Genetic Interactions between Chromosomes 11 and 18 Contribute to Airway Hyperresponsiveness in Mice

We used two-dimensional quantitative trait locus analysis to identify interacting genetic loci that contribute to the native airway constrictor hyperresponsiveness to methacholine that characterizes A/J mice, relative to C57BL/6J mice. We quantified airway responsiveness to intravenous methacholine boluses in eighty-eight (C57BL/6J X A/J) F2 and twenty-seven (A/J X C57BL/6J) F2 mice as well as ten A/J mice and six C57BL/6J mice; all studies were performed in male mice. Mice were genotyped at 384 SNP markers, and from these data two-QTL analyses disclosed one pair of interacting loci on chromosomes 11 and 18; the homozygous A/J genotype at each locus constituted the genetic interaction linked to the hyperresponsive A/J phenotype. Bioinformatic network analysis of potential interactions among proteins encoded by genes in the linked regions disclosed two high priority subnetworks - Myl7, Rock1, Limk2; and Npc1, Npc1l1. Evidence in the literature supports the possibility that either or both networks could contribute to the regulation of airway constrictor responsiveness. Together, these results should stimulate evaluation of the genetic contribution of these networks in the regulation of airway responsiveness in humans

Airway smooth muscle as a target of asthma therapy: history and new directions

Ultimately, asthma is a disease characterized by constriction of airway smooth muscle (ASM). The earliest approach to the treatment of asthma comprised the use of xanthines and anti-cholinergics with the later introduction of anti-histamines and anti-leukotrienes. Agents directed at ion channels on the smooth muscle membrane (Ca(2+ )channel blockers, K(+ )channel openers) have been tried and found to be ineffective. Functional antagonists, which modulate intracellular signalling pathways within the smooth muscle (β-agonists and phosphodiesterase inhibitors), have been used for decades with success, but are not universally effective and patients continue to suffer with exacerbations of asthma using these drugs. During the past several decades, research energies have been directed into developing therapies to treat airway inflammation, but there have been no substantial advances in asthma therapies targeting the ASM. In this manuscript, excitation-contraction coupling in ASM is addressed, highlighting the current treatment of asthma while proposing several new directions that may prove helpful in the management of this disease

Towards the Maturation and Characterization of Smooth Muscle Cells Derived from Human Embryonic Stem Cells

In this study we demonstrate that CD34+ cells derived from human embryonic stem cells (hESCs) have higher smooth muscle cell (SMC) potential than CD34− cells. We report that from all inductive signals tested, retinoic acid (RA) and platelet derived growth factor (PDGFBB) are the most effective agents in guiding the differentiation of CD34+ cells into smooth muscle progenitor cells (SMPCs) characterized by the expression of SMC genes and proteins, secretion of SMC-related cytokines, contraction in response to depolarization agents and vasoactive peptides and expression of SMC-related genes in a 3D environment. These cells are also characterized by a low organization of the contractile proteins and the contractility response is mediated by Ca2+, which involves the activation of Rho A/Rho kinase- and Ca2+/calmodulin (CaM)/myosin light chain kinase (MLCK)-dependent pathways. We further show that SMPCs obtained from the differentiation of CD34+ cells with RA, but not with PDGFBB, can be maturated in medium supplemented with endothelin-1 showing at the end individualized contractile filaments. Overall the hESC-derived SMCs presented in this work might be an unlimited source of SMCs for tissue engineering and regenerative medicine.Marie Curie-Reintegration GrantMIT-Portugal programCrioestaminalAssociação Viver a CiênciaFundação para a Ciência e a Tecnologia (PTDC/SA-BEB/098468/2008 and PTDC/CTM/099659/2008 to L.F.; SFRH/BD/40077/2007 to H.V.