BackgroundChlamydia trachomatis is an intracellular bacteria which consist of three biovariants; trachoma (serovars A-C), urogenital (serovars D-K) and lymphogranuloma venereum (L1-L3), causing a wide spectrum of disease in humans. Monocytes are considered to disseminate this pathogen throughout the body while dendritic cells (DCs) play an important role in mediating immune response against bacterial infection. To determine the fate of C. trachomatis within human peripheral blood monocytes and monocyte-derived DCs, these two sets of immune cells were infected with serovars Ba, D and L2, representative of the three biovariants of C. trachomatis.ResultsOur study revealed that the different serovars primarily infect monocytes and DCs in a comparable fashion, however undergo differential infection outcome, serovar L2 being the only candidate to inflict active infection. Moreover, the C. trachomatis serovars Ba and D become persistent in monocytes while the serovars predominantly suffer degradation within DCs. Effects of persistence gene Indoleamine 2, 3-dioxygenase (IDO) was not clearly evident in the differential infection outcome. The heightened levels of inflammatory cytokines secreted by the chlamydial infection in DCs compared to monocytes seemed to be instrumental for this consequence. The immune genes induced in monocytes and DCs against chlamydial infection involves a different set of Toll-like receptors, indicating that distinct intracellular signalling pathways are adopted for immune response.ConclusionOur results demonstrate that the host pathogen interaction in chlamydia infection is not only serovar specific but manifests cell specific features, inducing separate immune response cascade in monocytes and DCs.

No abstract

Contradicting reports exist about the pathogenicity of Chlamydia pneumoniae and the severity of the respiratory disease they cause. This study aimed to clarify, in mice, our hypothesis that marked differences in virulence of well-defined C. pneumoniae strains might exist for lung infections. C57BL/6J mice were intranasally infected with equal amounts of five different, identically prepared laboratory strains of C. pneumoniae. Based on the clinical score, weight, histopathological score, the granulocyte marker-enzyme myeloperoxidase, and the amount of Chlamydiae in the lung tissue, the C. pneumoniae isolates exhibited clear differences in overall growth characteristics or clearance, and pathological potential. Thus, we could identify chlamydial strains (Kajaani-K6 and CWL-029), where mice became seriously ill, as well as a relatively low-virulent isolate (TWAR-183). Cytokine profiles also varied drastically between the five strains in extent and kinetic. Our results indicate that C. pneumoniae isolates differ markedly with regard to their interaction with the host and their pathological potential. This might also be true for the infection in humans. Because the genomic diversity of C. pneumoniae is rather small, more subtle genomic deviations account most likely for the apparent functional differences. Our results will be useful to identify additional virulence factors in the future.

Inhibiting vascular endothelial growth factor (VEGF) is a therapeutic option in diabetic microangiopathy. However, VEGF is needed at physiological concentrations to maintain glomerular integrity; complete VEGF blockade has deleterious effects on glomerular structure and function. Anti-VEGF therapy in diabetes raises the challenge of reducing VEGF-induced pathology without accelerating endothelial cell injury. Heparan sulfate (HS) act as a coreceptor for VEGF. Calcium dobesilate (CaD) is a small molecule with vasoprotective properties that has been used for the treatment of diabetic microangiopathy. Preliminary evidence suggests that CaD interferes with HS binding sites of fibroblast growth factor. We therefore tested the hypotheses that (1) CaD inhibits VEGF signaling in endothelial cells, (2) that this effect is mediated via interference between CaD and HS, and (3) that CaD ameliorates diabetic nephropathy in a streptozotocin-induced diabetic mouse model by VEGF inhibition. We found that CaD significantly inhibited VEGF 165 -induced endothelial cell migration, proliferation, and permeability. CaD significantly inhibited VEGF 165 -induced phosphorylation of VEGFR-2 and suppressed the activity of VEGFR-2 mediated signaling cascades. The effects of CaD in vitro were abrogated by heparin, suggesting the involvement of heparin-like domain in the interaction with CaD. In addition, VEGF 121 , an isoform which does not bind to heparin, was not inhibited by CaD. Using the proximity ligation approach, we detected inhibition of interaction in situ between HS and VEGF and between VEGF and VEGFR-2. Moreover, CaD reduced VEGF signaling in mice diabetic kidneys and ameliorated diabetic nephropathy and neuropathy, suggesting CaD as a VEGF inhibitor without the negative effects of complete VEGF blockade and therefore could be useful as a strategy in treating diabetic nephropathy.

