MIR-181A-5P Attenuates Ovalbumin-Induced Allergic Inflammation in Nasal Epithelial Cells by Targeting IL-33/P38 MAPK Pathway

Purpose: Chronic inflammation of the nasal mucosal tissues plays an important role in the pathogenesis of allergic rhinitis (AR). Aberrantly-expressed micro ribonucleic acid (miRNA) has been found to have strong associations with the inflammatory reactions in allergic diseases; however, its functional significance and molecular mechanism in AR remains unclear. The purpose of this study is to determine the functional role and mechanism of miR-181a-5p in AR. Methods: Allergic inflammatory reaction was induced by ovalbumin in human nasal epithelial cell line RPMI2650. The anti-inflammatory effects of miR-181a-5p were evaluated by examining pro-inflammatory cytokines (interleukin (IL)-1β, IL-6, tumor necrosis factor-α (TNF-α)) in the culture of RPMI-2650 cells stimulated by ovalbumin, using quantitative real-time reverse transcription polymerase chain reaction and enzyme-linked immunosorbent assay. Luciferase assay and gain-of-function assay were used to investigate the association of miR-181a-5p and IL-33/p38 MAPK axis. Results: MiR-181a-5p was significantly downregulated in mucosal tissues of AR patients and in RPMI-2650 cells treated with ovalbumin. The overexpression of miR-181a-5p showed prominent suppression of inflammatory cytokine production in RPMI-2650 cells with the stimulation of ovalbumin. MiR-181a-5p directly targeted, and negatively regulated IL-33 to suppress the activation of p38 MAPK signalling. Conclusion: The results suggest that miR-181a-5p restricted allergic inflammation through inhibition of IL-33/p38 MAPK pathway, indicating miR-181a-5p may play an anti-inflammatory role in AR.

Complement C3a Activates Astrocytes to Promote Medulloblastoma Progression through TNF -α

Background: Medulloblastoma (MB) is the most common malignant brain tumor in children. Approximately one third of MB patients remain incurable. Understanding the molecular mechanism of MB tumorigenesis is therefore critical for developing specific and effective treatment strategies. Our previous work demonstrated that astrocytes constitute tumor microenvironment (TME) of MB and play an indispensable role in MB progression. However, the underlying mechanisms for how astrocytes are regulated and activated to promote MB remain elusive. Methods: By taking advantage of Math1-Cre/Ptch1 loxp/loxp mice which spontaneously develop MB, primary MB cells and astrocytes were isolated then underwent administration and coculture in vitro . Immunohistochemistry was utilized to determine C3a presence in MB sections. MB cell proliferation was evaluated by immunofluorescent staing. GFAP and cytokines expression in C3a stimulated astrocytes was assessed by immunofluorescent staining, western blotting, q-PCR and ELISA method. C3a receptor and TNF-α receptor expression was determined by PCR. p38 MAPK pathway was detected by western blotting. Transplanted MB mice were treated with C3a receptor or TNF-α receptor antagonist to investigate their role in MB progression in vivo . Results: We found that complement C3a, a fragment released from intact complement C3 following complement activation, was enriched in both human and murine MB tumor tissue, and its receptor was highly expressed on tumor-associated astrocytes (TAAs). We demonstrated that C3a activated astrocytes and promoted MB cell proliferation via p38 MAPK pathway. Moreover, we discovered that C3a upregulated production of pro-inflammatory cytokines such as IL-6, IL-8 and TNF-α in astrocytes. Application of the conditioned medium of C3a-stimulated astrocytes promoted MB cell proliferation, which was abolished by preincubation with TNF-α receptor antagonist, indicating a TNF-α -dependent event. Indeed, we further demonstrated that administration of selective C3a receptor or TNF-α receptor antagonist to subcutaneous transplantation MB mice suppressed tumor progression in vivo . Conclusions: C3a was released during MB development. C3a triggered astrocytes activation and TNF-α production via p38 pathway, which promoted MB cell proliferation. Our findings revealed the novel role of C3a-mediated TNF-α production by astrocytes in MB progression. The findings imply that targeting to C3a and TNF-α may represent a potential novel therapeutic approach for human MB.