Transplacental transfer efficiency of maternal antibodies against influenza A(H1N1)pdm09 virus and dynamics of naturally acquired antibodies in Chinese children: a longitudinal, paired mother-neonate cohort study.

BACKGROUND: The 2009 pandemic H1N1 influenza A virus (A(H1N1)pdm09 virus) evolves rapidly and has continued to cause severe infections in children since its emergence in 2009. We aimed to characterise the kinetics of maternally and naturally acquired antibodies against historical A(H1N1)pdm09 strains and to assess the extent to which the response to heterologous strains following infection or vaccination affects observed A(H1N1)pdm09 strain-specific antibody titres in a Chinese paediatric population. METHODS: In this retrospective study, we used residual serum samples from 528 mother-neonate pairs from a non-interventional, longitudinal cohort study in southern China conducted from Sept 20, 2013, to Aug 24, 2018, from six local hospitals in Anhua County, Hunan Province, China. Mother-neonate pairs were eligible for inclusion if the neonates were born after Sept 20, 2013, and their mothers had resided in the study sites for at least 3 months. We tested samples with a haemagglutination inhibition (HAI) assay to measure antibody levels against three historical A(H1N1)pdm09 strains that were antigenically similar to the strains that circulated during the 2009 pandemic (A/Hunan-Kaifu/SWL4204/2009 [SWL4204/09 strain], A/Hunan-Daxiang/SWL1277/2016 [SWL1277/16 strain], and A/Hunan-Yanfeng/SWL185/2018 [SWL185/18 strain]). We also determined the seroprevalence, geometric mean titres (GMTs), transfer ratio of maternal antibodies, and the dynamics of maternally and naturally acquired antibodies in children, from birth to 3 years of age. FINDINGS: 1066 mother-neonate pairs were enrolled in the original cohort between Sept 20, 2013, and Oct 14, 2015. Of these, 528 pairs (523 mothers, 528 neonates) were selected for the present study. The median age of the mothers was 25 years (IQR 23 to 29). 291 (55%) of 528 children were boys and 237 (45%) were girls, and most children (452 [86%]) were breastfed before the age of 6 months. The GMTs and the seroprevalence for the SWL4204/09 strain were higher than those for the SWL1277/16 and SWL185/18 strains among mothers (GMTs: 10·4 [95% CI 9·8 to 11·1] vs 9·3 [8·7 to 9·8] vs 8·0 [7·5 to 8·4], p<0·0001; seroprevalence: 11·1% [95% CI 8·5 to 14·1] vs 6·9% [4·9 to 9·4] vs 4·6% [3·0 to 6·8], p=0·0003) and among neonates (GMTs: 10·7 [10·0 to 11·5] vs 9·4 [8·8 to 10·0] vs 8·1 [7·6 to 8·6], p<0·0001; seroprevalence: 13·4% [10·7 to 16·7] vs 8·7% [6·5 to 11·5] vs 6·1% [4·2 to 8·5], p=0·0002). Regardless of the A(H1N1)pdm09-specific strain, maternal antibodies could be transferred efficiently via the placenta (mean transfer ratios: 1·10 for SWL4204/09 vs 1·09 for SWL1277/16 vs 1·06 for SWL185/18; p=0·93). The A(H1N1)pdm09 strain-specific antibodies waned below the protective threshold of 1:40 within 2 months after birth. After maternal antibody waning, there were periodic increases and decreases in HAI antibody titres against three A(H1N1)pdm09 strains, and such increases were all significantly associated with a higher immune response to heterologous strains. Vaccination against the SWL4204/09 strain was associated with a poor response to the SWL185/18 strain (ß-0·20, 95% CI -0·28 to -0·13; p<0·0001). INTERPRETATION: Our findings suggest low pre-existing immunity against influenza A(H1N1)pdm09 virus among unvaccinated Chinese adult female and paediatric populations. This evidence, together with the rapid decay of maternal antibodies and the observed cross-reactivity among different A(H1N1)pdm09 strains, highlights the importance of accelerating maternal and paediatric influenza vaccination in China. FUNDING: The Key Program of the National Natural Science Foundation of China. TRANSLATION: For the Chinese translation of the abstract see Supplementary Materials section.

