Tranglutaminase 2 contributes to the asthmatic inflammation by modulating activation of alveolar macrophages

Mollugin ameliorates murine allergic airway inflammation by inhibiting Th2 response and M2 macrophage activation

Mollugin, isolated from Rubia cordifolia L, is a pharmacological compound with anti-inflammatory activity. This study aimed to investigate whether mollugin protects mice against shrimp tropomyosin (ST)-induced allergic airway inflammation. Mice were sensitized with ST combined with Al(OH)₃ administered intraperitoneally (i.p.) once weekly for 3 wk followed by ST challenge for 5 d. Mice were i.p.-administered daily with mollugin for 7 d. Results showed that mollugin attenuated ST-induced infiltration of eosinophils and epithelial mucus secretion in the lung tissues and suppressed lung eosinophil peroxidase activity. Additionally, mollugin lowered the Th2 cytokine, IL-4 and IL-5, production and downregulated the mRNA levels of Il-4, Il-5, Il-13, eotaxin, Ccl-17, Muc5ac, arginase-1, Ym-1, and Fizz-1 in the lung tissues. Network pharmacology was employed to predict core targets, and the molecular docking approach was used to verify the compound targets. The results of the molecular docking study of mollugin into p38 MAPK or poly(ADP-ribose) polymerase 1 (PARP1) binding sites revealed that its mechanism was possibly similar to that of SB203580 (a p38 MAPK inhibitor) or olaparib (a PARP1 inhibitor). Immunohistochemistry analysis revealed that mollugin mitigated ST-induced elevation of arginase-1 expression and macrophage levels in the lungs and bronchoalveolar lavage fluid, respectively. Furthermore, arginase-1 mRNA level and phosphorylation of p38 MAPK were inhibited in IL-4-stimulated peritoneal macrophages. In ST-stimulated mouse primary splenocytes, mollugin notably inhibited IL-4 and IL-5 production and downregulated PARP1 and PAR protein expression. According to our findings, mollugin ameliorated allergic airway inflammation by inhibiting Th2 response and macrophage polarization.

Osthole regulates N6-methyladenosine-modified TGM2 to inhibit the progression of rheumatoid arthritis and associated interstitial lung disease

Rheumatoid arthritis (RA) is an inflammatory autoimmune disease, and RA interstitial lung disease (ILD) is a severe complication of RA. This investigation aims to determine the effect and underlying mechanism of osthole (OS), which could be extracted from Cnidium, Angelica, and Citrus plants and evaluate the role of transglutaminase 2 (TGM2) in RA and RA-ILD. In this work, OS downregulated TGM2 to exert its additive effect with methotrexate and suppress the proliferation, migration, and invasion of RA-fibroblast-like synoviocytes (FLS) by attenuating NF-κB signaling, resulting in the suppression of RA progression. Interestingly, WTAP-mediated N6-methyladenosine modification of TGM2 and Myc-mediated WTAP transcription cooperatively contributed to the formation of a TGM2/Myc/WTAP-positive feedback loop through upregulating NF-κB signaling. Moreover, OS could downregulate the activation of the TGM2/Myc/WTAP-positive feedback circuit. Furthermore, OS restrained the proliferation and polarization of M2 macrophages to inhibit the aggregation of lung interstitial CD11b⁺ macrophages, and the effectiveness and non-toxicity of OS in suppressing RA and RA-ILD progression were verified in vivo. Finally, bioinformatics analyses validated the importance and the clinical significance of the OS-regulated molecular network. Taken together, our work emphasized OS as an effective drug candidate and TGM2 as a promising target for RA and RA-ILD treatment.

Immunopharmacological Activities of Luteolin in Chronic Diseases

Flavonoids have been shown to have anti-oxidative effects, as well as other health benefits (e.g., anti-inflammatory and anti-tumor functions). Luteolin (3', 4', 5,7-tetrahydroxyflavone) is a flavonoid found in vegetables, fruits, flowers, and herbs, including celery, broccoli, green pepper, navel oranges, dandelion, peppermint, and rosemary. Luteolin has multiple useful effects, especially in regulating inflammation-related symptoms and diseases. In this paper, we summarize the studies about the immunopharmacological activity of luteolin on anti-inflammatory, anti-cardiovascular, anti-cancerous, and anti-neurodegenerative diseases published since 2018 and available in PubMed or Google Scholar. In this review, we also introduce some additional formulations of luteolin to improve its solubility and bioavailability.

