Higher titers of anti-Chlamydia pneumoniae IgG in diabetic retinopathy: a cross-sectional study.

BACKGROUND: Chronic inflammation has a role in the pathogenesis of diabetic retinopathy. Infection with intracellular organisms may incite chronic inflammation. This study was conducted to investigate the association between previous infection with Chlamydia pneumoniae (an intracellular microorganism) and diabetic retinopathy. METHODS: Patients with type 2 diabetes mellitus (30-60 years old) and age-matched normal controls were recruited. Patients with history of cardiovascular or cerebrovascular disease, recent pulmonary infection and the presence of age-related macular degeneration were excluded from the study. Complete ophthalmic examinations were performed. Fasting blood sugar and haemoglobin levels were measured in diabetic patients and controls, and HgbA1c , blood urea nitrogen, creatinine and 24-h urine protein were measured in diabetic patients. Anti-C. pneumoniae IgG (enzyme-linked immunosorbent assay) was measured in the sera of all participants. RESULTS: A total of 215 type 2 diabetic patients and 243 normal healthy controls were included. Anti-C. pneumoniae IgG titers were higher in patients affected by diabetic retinopathy than participants without retinopathy (74.78 ± 33.38 vs 66.18 ± 31.40, p = 0.028). Diabetic patients with diabetic retinopathy also had higher titers than diabetic patients without diabetic retinopathy (74.78 ± 33.38 vs 66.11 ± 33.41, p = 0.042). Of different variables including age, body mass index, haemoglobin level, glycated haemoglobin level, fasting blood sugar, mean arterial pressure and blood urea nitrogen, only age (r = 0.17; p = 0.001) and body mass index (r = 0.15; p = 0.003) were correlated with anti-C. pneumoniae IgG levels. In regression analysis, the presence of diabetic retinopathy was still a determinant of the antibody level (p = 0.03). CONCLUSION: Anti-C. pneumoniae IgG titers were higher in patients with diabetic retinopathy, which may indicate a role of this infection in the pathogenesis of diabetic retinopathy.

Chronic inflammation is correlated with percentage of body fat independent of the burden of infection.

The aim of this population-based study was to investigate the association of the percentage of body fat (BF) and high-sensitivity C-reactive protein (hs-CRP) when the infectious burden was adjusted for. A total of 1,546 subjects were randomly selected. BF was determined using bioelectrical impedance analysis. Sera were analyzed for IgG antibodies to Chlamydia pneumoniae, herpes simplex virus type 1, Helicobacter pylori, and cytomegalovirus using ELISA. Measurement of C-reactive protein (CRP) by a high-sensitivity CRP assay was performed. A linear relationship between an increase in the number of pathogens and CRP concentrations was observed (p = 0.007). Age-adjusted serum hs-CRP levels were correlated with percentage of BF in men (r = 0.28, p < 0.0001) and women (r = 0.37, p < 0.0001). In multiple regression analyses, hs-CRP showed significant correlations with percentage of BF after controlling for age, sex, cardiovascular risk factors, and the infectious burden was divided into two, three, and four pathogens [(ß = 0.24, p < 0.0001), (ß = 0.2 1, p < 0.0001), and (ß = 0.23, p = <0.0001), respectively]. In conclusion, there was a strong association between hs-CRP and percentage of body fat independent of viral and bacterial pathogens that had been previously associated with coronary artery disease as well as carotid atherosclerosis.

Chlamydophila pneumoniae infection induces alterations in vascular contractile responses.

