today. Thus, we explored the effect on allergic asthma relapse and the underlying immunoregulatory mechanism in this study. Here, we enrolled 50 allergic asthma participants, and 38 of them completed the treatment and follow-up (the allergic asthma group). In addition, 13 healthy participants (the control group) were enrolled. The recurrence number of allergic asthma participants and asthma control test (ACT) were used to evaluate the effect of treatment on relieving allergic asthma recurrence. Flow cytometry was performed to analyze the levels of Th1 and Th2 cells in the peripheral blood. The serum levels of IgE, IFN-γ, and IL-4 were detected by ELISA. (1) In the allergic asthma group, compared to before the first treatment, the recurrence number of allergic asthma participants decreased and the ACT score increased at end of the last treatment, 18 and 30 weeks of the trial (P < 0.05). At 18 and 30 weeks of the trial, the recurrence number of allergic asthma participants was less and the ACT score was higher than the ones from the same period last year in the allergic asthma group (P < 0.05). Compared to before the first treatment, the percentage of Th1 cell did not change significantly, the percentage of Th2 cell decreased, and the Th1/Th2 cell ratio increased in the allergic asthma group by the end of the last treatment (P < 0.05). Meanwhile, the release of IgE and IL-4 reduced (P < 0.05), and the release of IFN-γ did not significantly change in the allergic asthma group. (2) Compared with the control group, the serum levels of IgE and IL-4 and the percentage of Th2 cell were higher, and the Th1/Th2 cell ratio was lower in the allergic asthma group (P < 0.05). There was no significant difference between Th1 cell and IFN-γ before the first treatment. (3) Compared with the control group, the IgE levels and the percentage of Th2 cell were higher in the allergic asthma group (P < 0.01). Simultaneously, there was no significant difference between Th1 cell, the Th1/Th2 cell ratio, and the serum levels of IFN-γ and IL-4 by the end of the last treatment. The data suggested that RHAS reduced the amount of Th2 cell and elevated the Th1/Th2 cell ratio, thereby alleviating the inflammatory responses in the allergic asthma participants.