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Viral myocarditis (VMC) is one of the most common acquired heart diseases in children and teenagers. However, its pathogenesis is still unclear, and effective treatments are lacking. This study aimed to investigate the regulatory pathway by which exosomes alleviate ferroptosis in cardiomyocytes (CMCs) induced by coxsackievirus B3 (CVB3). CVB3 was utilized for inducing the VMC mouse model and cellular model. Cardiac echocardiography, left ventricular ejection fraction (LVEF), and left ventricular fractional shortening (LVFS) were implemented to assess the cardiac function. In CVB3-induced VMC mice, cardiac insufficiency was observed, as well as the altered levels of ferroptosis-related indicators (glutathione peroxidase 4 (GPX4), glutathione (GSH), and malondialdehyde (MDA)). However, exosomes derived from human umbilical cord mesenchymal stem cells (hucMSCs-exo) could restore the changes caused by CVB3 stimulation. Let-7a-5p was enriched in hucMSCs-exo, and the inhibitory effect of hucMSCs-exo let-7a-5p mimic on CVB3-induced ferroptosis was higher than that of hucMSCs-exo mimic NC (NC: negative control). Mothers against decapentaplegic homolog 2 (SMAD2) increased in the VMC group, while the expression of zinc-finger protein 36 (ZFP36) decreased. Let-7a-5p was confirmed to interact with SMAD2 messenger RNA (mRNA), and the SMAD2 protein interacted directly with the ZFP36 protein. Silencing SMAD2 and overexpressing ZFP36 inhibited the expression of ferroptosis-related indicators. Meanwhile, the levels of GPX4, solute carrier family 7, member 11 (SLC7A11), and GSH were lower in the SMAD2 overexpression plasmid (oe- SMAD2 )+ let-7a-5p mimic group than in the oe-NC+ let-7a-5p mimic group, while those of MDA, reactive oxygen species (ROS), and Fe 2+ increased. In conclusion, these data showed that ferroptosis could be regulated by mediating SMAD2 expression. Exo- let-7a-5p derived from hucMSCs could mediate SMAD2 to promote the expression of ZFP36, which further inhibited the ferroptosis of CMCs to alleviate CVB3-induced VMC.

Kawasaki disease (KD)), also known as mucocutaneous lymph node syndrome (MCLS), is an autoimmune and systemic vasculitis syndrome. Its etiology and pathogenesis are still unclear. microRNAs (miRNA), a novel class of small non-coding RNAs, regulate the expression of multiple protein-encoding genes at the post-transcriptional level. We intend to study the change of miRNA-133a in the plasma of patients with KD, explore the role of miRNA-133a on HUVEC and define the pathogenesis of vascular dysfunction in KD. miRNA-133a expression and the mRNA and protein expression of protein phosphatase 2 catalytic subunit alpha (PPP2CA) were assessed by RT-qPCR and Western blot, respectively. The PPP2CA mRNA 3'UTR was predicted to be the potential target of miRNA-133a by using the miRNA databases and verified by the luciferase assay. The plasmids of miRNA-133a mimics and inhibitors were transfected into HUVEC cells. The plasma soluble vascular endothelial cadherin (sVE-cadherin, the excised extracellular part of VE-cadherin) levels were investigated by ELISA. The results suggested that miRNA-133a was increased by 3.8 times in the acute KD group and by 2.7 times in the convalescent KD group compared with the control group (both P =  .000). PPP2CA is the target gene of miRNA-133a and its expression was inhibited by miRNA-133a acting on PPP2CA mRNA 3'UTR ( P =  .013). The plasma sVE-cadherin levels in the acute KD groups were increased compared with the control group ( P =  .024). The ROC curve analysis showed that the expression of miRNA-133a segregate acute KD patients from convalescent KD patients and healthy children. Our results suggest that miRNA-133a might be a new biomarker for KD.

Objectives: To provide clues for further study of the relationship between miRNAs and Kawasaki disease (KD) development, and to provide molecular markers for ultimately improve the rate of early diagnosis for KD., Methods: We collected acute, recovery KD children's plasma and normal samples, then used the miRNAs Assay Chip to screen the differentially expressed miRNAs in the plasma from KD children. Subsequently, miR-455-5p, which had identified via miRNAs assay chip, was validated by quantitative real-time PCR via independent cohort., Results: According to the results of miRNAs Assay chip, we identified a miRNAs panel including 5 miRNAs significantly up-regulated and 5 miRNAs remarkably down-regulated in the plasma from KD children compared to the normal control; miR-455-5p in both of acute and recovery KD children's plasma was remarkably lower than that in the normal control ( P <0.001, P =0.013, respectively), and miR-455-5p was also significantly lower than that in the recovery of KD children ( P =0.007) by independent cohort validation., Conclusions: There are significantly differentially expressed circulating miRNAs between the KD children and normal control. We identified 10 miRNAs dysregulation in the KD children's plasma compared with the normal group. Circulating miR-455-5p in both of acute and recovery KD children's plasma is remarkably lower than that in the normal control, and miR-455-5p may considered as a marker to show the recovery process of KD children. Plasma specific circulating miRNAs play an important role in the early diagnosis of KD and become the new molecular marker of KD in the future.

