The diffuse axonal damage in white matter and neuronal loss, along with excessive neuroinflammation, hinder long-term functional recovery after traumatic brain injury (TBI). MicroRNAs (miRs) are small noncoding RNAs that negatively regulate protein-coding target genes in a posttranscriptional manner. Recent studies have shown that loss of function of the miR-15a/16-1 cluster reduced neurovascular damage and improved functional recovery in ischemic stroke and vascular dementia. However, the role of the miR-15a/16-1 cluster in neurotrauma is poorly explored. Here, we report that genetic deletion of the miR-15a/16-1 cluster facilitated the recovery of sensorimotor and cognitive functions, alleviated white matter/gray matter lesions, reduced cerebral glial cell activation, and inhibited infiltration of peripheral blood immune cells to brain parenchyma in a murine model of TBI when compared with WT controls. Moreover, intranasal delivery of the miR-15a/16-1 antagomir provided similar brain-protective effects conferred by genetic deletion of the miR-15a/16-1 cluster after experimental TBI, as evidenced by showing improved sensorimotor and cognitive outcomes, better white/gray matter integrity, and less inflammatory responses than the control antagomir–treated mice after brain trauma. miR-15a/16-1 genetic deficiency and miR-15a/16-1 antagomir also significantly suppressed inflammatory mediators in posttrauma brains. These results suggest miR-15a/16-1 as a potential therapeutic target for TBI.

Ischemic stroke is a leading cause of disability and mortality worldwide. Recently, increasing evidence implicates microRNAs (miRs) in the pathophysiology of ischemic stroke. Studies have shown that miR-15a/16-1 is abnormally expressed in brains after ischemic stroke, and its upregulation may increase ischemic damage. Given that sex and age are significant modifiers of stroke outcomes, here we investigated whether inhibiting miR-15a/16-1 with antagomirs mitigates cerebral ischemia/reperfusion (I/R) injury in a sex- and age-dependent manner. Young (3 months) and aged (18 months) male and female C57/BL mice underwent 1-h middle cerebral artery occlusion and 3–7 days reperfusion (tMCAO). We administered miR-15a/16-1 antagomir (30 pmol/g) or control antagomir (NC, 30 pmol/g) via tail vein 2 h post-MCAO. Neurobehavioral testing and infarct volume assessment were performed on days 3 and 7. Compared to controls, antagomir treatment significantly improved neurobehavioral outcomes and reduced infarct volume in tMCAO mice at day 7, with the effects being more pronounced in young mice. Notably, young female mice exhibited superior survival and sensorimotor function compared to young male mice. These results were also replicated in a permanent MCAO (pMCAO) mice model. This suggests miR-15a/16-1 antagomir and estradiol may synergistically regulate genes involved in neurovascular cell death, inflammation, and oxidative stress, with sex and age-dependent expression of miR-15a/16-1 and its targets likely underlying the observed variations. Overall, our findings identify miR-15a/16-1 antagomir as a promising therapeutic for ischemic stroke and suggest that sex and age should be considered when developing miR-based therapeutic strategies.

The expression of viral antigens in chronic hepatitis B virus (HBV) infection drives continuous liver inflammation, one of the main risk factors to develop liver cancer. HBV developed immune-suppressive functions to escape from the host immune system, but their link to liver tumor development is not well understood. Here, we analyzed if and how HBV surface antigen (HBs) expression in combined hepatocellular-cholangiocarcinoma (cHCC/iCCA) cells influences their antigenicity for CD8 T cells. We randomly isolated liver tumor tissues from AlfpCre⁺-Trp53^fl/fl/Alb-HBs⁺ tg mice and established primary carcinoma cell lines (pCCL) that showed a bilineal (CK7⁺/HNF4α⁺) cHCC/iCCA phenotype. These pCCL uniformly expressed HBs (HBs^hi), and low levels of MHC-I (MHC-I^lo), and were transiently convertible to a high antigenicity (MHC-I^hi) phenotype by IFN-γ treatment. HBs^hi/pCCL induced HBs/(K^b/S_190–197)-specific CD8 T cells and developed slow-growing tumors in subcutaneously transplanted C57Bl/6J (B6) mice. Interestingly, pCCL-ex cells, established from HBs^hi/pCCL-induced and re-explanted tumors in B6 but not those in immune-deficient Rag1^−/− mice showed major alterations, like an MHC-I^hi phenotype, a prominent growth-biased gene expression signature, a significantly decreased HBs expression (HBs^lo) and a switch to fast-growing tumors in re-transplanted B6 or PD-1^−/− hosts with an unlocked PD-1/PD-L1 control system. CD8 T cell-mediated elimination of HBs^hi/pCCL, together with the attenuation of the negative restraints of HBs in the tumor cells, like ER-stress, reveals a novel mechanism to unleash highly aggressive HBs^lo/pCCL-ex immune-escape variants. Under certain conditions, HBs-specific CD8 T-cell responses thus potentiate tumor growth, an aspect that should be considered for therapeutic vaccination strategies against chronic HBV infection and liver tumors.

Introduction: Angiogenesis actively contributes to post-stroke functional recovery and improves long-term survival in stroke patients. Previously, we demonstrated that endothelium-targeted deletion of miR-15a/16-1 promotes post-stroke angiogenesis by enhancing classic pro-angiogenic factors and their receptors, and genetic deletion of miR-15a/16-1 in pericytes likewise promotes post-stroke functional recovery by stimulating cerebral angiogenesis. Here, we further investigate the underlying mechanisms and downstream targets of pericytic miR-15a/16-1 in cerebral angiogenesis after ischemic stroke. Methods: Pericyte-miR15a/16-1 conditional knockout mice (Pericyte-miR-15a/16-1 cKO) and wild-type (WT) controls were subjected to 1h MCAO followed by 7d reperfusion. Cerebral microvessels were extracted and subjected to RNA-seq to identify the significant differentially expressed genes (DEGs) that related to miR-15a/16-1 and angiogenesis among experimental groups. TargetScan and miRDB were used to predict potential miR-15a/16-1 downstream targets. Primary mouse brain vascular pericytes (mBVPs) were treated with lentivirus to achieve loss- or gain-of-miR-15a/16-1 function, and subjected to OGD 8h and reperfusion 24h. Pro-angiogenic factors were further verified by dual-luciferase reporter assay, qPCR, and western blotting. Results: RNA-seq analysis showed 289 upregulated genes (P < 0.05 & at least one CPM > 1) and 399 upregulated genes from 100 positive enriched gene sets (GESA) in cerebral microvessels of pericyte-miR-15a/16-1 cKO mice compared to WT controls 7d after MCAO. By comparing to miR-15a/16-1 potential target database from TargetScan and miRDB, 9 angiogenic genes were identified. Further biochemical analysis revealed that Pappa2, Fgf9, Islr, and Ccr2 mRNA and protein expression are significantly increased in cerebral microvessels of cKO mice and mBVPs with loss-of-miR-15a/16-1 function. Furthermore, dual-luciferase assay results verified that loss- or gain-of-miR-15a/16-1 function significantly increased or decreased luciferase reporter activity of these four genes, respectively. Conclusion: Our findings reveal novel pericytic miR-15a/16-1 mediated angiogenic targets in ischemic stroke.