Recent advance in macrophage pattern recognition receptors for lipopolysaccharide recognition

Sepsis is systemic inflammatory response syndrome (SIRS) associated with the presence of pathogenic microorganisms or their toxin. Lipopolysaccharide (LPS) is an important component of the outer membrane of Gram negative bacteria and has a pivotal role in inducing Gram negative sepsis. Macrophages play an essential role in infection and inflammation. Specific recognition of LPS is of particular importance in the defense system and pattern recognition receptors (PRR) have been considered to be important in initial steps for cellular recognition of LPS and consequence initiation of LPS responses. In the past few years, intense research in the fields of PRR and their recognition mechanism has been achieved. In this review, we attempt to expound recent research advances of macrophage PRRs for LPS recognition and their mechanism.     

High glucose up-regulates TRAIL-R4 expression in THP-1 cells and smooth muscle cells

AIM: To evaluate the expression of TNF-related apoptosis inducing ligand receptor 4 (TRAIL-R4) of THP-1 cells and human aorta smooth muscle cells under high glucose intervention. METHODS: Monocytic cell line THP-1 was incubated with PMA to induce to mature macrophage, Adhesion molecules CD11b and CD11c were assessed by FACS. TRAIL-R4 levels in THP-1 cells treated with different glucose concentrations were determined by Western blotting. The changes of TRAIL-R4 protein expressions were observed at different time points in human aorta smooth muscle cells. Western blotting was employed to evaluate TRAIL-R4 levels after the intervention of PKC activator. RESULTS: Incubation with 160 nmol/L PMA induced mature macrophages. TRAIL-R4 expression was up-regulated after incubation with 20 mmol/L glucose in macrophages. TRAIL-R4 was elevated in a time course manner under high glucose level in human aorta smooth muscle cells. Moreover, activation of PKC induced TRAIL-R4 expressions. CONCLUSION: Up-regulated TRAIL-R4 protein levels induced by high glucose levels might inhibit apoptosis of monocytes and smooth muscle cells and contribute to the progression of atherosclerosis.     

强力天麻杜仲胶囊对小鼠巨噬细胞活性的调节作用

[目的]研究强力天麻杜仲胶囊对小鼠巨噬细胞活性的影响。[方法]将强力天麻杜仲胶囊,连续给小鼠灌胃2周,计数小鼠腹腔巨噬细胞总数。采用ELISA法检测腹腔巨噬细胞TNF-α和IL-1β分泌水平;通过腹腔巨噬细胞吞噬鸡红细胞试验检测小鼠巨噬细胞的吞噬能力。[结果]结果表明,强力天麻杜仲胶囊能够轻度抑制小鼠腹腔巨噬细胞数量,明显降低腹腔巨噬细胞TNF-α和IL-1β的分泌水平和抑制小鼠腹腔巨噬细胞吞噬鸡红细胞的能力。[结论]强力天麻杜仲胶囊可降低小鼠巨噬细胞活性。     

SUMO-specific protease 3 aggravates CaPO4-induced mouse abdominal aortic aneurysm formation by promoting macrophage polarization