-Sitosterol inhibits ovalbumin-induced asthma-related inflammation by regulating dendritic cells

AIM

To investigate the effects of β-sitosterol (B-SIT) and the underlying mechanisms of action in an ovalbumin-induced rat model of asthma.

METHODS

The pathological and morphological changes in lung and tracheal tissues were observed by H&E, PAS, and Masson's staining. The levels of IgE, TNF-α, and IFN-γ in the bronchoalveolar lavage fluid (BALF) and those of IL-6, TGF-β1, and IL-10 in serum were measured by ELISA. The relative expression levels of IL-5, IL-13, IL-21, CD11c, CD80, and CD86 mRNA in lung tissue were examined by RT-qPCR. Flow cytometry was performed to assess the levels of immune cells, including macrophages and neutrophils in spleen tissue and Th cells, Tc cells, NK cells, and DCs in peripheral blood. The protein expression levels of CD68, MPO, CD11c, CD80, and CD86 were detected by western blotting or immunohistochemistry.

RESULTS

B-SIT improved the injury in OVA-induced pathology, decreased the levels of inflammatory factors of IgE, TNF-α, IL-6, TGF-β1, IL-5, IL-13, and IL-21 and increased the levels of IFN-γ and IL-10. In addition, B-SIT decreased the number of macrophages and neutrophils and the relative expression levels of CD68 and MPO in the spleen. Moreover, B-SIT increased the number of Th cells, Tc cells, NK cells, and DCs in peripheral blood and upregulated the levels of CD11c, CD80, and CD86 in the spleen and lung.

CONCLUSION

B-SIT improved symptoms in a rat model of asthma likely via the inhibition of inflammation by regulating dendritic cells.

Luteolin activates M2 macrophages and suppresses M1 macrophages by upregulation of hsa_circ_0001326 in THP-1 derived macrophages

Asthma is accompanied by inflammatory progression. Macrophages are a major type of cells to response inflammation caused by different type of factors by polarized into specific phenotypes. Luteolin and glycyrrhizic acid exert protect role in asthma; however, their role in THP-1 derived macrophages polarization whether through regulating the expression of hsa_circ_0001326 is still unknown. The effect of luteolin and glycyrrhizic acid on THP-1 derived macrophages polarization were evaluated using qRT-PCR, Western blotting, and ELISA assay. The function of hsa_circ_0001326 on macrophages polarization in luteolin treated THP-1 derived macrophages were assessed after silence of hsa_circ_0001326. And the expression of its’ potential downstream gene, including hsa-miR-136-5p and ubiquitin-specific protease 4 (USP4), were detected using qRT-PCR and Western blot analysis. Furthermore, the potential mechanism of hsa_circ_0001326 were validated using rescue experiment. Results showed that luteolin promoted M2 polarization and inhibited M1 polarization in THP-1 induced macrophages, but glycyrrhizic acid had no these effects. Hsa_circ_0001326 expression was upregulated in luteolin treat THP-1 derived macrophages. Silence of hsa_circ_0001326 reversed the function of luteolin on macrophages polarization. In addition, hsa_circ_0001326 attenuated the inhibition effect of luteolin on hsa-miR-136-5p expression, and the promotion effect on USP4 expression. Furthermore, hsa-miR-136-5p inhibitor reversed the effect of hsa_circ_0001326 on macrophages polarization and the USP4 expression. Taken together, luteolin activates M2 macrophages and suppresses M1 macrophages by upregulation of hsa_circ_0001326. Further mechanism maybe by regulating hsa_circ_0001326 downstream gene expression, including hsa-miR-136-5p and USP4, in THP-1 derived macrophages. These findings provide a new insight for macrophage polarization under stimulation of luteolin.

