No abstract

Rhinovirus (RV) infections are associated with asthma exacerbations. MicroRNA‐146a and microRNA‐146b (miR‐146a/b) are anti‐inflammatory miRNAs that suppress signaling through the nuclear factor kappa B (NF‐κB) pathway and inhibit pro‐inflammatory chemokine production in primary human bronchial epithelial cells (HBECs). In the current study, we aimed to explore whether miR‐146a/b could regulate cellular responses to RVs in HBECs and airways during RV‐induced asthma exacerbation. We demonstrated that expression of miR‐146a/b and pro‐inflammatory chemokines was increased in HBECs and mouse airways during RV infection. However, transfection with cell‐penetrating peptide (CPP)‐miR‐146a nanocomplexes before infection with RV significantly reduced the expression of the pro‐inflammatory chemokines CCL5, IL‐8 and CXCL1, increased interferon‐λ production, and attenuated infection with the green fluorescent protein (GFP)‐expressing RV‐A16 in HBECs. Concordantly, compared to wild‐type ( wt ) mice, Mir146a/b −/− mice exhibited more severe airway neutrophilia and increased T helper (Th)1 and Th17 cell infiltration in response to RV‐A1b infection and a stronger Th17 response with a less prominent Th2 response in house dust mite extract (HDM)‐induced allergic airway inflammation and RV‐induced exacerbation models. Interestingly, intranasal administration of CPP‐miR‐146a nanocomplexes reduced HDM‐induced allergic airway inflammation without a significant effect on the Th2/Th1/Th17 balance in wild ‐ type mice. In conclusion, the overexpression of miR‐146a has a strong anti‐inflammatory effect on RV infection in HBECs and a mouse model of allergic airway inflammation, while a lack of miR‐146a/b leads to attenuated type 2 cell responses in mouse models of allergic airway inflammation and RV‐induced exacerbation of allergic airway inflammation. Furthermore, our data indicate that the application of CPP‐miR‐146a nanocomplexes has therapeutic potential for targeting airway inflammation.

The miR-146 family consists of two microRNAs (miRNAs), miR-146a and miR-146b, which are both known to suppress a variety of immune responses. Here in this study, we show that miR-146b is abundantly expressed in neuronal cells, while miR-146a is mainly expressed in microglia and astroglia of adult mice. Accordingly, miR-146b deficient (Mir146b-/-) mice exhibited anxiety-like behaviors and enhanced cognition. Characterization of cellular composition of Mir146b-/- mice using flow cytometry revealed an increased number of neurons and a decreased abundancy of astroglia in the hippocampus and frontal cortex, whereas microglia abundancy remained unchanged. Immunohistochemistry showed a higher density of neurons in the frontal cortex of Mir146b-/- mice, enhanced hippocampal neurogenesis as evidenced by an increased proliferation, and survival of newly generated cells with enhanced maturation into neuronal phenotype. No microglial activation or signs of neuroinflammation were observed in Mir146b-/- mice. Further analysis demonstrated that miR-146b deficiency is associated with elevated expression of glial cell line-derived neurotrophic factor (Gdnf) mRNA in the hippocampus, which might be at least in part responsible for the observed neuronal expansion and the behavioral phenotype. This hypothesis is partially supported by the positive correlation between performance of mice in the object recognition test and Gdnf mRNA expression in Mir146b-/- mice. Together, these results show the distinct function of miR-146b in controlling behaviors and provide new insights in understanding cell-specific function of miR-146b in the neuronal and astroglial organization of the mouse brain.

No abstract

mRNA-based vaccines and candidate therapeutics have great potential in various medical fields. For the delivery of mRNA into target cells and tissues, lipid formulations are often employed. However, this approach could cause the activation of immune responses, making it unsuitable for the treatment of inflammatory conditions. Therefore, alternative delivery systems are highly demanded. In this study, we evaluated the transport efficiency and characteristics of cell-penetrating peptide PepFect14 (PF14) and mRNA nanoparticles in the presence of different additives. Our results show that all PF14-mRNA formulations entered cultured cells, while calcium chloride enhanced the transport and production of the encoded protein in HeLa and HaCaT cell lines, and polysorbate 80 did so in primary human keratinocytes. All formulations had similar physical properties and did not remarkably affect cell viability. By selectively blocking endocytosis pathways, we show that PF14-mRNA nanoparticles primarily entered HeLa cells via macropinocytosis and HaCaT cells via both macropinocytosis and clathrin-mediated endocytosis, while none of the blockers significantly affected the delivery into primary keratinocytes. Finally, subcutaneous injection of PF14-mRNA nanoparticles before inducing mouse irritant contact dermatitis resulted in the expression of a reporter protein without provoking harmful immune responses in the skin. Together, our findings suggest that PF14-mRNA nanoparticles have the potential for developing mRNA-based therapeutics for treating inflammatory skin conditions.