Chlamydophila pneumoniae infection has been associated in previous studies with coronary artery disease. The live bacterium has been detected within atherosclerotic plaques and can induce the structural remodeling of the vessel wall. However, the direct effects of infection on the contractile characteristics of the arteries remain unknown. Left anterior descending coronary arteries isolated from porcine hearts were dissected and placed in culture medium for 72 hours before infection with C. pneumoniae. Contractile responses to high molar KCl and u46619 levels and relaxation responses to bradykinin and sodium nitroprusside were assessed at days 5 and 10 postinfection. C. pneumoniae induced decreases in both KCl- and u46619-induced contractile responses at both time points. The altered contractile responses coincided with a down-regulation of L-type Ca(2+) channels at both time points and inositol 1,4,5-triphosphate receptor (IP3R) levels at day 10 postinfection. Infection also induced attenuation of the endothelial-dependent relaxation response to bradykinin at day 10 postinfection. A decrease in endothelial nitric oxide synthase expression levels was noted at day 10 postinfection. Furthermore, an increase in superoxide production combined with an increase in p22phox expression levels was also observed at this time point. These findings indicate that C. pneumoniae infection can directly alter the vascular contractile responses in porcine coronary arteries, providing additional evidence for the role of C. pneumoniae infection in cardiovascular disease.

[Promoting effect of Chlamydia pneumoniae infection on human laryngeal carcinoma HEp-2 cell adhesion and migration].

OBJECTIVE: To explore the effect of Chlamydia pneumoniae (C.pn) infection on human laryngeal carcinoma cell line HEp-2 cell adhesion and migration, to further clarify the role and mechanism of C.pn infection in tumor metastasis. METHODS: HEp-2 cells were infected with C.pn after the culture and propagation of C.pn. The cytopathic effect was observed by microscopy. Morphological characteristics of C.pn inclusions in HEp-2 cells were examined by fluorescence microscopy and acridine orange staining. The ultrastructural changes of C.pn inclusions in the HEp-2 cells were examined by transmission electron microscopy (TEM). Cell adhesion assay was performed to investigate the effect of C.pn infection on the adhesion of HEp-2 cells to collagen I. Wound-healing assay and transwell assay were performed to explore the effect of C.pn infection on HEp-2 cell migration. RESULTS: At 72 h post-infection, C.pn infected-HEp-2 cells were swollen and partially desquamated. Numerous vacuoles (inclusions) were observed and C.pn inclusions occupied almost the whole cytoplasm of the HEp-2 cells. Grape-like C.pn inclusions were observed in the HEp-2 cells stained with acridine orange under a fluorescence microscope at 72 h after infection. Under TEM, there were more mature pear-shaped elementary bodies, but less larger and round reticulate bodies in the HEp-2 cells infected with C.pn for 72 h. In the cell adhesion assay, the A value in C.pn infection group was 0.669 ± 0.011, significantly higher than that in the control group (0.558 ± 0.005) at 2 h after infection (P < 0.001). The cell adhesion ratio in the C.pn infection group was 119.89%. The migration distance of C.pn infected-HEp-2 cells in the wound-healing assay was significantly longer than that of control cells at 24 h after infection (P < 0.05). HEp-2 cells infected with C.pn for 12 h migrated more than the control cells in the transwell assay (23.40 ± 2.41 vs 10.40 ± 1.67) (P < 0.001). CONCLUSIONS: C.pn infection can significantly promote HEp-2 cell adhesion to collagen I and migration of HEp-2 cells, indicating that C.pn infection may play an important role in promoting the metastasis of laryngeal cancer.

Persistent Chlamydia Pneumoniae serology is related to decline in lung function in women but not in men. Effect of persistent Chlamydia pneumoniae infection on lung function.

BACKGROUND: Chlamydia pneumoniae (C pn) infection causes an acute inflammation in the respiratory system that may become persistent, but little is known about the long-term respiratory effects of C pn infections. AIM: To estimate the long term respiratory effects of C pn with change in forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) as a main outcome variable. METHODS: The study comprised of 1109 subjects (500 men and 609 women, mean age 28 ± 6 years) that participated in the Reykjavik Heart Study of the Young. Spirometry and blood samples for measurements of IgG antibodies for C pn were done at inclusion and at the end of the follow-up period (mean follow-up time 27 ± 4 years). RESULTS: Having IgG against C pn at both examinations was significantly associated to a larger decrease in FEV1 (6 mL/year) and FVC (7 mL/year) in women but not in men. In women the association between C pn and larger FEV1 decline was only found in women that smoked at baseline where having C pn IgG was associated with 10 mL/year decline compared to smokers without C pn IgG. These results were still significant after adjustment for age, smoking and change in body weight. CONCLUSION: Our results indicate that persistent C pn serology is related to increased decline in lung function in women but not in men. This effect was, however, primarily found in smoking women. This study is a further indication that the pathophysiological process leading to lung impairment may differ between men and women.

