One-hit wonder: Late after burn injury,granulocytes can clear one bacterial infection but cannot control a subsequent infection

ObjectiveBurn injury induces an acute hyperactive immune response followed by a chronic immune dysregulation that leaves those afflicted susceptible to multiple secondary infections. Many murine models are able to recapitulate the acute immune response to burn injury, yet few models are able to recapitulate long-term immune suppression and thus chronic susceptibility to bacterial infections seen in burn patients. This has hindered the field, making evaluation of the mechanisms responsible for these susceptibilities difficult to study. Herein we describe a novel mouse model of burn injury that promotes chronic immune suppression allowing for susceptibility to primary and secondary infections and thus allows for the evaluation of associated mechanisms.MethodsC57Bl/6 mice receiving a full-thickness contact burn were infected with Pseudomonas aeruginosa 14 days (primary infection) and/or 17 days (secondary infection) after burn or sham injury. The survival, pulmonary and systemic bacterial load as well as frequency and function of innate immune cells (neutrophils and macrophages) were evaluated.ResultsFollowing secondary infection, burn mice were less effective in clearance of bacteria compared to sham injured or burn mice following a primary infection. Following secondary infection both neutrophils and macrophages recruited to the airways exhibited reduced production of anti-bacterial reactive oxygen and nitrogen species and the pro-inflammatory cytokineIL-12 while macrophages demonstrated increased expression of the anti-inflammatory cytokine interleukin-10 compared to those from sham burned mice and/or burn mice receiving a primary infection. In addition the BALF from these mice contained significantly higher level so of the anti-inflammatory cytokine IL-4 compared to those from sham burned mice and/or burn mice receiving a primary infection.ConclusionsBurn-mediated protection from infection is transient, with a secondary infection inducing immune protection to collapse. Repeated infection leads to increased neutrophil and macrophage numbers in the lungs late after burn injury, with diminished innate immune cell function and an increased anti-inflammatory cytokine environment.     

Human apolipoprotein A-I Gly26Arg stimulation of inflammatory responses via NF-kB activation: Potential roles in amyloidosis?

The cascade of molecular events leading to Human apolipoprotein A–I (apoA–I) amyloidosis is not completely understood, not even the pathways that determine clinical manifestations associated to systemic protein deposition in organs such as liver, kidney and heart. About twenty natural variants of apoA–I were described as inducing amyloidosis, but the mechanisms driving their aggregation and deposition are still unclear. We previously identified that the mutant Gly26Arg but not Lys107-0 induced the release of cytokines and reactive oxygen species from cultured RAW 264.7 murine macrophages, suggesting that part of the pathogenic pathway could elicit of an inflammatory signal. In this work we gained deep insight into this mechanism and determined that Gly26Arg induced a specific pro-inflammatory cascade involving activation of NF-κB and its translocation into the nucleus. These findings suggest that some but not all apoA–I natural variants might promote a pro-oxidant microenvironment which could in turn result in oxidative processing of the variants into a misfolded conformation.     

Correlation between Profile of Circulating Mononuclear Cells and Clinical Manifestations in Patients with Pemphigus Vulgaris

Phenotypes of 38 samples of mononuclear (PBMC) cells from 11 different patients with pemphigus vulgaris (PV) at different stages of the disease were explored looking for a possible relationship between cell immunity, mucocutaneous or mucosal lesion intensity and capacity of serum autoantibodies to elicit the disease in mice. PBMC from 5 patients with mucocutaneous lesions and sera with IgG capable of inducing the disease in neonatal mice had a high proportion of mature monocytes with CD14^lowDR ^gh and co-expresing CD16 and CDllb. In addition, a high proportion of CD19⁺CD5⁺ activated B cells and a very low proportion of naive CD4⁺CD45RA⁺ and CD8⁺CDllb⁺ T lymphocytes was observed. Monocytes from these patients expressed inducible nitric oxide synthase (iNOS). In contrast, PBMC from 6 patients, with lesions restricted to mucosal membranes and IgG lacking the capacity to induce the disease in mice, contained a high proportion of CD14^hlg DR^low co-expressing CD16 circulating macrophages, CD8⁺CDllb⁺ T cells, and a low proportion of activated B lymphocytes. The results suggest a possible association between proportion of different antigen presenting cells (monocytes with high HLA-DR and low CD 14 expression and activated B lymphocytes, or differentiated monocytes/macrophages), type of PV and capacity of serum autoantibodies to elicit the disease in mice     

Early Effects Triggered by Larrea divaricata Cav. on Murine Macrophages at Apoptotic Concentrations

Decoction and infusion of Larrea divaricata were tested at apoptotic concentrations (1 and 4 mg/ml) on peritoneal murine macrophages. Consistent changes were observed after incubation with 4 mg/ml decoction. Phagocytosis of zymosan, lysosomal enzyme activity, nitric oxide production, TNF-α release, and expression of CD14, TLR4, and CR3 increased significantly. Decoction at 1 and 4 mg/ml increased the binding of LPS-FITC. Apoptosis triggered by L. divaricata decoction is consequence of cell activation. The effects are independent of nordihydroguaiaretic acid. This “activation and death” could be the mechanism of L. divaricata to exert the antituberculosis effect known in folk medicine.     

