Acute ischemic stroke : polymorphonuclear leukocyte membrane fluidity and cytosolic Ca(2+) concentration at baseline and after chemotactic activation

Sevoflurane preconditioning improves neuroinflammation in cerebral ischemia/reperfusion induced rats through ROS-NLRP3 pathway

AIM

We aimed to study the influence of sevoflurane on the nucleotide-binding domain and Leucine-rich repeat protein 3 (NLRP3) pathways in rats with cerebral ischemia/reperfusion (I/R) injury.

METHODS

Sixty Sprague-Dawley rats were equally divided into five groups randomly: sham-operated, cerebral I/R, sevoflurane (Sevo), NLRP3 inhibitor-treated (MCC950), and sevoflurane and NLRP3 inducer-treated groups. Rats' neurological functions were assessed using Longa scoring after 24 h of reperfusion, after which they were sacrificed, and cerebral infarction area was determined by triphenyl tetrazolium chloride staining. Pathological changes in damaged portions were assessed using hematoxylin-eosin and Nissl staining, and cell apoptosis was detected by terminal-deoxynucleotidyl transferase-mediated nick end labeling staining. Interleukin 1 beta (IL-1β), tumor necrosis factor α (TNF-α), interleukin-6 (IL-6), interleukin-18 (IL-18), malondialdehyde (MDA), and superoxide dismutase (SOD) levels in brain tissues were determined using enzyme-linked immunosorbent assay. Reactive oxygen species (ROS) levels were analyzed using a ROS assay kit. Protein levels of NLRP3, caspase-1, and IL-1β were determined by western blot.

RESULTS

Neurological function scores, cerebral infarction areas, and neuronal apoptosis index were decreased in the Sevo and MCC950 groups than in the I/R group. IL-1β, TNF-α, IL-6, IL-18, NLRP3, caspase-1, and IL-1β levels decreased in the Sevo and MCC950 groups (p < 0.05). ROS and MDA levels increased, but SOD levels increased in the Sevo and MCC950 groups than in the I/R group. NLPR3-inducer nigericin eliminated the protective effects of sevoflurane on cerebral I/R injury in rats.

CONCLUSION

Sevoflurane could alleviate cerebral I/R-induced brain damage by inhibiting the ROS-NLRP3 pathway.

Neutrophil Activated by the Famous and Potent PMA (Phorbol Myristate Acetate)

This review will briefly outline the major signaling pathways in PMA-activated neutrophils. PMA is widely used to understand neutrophil pathways and formation of NETs. PMA activates PKC; however, we highlight some isoforms that contribute to specific functions. PKC α, β and δ contribute to ROS production while PKC βII and PKC ζ are involved in cytoskeleton remodeling. Actin polymerization is important for the chemotaxis of neutrophils and its remodeling is connected to ROS balance. We suggest that, although ROS and production of NETs are usually observed together in PMA-activated neutrophils, there might be a regulatory mechanism balancing both. Interestingly, we suggest that serine proteases might determine the PAD4 action. PAD4 could be responsible for the activation of the NF-κB pathway that leads to IL-1β release, triggering the cleavage of gasdermin D by serine proteases such as elastase, leading to pore formation contributing to release of NETs. On the other hand, when serine proteases are inhibited, NETs are formed by citrullination through the PAD4 pathway. This review puts together results from the last 31 years of research on the effects of PMA on the neutrophil and proposes new insights on their interpretation.

Altered cellular membrane fluidity levels and lipid peroxidation during experimental pancreas transplantation

Although the pathogenesis of ischemia reperfusion (IR) injury is based on complex mechanisms, free radicals play a central role. We evaluated membrane fluidity and lipid peroxidation during pancreas transplantation (PT) performed in 12 pigs (six donors and six recipients). Fluidity was measured by fluorescence spectroscopy, and malondialdehyde (MDA) and 4-hydroxyalkenals (4-HDA) concentrations were used as an index of lipid oxidation. Pancreatic tissues were collected as follows: (A) donor, immediately before vascular clamping; (B) graft, following perfusion lavage with University of Wisconsin preservation fluid; (C) graft, after 16 h of cold ischemia; and (D) recipient, 30 min vascular postreperfusion. Fluidity and MDA and 4-HDA concentrations were similar in cases A, B, and C. However, there was significant membrane rigidity and increased lipid peroxidation after reperfusion (D). These findings suggest that reperfusion exaggerates oxidative damage and may account for the rigidity in the membranes of allografts during PT.

Herbal formula FBD extracts prevented brain injury and inflammation induced by cerebral ischemia-reperfusion

The aim of this work was to verify neuroprotective and anti-inflammatory properties of FBD, a herbal formula composed of Poria cocos, Atractylodes macrocephala and Angelica sinensis, in ICR mice subjected to repetitive 10 min of common carotid arteries occlusion followed 24 h reperfusion. Intragastrical pretreatment with supercritical carbon dioxide extract (FBD-CO(2), 37.5 mg/kg) twice daily for 3.5 d, significantly reduced Evans Blue influx, neuron specific enolase (NSE) efflux, brain infarction (all p<0.05), also inhibited polymorphonuclear leukocytes (PMNs) infiltration (p<0.001), suppressed secretion of tumor necrosis factor (TNF)-alpha in blood (p<0.05), interleukin (IL)-1beta and IL-8 in brain (both p<0.01), and down-regulated cerebral expression of phosphor-IkappaB-alpha and phosphor-nuclear factor kappa-B (NF-kappaB), whether coupled with aqueous extract (FBD-H(2)O, 150 mg/kg) or not. Moreover, FBD-CO(2) (0.1-10 microg/ml) inhibited 0.1 microM phorbol myristate acetate-evoked oxidative burst in rat PMNs, 20 ng/ml TNF-alpha-triggered PMNs adhesion to ECV304 endothelial cells, and PMNs neurotoxicity to PC12 neuron-like cells as well as NSE release (IC(50) 1.30, 0.98, 0.24 and 0.82 microg/ml, respectively). Our study demonstrated that FBD-CO(2) prevented brain ischemia/reperfusion injury, at least in part, by limiting PMNs infiltration and neurotoxicity mediated by TNF-alpha, IL-1beta and IL-8, via inhibition on NF-kappaB activation.

Granulocyte integrins before and after activation in acute ischaemic stroke

We examined in 19 subjects with acute ischaemic stroke (AIS) the PMN integrin pattern (CD11a, CD11b, CD11c, CD18), using indirect immunofluorescence and adopting a flow cytometer, at baseline and during activation, prolonged for 5 and 15 min, with 4-phorbol 12-myristate 13-acetate (PMA). At baseline, an increase in the expression of CD11c and CD18 and a decrease in the CD11b were evident in AIS subjects compared to normals. After activation, we found in normals a constant and significant increase of all PMN adhesive molecules, while in AIS subjects, we found an increase in CD11b and CD18, a decrease in CD11a and no variation in CD11c. While the basal upregulation of CD11c and CD18 may depend on the PMN spontaneous activation or on the increase of cytokines, the decrease of CD11b may be due to its self-consumption. After activation, the decrease in CD11a noted in AIS may be related to its cleavage or to an altered integrin phosphorylation/dephosphorylation balance.