The transfer of maternal antibodies and dynamics of maternal and natural infection-induced antibodies against coxsackievirus A16 in Chinese children 0-13 years of age: a longitudinal cohort study.

BACKGROUND: A major hand-foot-and-mouth disease (HFMD) pathogen, coxsackievirus A16 (CVA16), has predominated in several of the last 10 years and caused the largest number of HFMD outbreaks between 2011 and 2018 in China. We evaluated the efficacy of maternal anti-CVA16 antibody transfer via the placenta and explored the dynamics of maternal and natural infection-induced neutralizing antibodies in children. METHODS: Two population-based longitudinal cohorts in southern China were studied during 2013-2018. Participants were enrolled in autumn 2013, including 2475 children aged 1-9 years old and 1066 mother-neonate pairs, and followed for 3 years. Blood/cord samples were collected for CVA16-neutralizing antibody detection. The maternal antibody transfer efficacy, age-specific seroprevalence, geometric mean titre (GMT) and immune response kinetics were estimated. RESULTS: The average maternal antibody transfer ratio was 0.88 (95% CI 0.80-0.96). Transferred maternal antibody levels declined rapidly (half-life: 2.0 months, 95% CI 1.9-2.2 months). The GMT decayed below the positive threshold (8) by 1.5 months of age. Due to natural infections, it increased above 8 after 1.4 years and reached 32 by 5 years of age, thereafter dropping slightly. Although the average duration of maternal antibody-mediated protection was < 3 months, the duration extended to 6 months on average for mothers with titres ≥ 64. CONCLUSIONS: Anti-CVA16 maternal antibodies are efficiently transferred to neonates, but their levels decline quickly. Children aged 0-5 years are the main susceptible population and should be protected by CVA16 vaccination, with the optimal vaccination time between 1.5 months and 1 year of age.

Comparison of Neutralizing Antibody Response Kinetics in Patients with Hand, Foot, and Mouth Disease Caused by Coxsackievirus A16 or Enterovirus A71: A Longitudinal Cohort Study of Chinese Children, 2017-2019.

Hand, foot, and mouth disease (HFMD), which is mainly caused by coxsackievirus A16 (CVA16) or enterovirus A71 (EV-A71), poses a serious threat to children's health. However, the long-term dynamics of the neutralizing Ab (NAb) response and ideal paired-serum sampling time for serological diagnosis of CVA16-infected HFMD patients were unclear. In this study, 336 CVA16 and 253 EV-A71 PCR-positive HFMD inpatients were enrolled and provided 452 and 495 sera, respectively, for NAb detection. Random-intercept modeling with B-spline was conducted to characterize NAb response kinetics. The NAb titer of CVA16 infection patients was estimated to increase from negative (2.1, 95% confidence interval [CI]: 1.4-3.3) on the day of onset to a peak of 304.8 (95% CI: 233.4-398.3) on day 21 and then remained >64 until 26 mo after onset. However, the NAb response level of EV-A71-infected HFMD patients was much higher than that of CVA16-infected HFMD patients throughout. The geometric mean titer was significantly higher in severe EV-A71-infected patients than in mild patients, with a 2.0-fold (95% CI: 1.4-3.2) increase. When a 4-fold rise in titer was used as the criterion for serological diagnosis of CVA16 and EV-A71 infection, acute-phase serum needs to be collected at 0-5 d, and the corresponding convalescent serum should be respectively collected at 17.4 (95% CI: 9.6-27.4) and 24.4 d (95% CI: 15.3-38.3) after onset, respectively. In conclusion, both CVA16 and EV-A71 infection induce a persistent humoral immune response but have different NAb response levels and paired-serum sampling times for serological diagnosis. Clinical severity can affect the anti-EV-A71 NAb response.