巨噬细胞对小鼠诱导多能干细胞向肝祖细胞分化的影响

目的探讨巨噬细胞(Mc)对小鼠诱导多能干细胞(iPSCs)向肝祖细胞(HPCs)分化的影响。方法C57BL/6N小鼠24只,采取腹腔冲洗法获得巨噬细胞,收集上清获得巨噬细胞条件培养基(Mc-CDM)。通过激活素A、骨形态发生蛋白4和成纤维细胞生长因子等诱导小鼠iPSCs向HPCs分化。将HPCs的诱导分为两组,一组使用正常培养基,为对照组(Ctrl组);另一组在诱导D5使用Mc-CDM培养基,为实验组(Mc组)。通过形态学、免疫荧光、Western Blot检测方法,比较正常Ctrl组与Mc组HPCs的形态及相关蛋白表达的差异。计量资料两组间比较采用t检验。结果在体外建立了iPSCs来源的HPCs;HPCs具有向肝细胞分化的潜能。免疫荧光结果显示:与第12天的Ctrl组相比,第12天的Mc组的肝祖细胞特异性蛋白CK19的表达显著增高(0.901±0.072 vs 0.686±0.097,t=-3.093,P<0.05);Western Blot结果显示:与第12天Ctrl组相比,第12天Mc组肝祖细胞相关蛋白CK19的表达显著增高(1.922±0.103 vs 1.448±0.012,t=-7.881,P<0.05);同时,第12天Mc组自噬相关蛋白LC3的表达亦显著增高(1.392±0.042 vs 1.101±0.048,t=-5.978,P<0.05)。结论巨噬细胞可促进小鼠iPSCs向HPCs分化,其机制可能与HPCs细胞自噬水平增加有关。     

不同压力对巨噬细胞ATP结合盒转运子A1表达的影响

目的观察不同压力对巨噬细胞ABCA1 mRNA及蛋白表达的影响。方法将THP—1源巨噬细胞依照不同压力分为对照组、60组、80组、100组、120组、140组、160组和180组，分别在大气压下，60mmHg、80mmHg、100mmHg、120mmHg、140mmHg、160mmHg和180mmHg压力下继续培养48h。观察巨噬细胞ABCA1 mRNA及蛋白表达。结果60组、80组、100组、120组ABCA1 mRNA分别为1．11±0．08、1．31±0．04、1．53±0．11和1．15±0．07，较对照组（0．91±0．10）明显增加（P〈0．05或P〈0．01），以100组增加最显著；140组、160组和180组ABCA1mRNA分别为0．75±0．06，0．46±0．08及0．35±0．05，较对照组明显减少（P〈0．01）。ABCA1蛋白表达与mRNA情况相似：60组（1．09±0．06），80组（1．12±0．09），100组（1．41±0．06），120组（1．11±0．06）较对照组（1．00±0．00）明显增加（P〈0．05或P〈0．01），而140组（0．78±0．07）、160组（0．49±0．09）和180组（0．47±0．10）较对照组明显减少（P〈0．01）。结论压力在80---120mmHg范围时，压力升高促进了巨噬细胞ABCA1 mRNA及蛋白表达，压力〉120mmHg后，随着压力的增高，巨噬细胞ABCA1 mRNA及蛋白表达反而减少。     

巨噬细胞影响骨质疏松性骨折骨愈合的研究进展

骨质疏松性骨折愈合缓慢,预后差。募集的巨噬细胞极化为促炎M1型巨噬细胞及抑炎M2型巨噬细胞,两种亚型的动态平衡影响骨折愈合速度和预后。但在原发性骨质疏松性骨折及继发性骨质疏松性骨折中,M1型和M2型巨噬细胞极化失衡,严重影响骨折愈合。研究表明,通过一些生物学方法重建巨噬细胞极化平衡,如生物医用仿生材料和外泌体携载miRNA治疗等,可有效改善巨噬细胞表型极化,减少骨吸收,促进成骨分化,加速骨质疏松性骨折骨愈合。因此,笔者从巨噬细胞在骨折愈合过程中的作用、巨噬细胞极化失衡导致骨质疏松性骨折延迟愈合及重建巨噬细胞极化平衡加速骨质疏松性骨折骨愈合等方面,就巨噬细胞对骨质疏松性骨折骨愈合影响的研究进展进行综述,为临床治疗骨质疏松性骨折提供新的思路。