Marilena Galdiero

Can Chlamydia trachomatis directly damage your sperm

Although Chlamydia trachomatis causes symptomatic infection in the lower genital tract of approximately 50% of men, its role in the upper genital tract is less well known. Moreover, for a number of reasons, mostly based on methodological aspects, the impact of chlamydia on semen quality is controversial. Overall, in-vivo studies of C trachomatis in men have provided conflicting evidence as to whether it is associated with reduced fertility. By contrast, in-vitro studies show that co-incubation of spermatozoa with chlamydia causes a significant decline in numbers of motile sperm and results in premature sperm death. Since evidence suggests that chlamydial lipopolysaccharide is the principal factor leading to sperm apoptosis, a new line of inquiry would be to measure the levels of lipopolysaccharide in semen and relate these to parameters of semen quality, including that of sperm function. If these new lines of inquiry are proven, this could lead to potentially novel approaches in the treatment of infertile men.

Haemophilus influenzae Porin Induces Toll-Like Receptor 2-Mediated Cytokine Production in Human Monocytes and Mouse Macrophages

ABSTRACT The production of proinflammatory cytokines is likely to play a major pathophysiological role in meningitis and other infections caused by Haemophilus influenzae type b (Hib). Previous studies have shown that Hib porin contributes to signaling of the inflammatory cascade. We examined here the role of Toll-like receptors (TLRs) and the TLR-associated adaptor protein MyD88 in Hib porin-induced production of tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6). Hib porin-induced TNF-α and IL-6 production was virtually eliminated in macrophages from TLR2- or MyD88-deficient mice. In contrast, macrophages from lipopolysaccharide (LPS)-hyporesponsive C3H/HeJ mice, which are defective in TLR4 function, responded normally to Hib porin. Moreover anti-TLR2 antibodies but not anti-TLR4 antibodies significantly reduced Hib porin-stimulated TNF-α and IL-6 release from the human monocytic cell line THP-1. These data indicate that the TLR2/MyD88 pathway plays an essential role in Hib porin-mediated cytokine production. These findings may be useful in the development of alternative therapies aimed at reducing excessive inflammatory responses during Hib infections.

Porins and Lipopolysaccharide Induce Apoptosis in Human Spermatozoa

ABSTRACT Treatment of human spermatozoa with porins or lipopolysaccharide (LPS) increases spontaneous apoptosis in these cells. Porins and LPS were extracted from Salmonella enterica serovar Typhimurium and Pasteurella multocida and were mixed with human spermatozoa for detection of levels of apoptosis.

Recombinant human prolactin induces protection against Salmonella typhimurium infection in the mouse: role of nitric oxide

In the present study, we demonstrated that repeated treatment with recombinant human prolactin (rhPRL) protected mice against Salmonella typhimurium infection. The protective activity was statistically significant, dose-dependent and present only when rhPRL treatments were performed before the infection. This activity was probably related to the observed increases in phagocytosis and intracellular killing of peritoneal macrophages induced by the hormonal treatment. The number of peripheral leukocytes was not modified, excluding a mobilization of cells from other compartments. A decrease in the mortality rate after challenge was also observed in mice treated with the monoclonal antibody anti-PRL receptor U5, confirming that the protective activity was associated with receptor activation. Our studies also suggest that nitric oxide (NO) production was involved in the protective effect of rhPRL since pre-treatment of the animals with L-NAME, an inhibitor of NO-synthase, was able to completely revert the protective activity, whereas D-NAME, the inactive D-isomer, was without effect.

Effect of Salmonella typhimurium porins on biological activities of human polymorphonuclear leukocytes

The effect of Salmonella typhimurium porins on human polymorphonuclear leukocytes (PMNs) was studied. Labeled porins were shown to bind to the PMNs, and could be completely displaced by unlabeled porins. The binding caused modifications of membrane integrity and of the physico-chemical characteristics of the PMN surface, e.g. decreased oxidative burst, decreased hydrophobicity and altered cell morphology. The porins acted as both chemotaxins and chemotaxinogens. When PMNs were preincubated with porins their migration in the presence of commonly used chemoattractants (serum activated by zymosan or N-formyl-L-methionyl-L-leucyl-L-phenylalanine) was inhibited.

In vivo inhibition of cell-mediated and humoral immune responses to cellular antigens by SV-IV, a major protein secreted from the rat seminal vesicle epithelium

Microgram amounts of protein SV-IV, a major secretory protein produced by adult rat seminal vesicle epithelium, markedly decrease the mouse humoral immune response to cellular xenogeneic or allogeneic antigens (sheep red blood cells (SRBC) or mouse epididymal spermatozoa). The significant reduction in the total number of splenocytes and their main cell subsets in SRBC-immunized mice, the dramatic decrease in the number of Ia+ splenic T cells and the marked inhibition of splenocyte ability to respond in vitro to polyclonal mitogen stimuli suggest that the macrophage accessory cells are the primary target of the SV-IV immunosuppressive activity in vivo. Moreover, the infection of SV-IV-treated mice with Salmonella typhimurium produced an increased mortality of the experimental animals associated with a marked decrease of the phagocytic and intracellular killing activities of their peritoneal macrophages.

