Human astrocytic bradykinin B(2) receptor modulates zymosan-induced cytokine expression in 1321N1 cells

An overview of kinin mediated events in cancer progression and therapeutic applications

Kinins are bioactive peptides generated in the inflammatory milieu of the tissue microenvironment, which is involved in cancer progression and inflammatory response. Kinins signals through activation of two G-protein coupled receptors; inducible Bradykinin Receptor B1 (B1R) and constitutive receptor B2 (B2R). Activation of kinin receptors and its cross-talk with receptor tyrosine kinases activates multiple signaling pathways, including ERK/MAPK, PI3K, PKC, and p38 pathways regulating cancer hallmarks. Perturbations of the kinin-mediated events are implicated in various aspects of cancer invasion, matrix remodeling, and metastasis. In the tumor microenvironment, kinins initiate fibroblast activation, mesenchymal stem cell interactions, and recruitment of immune cells. Albeit the precise nature of kinin function in the metastasis and tumor microenvironment are not completely clear yet, several kinin receptor antagonists show anti-metastatic potential. Here, we showcase an overview of the complex biology of kinins and their role in cancer pathogenesis and therapeutic aspects.

Implication of the Kallikrein-Kinin system in neurological disorders: Quest for potential biomarkers and mechanisms

Neurological disorders represent major health concerns in terms of comorbidity and mortality worldwide. Despite a tremendous increase in our understanding of the pathophysiological processes involved in disease progression and prevention, the accumulated knowledge so far resulted in relatively moderate translational benefits in terms of therapeutic interventions and enhanced clinical outcomes. Aiming at specific neural molecular pathways, different strategies have been geared to target the development and progression of such disorders. The kallikrein-kinin system (KKS) is among the most delineated candidate systems due to its ubiquitous roles mediating several of the pathophysiological features of these neurological disorders as well as being implicated in regulating various brain functions. Several experimental KKS models revealed that the inhibition or stimulation of the two receptors of the KKS system (B1R and B2R) can exhibit neuroprotective and/or adverse pathological outcomes. This updated review provides background details of the KKS components and their functions in different neurological disorders including temporal lobe epilepsy, traumatic brain injury, stroke, spinal cord injury, Alzheimer's disease, multiple sclerosis and glioma. Finally, this work will highlight the putative roles of the KKS components as potential neurotherapeutic targets and provide future perspectives on the possibility of translating these findings into potential clinical biomarkers in neurological disease.

Human salivary gland cells express bradykinin receptors that modulate the expression of proinflammatory cytokines

Bradykinin is an important peptide modulator that affects the function of neurons and immune cells. However, there is no evidence of the bradykinin receptors and their functions in human salivary glands. Here we have identified and characterized bradykinin receptors on human submandibular gland cells. Both bradykinin B1 and B2 receptors are expressed on human submandibular gland cells, A253 cells, and HSG cells. Bradykinin increased the intracellular Ca²⁺ concentration ([Ca²⁺ ]_i ) in a concentration-dependent manner. Interestingly, a specific agonist of the B1 receptor did not have any effect on [Ca²⁺ ]_i in HSG cells, whereas specific agonists of the B2 receptor had a Ca²⁺ mobilizing effect. Furthermore, application of the B1 receptor antagonist, R715, did not alter the bradykinin-mediated increase in cytosolic Ca²⁺ , whereas the B2 receptor antagonist, HOE140, showed a strong inhibitory effect, which implies that bradykinin B2 receptors are functional in modulating the concentration of cytosolic Ca²⁺ . Bradykinin did not affect a carbachol-induced rise of [Ca²⁺ ]_i and did not modulate translocation of aquaporin-5. However, bradykinin did promote the expression of proinflammatory cytokines, including tumor necrosis factor-α (TNF-α), implying the role of bradykinin in salivary gland inflammation. These data suggest that bradykinin receptors are involved in Ca²⁺ signaling in human submandibular gland cells and serve a unique role, which is separate from that of other salivary gland G protein-coupled receptors.

Prostaglandin modulates TLR3-induced cytokine expression in human astroglioma cells

Cyclooxygenase (COX) products and pattern recognition receptors are important modulators of neuroinflammation; however, the role of prostaglandins and toll-like receptor (TLR) signaling and the functional crosstalk between COX modulators remains unclear, especially in astrocytes that closely modulate neuronal functions. Here, we studied the effect of prostaglandins on toll-like receptor 3 (TLR3)-induced cytokine expression in human astroglioma CRT-MG cells. Prostaglandin E2 (PGE2) was shown to increase cytosolic cAMP levels in an EP2 receptor dependent manner. Interestingly, the TLR3 agonist polyinosinic:polycytidylic acid (poly(I:C)) mediated phosphorylation of NF-κB and extracellular stress-related kinase 1/2 (ERK1/2), which significantly decreased following PGE2 treatment. In addition, PGE2 increased the phosphorylation and inactivation of glycogen synthesis kinase-3β (GSK-3β), whereas poly(I:C) decreased it. We observed that PGE2 decreased tumor necrosis factor-α (TNF-α) production evoked by poly(I:C), whereas PGE2 potentiated poly(I:C)-triggered interleukin-8 (IL-8) production. These results suggest that prostaglandin modulates the TLR3-mediated cytokine profile in astrocytes via EP2 receptors and regulates the NF-κB, ERK1/2 and GSK-3β signaling pathways.

