MerTK negatively regulates Staphylococcus aureus induced inflammatory response via SOCS1/SOCS3 and Mal
IMMUNOBIOLOGY
Authors: Zahoor, Arshad; Yang, Chao; Yang, Yaping; Akhtar, Muhammad; Umar, Talha; Khan, Murad Ali; Ahmad, Shakoor; Deng, Ganzhen; Guo, Meng-yao
Abstract
Objective: Staphylococcus aureus (S. aureus), one of Gram-positive pathogen, is frequently associated with acute lung inflammation. The central feature of S. aureus acute lung inflammation are pulmonary dysfunctioning and impeded host defence response, which cause failure in inflammatory cytokines homeostasis and leads to serious tissue damage. However, the role of the Mer receptor tyrosine kinase (MerTK) in the lung following S. aureus infection remains elusive. Here, we investigate whether MerTK alleviates S. aureus induced uncontrolled inflammation through negatively regulating toll-like receptor 2 and 6 (TLR2/ TLR6) via suppressor of cytokine signalling 1, 3 (SOCS1/SOCS3). Methods and results: We found in mice lung tissues and RAW 264.7 macrophages upon S. aureus infection activates TLR2 and TLR6 driven mitogen-activated protein kinases (MAPKs) and nuclear factor kappa B (NF-kappa B) signalling pathways, resulting in production of inflammatory cytokines including tumour necrosis factor-alpha (TNF-alpha), interleukin 1 beta (IL-1 beta), interleukin 6 (IL-6). Furthermore, S. aureus-infection groups showed a significant upregulation of MerTK which serves as mediator of SOCS1 and SOCS3. Subsequently, through feedback mechanism SOCS1/3 degrade Mal, resulting in inhibition of downstream TLR mediated inflammatory pathways. Moreover, MerTK(-/-) mice lung tissues and silencing MerTK in RAW 264.7 inhibited the S. aureus-induced activation of MerTK, which significantly upregulated the phosphorylation of crucial protein in MAPKs (ERK, JNK, p38) and NF-kappa B (I kappa B alpha, p65) signalling pathways, as well as the production of pro-inflammatory cytokines. Conclusion: Collectively, these findings indicate the important role of MerTK in self-regulatory resolution of S. aureus-induced inflammatory pathways and cytokines through intrinsic SOCS1 and SOCS3 repressed feedback on TLR2, TLR6 both in vivo and in vitro.
Whole Blood DNA Methylation Signatures of Diet Are Associated With Cardiovascular Disease Risk Factors and All-Cause Mortality
CIRCULATION-GENOMIC AND PRECISION MEDICINE
Authors: Ma, Jiantao; Rebholz, Casey M.; Braun, Kim V. E.; Reynolds, Lindsay M.; Aslibekyan, Stella; Xia, Rui; Biligowda, Niranjan G.; Huan, Tianxiao; Liu, Chunyu; Mendelson, Michael M.; Joehanes, Roby; Hu, Emily A.; Vitolins, Mara Z.; Wood, Alexis C.; Lohman, Kurt; Ochoa-Rosales, Carolina; van Meurs, Joyce; Uitterlinden, Andre; Liu, Yongmei; Elhadad, Mohamed A.; Heier, Margit; Waldenberger, Melanie; Peters, Annette; Colicino, Elena; Whitsel, Eric A.; Baldassari, Antoine; Gharib, Sina A.; Sotoodehnia, Nona; Brody, Jennifer A.; Sitlani, Colleen M.; Tanaka, Toshiko; Hill, W. David; Corley, Janie; Deary, Ian J.; Zhang, Yan; Schoettker, Ben; Brenner, Hermann; Walker, Maura E.; Ye, Shumao; Nguyen, Steve; Pankow, Jim; Demerath, Ellen W.; Zheng, Yinan; Hou, Lifang; Liang, Liming; Lichtenstein, Alice H.; Hu, Frank B.; Fornage, Myriam; Voortman, Trudy; Levy, Daniel
Abstract
Background: DNA methylation patterns associated with habitual diet have not been well studied. Methods: Diet quality was characterized using a Mediterranean-style diet score and the Alternative Healthy Eating Index score. We conducted ethnicity-specific and trans-ethnic epigenome-wide association analyses for diet quality and leukocyte-derived DNA methylation at over 400 000 CpGs (cytosine-guanine dinucleotides) in 5 population-based cohorts including 6662 European ancestry, 2702 African ancestry, and 360 Hispanic ancestry participants. For diet-associated CpGs identified in epigenome-wide analyses, we conducted Mendelian randomization (MR) analysis to examine their relations to cardiovascular disease risk factors and examined their longitudinal associations with all-cause mortality. Results: We identified 30 CpGs associated with either Mediterranean-style diet score or Alternative Healthy Eating Index, or both, in European ancestry participants. Among these CpGs, 12 CpGs were significantly associated with all-cause mortality (Bonferroni correctedP<1.6x10(-3)). Hypermethylation of cg18181703 (SOCS3) was associated with higher scores of both Mediterranean-style diet score and Alternative Healthy Eating Index and lower risk for all-cause mortality (P=5.7x10(-15)). Ten additional diet-associated CpGs were nominally associated with all-cause mortality (P<0.05). MR analysis revealed 8 putatively causal associations for 6 CpGs with 4 cardiovascular disease risk factors (body mass index, triglycerides, high-density lipoprotein cholesterol concentrations, and type 2 diabetes mellitus; Bonferroni corrected MRP<4.5x10(-4)). For example, hypermethylation of cg11250194 (FADS2) was associated with lower triglyceride concentrations (MR,P=1.5x10(-14)).and hypermethylation of cg02079413 (SNORA54;NAP1L4) was associated with body mass index (corrected MR,P=1x10(-6)). Conclusions: Habitual diet quality was associated with differential peripheral leukocyte DNA methylation levels of 30 CpGs, most of which were also associated with multiple health outcomes, in European ancestry individuals. These findings demonstrate that integrative genomic analysis of dietary information may reveal molecular targets for disease prevention and treatment.