Prenatal Infection by Respiratory Viruses Is Associated with Immunoinflammatory Responses in the Fetus.

Rationale: Respiratory viral infections can be transmitted from pregnant women to their offspring, but frequency, mechanisms, and postnatal outcomes remain unclear. Objectives: The aims of this prospective cohort study were to compare the frequencies of transplacental transmission of respiratory syncytial virus (RSV) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), analyze the concentrations of inflammatory mediators in maternal and fetal blood, and assess clinical consequences. Methods: We recruited pregnant women who developed upper respiratory infections or tested positive for SARS-CoV-2. Maternal and cord blood samples were collected at delivery. Study questionnaires and electronic medical records were used to document demographic and medical information. Measurements and Main Results: From October 2020 to June 2022, droplet digital PCR was used to test blood mononuclear cells from 103 mother-baby dyads. Twice more newborns in our sample were vertically infected with RSV compared with SARS-CoV-2 (25.2% [26 of 103] vs. 11.9% [12 of 101]; P = 0.019). Multiplex ELISA measured significantly increased concentrations of several inflammatory cytokines and chemokines in maternal and cord blood from newborns, with evidence of viral exposure in utero compared with control dyads. Prenatal infection was associated with significantly lower birth weight and postnatal weight growth. Conclusions: Data suggest a higher frequency of vertical transmission for RSV than SARS-CoV-2. Intrauterine exposure is associated with fetal inflammation driven by soluble inflammatory mediators, with expression profiles dependent on the virus type and affecting the rate of viral transmission. Virus-induced inflammation may have pathological consequences already in the first days of life, as shown by its effects on birth weight and postnatal weight growth.

Renin-a in the Subfornical Organ Plays a Critical Role in the Maintenance of Salt-Sensitive Hypertension.

The brain renin-angiotensin system plays important roles in blood pressure and cardiovascular regulation. There are two isoforms of prorenin in the brain: the classic secreted form (prorenin/sREN) encoded by renin-a, and an intracellular form (icREN) encoded by renin-b. Emerging evidence indicates the importance of renin-b in cardiovascular and metabolic regulation. However, the role of endogenous brain prorenin in the development of salt-sensitive hypertension remains undefined. In this study, we test the hypothesis that renin-a produced locally in the brain contributes to the pathogenesis of hypertension. Using RNAscope, we report for the first time that renin mRNA is expressed in several regions of the brain, including the subfornical organ (SFO), the paraventricular nucleus of the hypothalamus (PVN), and the brainstem, where it is found in glutamatergic, GABAergic, cholinergic, and tyrosine hydroxylase-positive neurons. Notably, we found that renin mRNA was significantly elevated in the SFO and PVN in a mouse model of DOCA-salt-induced hypertension. To examine the functional importance of renin-a in the SFO, we selectively ablated renin-a in the SFO in renin-a-floxed mice using a Cre-lox strategy. Importantly, renin-a ablation in the SFO attenuated the maintenance of DOCA-salt-induced hypertension and improved autonomic function without affecting fluid or sodium intake. Molecularly, ablation of renin-a prevented the DOCA-salt-induced elevation in NADPH oxidase 2 (NOX2) in the SFO without affecting NOX4 or angiotensin II type 1 and 2 receptors. Collectively, our findings demonstrate that endogenous renin-a within the SFO is important for the pathogenesis of salt-sensitive hypertension.

High glucose induces trafficking of prorenin receptor and stimulates profibrotic factors in the collecting duct.

