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Respiratory syncytial virus (RSV) is a leading cause of severe lower respiratory tract infection in early childhood. Underlying pathomechanisms of elevated pulmonary morbidity in later infancy are largely unknown. We found that RSV‐infected H441 cells showed increased mRNA expression of connective tissue growth factor (CTGF), a key factor in airway remodeling. Additional dexamethasone treatment led to further elevated mRNA levels, indicating additive effects. Caffeine treatment prevented RSV‐mediated increase in CTGF mRNA. RSV may be involved in airway remodeling processes by increasing CTGF mRNA expression. Caffeine might abrogate these negative effects and thereby help to restore lung homeostasis.
Effect of progesterone on Smad signaling and TGF-β/Smad-regulated genes in lung epithelial cells
(2018)
The effect of endogenous progesterone and/or exogenous pre- or postnatal progesterone application on lung function of preterm infants is poorly defined. While prenatal progesterone substitution may prevent preterm birth, in vitro and in vivo data suggest a benefit of postnatal progesterone replacement on the incidence and severity of bronchopulmonary dysplasia (BPD). However, the molecular mechanisms responsible for progesterone’s effects are undefined. Numerous factors are involved in lung development, airway inflammation, and airway remodeling: the transforming growth factor beta (TGF-β)/mothers against decapentaplegic homolog (Smad) signaling pathway and TGF-β-regulated genes, such as connective tissue growth factor (CTGF), transgelin (TAGLN), and plasminogen activator inhibitor-1 (PAI-1). These processes contribute to the development of BPD. The aim of the present study was to clarify whether progesterone could affect TGF-β1-activated Smad signaling and CTGF/transgelin/PAI-1 expression in lung epithelial cells. The pharmacological effect of progesterone on Smad signaling was investigated using a TGF-β1-inducible luciferase reporter and western blotting analysis of phosphorylated Smad2/3 in A549 lung epithelial cells. The regulation of CTGF, transgelin, and PAI-1 expression by progesterone was studied using a promoter-based luciferase reporter, quantitative real-time PCR, and western blotting in the same cell line. While progesterone alone had no direct effect on Smad signaling in lung epithelial cells, it dose-dependently inhibited TGF-β1-induced Smad3 phosphorylation, as shown by luciferase assays and western blotting analysis. Progesterone also antagonized the TGF-β1/Smad-induced upregulation of CTGF, transgelin, and PAI-1 at the promoter, mRNA, and/or protein levels. The present study highlights possible new molecular mechanisms involving progesterone, including inhibition of TGF-β1-activated Smad signaling and TGF-β1-regulated genes involved in BPD pathogenesis, which are likely to attenuate the development of BPD by inhibiting TGF-β1-mediated airway remodeling. Understanding these mechanisms might help to explain the effects of pre- or postnatal application of progesterone on lung diseases of preterm infants.
Background: Recurrent airway infections are common in patients with Down’s syndrome (DS). Hence, ruling out Cystic Fibrosis (CF) in these patients is often required. In the past, the value of sweat testing – the gold standard to diagnose CF – has been questioned in DS as false positive results have been reported. However, these reports are based on measurements of sweat osmolality or sodium concentrations, not chloride concentrations. This study analyses sweat secretion rate and chloride concentration in sweat samples of patients with DS in comparison to healthy controls.
Methods: We assessed sweat samples in 16 patients with DS and 16 healthy controls regarding sweat secretion rate (SSR) and sweat chloride concentration.
Results: All measured chloride concentrations were within the normal range. The chloride concentrations were slightly, but not significantly lower in patients with DS (15,54 mmol/l (±4,47)) compared to healthy controls (18,31 mmol/l (±10,12)). While no gender gap in chloride concentration could be found, chloride concentration increased with age in both groups.
Insufficient sweat was collected in 2 females with DS (12.5% of the study group) but not in an individual of the control group. A significant lower sweat secretion rate was found in the DS group (27,6 μl/30 min (± 12,18)) compared to the control group (42,7 μl/30 min (± 21,22)). In a sub-analysis, female patients produced significantly less sweat (20,8 ± 10,6 μl/30 min) than male patients with DS (36,4 ± 7,8 μl/30 min), which accounts for the difference between patients and controls. Furthermore, while the sweating secretion rate increased with age in the control group, it did not do so in the DS group. Once again this was due to female patients with DS, who did not show a significant increase of sweat secretion rate with age.
Conclusions: Sweat chloride concentrations were within the normal range in patients with DS and therefore seem to be a reliable tool for testing for CF in these patients. Interestingly, we found a reduced sweat secretion rate in the DS group. Whether the last one has a functional and clinical counterpart, possibly due to a disturbed thermoregulation in DS patients, requires further investigation.