AIMTo investigate the role of SUMO-specific protease 3 (SENP3) in macrophage polarization and calcium phosphate (CaPO₄)-induced abdominal aortic aneurysm (AAA) formation in mice. METHODS（1） Bone marrow-derived monocytes (BMDMs) in Senp3^flox/flox (wild-type, WT) mice and Senp3^flox/flox; Lyz2-Cre (monocyte-specific SENP3 knockout, i.e. conditioned knockout, cKO) mice were isolated and induced for M1 and M2 polarization. The mRNA and protein expression level of SENP3 were detected by RT-qPCR, Western blot and immunocytofluorescence, and the differential distribution of M1/M2 BMDMs from WT and cKO mice was analyzed. （2） CaPO₄ was administrated to induce AAA model in 8~12-week-old male WT and cKO mice. The AAA incidence, survival rate and maximal aortic diameter were analyzed between the 2 groups. Aortic aneurysm tissues were collected for pathological analysis, and the expression levels of SENP3, interleukin-1β (IL-1β), tumor necrosis factor-α (TNFα), IL-6 and matrix metalloproteinases-9 (MMP-9) were measured by RT-qPCR and Western blot. Dihydroethidium staining in situ in frozen sections was used to analyze the production of reactive oxygen species (ROS). （3） To explore the potential mechanisms, Western blot and co-immunoprecipitation were used to verify the de-SUMO modification of mitogen-activated protein kinase kinase 7 (MKK7) induced by SENP3. Besides, BMDMs were transfected with Flag-MKK7 wild type (Flag-MKK7 WT) and SUMO-modified site K18 mutant (Flag-MKK7 K18R mutant), and then M1 polarization of the cells was induced. The protein levels of p-JNK and MMP-9 in the 2 groups were determined by Western blot. RESULTS(1) SENP3 expression was up-regulated in M1 polarized macrophages (P<0.01), but was down-regulated in M2 polarized macrophages (P<0.01). The expression of SENP3 was decreased during the transformation of M1 to M2 in the macrophages (P<0.01), but was significantly up-regulated during the opposite process (P<0.01). Besides, more M1 macrophages and less M2 macrophages after induction were observed in the BMDMs from cKO mice than those from WT mice. (2) SENP3 expression was up-regulated in AAA tissues (P<0.05). The AAA incidence of cKO mice was significantly reduced after CaPO₄ induction (P<0.01), the survival rate was significantly improved (P<0.05), and maximal aortic diameter was significantly reduced in cKO group (P<0.01). The levels of IL-1β, IL-6 and TNFα, and the production of ROS were significantly down-regulated (P<0.01), meanwhile MMP-9 expression was also down-regulated in cKO mice (P<0.05). (3) the SUMO2/3 modification of MKK7 was reduced during M1 polarization, and MKK7 interaction with SENP3 was enhanced. Significantly up-regulated protein level of p-JNK and MMP-9 were verified in the M1 macrophages transfected with Flag-MKK7 K18R mutant (P<0.05). CONCLUSION SENP3 activates the MAPK/JNK pathway via de-SUMOylation of MKK7, regulates the M1/M2 polarization of macrophages and promotes the protein level of MMP-9, thus aggravating AAA formation.     

Improvement of insulin sensitivity by osteocalcin inhibits inflammation in the adipose tissue of obese mice

AIM: To explore the improving effect of osteocalcin on obesity-related insulin resistance and inflammation in the adipose tissue of obese mice.METHODS: The C57BL/6 mice were fed with high-fat diet for 12 weeks to obtain obese mice. Osteocalcin (30 ng/kg or 3 ng/kg) and saline solution (control) were intraperitoneally injected for other 4 weeks. The fat mass, body weight, serum triglycerides and serum free fatty acid were analyzed. Intraperitoneal glucose tolerance test and insulin tolerance test were carried out. Macrophage infiltration degree in the adipose tissue was observed by immunohistochemical staining. The mRNA expression of monocyte chemotactic protein-1 (MCP-1) and CD68 was detected by real-time fluorescence quantitative PCR.RESULTS: Osteocalcin (30 ng/kg or 3 ng/kg) treatment for 4 weeks significantly reduced the body weight, fat mass and insulin level, and improved abnormal glucose tolerance and insulin resistance in the obese mice. Moreover, the macrophage infiltration decreased, and the mRNA expression of MCP-1 and CD68 was down-regulated in the adipose tissue of obese mice treated with osteocalcin at 30 ng/kg.CONCLUSION: Osteocalcin at 30 ng/kg significantly reduces body weight and fat mass, and attenuates the severity of insulin resistance through down-regulating the mRNA expression of MCP-1 and CD68 and inbihiting macrophage infiltration in the adipose tissue of obese mice induced by high-fat diet.     