Role of mitogen-activated protein kinases in the iNOS production and cytokine secretion by Salmonella enterica serovar Typhimurium porins

The expression of inducible nitric oxide synthase (iNOS) is a critical factor in both physiological and pathological functions. The present study examined the role of mitogen-activated protein kinases (MAPKs) in the regulation of iNOS and proinflammatory cytokine production in RAW 264.7 cells in response to Salmonella enterica serovar Typhimurium porins. By use of Western blotting for iNOS detection and enzyme-linked immunosorbent assay (ELISA) for quantization of cytokine secretion, selective pharmacological inhibitors of MAPK pathways were tested for dissecting the molecular mechanisms underlying the mediation of these signaling in porins-stimulated murine macrophages. S. enterica serovar Typhimurium porins activated iNOS expression, NO production and interleukin (IL)-6, IL-8 and tumor necrosis factor-alpha (TNF-alpha) release. Treatment of cells with SB203580 and SP600125 (inhibitors of p38 and JNK, respectively) significantly affected porin-stimulated iNOS and NO production. Concomitant decrease in the proinflammatory cytokine secretion was detected. These data confirm the importance of the MAPKs cascade in macrophage activation by bacterial product opening up new strategies for therapy of septic shock.

Peptides complementary to the active loop of porin P2 from Haemophilus influenzae modulate its activity

Haemophilus influenzae type b (Hib) is one of the leading causes of invasive bacterial infection in young children. It is characterized by inflammation that is mainly mediated by cytokines and chemokines. One of the most abundant components of the Hib outer membrane is the P2 porin, which has been shown to induce the release of several inflammatory cytokines. A synthetic peptide corresponding to loop L7 of the porin activates JNK and p38 mitogen-activated protein kinase (MAPK) pathways. We report a novel use of the complementary peptide approach to design a peptide that is able to bind selectively to the protein P2, thereby reducing its activity. This work provides insights into essential molecular details of P2 that may affect the pathogenesis of Hib infections where interruption of the signaling cascade could represent an attractive therapeutic strategy.

Induction of cytokine mRNA expression in U937 cells by Salmonella typhimurium porins is regulated by different phosphorylation pathways

Lipopolysaccharide (LPS) and porins of Gram-negative outer membranes are the main pathogenic factors implicated in the clinical syndrome of septic shock. The biological activity of porins and LPS are similar, but they occur by different mechanisms. It seems that porins act through different intracellular pathways with respect to LPS. In this study we analyzed the role of several inhibitors of the MEK/ERK signal pathway on the induction of proinflammatory and immunological cytokines in U937 cell line stimulated by Salmonella typhimurium porins and compared it to the cytokine induction after LPS stimulation. We investigated the effects of p38 MAP kinase inhibitor SB-203580, MEK/ERK kinase inhibitor PD-098059 and Raf-1 inhibitor forskolin, and demonstrated that they modulate cytokine mRNA expression in a different manner as a consequence of the use of porins or LPS as stimuli. TNF-α and IL-1β mRNA expression is decreased by PD-098059 after stimulation with LPS but not with porins in differentiated U937 cells. IL-10 mRNA expression is inhibited by SB-203580 and PD-098059 after stimulation with porins in U937 cells. IL-6 and IL-8 mRNA expression is not changed by PD-098059 or SB-203580, after stimulation either with porins or LPS. Furthermore, mRNA expression of the studied cytokines, except for GM-CSF, is not changed using forskolin.

Inhibition of Viral-Induced Membrane Fusion by Peptides

Enveloped animal viruses fuse their membrane with a host cell membrane in order to deliver their genome into the cytoplasm of the cell and thus initiating infection. This crucial step is mediated by virally encoded transmembrane proteins that, following an appropriate triggering, insert their fusion peptides into the target membrane and, through a cascade of conformational changes, drive the merging of the two apposing membranes. The battle against viruses is ongoing with the constant threat of viruses developing resistance to present drugs and emerging viruses, therefore there is a continuous challenge to improve our defence strategies. Entry inhibitors are currently in development for diverse human and animal viral pathogens, and advances in our understanding on how viral entry proteins undergo conformational changes that lead to entry offer a huge potential for the development of novel therapeutics. This review describes recent advances on viral-mediated fusion mechanisms concentrating on the development of peptidic inhibitors of membrane fusion.