Ulinastatin alone does not reduce caspase 3-mediated apoptosis in protease-positive Aeromonas hydrophilia-induced sepsis

Prospective experimental studies on the renal protective effect of ulinastatin after paraquat poisoning

BACKGROUND

Paraquat (PQ) is an effective herbicide and is widely used in agricultural production, but PQ poisoning is frequently seen in humans with the lung as the target organ. Currently, there are many studies on lung injury after PQ poisoning. But the kidney as the main excretory organ after PQ poisoning is rarely studied and the mechanisms of this poisoning is not very clear. In this study, we observed the expression of caspase-3 and livin protein in rat renal tissue after PQ poisoning as well as the therapeutic effects of ulinastatin.

METHODS

Fifty-four Sprague-Dawley (SD) rats were randomly divided into three experimental groups: control group (group A), paraquat poisoning group (group B) and ulinastatin group (group C), with 18 rats in each group. Rats in group B and group C were administered intragastrically with 80 mg/kg PQ, rats in group C were injected peritoneally with 100 000 U/kg ulinastatin once a day, while rats in group A were administered intragastrically with the same volume of saline as PQ. At 24, 48, 72 hours after poisoning, the expression of livin in renal tissue was detected by Westen blotting, the expression of caspase-3 was detected by immunohistochemistry, and the rate of renal cell apoptosis was tested by TUNEL detection. The histopathological changes were observed at the same time.

RESULTS

Compared to group A, the expression of caspase-3 in the renal tissue of rats in groups B and C increased significantly at any time point. Compared with group B, the expression of caspase-3 in renal tissue of rats in group C decreased. Compared with group A, the expression of livin in renal tissue in rats of groups B and C increased significantly at any time point (P<0.01), especially in group C (P<0.01). TUNEL method showed that the rate of renal cell apoptosis index was higher in group B at corresponding time points than in group A (P<0.01), and was lower in group C at corresponding time points than in group B (P<0.01).

CONCLUSION

UTI has a protective effect on the renal tissue of rats after paraquat poisoning through up-regulating the expression of livin and down-regulating the expression of caspase-3, but the regulation path still needs a further research.

Modulation of host immune defenses by Aeromonas and Yersinia species: convergence on toxins secreted by various secretion systems

Like other pathogenic bacteria, Yersinia and Aeromonas species have been continuously co-evolving with their respective hosts. Although the former is a bonafide human pathogen, the latter has gained notararity as an emerging disease-causing agent. In response to immune cell challenges, bacterial pathogens have developed diverse mechanism(s) enabling their survival, and, at times, dominance over various host immune defense systems. The bacterial type three secretion system (T3SS) is evolutionarily derived from flagellar subunits and serves as a vehicle by which microbes can directly inject/translocate anti-host factors/effector proteins into targeted host immune cells. A large number of Gram-negative bacterial pathogens possess a T3SS empowering them to disrupt host cell signaling, actin cytoskeleton re-arrangements, and even to induce host-cell apoptotic and pyroptotic pathways. All pathogenic yersiniae and most Aeromonas species possess a T3SS, but they also possess T2- and T6-secreted toxins/effector proteins. This review will focus on the mechanisms by which the T3SS effectors Yersinia outer membrane protein J (YopJ) and an Aeromonas hydrophila AexU protein, isolated from the diarrheal isolate SSU, mollify host immune system defenses. Additionally, the mechanisms that are associated with host cell apoptosis/pyroptosis by Aeromonas T2SS secreted Act, a cytotoxic enterotoxin, and Hemolysin co-regulated protein (Hcp), an A. hydrophila T6SS effector, will also be discussed.