Objective: To investigate the genetic association of miR-146a gene polymorphisms at loci rs2910164 G/C, rs57095329 A/G, and rs6864584 T/C in patients with Kawasaki disease (KD) and coronary artery lesions (CAL)., Methods: There were 120 patients with KD and 126 healthy subjects in this study. The genotype of loci rs2910164 G/C, rs57095329 A/G, and rs6864584 T/C of miR-146a gene were detected by polymerase chain reaction-sequence-based typing., Results: For miR-146a gene polymorphisms at loci rs2910164 G/C, rs57095329 A/G, and rs6864584 T/C, there were no significant difference of genotype frequencies and allele frequencies between KD group and healthy control group, or between the IVIG-resistant group and IVIG-sensitive group (P > 0.05). In KD with coronary artery lesions (KD-CAL) group, the genotype frequencies of GG were higher than that in KD without coronary artery lesion (KD-WO) group at locus rs2910164 G/C polymorphisms of miR-146a gene (χ 2  = 6.660, P = 0.036), patients with KD carried genotype of GG were at 3.636 times higher risk of getting coronary artery lesions than those of non-carriers (χ 2  = 6.455, P = 0.018, OR = 3.636, 95%CI = 1.280-10.262). While there was no significant difference of allele frequency of G and C between KD-CAL group and KD-WO group (P > 0.05). In KD-CAL group, the allele frequency of A was higher than that in KD-WO group at locus rs57095329 A/G polymorphisms of miR-146a gene (χ 2  = 4.745, P = 0.035), carriers with allele A were at 2.422 times higher risk of getting coronary artery lesions than those of non-carriers (χ 2  = 4.745, P = 0.035, OR = 2.422, 95%CI = 1.073-5.465), while there was no significant difference of genotype frequency of AA, AG, and GG types between KD-CAL group and KD-WO group (P > 0.05). There was no significant difference of genotype frequencies of TT, TC, and CC types and allele frequencies of T and C types between KD-CAL group and KD-WO group at locus rs6864584 T/C polymorphisms of miR-146a gene (P > 0.05)., Conclusions: The significant association has been found between the genotype and allele frequency of the miR-146a gene loci rs2910164 G/C and rs57095329 A/G, the genotype GG of rs2910164 G/C, and allele A of rs57095329 A/G were risk factors for getting coronary artery lesions.

Background: Kawasaki disease (KD) is a childhood systemic vasculitis that exhibits a specific preference for the coronary arteries. The aetiology remains unknown and there are no especially diagnostic tests. microRNAs (miRNAs) are 18 to 23 nucleotides non-coding RNAs that are negative regulator of gene expression and play a crucial role in the regulatory network of the genome. Recently, circulating miRNAs have been found presentation in human plasma and displayed some characteristics of the ideal biomarker. However, few researches explored differentially expressed miRNAs in the plasma of KD patients. Our study is to identify circulating miRNAs in KD plasma which can serve as potential biomarkers of KD diagnosis., Materials and Methods: The total of five pairs of acute KD and normal plasma samples were analyzed using ABI miRNAs TLDA Assay chip. Differentially expression of miR-125a-5p in plasma were confirmed by quantitative real-time PCR (qRT-PCR) in independent cohort (acute KD = 30, convalescent KD = 30 and healthy control = 32). After bioinformatics prediction, miR-125a-5p vector and inhibitor were transfected into HUVECs respectively, to observe MKK7 expression as a potential target gene. Flow cytometry was used to analyze apoptosis. The mRNA and protein levels of desired genes including MKK7, Caspase-3, Bax and Bcl2 were detected by qRT-PCR and western blotting., Results: Eighteen miRNAs were differentially expressed in acute KD's plasma compared with healthy control. miR-125a-5p was significantly increased in plasma of KD patients (p = 0.000), but no variation between acute and convalescent KD (p = 0.357). Moreover, the results from the gain and loss functions of miR-125a-5p in HUVECs have shown that miR-125a-5p remarkably suppressed MKK7 expression, as a novel target gene. Importantly, miR-125a-5p also induced apoptosis in HUVECs through inhibition MKK7 levels to regulate Bax/Bcl2 pathway resulting to activate Caspase-3., Conclusion: Our study indicated that the circulating miR-125a-5p levels in KD's plasma have remarkably evaluated compared with healthy individuals. miR-125a-5p might play a role in the development of KD by regulating target gene MKK7 to induce apoptosis in vascular endothelial cells. Therefore, our findings have suggested that detected miR-125a-5p levels in plasma could be used as a potential biomarker in early KD diagnosis.