Divergent modulation of Chlamydia pneumoniae infection cycle in human monocytic and endothelial cells by iron, tryptophan availability and interferon gamma.

Chlamydia pneumoniae is an obligatory intracellular bacterium causing chronic inflammatory diseases in humans. We studied the role of the nutritive factors, iron and tryptophan, towards the course of infection and immune response pathways in C. pneumoniae infected endothelial cells and monocytes. Human endothelial (EA.hy923) and monocytic cells (THP-1) were infected with C. pneumoniae, supplemented with iron or 1-methyltryptophan (1-MT), an inhibitor of the tryptophan degrading enzyme indoleamine 2,3-dioxygenase (IDO), and subsequently stimulated with IFN-gamma or left untreated. The number of infected cells, the morphology and quantity of C. pneumoniae inclusion bodies, IDO activity and innate immune effector pathways were analysed. While neither iron challenge, IDO inhibition or IFN-gamma treatment had a significant effect on C. pneumoniae morphology or numbers within THP-1 monocytic cells, iron supplementation to EA.hy926 cells resulted in promotion of C. pneumoniae proliferation and differentiation while IFN-gamma had an inhibitory effect. Furthermore, the number of infected endothelial cells was significantly decreased upon 1-MT treatment. C. pneumoniae infection induced a pro-inflammatory immune response as evidenced by increased IDO activity, neopterin formation or TNF-alpha production in THP-1 but not in endothelial cells. These pathways were superinduced upon IFN-gamma treatment and partly modulated by iron supplementation. Our results demonstrate that the infectious cycle of C. pneumoniae behaves differently between monocytic and endothelial cells. While the intracellular pathogen remains in a persistent form within monocytes, it can differentiate and proliferate within endothelial cells indicating that endothelial cells are a preferred environment for Chlamydia. Nutritive factors such as iron have subtle effects on C. pneumoniae biology in endothelial, but not monocytic cells. Our results contribute to a better understanding of C. pneumoniae infection and its role in chronic inflammatory diseases such as atherosclerosis.

Chlamydophila pneumoniae infection leads to smooth muscle cell proliferation and thickening in the coronary artery without contributions from a host immune response.

Chlamydophila pneumonia (C. pneumonia) infection has been associated with the progression of atherosclerosis. It remains unclear, however, whether C. pneumoniae in the absence of an immune response can alone initiate atherogenic events within a complex vessel environment. Left anterior descending coronary arteries isolated from porcine hearts were dissected and placed in culture medium for 72 hours before infection with C. pneumoniae. C. pneumoniae replicated within the arterial wall for the duration of the experiment (up to 10 days). A significant increase in chlamydial-HSP60 protein expression from day 2 to 10 post-infection (pi) indicated the presence of metabolically active C. pneumonia within infected vessels. Significant arterial thickening in infected coronary segments was observed by a considerable decrease in the ratio of lumen to total vessel area (48 +/- 3% at day 4 pi versus 23 +/- 3% at day 10 pi) and a significant increase in the ratio of media to luminal area (113 +/- 16% at day 4 pi versus 365 +/- 65% at day 10 pi). Structural changes were accompanied by an up-regulation of host HSP60 and proliferating cell nuclear antigen expression levels. Immunohistochemical staining confirmed proliferating cell nuclear antigen expression to be primarily localized within smooth muscle cells of the medial area. These results demonstrate that C. pneumoniae infection can stimulate arterial thickening in a complex vessel environment without the presence of a host immune response and further supports the involvement of HSP60 in this action.

Molecular biology of infectious agents in chronic arthritis.

