Drug repurposing of histone deacetylase inhibitors that alleviate neutrophilic inflammation in acute lung injury and idiopathic pulmonary fibrosis via inhibiting leukotriene a4 hydrolase and blocking LTB4 biosynthesis

OBJECTIVE Leukotriene B4(LTB4)biosynthesis and subsequently neutrophilic inflammation may provide a potential strategy for the treatment of acute lung injury(ALI)or idiopathic pulmonary fibrosis(IPF).To provide a potential strategy for the treatment of ALI or IPF,we identified potent inhibitors of Leukotriene A4 hydrolase(LTA4H),a key enzyme in the biosynthesis of LTB4.METHODS In this study,we identified two known histone deacetylase(HDAC)inhibitors,suberanilohydroxamic acid(SAHA)and its analogue 4-(dimethylamino)-N-[7-(hydroxyamino)-7-oxoheptyl]benzamide(M344),as effective inhibitors of LTA4H using enzymatic assay,thermofluor assay,and X-ray crystallographic investigation.We next tested the effect of SAHA and M344 on endogenous LTB4 biosynthesis in neutrophils by ELISA and neutrophil migration by transwell migration assay.A murine experimental model of ALI was induced by lipopolysaccharide(LPS)inhalation.Histopathological analysis of lung tissue using H&E staining revealed the serious pulmonary damage caused by LPS treatment and the effect of the SAHA.We next examined m RNA and protein levels of pro-inflammatory cytokines in lung tissue and bronchoalveolar lavage fluid using q RT-PCR and ELISA to further investigate the underlying mechanisms of anti-inflammatory activities by SAHA.We also investigated the effects of SAHA and M344 on a murine experimental model of bleomycin(BLM)-induced IPF model.RESULTS The results of enzymatic assay and X-ray crystallography showed that both SAHA and M344 bind to LTA4H,significantly decrease LTB4 levels in neutrophil,and markedly diminish early neutrophilic inflammation in mouse models of ALI and IPF under a clinical safety dose.CONCLUSION Collectively,SAHA and M344 would provide promising agents with well-known clinical safety for potential treatment in patients with ALI and IPF via pharmacologically inhibiting LAT4H and blocking LTB4 biosynthesis.

Expression of fatty acid sensing G-protein coupled receptors in peripartal Holstein cows

Background： G-protein coupled receptors（GPCR）, also referred as Free Fatty Acid Receptors（FFAR）, are widely studied within human medicine as drug targets for metabolic disorders. To combat metabolic disorders prevalent in dairy cows during the transition period, which co-occur with negative energy balance and changes to lipid and glucose metabolism, it may be helpful to identify locations and roles of FFAR and other members of the GPCR family in bovine tissues.Results： Quantitative RT-PCR（qPCR） of subcutaneous adipose, liver, and PMNL samples during the transition period（-10, ＋7, and ＋20 or ＋30 d） were used for expression profiling of medium-（MCFA） and long-chain fatty acid（LCFA）receptors GPR120 and GPR40, MCFA receptor GPR84, and niacin receptor HCAR2/3. Adipose samples were obtained from cows with either high（HI; BCS ≥ 3.75） or low（LO; BCS ≤ 3.25） body condition score（BCS） to examine whether FFAR expression is correlated with this indicator of health and body reserves. Supplementation of rumen-protected methionine（MET）, which may improve immune function and production postpartum, was also compared with unsupplemented control（CON） cows for liver and blood polymorphonuclear leukocytes（PMNL） samples. In adipose tissue, GPR84 and GPR120 were differentially expressed over time, while GPR40 was not expressed; in PMNL, GPR40 was differentially expressed over time and between MET vs. CON, GPR84 expression differed only between dietary groups, and GPR120 was not expressed; in liver, GPCR were either not expressed or barely detectable.Conclusions： The data indicate that there is likely not a direct role in liver for the selected GPCR during the transition period, but they do play variable roles in adipose and PMN. In future, these receptors may prove useful targets and/or markers for peripartal metabolism and immunity.

Emerging roles and therapeutic implications of HDAC2 and IL-17A in steroid-resistant asthma

Steroid resistance represents a major clinical problem in the treatment of severe asthma,and therefore a better understanding of its pathogenesis is warranted.Recent studies indicated that histone deacetylase 2(HDAC2)and interleukin 17A(IL-17A)play important roles in severe asthma.HDAC2 activity is reduced in patients with severe asthma and smoking-induced asthma,perhaps accounting for the amplified expression of inflammatory genes,which is associated with increased acetylation of glucocorticoid receptors.Neutrophilic inflammation contributes to severe asthma and may be related to T helper(Th)17 rather than Th2 cytokines.IL-17A levels are elevated in severe asthma and correlate with the presence of neutrophils.Restoring the activity of HDAC2 or targeting the Th17 signaling pathway is a potential therapeutic approach to reverse steroid insensitivity.