Public Interest in Distribution and Determinants of Influenza and Pneumonia Vaccination during the COVID-19 Pandemic: An Infodemiology and Cross-Sectional Study from China.

BACKGROUND: Following the COVID-19 pandemic, global interest in influenza vaccines and pneumonia vaccines has increased significantly. We aimed to examine public interest in and actual market circulation of influenza and pneumonia vaccines before and after the initial outbreak of COVID-19 and estimate the coverage and determinants of influenza and pneumonia vaccination uptake following the COVID-19 pandemic. METHODS: We obtained search volume data for vaccines using the Baidu search index and collected the numbers of vaccines issued from the National Institutes for Food and Drug Control. We also conducted a cross-sectional survey among 3346 adult residents to evaluate the coverage and determinants of influenza and pneumonia vaccination uptake in the Yangtze River delta, China, from 29 January to 4 February 2021. RESULTS: Public searches and the number of vaccines issued for the influenza vaccines and pneumonia vaccines obviously increased after the initial outbreak of COVID-19. In the total sample, 12.5% were vaccinated against influenza, and 21.5% had at least one family member vaccinated against pneumonia. A minority of participants perceived that they were highly or very highly susceptible to influenza (15.9%) and COVID-19 (6.7%). A range of socio-economic factors and perceived susceptibility to COVID-19 were associated with influenza and pneumonia vaccination uptake. CONCLUSIONS: Public interest in and issued volumes of influenza and pneumonia vaccines increased nationally following the COVID-19 pandemic. Perceptions of high susceptibility to COVID-19 were associated with the uptake of the influenza and pneumonia vaccines. Targeted interventions were needed to improve vaccination coverage.

Time-varying optimization of COVID-19 vaccine prioritization in the context of limited vaccination capacity.

Dynamically adapting the allocation of COVID-19 vaccines to the evolving epidemiological situation could be key to reduce COVID-19 burden. Here we developed a data-driven mechanistic model of SARS-CoV-2 transmission to explore optimal vaccine prioritization strategies in China. We found that a time-varying vaccination program (i.e., allocating vaccines to different target groups as the epidemic evolves) can be highly beneficial as it is capable of simultaneously achieving different objectives (e.g., minimizing the number of deaths and of infections). Our findings suggest that boosting the vaccination capacity up to 2.5 million first doses per day (0.17% rollout speed) or higher could greatly reduce COVID-19 burden, should a new wave start to unfold in China with reproduction number ≤1.5. The highest priority categories are consistent under a broad range of assumptions. Finally, a high vaccination capacity in the early phase of the vaccination campaign is key to achieve large gains of strategic prioritizations.

The impact of relaxing interventions on human contact patterns and SARS-CoV-2 transmission in China.

Nonpharmaceutical interventions to control SARS-CoV-2 spread have been implemented with different intensity, timing, and impact on transmission. As a result, post-lockdown COVID-19 dynamics are heterogeneous and difficult to interpret. We describe a set of contact surveys performed in four Chinese cities (Wuhan, Shanghai, Shenzhen, and Changsha) during the pre-pandemic, lockdown and post-lockdown periods to quantify changes in contact patterns. In the post-lockdown period, the mean number of contacts increased by 5 to 17% as compared to the lockdown period. However, it remains three to seven times lower than its pre-pandemic level sufficient to control SARS-CoV-2 transmission. We find that the impact of school interventions depends nonlinearly on the intensity of other activities. When most community activities are halted, school closure leads to a 77% decrease in the reproduction number; in contrast, when social mixing outside of schools is at pre-pandemic level, school closure leads to a 5% reduction in transmission.

Infectivity, susceptibility, and risk factors associated with SARS-CoV-2 transmission under intensive contact tracing in Hunan, China.