Severe and chronic inflammatory arthritis sometimes follows urogenital infection with Chlamydia trachomatis or gastrointestinal infection with enteric bacterial pathogens. A similar clinical entity can be elicited by the respiratory pathogen Chlamydophila (Chlamydia) pneumoniae. Arthritogenesis does not universally require viable enteric bacteria in the joint. In arthritis induced by either of the chlamydial species, organisms are viable and metabolically active in the synovium. They exist in a "persistent" state of infection. Conventional antibiotic treatment of patients with Chlamydia-induced arthritis is largely ineffective. The authors outline the current understanding of the molecular genetic and biologic aspects underlying bacterially-induced joint pathogenesis, available information regarding host-pathogen interaction at that site, and several directions for future study to inform development of more effective therapies.

Trophoblast infection with Chlamydia pneumoniae and adverse pregnancy outcomes associated with placental dysfunction.

OBJECTIVE: We sought to determine whether Chlamydia pneumoniae impairs invasive trophoblast function and is associated with preeclampsia. STUDY DESIGN: We conducted cell viability and invasion assays using primary extravillous trophoblast cells isolated from first-trimester placentas. We performed a case-control study to identify C pneumoniae in trophoblast cells dissected by laser capture microscopy from placentas in women with severe preeclampsia and control subjects who delivered at term. RESULTS: Trophoblast cell viability and invasion through extracellular matrices were decreased after infection with C pneumoniae (both P < .05). C pneumoniae DNA was detected in trophoblast cells in 15/48 cases but only 3/30 controls (odds ratio, 4.1; P = .02). Positive and negative controls yielded expected results. CONCLUSION: C pneumoniae infection can reduce trophoblast invasion into the uterine wall and is associated with preeclampsia. Further investigation of the mechanisms by which C pneumoniae induces trophoblast dysfunction, and the identification of therapies to prevent adverse outcomes attributed to trophoblast dysfunction, are warranted.

Ovine trophoblast is a primary source of TNFalpha during Chlamydophila abortus infection.

Chlamydophila abortus is a Gram-negative obligate intracellular bacterium that causes infectious abortion in sheep (ovine enzootic abortion, OEA) and humans. Infected placentas recovered from sheep that experience OEA have thickened membranes, contain dense inflammatory cellular infiltrates and show evidence of intravascular thrombosis. Despite widespread inflammation, chlamydial multiplication is restricted to the chorionic trophoblast cells. To investigate the potential role of trophoblast in the initiation and propagation of placental inflammation during OEA, the AH-1 ovine trophoblast cell line was experimentally infected with C. abortus and analysed for the release of pro-inflammatory mediators. C. abortus was found to induce the release of both tumour necrosis factor-alpha (TNFalpha) and CXCL8 (interleukin-8) from AH-1 cells in a dose- and time-dependent manner. Ultra-violet (UV)-killed organisms did not elicit this profile, indicating that intracellular multiplication of C. abortus was required for release of these pro-inflammatory mediators. Exposure of AH-1 cells to recombinant ovine TNFalpha alone resulted in the release of CXCL8, suggestive of a self-propagating inflammatory cytokine and chemokine cascade. These data indicate a primary role for trophoblast in the initiation and propagation of placental inflammation during chlamydial abortion.

Host molecular defense mechanisms against Chlamydophila pneumoniae and genetic studies of immune-response-related genes in asthma.

Chlamydophila pneumoniae is an intracellular pathogen and a major cause of pneumonia that can cause chronic, persistent, and often asymptomatic, infections in target cells such as monocytes, macrophages, endothelial cells, fibroblasts, and smooth muscle cells. Chlamydial infections play roles in new-onset wheezing, exacerbation of prevalent asthma, and long-term decrements in lung function. However, accurate standardized laboratory tests to diagnose infection with C. pneumoniae have not been established. Human and animal studies have clarified the molecular mechanisms of resistance to C. pneumoniae and have shown the importance of innate and mucosal immune responses to the microorganisms. A large number of genetic studies have intensively examined the associations between asthma and polymorphisms in the genes located at the interface between innate immune sensing and regulation. The rapid progress in understanding the immunology of infectious diseases and genetics of asthma is providing a better understanding of the pathogenesis of bronchial asthma, and that will help to define patient populations who are most likely to benefit from various treatments, and lead to development of new treatments. The review article also discussed some patent related to the field.

