Ablation of C-type natriuretic peptide/cGMP signaling in fibroblasts exacerbates adverse cardiac remodeling in mice

Excessive activation of cardiac fibroblasts (CFs) in response to injury provokes cardiac fibrosis, stiffness, and failure. The local mediators counter-regulating this response remain unclear. Exogenous C-type natriuretic peptide (CNP) exerted antifibrotic effects in preclinical models. To unravel the role of the endogenous hormone, we generated mice with fibroblast-restricted deletion (KO) of guanylyl cyclase-B (GC-B), the cGMP-synthesizing CNP receptor.CNP activated GC-B/cGMP signaling in human and murine CFs, preventing proliferative and promigratory effects of AngiotensinII (AngII) and TGF-β. Fibroblast-specific GC-B-KO mice showed enhanced fibrosis in response to AngII infusions. Moreover, after two weeks of mild pressure-overload induced by transverse aortic constriction (TAC), such KO mice had augmented cardiac fibrosis and hypertrophy, together with systolic and diastolic contractile dysfunction. This was associated with increased expression of the profibrotic genes collagen I, III and periostin. Notably, such responses to AngII and TAC were greater in female as compared to male KO mice. Enhanced AngII-induced CNP expression in female hearts and augmented GC-B expression and activity in female CFs may contribute to this sex disparity.The results show that paracrine CNP signaling in CFs has antifibrotic and antihypertrophic effects. The CNP/GC-B/cGMP pathway might be a target for therapies combating pathological cardiac remodeling.

Comparing in vivo biodistribution with radiolabeling and Franz cell permeation assay to validate the efficacy of both methodologies in the evaluation of nanoemulsions: a safety approach

The Franz cells permeation assay has been performed for over 25 years. However, the advent of nanotechnology created a whole new world, especially with regard to topical products. In this new global scenario an increasing number of nanostructure-based delivery systems (NDSs) have emerged and a global warning relating to the safety of these NDSs is arising. This work studied the efficacy of the Franz cells assay, comparing it with the radiolabeling biodistribution test. For this purpose a formulation of sunscreen based on an NDS was developed and characterized. The results demonstrated both that the NDS did not present in vitro cytotoxicity and that the radiolabeling biodistribution test is more precise for the evaluation of NDS cosmetics than the Franz cells assay, since it detected the permeation of the NDS at a picogram order. Due to this fact, and considering all the concerns related to NDSs and nanoparticles in general, more precise methods must be used in order to guarantee the safe use of these new classes of products.

Preliminary studies towards utilization of various plant extracts as antisolar agents

Synopsis The aim of this work was to evaluate several plant extracts with regard to ultraviolet absorption spectra in view of a possible application as antisolar agents. Liquid and dry extracts of Hamamelis virginiana, Matricaria recutita, Aesculus hippocastanum, Rhamnus purshiana and Cinnamomum zeylanicum were prepared by repercolation, maceration and microwave oven extraction. UVB absorption spectra (290-320nm) were obtained and the solar protection factors (SPF) of these preparations were determined by a spectrophotometric method. The results showed that after incorporation to a 2% solution of the synthetic sunscreen octylmethoxycinnamate, the extracts showed an intensification in SPF values, suggesting that this can be an interesting method to intensify SPF. In addition, these extracts can contribute their emollient and moistening properties to the product. These are important characteristics for protecting skin against exposure to the sun.