Monari Claudia, Kozel Thomas R, Bistoni Francesco, Vecchiarelli Anna
Microbiology Section, Department of Experimental Medicine and Biochemical Sciences, University of Perugia, 06122 Perugia, Italy.
Infect Immun. 2002 Jul;70(7):3363-70. doi: 10.1128/IAI.70.7.3363-3370.2002.
Cryptococcus neoformans and cryptococcal surface polysaccharides influenced C5aR expression on human polymorphonuclear neutrophils (PMN). Encapsulated and acapsular strains produced dramatically different effects. Treatment of PMN with acapsular cryptococci up-regulated C5aR expression; whereas treatment with encapsulated cells suppressed C5aR expression. Glucuronoxylomannan (GXM), the principal constituent of the cryptococcal capsule, was responsible for such inhibition. Increased C5aR expression following treatment with acapsular cryptococci was accompanied by increased binding of C5a to PMN, increased superoxide production in response to stimulation with C5a, and an increased chemotactic response to C5a. Conversely, decreased C5aR expression following treatment with encapsulated cryptococci or acapsular cryptococci that had been pretreated with GXM was accompanied by decreased binding of C5a to PMN and a decreased chemotactic response to C5a. Our results raise the possibility that the down-regulation of C5aR expression by encapsulated cryptococci might alter PMN function at the site of cryptococcal infection.
新型隐球菌和隐球菌表面多糖会影响人多形核中性粒细胞（PMN）上C5aR的表达。有荚膜菌株和无荚膜菌株产生的影响截然不同。用无荚膜隐球菌处理PMN会上调C5aR的表达；而用有荚膜细胞处理则会抑制C5aR的表达。隐球菌荚膜的主要成分葡糖醛酸木聚糖（GXM）是造成这种抑制的原因。用无荚膜隐球菌处理后C5aR表达增加，同时C5a与PMN的结合增加、对C5a刺激产生的超氧化物生成增加以及对C5a的趋化反应增加。相反，用有荚膜隐球菌或经GXM预处理的无荚膜隐球菌处理后C5aR表达降低，同时C5a与PMN的结合减少以及对C5a的趋化反应降低。我们的结果提示，有荚膜隐球菌下调C5aR表达可能会改变隐球菌感染部位的PMN功能。