Chlamydia pneumoniae infection results in generalized bone loss in mice.

Osteoporosis is associated with a general bone loss. Whether infections could contribute to osteoporosis is not known. Chlamydia pneumoniae causes chronic infections and produces potentially bone resorptive cytokines. The effect of C. pneumoniae infection was investigated in vivo in 10-week old mice (c57BL/6) and in vitro in the human osteoblast-like cell line hFOB 1.19 (hFOB). Bone mineral density (BMD) was measured before and 16 days after infection. C. pneumoniae-infected mice had decreased (p<0.05) total and subcortical BMD at the distal femur and proximal tibia compared with controls, but no body-weight gain differences. IL-6 (56 vs. 39pg/mL, p=0.02) and IL-1beta (11 vs. 0pg/mL, p=0.003) levels in sera, and CD3(+) T-cells (p=0.04) were higher in infected mice compared with controls. In vitro, hFOB infected with C. pneumoniae was associated with increased IL-6 (p=0.01) and RANKL (p<0.05) mRNA expression; additionally, IL-6 secretion increased in a dose-dependent manner (p<0.05). In summary, mice infected with C. pneumoniae had generalized bone loss associated with increased IL-6 and IL-1. In addition, C. pneumoniae established an infection in an osteoblast cell line in vitro with similar cytokine profiles as those in vivo, supporting a causal linkage.

Severe asthma exacerbation: role of acute Chlamydophila pneumoniae and Mycoplasma pneumoniae infection.

BACKGROUND: Chlamydophila pneumoniae and Mycoplasma pneumoniae are associated with acute exacerbation of bronchial asthma (AEBA). The aim of this study was to evaluate the correlation between these acute bacterial infections and the severity of AEBA. METHODS: We prospectively analysed consecutive patients admitted to the Emergency Department with acute asthma exacerbation. In every patient peak expiratory flow (PEF) measurement was performed on admission, and spirometry during follow-up. Serology for Chlamydophila and Mycoplasma pneumoniae was performed on admission and after 4-8 weeks. RESULTS: Fifty-eight patients completed the study. Acute atypical infections (AAI) was observed in 22/58 cases; we found single acute C. pneumoniae in 19 cases, single acute M. pneumoniae in 2 cases, and double acute infection in one case. Functional impairment on admission was greater in patients with AAI than in patients without AAI (PEF 205 +/- 104 L/min vs 276 +/- 117 p = 0.02) and persisted until visit 2 (FEV1% 76.30 +/- 24.54 vs FEV1% 92.91 +/- 13.89, p = 0.002). Moreover, the proportion of patients who presented with severe AEBA was significantly greater in the group with AAI than in the group without AAI (15/22 vs 12/36, p = 0.01; OR 4.29, 95% CI 1.38-13.32). CONCLUSION: Our data suggest an association between acute atypical infection and a more severe AEBA.

Inflammatory- and immune responses in relation to bacterial replication in mice following re-infections with Chlamydophila pneumoniae.

OBJECTIVE: Investigation of chronic infections with Chlamydophila pneumoniae. METHODS: BALB/c mice were repeatedly infected with C. pneumoniae and tested during a 1-year period. Production of histamine, IFN-gamma, IL-6 and antibodies was monitored by ELISA. Live bacteria were cultured and DNA was detected by PCR. Cellular immunity was tested by ELISPOT. RESULTS: After re-infections, culture positivity and persistence of DNA in lungs and blood were shorter. Detection of DNA at late time points indicated persistent infection in a few mice. Histamine was produced after primary and re-infections, and the level correlated with the number of viable bacteria in lung. IFN-gamma, IL-6 levels, IgG2/IgG1 ratio, IgA titres, and level of chlamydial heat-shock protein antibodies were higher after re-infections. IgM antibodies were demonstrated even after re-infections. High number of IFN-gamma-producing splenocytes was observed after the third inoculation. CONCLUSION: These results promote an understanding of the patho- and immune mechanisms after C. pneumoniae re-infections.