Several mechanisms driving SARS-CoV-2 transmission remain unclear. Based on individual records of 1178 potential SARS-CoV-2 infectors and their 15,648 contacts in Hunan, China, we estimated key transmission parameters. The mean generation time was estimated to be 5.7 (median: 5.5, IQR: 4.5, 6.8) days, with infectiousness peaking 1.8 days before symptom onset, with 95% of transmission events occurring between 8.8 days before and 9.5 days after symptom onset. Most transmission events occurred during the pre-symptomatic phase (59.2%). SARS-CoV-2 susceptibility to infection increases with age, while transmissibility is not significantly different between age groups and between symptomatic and asymptomatic individuals. Contacts in households and exposure to first-generation cases are associated with higher odds of transmission. Our findings support the hypothesis that children can effectively transmit SARS-CoV-2 and highlight how pre-symptomatic and asymptomatic transmission can hinder control efforts.

Who should be prioritized for COVID-19 vaccination in China? A descriptive study.

BACKGROUND: All countries are facing decisions about which population groups to prioritize for access to COVID-19 vaccination after the first vaccine products have been licensed, at which time supply shortages are inevitable. Our objective is to define the key target populations, their size, and priority for a COVID-19 vaccination program in the context of China. METHODS: On the basis of utilitarian and egalitarian principles, we define and estimate the size of tiered target population groups for a phased introduction of COVID-19 vaccination, considering evolving goals as vaccine supplies increase, detailed information on the risk of illness and transmission, and past experience with vaccination during the 2009 influenza pandemic. Using publicly available data, we estimated the size of target population groups, and the number of days needed to vaccinate 70% of the target population. Sensitivity analyses considered higher vaccine coverages and scaled up vaccine delivery relative to the 2009 pandemic. RESULTS: Essential workers, including staff in the healthcare, law enforcement, security, nursing homes, social welfare institutes, community services, energy, food and transportation sectors, and overseas workers/students (49.7 million) could be prioritized for vaccination to maintain essential services in the early phase of a vaccination program. Subsequently, older adults, individuals with underlying health conditions and pregnant women (563.6 million) could be targeted for vaccination to reduce the number of individuals with severe COVID-19 outcomes, including hospitalizations, critical care admissions, and deaths. In later stages, the vaccination program could be further extended to target adults without underlying health conditions and children (784.8 million), in order to reduce symptomatic infections and/or to stop virus transmission. Given 10 million doses administered per day, and a two-dose vaccination schedule, it would take 1 week to vaccinate essential workers but likely up to 7 months to vaccinate 70% of the overall population. CONCLUSIONS: The proposed framework is general but could assist Chinese policy-makers in the design of a vaccination program. Additionally, this exercise could be generalized to inform other national and regional strategies for use of COVID-19 vaccines, especially in low- and middle-income countries.

Disease burden and clinical severity of the first pandemic wave of COVID-19 in Wuhan, China.

The novel coronavirus disease 2019 (COVID-19) was first reported in Wuhan, China, where the initial wave of intense community transmissions was cut short by interventions. Using multiple data sources, here we estimate the disease burden and clinical severity by age of COVID-19 in Wuhan from December 1, 2019 to March 31, 2020. Our estimates account for the sensitivity of the laboratory assays, prospective community screenings, and healthcare seeking behaviors. Rates of symptomatic cases, medical consultations, hospitalizations and deaths were estimated at 796 (95% CI: 703-977), 489 (472-509), 370 (358-384), and 36.2 (35.0-37.3) per 100,000 persons, respectively. The COVID-19 outbreak in Wuhan had a higher burden than the 2009 influenza pandemic or seasonal influenza in terms of hospitalization and mortality rates, and clinical severity was similar to that of the 1918 influenza pandemic. Our comparison puts the COVID-19 pandemic into context and could be helpful to guide intervention strategies and preparedness for the potential resurgence of COVID-19.

