The alveolar type I epithelial cell forms the major cellular surface (ϳ70 m 2 , human) for gas exchange in the mammalian lung. Despite this important function, very little is known about its molecular phenotype or regulation of expression of its cell-specific genes (1). We have recently cloned, sequenced, and characterized a gene, T1␣, that we believe is the first definitive marker for this cell type in the adult rat lung (2, 3). The gene encodes an apical transmembrane protein that is expressed by type I cells but not by adjacent alveolar epithelial type II cells.Characterizing the regulation of this new marker for the type I cell phenotype is likely to be important for understanding the general processes by which type I cells differ in gene regulation, structure, and biology from other lung epithelial cells, particularly alveolar type II cells.Expression of T1␣ is developmentally regulated (2, 3). Both mRNA and protein are expressed in many fore-and midgut derivatives as early as embryonic day 10.5 (rat) including the primitive lung (day 12.5) and the anterior pituitary anlage (Rathke's pouch), in the early embryonic brain, spinal cord, other neural structures, and several other organs. In most of these tissues, however, expression is rapidly repressed during fetal development (brain) or postnatally (bronchiolar epithelium). In the adult rat, T1␣ mRNA and protein expression can be detected at high levels only in the alveolar type I cell, in choroid plexus epithelium, in ciliary body of the eye, and in a subset of osteoblasts (4, 5). These complex developmental temporal-spatial patterns suggest that active mechanisms of gene regulation determine the highly specific pattern of T1␣ expression in the adult.In situ hybridization, immunocytochemical, biochemical, and molecular analyses (2, 6) show that adult alveolar type II cells do not express T1␣ in vivo, although these cells reside in the alveolar epithelium and act as stem cells to generate new type I cells in normal and injured lung (7). However, when type II cells from normal lung are cultured under conditions where they do not proliferate, they rapidly (within Ͻ24 h) express both T1␣ mRNA and protein, while down-regulating type II cell genes (8).These and other similar findings suggest that type II and type I cell genes share certain common regulatory elements and transactivating molecules but not others, allowing for expression of their cell-specific phenotypes. There is now considerable information about the regulation of type II cell genes because of an interest in defining the molecular control of synthesis of pulmonary surfactant, a complex lipid-protein material secreted by type II cells. The promoters for surfactant protein (SP) 1 -A (9 -12), -B (13-17), -C (18, 19), -D (20), and Clara cell-specific protein (CCSP) (21-24) genes have been partially characterized, and some cis-regulatory elements and transactivating proteins have been identified. Most of these genes have in common their transactivation by 14,

Angiotensin converting enzyme (ACE) 2 is a carboxypeptidase that shares 42% amino acid homology with ACE. Little is known about the regulation or pattern of expression of ACE2 in the mouse lung, including its definitive cellular distribution or developmental changes. Based on Northern blot and RT-PCR data, we report two distinct transcripts of ACE2 in the mouse lung and kidney and describe a 5' exon 1a previously unidentified in the mouse. Western blots show multiple isoforms of ACE2, with predominance of a 75-80 kDa protein in the mouse lung versus a 120 kDa form in the mouse kidney. Immunohistochemistry localizes ACE2 protein to Clara cells, type II cells, and endothelium and smooth muscle of small and medium vessels in the mouse lung. ACE2 mRNA levels peak at embryonic day 18.5 in the mouse lung, and immunostaining demonstrates protein primarily in the bronchiolar epithelium at that developmental time point. In murine cell lines ACE2 is strongly expressed in the Clara cell line mtCC, as opposed to the low mRNA expression detected in E10 (type I-like alveolar epithelial cell line), MLE-15 (type II alveolar epithelial cell line), MFLM-4 (fetal pulmonary vasculature cell line), and BUMPT-7 (renal proximal tubule cell line). In summary, murine pulmonary ACE2 appears to be primarily epithelial, is developmentally regulated, and has two transcripts that include a previously undescribed exon.

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Background/Aims: Mastitis is an acute clinical inflammatory response. The occurrence and development of mastitis seriously disturb women's physical and mental health. Licochalcone A, a phenolic compound in Glycyrrhiza uralensis , has anti-inflammatory properties. Here, we examined the effect of licochalcone A on blood-milk barrier and inflammatory response in LPS-induced mice mastitis. Methods: In vivo , we firstly established mice models of mastitis by canal injection of LPS to mammary gland, and then detected the effect of licochalcone A on pathological indexes, inflammatory responses and blood-milk barrier in this model. In vivo , Mouse mammary epithelial cells (mMECs) were treated with licochalcone A prior to the incubation of LPS, and then the inflammatory responses, tight junction which is the basic structure of blood-milk barrier were analyzed. Last, we elucidated the anti-inflammatory mechanism by examining the activation of mitogen-activated protein kinase ( MAPK) and AKT/NF-κB signaling pathways in vivo and in vitro . Result: The in vivo results showed that licochalcone A significantly decreased the histopathological impairment and the inflammatory responses, and improved integrity of blood-milk barrier. The in vitro results demonstrated that licochalcone A inhibited LPS-induced inflammatory responses and increase the protein levels of ZO-1, occludin, and claudin3 in mMECs. The in vivo and in vitro mechanistic study found that the anti-inflammatory effect of licochalcone A in LPS-induced mice mastitis was mediated by MAPK and AKT/NF-κB signaling pathways. Conclusions and Implications: Our experiments collectively indicate that licochalcone A protected against LPS-induced mice mastitis via improving the blood–milk barrier integrity and inhibits the inflammatory response by MAPK and AKT/NF-κB signaling pathways.

Mastitis, an inflammation of mammary gland, is a serious disease that affects the health of dairy cows around the world. Myricetin, a flavonoid from Bayberry, has been reported to suppress various inflammatory response. The aim of this study was to evaluate the effect of myricetin on lipopolysaccharide (LPS)‐induced in vivo and in vitro mastitis model and clarify the underlying mechanism. In vivo experiments, myricetin attenuated the severity of inflammatory lesion and neutrophil infiltration. Moreover, myricetin pretreatment induced a significant decrease in the activity of myeloperoxidase (MPO) and the production of TNF‐α, IL‐6, and IL‐1β triggered by LPS. Myricetin pretreatment could also increase the integrity of the blood–milk barrier and upregulate the tight junction proteins in LPS‐induced mice mastitis. In vitro, myricetin inhibited LPS‐induced inflammatory response in mice mammary epithelial cells (mMECs). In the further mechanism studies, we found that the anti‐inflammatory effect of myricetin was mediated by inhibiting LPS‐induced phosphorylation of AKT, IKK‐α, IκB‐α, and P65 in vivo and in vitro. Collectively, these data suggested that myricetin effectively ameliorated the inflammatory response by inhibiting the AKT/IKK/NF‐κB signaling pathway and repairing the integrity of blood–milk barrier in LPS‐induced mice mastitis.