Zhang ZhanQin, Cui Ping, Zhang Kai, Chen QiXing, Fang XiangMing
From the Department of Anesthesiology and Intensive Care Unit, The First Affiliated Hospital (Z.Z., P.C., K.Z., X.F.) and Clinical Research Center, The Children's Hospital (Q.C.), School of Medicine, Zhejiang University, Hangzhou, China.
Anesthesiology. 2017 Jan;126(1):128-139. doi: 10.1097/ALN.0000000000001430.
Transient receptor potential melastatin 2 is a Ca-permeable cation channel abundantly expressed in macrophages. Trpm2 mice showed exacerbated infection and mortality during polymicrobial sepsis, which is associated with inefficient bacterial killing in macrophages. However, the mechanism of transient receptor potential melastatin 2 regulating bacterial killing remains unknown.
Trpm2 mice were intraperitoneally injected with Escherichia coli. The survival rate (n = 21) and bacterial burden (n = 5) were assessed. The processes of phagosome maturation and phagosome-lysosome fusion in peritoneal macrophages were extensively studied. The impact of increasing intracellular Ca concentration on bacterial clearance in macrophages (n = 3) and on survival rate of Trpm2 mice infected with E. coli (n = 21) was investigated.
Trpm2 mice exhibited increased mortality (85% vs. 54%; P < 0.01) and aggravated bacterial burden during E. coli sepsis. Trpm2 peritoneal macrophages infected with E. coli showed dampened recruitment of lysosomal-associated membrane protein 1 and impaired phagosome maturation evidenced by a decrease in the accumulation of early endosome antigen 1, whereas a normal acquisition of Ras-related protein in brain 5. Increasing the cytosolic Ca concentration in Trpm2 peritoneal macrophages via ionomycin treatment facilitated early endosome antigen 1 recruitment to Ras-related protein in brain 5 and phagosomal localization of lysosomal-associated membrane protein 1 and consequently enhanced bactericidal activity. Adoptive transfer of ionomycin-treated Trpm2 peritoneal macrophages improved bacterial clearance and survival (67% vs. 29%; P < 0.01) in Trpm2 mice challenged with E. coli.
Transient receptor potential melastatin 2 plays a critical role in host defense against invading bacteria via promoting phagosome maturation through facilitation of early endosome antigen 1 recruitment.
瞬时受体电位香草酸亚家族成员2（TRPM2）是一种钙离子通透的阳离子通道，在巨噬细胞中大量表达。TRPM2基因敲除小鼠在多重微生物败血症期间感染加剧且死亡率升高，这与巨噬细胞内细菌杀伤效率低下有关。然而，TRPM2调节细菌杀伤的机制仍不清楚。
给TRPM2基因敲除小鼠腹腔注射大肠杆菌。评估存活率（n = 21）和细菌负荷（n = 5）。广泛研究了腹腔巨噬细胞中吞噬体成熟和吞噬体-溶酶体融合的过程。研究了提高细胞内钙离子浓度对巨噬细胞内细菌清除（n = 3）以及感染大肠杆菌的TRPM2基因敲除小鼠存活率（n = 21）的影响。
在大肠杆菌败血症期间，TRPM2基因敲除小鼠死亡率增加（85% 对54%；P < 0.01）且细菌负荷加重。感染大肠杆菌的TRPM2腹腔巨噬细胞显示溶酶体相关膜蛋白1的募集减少，吞噬体成熟受损，表现为早期内体抗原1的积累减少，而脑Ras相关蛋白5的获取正常。通过离子霉素处理提高TRPM2腹腔巨噬细胞的胞质钙离子浓度，促进了早期内体抗原1募集到脑Ras相关蛋白5以及溶酶体相关膜蛋白1的吞噬体定位，从而增强了杀菌活性。将经离子霉素处理的TRPM2腹腔巨噬细胞进行过继转移，可改善感染大肠杆菌的TRPM2基因敲除小鼠的细菌清除率和存活率（67% 对29%；P < 0.01）。
TRPM2通过促进早期内体抗原1的募集来促进吞噬体成熟，从而在宿主抵御入侵细菌的防御中发挥关键作用。