Fasudil ameliorates myocardial fibrosis by regulating polarization of macrophages in diabetic mice

AIM: To investigate the effect of hydroxyl fasudil (HF) on myocardial fibrosis and macrophage polarization in the diabetic (D) mice. METHODS: C57BL/6 mice (n=60) were randomly divided into normal saline group (NS group), normal+hydroxyl fasudil group (N+HF group), diabetes group (D+NS group), diabetes+low dose of HF group (D+LHF group), diabetes+middle dose of HF group (D+MHF group) and diabetes+high dose of HF group (D+HHF group). A mouse model of type 1 diabetes mellitus was established by intraperitoneal injection of streptozotocin (STZ). The mice in treatment groups received different doses of fasudil through intraperitoneal injection for 8 weeks. At the end of the study, the effects of fasudil at different doses on the body weight and blood glucose were observed. The histopathological changes of the cardiac tissues were observed by HE staining. The myocardial collagen volume fraction (CVF) was calculated by Masson staining. Immumohistochemical staining was used to test the macrophage polarization and protein expression of interleukin-6 (IL-6), tumor necrosis factor-α(TNF-α) and IL-10 and Western blot was applied to determine the protein levels of p-MYPT1 Thr853, inducible nitric oxide synthase (iNOS) and Arginase-1 (Arg-1).RESULTS: Compared with NS group, the body weight of the mice in D+NS group was decreased and the blood glucose was increased significantly(P<0.05). However, no statistically difference of blood glucose and body weight between the treatment groups and D+NS group was observed. Compared with NS group, CVF, the number of M1-type macrophages and the protein levels of IL-6, TNF-α, p-MYPT1 Thr853 and iNOS were increased markedly, while M2-type macrophages and the expression of IL-10 and Arg-1 were decreased in D+NS group (P<0.05). Compared with D+NS group, CVF, the number of M1-type macrophages, and the protein levels of IL-6 and TNF-α were relatively decreased, conversely the number of M2-type macrophages and the protein level of IL-10 was increased in treatment groups (P<0.05). Moreover, the protein levels of p-MYPT1 Thr853 and iNOS were reduced and the protein level of Arg-1 was increased in D+MHF and D+HHF group compared with D+NS group (P<0.05). No statistical difference in above mentioned indexes between NS group and N+HF group was observed. CONCLUSION: Fasudil significantly attenuates the myocardial fibrosis of diabetic cardiomyopathy in mice, which is possibly related to increased polarization of M2-type macrophages, decreased polarization of M1-type macrophages and inflammation.     

Role of receptors for oxidized low-density lipoprotein in pathogenesis of atherosclerosis

The formation of atherosclerosis （AS） is an evolutionary process. It undergoes lipid deposition， focal fibrosis in the intima of the arteries and atherosclerotic plaque formation， resulting in hardening of the vessel wall and stenosis of the lumen， which eventually leads to ischemic changes in the corresponding organs. In these processes， oxidized low-density lipoprotein （oxLDL）， an oxidative product of low-density lipoprotein， is considered to be a key trigger for AS development. In this paper， the role of the receptors for oxLDL in the development of AS is reviewed based on the recent studies.     

甘肃省马类动物气喘病病理研究

用电子探针、光镜与电镜对甘肃河西地区12例气喘病畜进行了病理研究。这些病畜包括马5例、骡5例和驴2例,年龄为5～18岁。病肺高度膨大,其切面细支气管明显。主要组织变化有慢性支气管炎和血管周炎、间质性肺炎、内含折光性无机粉尘的巨噬细胞和巨细胞。从这些病例的肺中分到了普通高温放线菌、干草小多孢菌、热吸水链霉菌和高大毛霉菌。在肺尘细胞中看到了线粒体空泡化和内织网脱粒等超微结构变化。同时这些细胞的无机元素(铝、硅等)含量增加。因此认为甘肃马气喘病是一种由外界吸入的无机与有机尘所致的混合性尘肺。