Disease burden and clinical severity of the first pandemic wave of COVID-19 in Wuhan, China.

The pandemic of novel coronavirus disease 2019 (COVID-19) began in Wuhan, China, where a first wave of intense community transmission was cut short by interventions. Using multiple data source, we estimated the disease burden and clinical severity of COVID-19 by age in Wuhan from December 1, 2019 to March 31, 2020. We adjusted estimates for sensitivity of laboratory assays and accounted for prospective community screenings and healthcare seeking behaviors. Rates of symptomatic cases, medical consultations, hospitalizations and deaths were estimated at 796 (95%CI: 703-977), 489 (472-509), 370 (358-384), and 36.2 (35.0-37.3) per 100,000 persons, respectively. The COVID-19 outbreak in Wuhan had higher burden than the 2009 influenza pandemic or seasonal influenza, and that clinical severity was similar to that of the 1918 influenza pandemic. Our comparison puts the COVID-19 pandemic into context and could be helpful to guide intervention strategies and preparedness for the potential resurgence of COVID-19.

The impact of relaxing interventions on human contact patterns and SARS-CoV-2 transmission in China.

Non-pharmaceutical interventions to control COVID-19 spread have been implemented in several countries with different intensity, timing, and impact on transmission. As a result, post-lockdown COVID-19 dynamics are heterogenous and difficult to interpret. Here we describe a set of contact surveys performed in four Chinese cities (Wuhan, Shanghai, Shenzhen, and Changsha) during the pre-pandemic, lockdown, and post-lockdown period to quantify the transmission impact of relaxing interventions via changes in age-specific contact patterns. We estimate that the mean number of contacts increased 5%-17% since the end of the lockdown but are still 3-7 times lower than their pre-pandemic levels. We find that post-lockdown contact patterns in China are still sufficiently low to keep SARS-CoV-2 transmission under control. We also find that the impact of school interventions depends non-linearly on the share of other activities being resumed. When most community activities are halted, school closure leads to a 77% decrease in the reproductive number; in contrast, when social mixing outside of schools is at pre-pandemic level, school closure leads to a 5% reduction in transmission. Moving forward, to control COVID-19 spread without resorting to a lockdown, it will be key to dose relaxation in social mixing in the community and strengthen targeted interventions.

Infectivity, susceptibility, and risk factors associated with SARS-CoV-2 transmission under intensive contact tracing in Hunan, China.

Several mechanisms driving SARS-CoV-2 transmission remain unclear. Based on individual records of 1,178 SARS-CoV-2 infectors and their 15,648 contacts in Hunan, China, we estimated key transmission parameters. The mean generation time was estimated to be 5.7 (median: 5.5, IQR: 4.5, 6.8) days, with infectiousness peaking 1.8 days before symptom onset, with 95% of transmission events occurring between 8.8 days before and 9.5 days after symptom onset. Most of transmission events occurred during the pre-symptomatic phase (59.2%). SARS-CoV-2 susceptibility to infection increases with age, while transmissibility is not significantly different between age groups and between symptomatic and asymptomatic individuals. Contacts in households and exposure to first-generation cases are associated with higher odds of transmission. Our findings support the hypothesis that children can effectively transmit SARS-CoV-2 and highlight how pre-symptomatic and asymptomatic transmission can hinder control efforts.

The Effect of Electronic-Cigarette Vaping on Cardiac Function and Angiogenesis in Mice.

