Enhanced Neutrophil Longevity and Recruitment Contribute to the Severity of Oviduct Pathology during Chlamydia muridarum Infection

Abstract

Our previous studies revealed that intravaginal infection of mice with a plasmid-deficient strain of Chlamydia muridarum, CM3.1, does not induce the development of oviduct pathology. In this study, we determined that infection with CM3.1 resulted in a significantly reduced frequency and absolute number of neutrophils in the oviducts during acute infection. This reduction in neutrophils was associated with significantly lower levels of neutrophil chemokines in the oviducts and decreased production of neutrophil chemokines by oviduct epithelial cells infected with CM3.1 in vitro. Infection with CM3.1 also resulted in an increased frequency of late apoptotic/dead neutrophils in the oviduct. Examination of the ability of Chlamydia trachomatis to prevent neutrophil apoptosis in vitro revealed that C. trachomatis strain D/UW-3/Cx exhibited an enhanced ability to prevent neutrophil apoptosis compared to plasmid-deficient CTD153, and this effect was dependent on the presence of CD14 high monocytes. The presence of monocytes also resulted in enhanced neutrophil cytokine production and increased production of tissue-damaging molecules in response to D/UW-3/Cx relative to results with CTD153. Attempts to use antibody-mediated depletion to discern the specific role of neutrophils in infection control and pathology in vivo revealed that although Ly6G high neutrophils were eliminated from the blood and oviducts with this treatment, immature neutrophils and high levels of tissue-damaging molecules were still detectable in the upper genital tract. These data support the role of neutrophils in chlamydia-induced pathology and reveal that novel methods of depletion must be developed before their role can be specifically determined in vivo.Chlamydia trachomatis represents the most common bacterial sexually transmitted infection in the world, with WHO estimates indicating that 90 million individuals are infected worldwide (48). Acute infection is often asymptomatic, but untreated or repeat infections can result in immunopathology including pelvic inflammatory disease (PID), chronic pelvic pain, ectopic pregnancy, and infertility. This pathology results from an aggressive host inflammatory response, and human studies have provided insight into potential inflammatory mediators of reproductive tract sequelae. A study examining endometrial biopsy specimens from women exhibiting signs of PID correlated C. trachomatis infection with an inflammatory milieu consisting of both acute and chronic leukocyte populations, including neutrophils, plasma cells, and periglandular lymphoid follicles containing transformed lymphocytes (21). In patients with documented endometrial and oviduct infection with C. trachomatis, neutrophils were observed infiltrating the glandular epithelium (21). A separate study of women at risk for PID associated the presence of increased vaginal levels of neutrophil alpha defensins, a marker of neutrophil activation, with the development of endometritis due to C. trachomatis infection (47).Although studies in humans have ...

Yersinia pseudotuberculosis Efficiently Escapes Polymorphonuclear Neutrophils during Early Infection

“…In addition, the level of Gr-1 ϩ F4/80 ϩ monocytes increased slightly in the blood of infected PMN-depleted mice, and the level of F4/80 ϩ macrophages increased in infected tissues. Similar results have been observed in the oviducts of PMN-depleted mice infected with Chlamydia muridarum (46). Hence, the release of immature PMNs and increased levels of monocytes/ macrophages appear to be general effects in anti-Ly6G-treated mice upon infection.…”

CD4+CD25+Foxp3+ Regulatory T Cells Promote Th17 Responses and Genital Tract Inflammation upon Intracellular Chlamydia muridarum Infection

“…RBCs were lysed by incubation in ACK (0.1 mM EDTA, 0.15 M NH 4 Cl, and 1 mM KHCO 3 In vitro coculture system ) were purified from naive splenocytes by CD4 enrichment followed by CD25-positive selection using MACS (Miltenyi Biotec) according to the manufacturer's instructions. The purity of both populations was consistently .90%.…”

“…A reliable surrogate marker for fibrotic oviduct occlusion and infertility in mice is the development of hydrosalpinx, which is characterized by accumulation of inflammatory exudates and oviduct dilation (3). Histological or cytological examinations of samples collected from mice and human subjects have revealed a profound chronic accumulation of neutrophils associated with Chlamydia infections (3)(4)(5)(6). Experimental blockade or attenuation of neutrophil infiltration during C. muridarum infection results in significantly reduced tissue damage and oviduct pathology without delaying bacterial clearance (4,6), indicating that prolonged neutrophilic inflammation is an important pathological host response to Chlamydia infection.…”

“…Histological or cytological examinations of samples collected from mice and human subjects have revealed a profound chronic accumulation of neutrophils associated with Chlamydia infections (3)(4)(5)(6). Experimental blockade or attenuation of neutrophil infiltration during C. muridarum infection results in significantly reduced tissue damage and oviduct pathology without delaying bacterial clearance (4,6), indicating that prolonged neutrophilic inflammation is an important pathological host response to Chlamydia infection. In addition, inappropriate CD8 + T cell responses (particularly TNF-a-producing CD8 + T cells) and production of proinflammatory cytokines downstream of TLR2, such as IL-1b, have also been demonstrated to play important roles in oviduct pathology in mice (7)(8)(9)(10).…”

Steroids Alone or as Adjunctive Therapy with Doxycycline Fail To Improve Oviduct Damage in Mice Infected with Chlamydia muridarum

“…1, experiments 2 and 3). These are days on which we have noted that neutrophil numbers peak in the oviducts of the respective mouse strains after C. muridarum infection (9,39). We detected a 6-fold reduction in the numbers of neutrophils (Fig.…”