Growing evidence indicates that prorenin receptor (PRR) is upregulated in collecting duct (CD) of diabetic kidney. Prorenin is secreted by the principal CD cells, and is the natural ligand of the PRR. PRR activation stimulates fibrotic factors, including fibronectin, collagen, and transforming growth factor-ß (TGF-ß) contributing to tubular fibrosis. However, whether high glucose (HG) contributes to this effect is unknown. We tested the hypothesis that HG increases the abundance of PRR at the plasma membrane of the CD cells, thus contributing to the stimulation of downstream fibrotic factors, including TGF-ß, collagen I, and fibronectin. We used streptozotocin (STZ) male Sprague-Dawley rats to induce hyperglycemia for 7 days. At the end of the study, STZ-induced rats showed increased prorenin, renin, and angiotensin (Ang) II in the renal inner medulla and urine, along with augmented downstream fibrotic factors TGF-ß, collagen I, and fibronectin. STZ rats showed upregulation of PRR in the renal medulla and preferential distribution of PRR on the apical aspect of the CD cells. Cultured CD M-1 cells treated with HG (25 mM for 1 h) showed increased PRR in plasma membrane fractions compared to cells treated with normal glucose (5 mM). Increased apical PRR was accompanied by upregulation of TGF-ß, collagen I, and fibronectin, while PRR knockdown prevented these effects. Fluorescence resonance energy transfer experiments in M-1 cells demonstrated augmented prorenin activity during HG conditions. The data indicate HG stimulates profibrotic factors by inducing PRR translocation to the plasma membrane in CD cells, which in perspective, might be a novel mechanism underlying the development of tubulointerstitial fibrosis in diabetes mellitus.

Measurement of respiratory function in isolated cardiac mitochondria using Seahorse XFe24 Analyzer: applications for aging research.

Mitochondria play a critical role in the cardiomyocyte physiology by generating majority of the ATP required for the contraction/relaxation through oxidative phosphorylation (OXPHOS). Aging is a major risk factor for cardiovascular diseases (CVD) and mitochondrial dysfunction has been proposed as potential cause of aging. Recent technological innovations in Seahorse XFe24 Analyzer enhanced the detection sensitivity of oxygen consumption rate and proton flux to advance our ability study mitochondrial function. Studies of the respiratory function tests in the isolated mitochondria have the advantages to detect specific defects in the mitochondrial protein function and evaluate the direct mitochondrial effects of therapeutic/pharmacological agents. Here, we provide the protocols for studying the respiratory function of isolated murine cardiac mitochondria by measuring oxygen consumption rate using Seahorse XFe24 Analyzer. In addition, we provide details about experimental design, measurement of various respiratory parameters along with interpretation and analysis of data.

The role of IL-6 in the physiologic versus hypertensive blood pressure actions of angiotensin II.

Angiotensin II (AngII) is a critical physiologic regulator of volume homeostasis and mean arterial pressure (MAP), yet it also is known to induce immune mechanisms that contribute to hypertension. This study determined the role of interleukin-6 (IL-6) in the physiologic effect of AngII to maintain normal MAP during low-salt (LS) intake, and whether hypertension induced by plasma AngII concentrations measured during LS diet required IL-6. IL-6 knockout (KO) and wild-type (WT) mice were placed on LS diet for 7 days, and MAP was measured 19 h/day with telemetry. MAP was not affected by LS in either group, averaging 101 ± 4 and 100 ± 4 mmHg in WT and KO mice, respectively, over the last 3 days. Seven days of ACEI decreased MAP ~25 mmHg in both groups. In other KO and WT mice, AngII was infused at 200 ng/kg per minute to approximate plasma AngII levels during LS. Surgical reduction of kidney mass and high-salt diet were used to amplify the blood pressure effect. The increase in MAP after 7 days was not different, averaging 20 ± 5 and 22 ± 6 mmHg in WT and KO mice, respectively. Janus Kinase 2 (JAK2)/signal transducer of activated transcription (STAT3) phosphorylation were not affected by LS, but were increased by AngII infusion at 200 and 800 ng/kg per minute. These data suggest that physiologic levels of AngII do not activate or require IL-6 to affect blood pressure significantly, whether AngII is maintaining blood pressure on LS diet or causing blood pressure to increase. JAK2/STAT3 activation, however, is tightly associated with AngII hypertension, even when caused by physiologic levels of AngII.