Chlamydia pneumoniae infection in adolescents with type 1 diabetes mellitus.

Chlamydia pneumoniae, an intracellular bacterium, is associated with respiratory diseases, reinfectivity and chronic diseases such as cardiovascular disease, hypertension and stroke. The risk of infection is higher and infections are a serious clinical problem in patients with type 1 (insulin-dependent) diabetes mellitus (T1DM). Although diabetes mellitus and hyperglycaemia are considered possible risk factors for various types of aetiological agents, the epidemiological evidence concerning C. pneumoniae infection is scanty. The aim of the present study was to evaluate the impact of glycosylated haemoglobin (HbA1c) levels, an indicator of a hyperglycaemic state, on C. pneumoniae infection and disease chronicity; in addition we compared the duration of diabetes with the occurrence of C. pneumoniae infection. C. pneumoniae blood real time PCR and serology (IgG, IgA and IgM) assays by an ELISA method were performed. C. pneumoniae DNA was detected in 46.5 % [95 % confidence interval (CI) = 35.1-57.9 %] of the patients with T1DM; this prevalence is higher (P<0.05) than in non-diabetic paediatric controls, 10.5 % (95 % CI = 3.6-17.4 %). IgG/IgA C. pneumoniae antibody positivity was significantly (P≤0.05) more common in patients in poor metabolic control (HbA1c >9 %) versus patients in good metabolic control (HbA1c <7 %), suggesting that the metabolic control of the disease is compromised in the patients with T1DM. In conclusion, adolescents with T1DM were more likely to show signs of infection with C. pneumoniae compared with healthy adolescents and the results suggest an increased risk of progressing from an acute C. pneumoniae infection to a chronic form.

Effect of resveratrol and modulation of cytokine production on human periodontal ligament cells.

Periodontitis is a multifactorial polymicrobial infection characterized by a destructive inflammatory process. Porphyromonas gingivalis, a Gram-negative anaerobic black-pigmented rod, which produces several virulence factors that stimulate human periodontal ligament cells (HPLCs) to produce various inflammatory mediators, has been implicated as a crucial etiologic agent in the initiation and progression of periodontitis. Since natural polyphenols such as resveratrol have growth-inhibitory effects on some bacterial pathogens and have shown chemo-preventive, anti-inflammatory and antioxidant activity, in the present study we used an HPLC model stimulated with lipopolysaccharide (LPS) of P. gingivalis to simulate the in vivo conditions such as those found in diseased periodontal sites. To determine whether resveratrol interferes with P. gingivalis LPS-activity and reduces the production of pro-inflammatory molecules, we investigated its effect on the cytokines IL-1ß, IL-6, IL-8, IL-12 and TNF-α and NO production of HPLCs. The results showed that resveratrol treatment decreased in a dose- and time-dependent manner the NO expression induced by P. gingivalis LPS, correlated to an increased viability of infected HPLCs, and decreased the production of pro-inflammatory cytokines in HPLCs stimulated by P. gingivalis LPS. These results suggest that the ability of resveratrol to determine immunomodulatory effects could provide possible therapeutic applications for the treatment of periodontitis.

Toll-like receptor-4 (TLR4) mediates human beta-defensin-2 (HBD-2) induction in response to Chlamydia pneumoniae in mononuclear cells.

Monocytes are pivotal effector cells of the innate immune system that are vital for recognizing and eliminating invasive microbial pathogens. When microbial products bind to pathogen-recognition receptors, monocytes are activated and release a broad array of cytokines and defensins that orchestrate the host innate and adaptive immune responses. The aim of the present study is to investigate whether Toll-like receptor-4 (TLR4) mediates human beta-defensin-2 (HBD-2) induction in response to Chlamydia pneumoniae in mononuclear cells. We showed that TLR4 is expressed in U937 cells and monocytes infected with viable microorganisms in a time-dependent fashion, while heat-inactivated microorganisms induced a lesser expression, albeit still significant, of TLR4 compared with viable organisms; flow cytometric analysis, in particular, revealed a higher level of TLR4 expression at 48 and 72 h postinfection. In addition, U937 cells and monocytes responded to C. pneumoniae in a TLR4-dependent manner with induction of mRNA and protein of the antimicrobial peptide HBD-2. The treatment of cells with TLR4-neutralizing antibody resulted in a decrease in C. pneumoniae-induced HBD-2 production. This study reveals that TLRs not only recognize ligands but also the types of effector molecules induced, namely, antimicrobial peptides. An understanding of the importance of the TLR-mediated antimicrobial mechanisms may provide new avenues for the development of therapeutic regimens aimed at activating the body's own defenses by stimulating TLR-dependent pathways.