Prevalence of Mycoplasma and Chlamydia pneumonia in severe community-acquired pneumonia among hospitalized children in Thailand.

Pneumonia is the leading cause of pediatric morbidity and mortality worldwide, and Mycoplasma pneumoniae and Chlamydia pneumoniae are the two most common atypical pathogens. This study was designed to determine the prevalence and clinical impact of mycoplasma and chlamydia pneumonia in children hospitalized with severe pneumonia. Children 1 month-15 years old with a diagnosis of severe pneumonia (WHO criteria) were recruited between March 2005 and March 2006. Serologic studies were performed for anti-M. pneumoniae and anti-C. pneumoniae IgG/M on admission and 2-4 weeks afterward using ELISA. Of 52 patients, 13 (25%) were positive for Mycoplasma, 8 (15%) were positive for Chlamydia, 4 (7.6%) were positive for a mixed infection and 27 (52%) were negative. The subjects' mean age was 23.8+/-4.1 months. The mean of initial oxygen saturation on admission was 87.5+/-1.2%. Fever and prolonged cough were the leading symptoms. The mean of hospitalization was 18.8+/-2.6 days, chlamydia pneumonia had the longest duration, 30+/-10.2 days and 13/52 (25%) study subjects developed respiratory failure. Only 10% were treated with adequate antibiotic prior to serologic results. There was one mortality (1/52, 2%). Our study suggests that mycoplasma and chlamydia infections are commonly found among children hospitalized with severe pneumonia. Coverage with an appropriate antibiotic should be considered to hasten recovery.

Chlamydophila spp. infection in horses with recurrent airway obstruction: similarities to human chronic obstructive disease.

BACKGROUND: Recurrent airway obstruction (RAO) in horses is a naturally occurring dust-induced disease mainly characterized by bronchiolitis which shows histological and pathophysiological similarities to human chronic obstructive pulmonary disease (COPD). In human COPD previous investigations indicated an association with Chlamydophila psittaci infection. The present study was designed (1) to clarify a possible role of this infectious agent in RAO and (2) to investigate the suitability of this equine disorder as a model for human COPD. METHODS: Clinico-pathological parameters of a total of 45 horses (25 horses with clinical signs of RAO and 20 clinically healthy controls) were compared to histological findings in lung tissue samples and infection by Chlamydiaceae using light microscopy, immunohistochemistry, and PCR. RESULTS: Horses with clinical signs of RAO vs. controls revealed more inflammatory changes in histology (p = 0.01), and a higher detection rate of Chlamydia psittaci antigens in all cells (p < 0.001) and bronchiolar epithelial cells alone (p < 0.001) by immunohistochemistry. The abundance of chlamydial inclusions increased with the severity of disease. PCR was positive in 60% of horses with RAO vs. 45% of the controls (p = 0.316). OmpA sequencing identified Chlamydophila psittaci (n = 9) and Chlamydophila abortus (n = 13) in both groups with no significant differences. Within the group of clinically healthy horses subgroups with no changes (n = 15) and slight inflammation of the small airways (n = 5) were identified. Also in the group of animals with RAO subgroups with slight (n = 16) and severe (n = 9) bronchiolitis could be formed. These four subgroups can be separated in parts by the number of cells positive for Chlamydia psittaci antigens. CONCLUSION: Chlamydophila psittaci or abortus were present in the lung of both clinically healthy horses and those with RAO. Immunohistochemistry revealed acute chlamydial infections with inflammation in RAO horses, whereas in clinically healthy animals mostly persistent chlamydial infection and no inflammatory reactions were seen. Stable dust as the known fundamental abiotic factor in RAO is comparable to smoking in human disease. These results show that RAO can be used as a model for human COPD.