No abstract

Dendritic cells (DCs) produce tumor necrosis factor (TNF)-alpha upon infection and contribute in various ways to defense against pathogenic agents. Several biological agents have been designed to inhibit TNF-alpha activity. However, the use of these inhibitors has been associated with an increased rate of certain opportunistic infections. To study the effect of TNF-alpha inhibition, human monocyte-derived DCs were infected with Chlamydia pneumoniae. TNF-alpha was neutralized by adalimumab, a human anti-TNF-alpha monoclonal antibody. Chlamydiae induced the maturation of DC as determined by flow cytometry and quantitative real-time PCR. However, DC maturation was impaired in the presence of adalimumab. Moreover, neutralization of TNF-alpha resulted in a significant increase of infectious progeny, 16S rRNA gene copy number and development of larger inclusions consisting of different stages of chlamydial development. Additionally, chlamydial infection induced secretion of cytokines/chemokines, which were downregulated by adalimumab treatment. Our data reveal an indirect effect on maturation of DC by C. pneumoniae and that maturation is crucial for the restriction of chlamydial development. The results also demonstrate an increase in infectious progeny after TNF-alpha inhibition, suggesting a contribution of TNF-alpha produced by DCs to chlamydial growth arrest. These data suggest a possible mechanism by which TNF-alpha inhibition enhances the risk of intracellular infections.

No abstract

AIMTo investigate the therapeutic potential of vasculotide (VT) - a Tie2 activating therapeutic - in kidney transplantation.METHODSWe performed a murine MHC-mismatched renal transplant model (C57Bl/6 male into Balb/c female) with 60 min cold and 30 min warm ischemia time. 500 ng VT was administered i.p. to donor mice 1 h before organ removal. In addition, recipients received 500 ng VT i.p. directly and 3 d after surgery. Survival was monitored and remaining animals were sacrificed 28 d after transplantation. In this model, we analyzed: (1) organ function; (2) Kaplan-Meier survival; (3) organ damage (periodic acid Schiff staining) via semi-quantitative scoring [0-4 (0 = no injury/inflammation to 4 = very severe injury/inflammation)]; (4) expression of renal endothelial adhesion molecules (ICAM-1) via immunofluorescence (IF) staining, immunoblotting and qPCR; (5) infiltration of inflammatory cells (IF Gr-1, F4/80); and (6) fibrosis via staining of α-smooth muscle actin (αSMA), Sirius red staining and immunoblotting of SMAD3 activation.RESULTSExogenous activation of Tie2 with VT resulted in diminished expression of peritubular and glomerular endothelial adhesion molecules. Consequently, infiltration of inflammatory cells (analyzed as ICAM-1, Gr-1 and F4/80 positive cells) was reduced in VT-treated mice compared to controls. Additionally, VT was protective against fibrogenesis after kidney transplantation. Trends towards lower serum creatinine (vehicle: 142 ± 17 μmol/L vs VT: 94 ± 23 μmol/L), urea (vehicle: 76 ± 5 mmol/L vs VT: 60 ± 8 mmol/L) and lactate dehydrogenase (vehicle: 1288 ± 383 iU vs VT: 870 ± 275 iU) were observed on day 6 after transplantation. Kaplan-Meier survival analysis showed improved survival rates in the VT-treated mice that did not reach statistical significance (27% vs 54%, P = 0.24, n = 11 per group). Exogenous activation of Tie2 via VT might reduce infiltration of inflammatory cells into renal tissue thereby protecting the transplant from early graft dysfunction potentially affecting long-term function.CONCLUSIONProtection of the endothelial microvasculature via the Tie2 axis in the early transplant setting might hold promise as a therapeutic target.