The rapid increase in use of electronic-cigarettes (e-cigarettes), especially among youth, raises the urgency for regulating bodies to make informed decisions, guidance, and policy on these products. This study evaluated cardiac function in an experimental model following exposure to e-cigarettes. We subjected C57BL/6 mice to e-cigarette vaping for 2-weeks, and cardiac function was assessed using echocardiography. Cardiac tissues were collected at the end of e-cigarette exposure for pathological analysis. The experimental data showed that e-cigarette vaping (3 h/day for 14 days) had no significant effect on cardiac contractility as measured by ejection fraction. However, it significantly increased angiogenesis in mouse heart tissue. We found that e-cigarette exposure increased the endothelial cell marker CD31 and CD34 to approximately 2 fold (p < 0.05) in heart tissue from female mice and about 150% (p < 0.05) in male mice. E-cigarette vaping also caused slower weight gain compared to mice exposed to room air. In addition, short-term e-cigarette exposure slightly increased collagen content in heart tissue but did not result in significant tissue fibrosis. These results suggest that short-term exposure to e-cigarettes has no acute effect on cardiac contractile function or tissue fibrosis, but it increases cardiac angiogenesis.

Channelopathy as a SUDEP Biomarker in Dravet Syndrome Patient-Derived Cardiac Myocytes.

Dravet syndrome (DS) is a severe developmental and epileptic encephalopathy with a high incidence of sudden unexpected death in epilepsy (SUDEP). Most DS patients carry de novo variants in SCN1A, resulting in Nav1.1 haploinsufficiency. Because SCN1A is expressed in heart and in brain, we proposed that cardiac arrhythmia contributes to SUDEP in DS. We generated DS patient and control induced pluripotent stem cell-derived cardiac myocytes (iPSC-CMs). We observed increased sodium current (INa) and spontaneous contraction rates in DS patient iPSC-CMs versus controls. For the subject with the largest increase in INa, cardiac abnormalities were revealed upon clinical evaluation. Generation of a CRISPR gene-edited heterozygous SCN1A deletion in control iPSCs increased INa density in iPSC-CMs similar to that seen in patient cells. Thus, the high risk of SUDEP in DS may result from a predisposition to cardiac arrhythmias in addition to seizures, reflecting expression of SCN1A in heart and brain.

Characterization of a Long Non-Coding RNA, the Antisense RNA of Na/K-ATPase α1 in Human Kidney Cells.

Non-coding RNAs are important regulators of protein-coding genes. The current study characterized an antisense long non-coding RNA, ATP1A1-AS1, which is located on the opposite strand of the Na/K-ATPase α1 gene. Our results show that four splice variants are expressed in human adult kidney cells (HK2 cells) and embryonic kidney cells (HEK293 cells). These variants can be detected in both cytosol and nuclear fractions. We also found that the inhibition of DNA methylation has a differential effect on the expression of ATP1A1-AS1 and its sense gene. To investigate the physiological role of this antisense gene, we overexpressed the ATP1A1-AS1 transcripts, and examined their effect on Na/K-ATPase expression and related signaling function in human kidney cells. The results showed that overexpression of the ATP1A1-AS1-203 transcript in HK2 cells reduced the Na/K-ATPase α1 (ATP1A1) gene expression by approximately 20% (p < 0.05), while reducing the Na/K-ATPase α1 protein synthesis by approximately 22% (p < 0.05). Importantly, overexpression of the antisense RNA transcript attenuated ouabain-induced Src activation in HK2 cells. It also inhibited the cell proliferation and potentiated ouabain-induced cell death. These results demonstrate that the ATP1A1-AS1 gene is a moderate negative regulator of Na/K-ATPase α1, and can modulate Na/K-ATPase-related signaling pathways in human kidney cells.

Hiding inside? Intracellular expression of non-glycosylated c-kit protein in cardiac progenitor cells.

