Protective effect of crocetin on bovine spermatozoa against oxidative stress during in vitro fertilization.

Oxidative stress is one of the major factors that contribute to poor semen quality and low rates of in vitro fertilization. Crocetin, a main constituent of saffron (Crocus sativus L.) possesses potent antioxidant activity, by scavenging reactive oxygen species (ROS) and/or enhancing the activity of intracellular antioxidant enzymes. The aim of this study was to investigate, for the first time, the effect of crocetin on the quality characteristics of bull spermatozoa and fertilization rate. For this reason, frozen/thawed bovine spermatozoa were incubated with crocetin (1, 2.5, and 5 µm), for 120 or 240 min, in the presence of a negative control, and evaluated in terms of motility, viability, acrosomal status, DNA fragmentation index, intracellular ROS, and lipid peroxidation. In order to evaluate the impact of crocetin on cleavage and blastocyst rate, the compound was added in the IVF medium at the previously identified optimal concentration (2.5 µm). The results indicate that incubation of spermatozoa with 2.5 µm of crocetin resulted in a statistically significant lower production of superoxide anion and hydrogen peroxide, lower lipid peroxidation, and in better maintenance of motility parameters, viability, and acrosomal integrity, with a very small number of cells with DNA fragmentation, compared to the other groups (p < 0.05). The presence of crocetin (2.5 µm) in the fertilization medium also resulted in a significant increase in acrosome-reacted spermatozoa and blastocyst production, compared to the control group (p < 0.01). These data indicate that crocetin (2.5 µm) positively affects bovine sperm quality characteristics during a 240-min incubation and improves its fertilizing ability, directly and/or indirectly, by regulating ROS concentration and lipid peroxidation.

Antioxidant effect of crocin on bovine sperm quality and in vitro fertilization.

Reactive oxygen species (ROS) production above critical levels affects the genetic and functional integrity of spermatozoa by causing oxidative stress. Spermatozoa are susceptible to oxidative stress in terms of motility and fertilization capacity. Crocin (crocetin di-gentiobiose ester), a main constituent of Crocus Sativus L. (saffron), is known for its antioxidant activity by scavenging ROS, especially superoxide anion. The aim of the present study is to evaluate the effect of crocin on the quality characteristics of spermatozoa and fertilization rate. Frozen-thawed and washed spermatozoa from four different bulls were incubated with three different concentrations of crocin (0.5, 1, and 2 mM), for 120 and 240 minutes, in the presence of a negative control, and were evaluated in terms of motility, viability, acrosomal status, DNA fragmentation index, intracellular ROS, and lipid peroxidation. The most potent concentration of crocin (1 mM) was also added in the fertilization medium to test its impact on fertilization outcome. The results indicate that the incubation of spermatozoa with 1 mM of crocin resulted in a statistically significant lower production of ROS, lower lipid peroxidation and in better maintenance of motility, viability, and acrosomal integrity, with a very small number of fragmented cells, compared to the control and the other treated groups (P < 0.05). Crocin concentration of 1 mM resulted in a significant increase of blastocyst rate, compared to the control group (P < 0.01). These data indicate that crocin (1 mM) improves bovine sperm quality and its fertilization capability, directly and/or indirectly, by modulating ROS concentration.

Complement inhibition in a xenogeneic model of interactions between human whole blood and porcine endothelium.

Xenotransplantation (xeno-Tx) is considered as an alternative solution to overcome the shortage of human donor organs. However, the success of xeno-Tx is hindered by immune reactions against xenogeneic cells (e. g. of porcine origin). More specifically, activation of innate immune mechanisms such as complement and triggering of the coagulation cascade occur shortly after xeno-Tx, and adhesion of human leukocytes to porcine endothelium is another early critical step mediating the immune attack. To investigate the therapeutic potential of complement inhibition in the context of xenogeneic interactions, we have employed a whole-blood model in the present study. Incubation of human blood with porcine endothelial cells (PAECs) led to activation of complement and coagulation as well as to increased leukocyte adhesion. The observed responses can be attributed to the pig-to-human xenogeneicity, since the presence of human endothelium induced a minor cellular and plasmatic inflammatory response. Importantly, complement inhibition using a potent complement C3 inhibitor, compstatin analogue Cp40, abrogated the adhesion of leukocytes and, more specifically, the attachment of neutrophils to porcine endothelium. Moreover, Cp40 inhibited the activation of PAECs and leukocytes, since the levels of the adhesion molecules E-selectin, ICAM-1, ICAM-2, and VCAM-1 on PAECs and the surface expression of integrin CD11b on neutrophils were significantly decreased. Along the same line, inhibition of CD11b resulted in decreased leukocyte adhesion. Taken together, our findings provide a better understanding of the mechanisms regulating the acute innate immune complications in the context of xeno-Tx and could pave the way for complement-targeting therapeutic interventions.

Leptin induces the expression of functional tissue factor in human neutrophils and peripheral blood mononuclear cells through JAK2-dependent mechanisms and TNFalpha involvement.

INTRODUCTION: Leptin is an adipocyte-derived cytokine primarily involved in the regulation of body weight and energy balance. In vivo studies suggest that leptin promotes platelet aggregation and thrombosis. Neutrophils are involved in the crosstalk between inflammation and thrombosis in clinical disorders. Leptin is also involved in the regulation of inflammation. AIM: We examined the in vitro effects of leptin on the expression of tissue factor (TF), the primary initiator of coagulation, in healthy neutrophils. MATERIALS AND METHODS/RESULTS: The effects on TF expression were assayed functionally using a modified prothrombin time (mPT), as well as at mRNA and protein levels. The same experiments were performed in parallel with PBMC. Leptin induced functional TF and increased TF mRNA and protein expression in both cell types, as determined by mPT, real-time RT-PCR, western blot, flow cytometry, immunocytochemistry. Inhibition studies revealed that the effect of leptin on TF expression is mediated, at least in part, by JAK2 and PI3K. Our findings, after neutralising TNFalpha in supernatants of leptin-treated cells, also suggest the involvement of TNFalpha in the leptin-induced TF expression in leukocytes. CONCLUSIONS: This study indicates a novel link between inflammation, obesity and thrombosis by showing that leptin is able to trigger the extrinsic coagulation cascade. This work suggests a possible mechanism of the thrombotic effects of hyperleptinemic-associated clinical disorders.