Immunomodulatory effects of Lactobacillus plantarum on human colon cancer cells.

Probiotics, defined as live microbial food supplements which improve the health of the host, have obtained increasing medical importance. In the intestine they may prevent the overgrowth of pathogenic bacteria, increase the resistance of the gut to invasion by pathogens and ameliorate disease processes by inducting the secretion of soluble factors such as cytokines and antimicrobial beta-peptides. One important class of human antimicrobial peptides is the family of defensins. Human beta-defensin 2 (HBD-2) is a major inducible peptide which plays an important role in host defense and represents a link between innate and adaptive immune responses. This linkage is in part mediated through the recognition of conserved bacterial products or bacteria by Toll-like receptors (TLRs). The aim of this study was to investigate the effects of Lactobacillus plantarum on intestinal epithelial cells. We found that Caco-2 cells exposed to L. plantarum bacteria significantly induced HBD-2 mRNA expression and HBD-2 secretion in a dose- (16+/-1.4 pg/ml and 31.5+/-2.3 pg/ml at MOI 10 and 50, respectively) and time-dependent manner, but not HBD-3, compared to controls; in addition, when LPS was added to cells for 48 h, the interleukin (IL)-23 secretion (850+/-5.4 pg/ml) and IL-23 mRNA expression increased; while it was reduced when LPS was cocultured with L. plantarum (330+/-4.2 pg/ml). The L. plantarum-induced increase in HBD-2 expression is inhibited by anti-TLR-2 neutralizing antibodies, in the same way the pre-treatment with the anti-TLR-2 antibody inhibited the production of IL-23 induced by LPS in Caco-2 cells. The results of our study help to achieve a better understanding of how the intestinal epithelium participates in the innate immune response to commensal bacteria and pathogens in the gut.

Effect of protein SV-IV on experimental Salmonella enterica serovar Typhimurium infection in mice.

Seminal vesicle protein IV (SV-IV) is a secretory anti-inflammatory, procoagulant, and immunomodulatory protein produced in large amounts by the seminal vesicle epithelium of the rat under the strict transcriptional control of androgen. In particular, this protein was shown to possess the ability to markedly inhibit in vivo the humoral and cell-mediated immune responses of mice to nonbacterial cellular antigens (sheep erythrocytes and spermatozoa). We report data that demonstrate that in mice treated with SV-IV and infected with Salmonella enterica serovar Typhimurium, SV-IV is able to downregulate some important immunological and biochemical parameters that serovar Typhimurium normally upregulates in these animals. This event did not correlate with a lower bacterial burden but was associated with a markedly increased one (300%). Furthermore, the treatment of mice with SV-IV alone also produced a significant increase in the rate of mortality among serovar Typhimurium-infected animals. The mechanism underlying these phenomena was investigated, and the strong immunosuppression produced by SV-IV in serovar Typhimurium-infected mice was suggested to be the basis for the increased rate of mortality. The SV-IV-mediated immunosuppression was characterized by a decrease in the humoral and cell-mediated immune responses, altered lymphocyte-macrophage interaction, downregulation of cytokine and inducible nitric oxide synthase gene expression, inhibition of macrophage phagocytosis and intracellular killing activities, and absence of apoptosis in the splenocyte population of SV-IV- and serovar Typhimurium-treated mice. The immunosuppressive activity of SV-IV was specific and was not due to aspecific cytotoxic effects. SV-IV-specific receptors (K(d) = 10(-8) M) occurring on the macrophage and lymphocyte plasma membranes may be involved in the molecular mechanism underlying the SV-IV-mediated immunosuppression. Some results obtained by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay also revealed a functional impairment of mitochondria (a decrease in mitochondrial dehydrogenase activity), thus indicating the possible implication of these organelles in the immunosuppressive process.