Cardiac progenitor cells including c-kit(+) cells and cardiosphere-derived cells (CDCs) play important roles in cardiac repair and regeneration. CDCs were reported to contain only small subpopulations of c-kit(+) cells and recent publications suggested that depletion of the c-kit(+) subpopulation of cells has no effect on regenerative properties of CDCs. However, our current study showed that the vast majority of CDCs from murine heart actually express c-kit, albeit, in an intracellular and non-glycosylated form. Immunostaining and flow cytometry showed that the fluorescent signal indicative of c-kit immunostaining significantly increased when cell membranes were permeabilized. Western blots further demonstrated that glycosylation of c-kit was increased during endothelial differentiation in a time dependent manner. Glycosylation inhibition by 1-deoxymannojirimycin hydrochloride (1-DMM) blocked c-kit glycosylation and reduced expression of endothelial cell markers such as Flk-1 and CD31 during differentiation. Pretreatment of these cells with a c-kit kinase inhibitor (imatinib mesylate) also attenuated Flk-1 and CD31 expression. These results suggest that c-kit glycosylation and its kinase activity are likely needed for these cells to differentiate into an endothelial lineage. In vivo, we found that intracellular c-kit expressing cells are located in the wall of cardiac blood vessels in mice subjected to myocardial infarction. In summary, our work demonstrated for the first time that c-kit is not only expressed in CDCs but may also directly participate in CDC differentiation into an endothelial lineage.

The Online Morphology Control and Dynamic Studies on Improving Vitamin B12 Production by Pseudomonas denitrificans with Online Capacitance and Specific Oxygen Consumption Rate.

The relationship between the morphological character of Pseudomonas denitrificans and vitamin B12 synthesis based on real-time capacitance measurement and online specific oxygen consumption rate (Q O2) control was established for enhancing vitamin B12 production. Results demonstrated that the threshold Q O2 value lower than 2.0 mmol/gDCW/l would greatly stimulate the state transfer from the cell number growth phase to the cell elongation phase and promote rapid vitamin B12 biosynthesis, while the vitamin B12 biosynthesis rate could also be inhibited when the rate of cell's length-to-width ratio (ratio-LW) was higher than 10:1. Furthermore, the optimal morphology controlling strategy was achieved based on online Q O2 control, which increases the appropriate active cell numbers at the former phase, and then control the elongation of ratio-LW no more than 10:1 at the vitamin B12 biosynthesis phase. The maximal vitamin B12 production reached 239.7 mg/l at 168 h, which was improved by 14.7 % compared with the control (208 mg/l). This online controlling strategy would be effectively applied for improving industrial vitamin B12 fermentation.

Na/K-ATPase signaling regulates collagen synthesis through microRNA-29b-3p in cardiac fibroblasts.

Chronic kidney disease (CKD) is accompanied by cardiac fibrosis, hypertrophy, and dysfunction, which are commonly referred to as uremic cardiomyopathy. Our previous studies found that Na/K-ATPase ligands or 5/6th partial nephrectomy (PNx) induces cardiac fibrosis in rats and mice. The current study used in vitro and in vivo models to explore novel roles for microRNA in this mechanism of cardiac fibrosis formation. To accomplish this, we performed microRNA profiling with RT-qPCR based arrays on cardiac tissue from rats subjected to marinobufagenin (MBG) infusion or PNx. The analysis showed that a series of fibrosis-related microRNAs were dysregulated. Among the dysregulated microRNAs, microRNA (miR)-29b-3p, which directly targets mRNA of collagen, was consistently reduced in both PNx and MBG-infused animals. In vitro experiments demonstrated that treatment of primary cultures of adult rat cardiac fibroblasts with Na/K-ATPase ligands induced significant increases in the fibrosis marker, collagen protein, and mRNA expression compared with controls, whereas miR-29b-3p expression decreased >50%. Transfection of miR-29b-3p mimics into cardiac fibroblasts inhibited cardiotonic steroids-induced collagen synthesis. Moreover, a specific Na/K-ATPase signaling antagonist, pNaKtide, prevented ouabain-induced increases in collagen synthesis and decreases in miR-29b-3p expression in these cells. In conclusion, these data are the first to indicate that signaling through Na/K-ATPase regulates miRNAs and specifically, miR-29b-3p expression both in vivo and in vitro. Additionally, these data indicate that miR-29b-3p expression plays an important role in the formation of cardiac fibrosis in CKD.