Zhike Pingchuan Granule suppresses interleukin (IL)-6 or the medium of M2 macrophages induced apoptosis in human bronchial epithelial cells

The aim of this study was to explore the effects and action mechanism of Zhike Pingchuan Granule in human bronchial epithelial cells induced by IL-6 or the supernatant of M2. Upon IL-6 stimulation at different doses, Cell Counting Kit-8 (CCK8) assay and flow cytometry were, respectively, utilized to detect the cell viability and apoptosis levels of 16-HBE cells. ELISA and Western blot were, respectively, used to analyze the inflammatory markers and JAK2/STAT3 signals. Immunofluorescence assay was performed to identify M0 and M2 cells. As shown in results, ZKPC perturbed the expression of IL-6 inducible genes important for apoptosis, oxidative and inflammatory response, which was enhanced by JAK2 inhibitor. Besides the inhibitory effects on the phosphorylation levels of JAK2/STAT3, ZKPC markedly increased cell viability and reduced apoptosis in human bronchial epithelial cells (16-HBE) cultured in the supernatant of M2 cells. Collectively, ZKPC could inhibit the IL-6-induced JAK/STAT3 signaling cascade, increase cell viability and decrease apoptosis induced by the supernatant of M2. A more comprehensive understanding of the action mechanism of ZKPC on JAK2/STAT3 signaling pathway in human bronchial epithelial cells induced by IL-6 or M2 supernatant will enable ZKPC development in the control of asthma.

Isoalantolactone alleviates ovalbumin‑induced asthmatic inflammation by reducing alternatively activated macrophage and STAT6/PPAR‑γ/KLF4 signals

Isoalantolactone (IAL), a sesquiterpene lactone, has anti‑inflammatory activity in lipopolysaccharide (LPS)‑induced sepsis. However, it remains to be elucidated whether IAL influences asthmatic inflammation. The present study found that IAL inhibited ovalbumin (OVA)‑induced asthmatic inflammation and attenuated OVA‑induced eosinophil infiltration, immunoglobulin E generation and the production of interleukin (IL)‑4, IL‑5, C‑C motif chemokine ligand (CCL)17 and CCL22. In addition, IAL treatment with IL‑4 reduced the expression of arginase‑1, Ym‑1, CCL17 and CCL22 in bone marrow‑derived macrophages in vitro. Furthermore, IAL inhibited IL‑4‑induced STAT6 phosphorylation and the expression of peroxisome proliferator‑activated receptor γ and Krüppel‑like factor 4. Collectively, the results suggested that IAL attenuated asthmatic inflammation and is a potential therapeutic agent for the treatment of asthma.

Tranglutaminase 2 contributes to the asthmatic inflammation by modulating activation of alveolar macrophages

BACKGROUND

Transglutaminase 2 (TG2), a multifunctional calcium-dependent acyltransferase, is upregulated in asthmatic airways and reported to play a role in the pathogenesis of allergic asthma. However, the underlying mechanism is not fully understood.

OBJECTIVE

To investigate the role of TG2 in alternative activation of alveolar macrophages by using murine asthma model.

METHODS

TG2 expression was assessed in induced sputum of 21 asthma patients and 19 healthy controls, and lung tissue of ovalbumin (OVA)-induced murine asthma model. To evaluate the role of TG2 in asthma, we developed an OVA asthma model in both TG2 null and wild-type mice. The expression of M2 macrophage markers was measured by fluorescence-activated cell sorting (FACS) after OVA sensitization and challenge. To evaluate the effect of TG2 inhibition in vitro, interleukin 4 (IL-4) or IL-13-stimulated expression of M2 macrophage markers was measured in CRL-2456 cells in the presence and absence of a TG2 inhibitor.

RESULTS

The expression of both TG2 and M2 markers was increased in the sputum of asthmatics compared with that of healthy controls. The expression of TG2 was increased in macrophages of OVA mice. Airway hyperresponsiveness, and the number of inflammatory cells, including eosinophils, was significantly reduced in TG2 null mice compared with wild-type mice. Enhanced expression of M2 markers in OVA mice was normalized by TG2 knockout. IL-4 or IL-13-stimulated expression of M2 markers in alveolar macrophages was also attenuated by TG2 inhibitor treatment in vitro.

CONCLUSION

Our results suggest that TG2-mediated modulation of alveolar macrophage polarization plays important roles in the pathogenesis of asthma.