Neuroprotection against degeneration of sk-N-mc cells using neuron growth factor-encapsulated liposomes with surface cereport and transferrin

Liposomes with Cereport (RMP-7) and transferrin (Tf) (RMP-7/Tf/liposomes) were employed to target the blood-brain barrier (BBB) and to inhibit the degeneration of neurons insulted with fibrillar β-amyloid peptide 1-42 (Aβ1-42). Neuron growth factor (NGF)-encapsulated RMP-7/Tf/liposomes (RMP-7/Tf/NGF-liposomes) were used to permeate a monolayer of human brain-microvascular endothelial cells (HBMECs) regulated by human astrocytes (HAs) and to treat Aβ1-42 -attacked SK-N-MC cells. An increase in RMT-7 concentration increased the particle size, zeta potential, propidium iodide (PI) permeability, and NGF permeability, but decreased the cross-linking efficiency of RMT-7, viability of HBMECs and HAs, and transendothelial electrical resistance (TEER). In addition, an increase in Tf concentration enhanced the particle size, viability of HBMECs, HAs, and SK-N-MC cells, PI permeability, and NGF permeability, but reduced the zeta potential, cross-linking efficiency of RMT-7 and Tf, and TEER. RMP-7/Tf/NGF-liposomes can transport NGF across the BBB and improve the neuroprotection for Alzheimer's disease therapy in preclinical trials.

Sevoflurane anesthesia in pregnant mice induces neurotoxicity in fetal and offspring mice

BACKGROUND

Each year, over 75,000 pregnant women in the United States undergo anesthesia care. The authors set out to assess the effects of the anesthetic sevoflurane on neurotoxicity in pregnant mice and on learning and memory in fetal and offspring mice.

METHODS

Pregnant mice (gestational day 14) and mouse primary neurons were treated with 2.5% sevoflurane for 2 h and 4.1% sevoflurane for 6 h, respectively. Brain tissues of both fetal and offspring mice (P31) and the primary neurons were harvested and subjected to Western blot and immunohistochemistry to assess interleukin-6, the synaptic markers postsynaptic density-95 and synaptophysin, and caspase-3 levels. Separately, learning and memory function in the offspring mice was determined in the Morris water maze.

RESULTS

Sevoflurane anesthesia in pregnant mice induced caspase-3 activation, increased interleukin-6 levels (256 ± 50.98% [mean ± SD] vs. 100 ± 54.12%, P = 0.026), and reduced postsynaptic density-95 (61 ± 13.53% vs. 100 ± 10.08%, P = 0.036) and synaptophysin levels in fetal and offspring mice. The sevoflurane anesthesia impaired learning and memory in offspring mice at P31. Moreover, interleukin-6 antibody mitigated the sevoflurane-induced reduction in postsynaptic density-95 levels in the neurons. Finally, environmental enrichment attenuated the sevoflurane-induced increases in interleukin-6 levels, reductions of synapse markers, and learning and memory impairment.

CONCLUSIONS

These results suggest that sevoflurane may induce detrimental effects in fetal and offspring mice, which can be mitigated by environmental enrichment. These findings should promote more studies to determine the neurotoxicity of anesthesia in the developing brain.

Isoflurane and sevoflurane increase interleukin-6 levels through the nuclear factor-kappa B pathway in neuroglioma cells

BACKGROUND

Isoflurane can increase pro-inflammatory cytokine interleukin (IL)-6 levels. However, the up-stream mechanism remains unknown. Nuclear factor-kappa B (NF-κB) promotes the generation of pro-inflammatory cytokines. We examined the effects of isoflurane and sevoflurane on the NF-κB signalling pathway and its association with IL-6 levels in cultured cells.

METHODS

H4 human neuroglioma cells (H4 cells), and mouse primary neurones and microglia were treated with 2% isoflurane or 4.1% sevoflurane for 6 h, for analysis of IL-6 and NF-κB. Pyrrolidine dithiocarbamate (an NF-κB inhibitor) or 2-deoxy-d-glucose (2-DG) (an inhibitor of glucose glycolysis) was applied 1 h before anaesthetic treatment.

RESULTS

Isoflurane or sevoflurane treatment increased the levels of IL-6 [isoflurane: 410% (54); sevoflurane: 290% (24)], the nuclear levels of NF-κB [isoflurane: 170% (36); sevoflurane: 320% (30)], and the transcription activity of NF-κB in H4 cells. Moreover, isoflurane enhanced the transcription activity of NF-κB in mouse microglia, but not primary neurones. Finally, pyrrolidine dithiocarbamate and 2-DG attenuated isoflurane-induced increases in IL-6 and NF-κB, and the transcription activity of NF-κB.

CONCLUSIONS

These studies in H4 cells suggest that the NF-κB signalling pathway could contribute to isoflurane or sevoflurane-induced neuroinflammation. This could lead to the targeted intervention of anaesthetic-induced neuroinflammation.

Selective anesthesia-induced neuroinflammation in developing mouse brain and cognitive impairment

BACKGROUND

: Recent population studies have suggested that children with multiple exposures to anesthesia and surgery at an early age are at an increased risk of cognitive impairment. The authors therefore have established an animal model with single versus multiple exposures of anesthetic(s) in young versus adult mice, aiming to distinguish the role of different types of anesthesia in cognitive impairment.

METHODS

: Six- and 60-day-old mice were exposed to various anesthesia regimens. The authors then determined the effects of the anesthesia on learning and memory function, levels of proinflammatory cytokine interleukin-6 and tumor necrosis factor-α in brain tissues, and the amount of ionized calcium-binding adaptor molecule 1-positive cells, the marker of microglia activation, in the hippocampus.

RESULTS

: In this article, the authors show that anesthesia with 3% sevoflurane for 2 h daily for 3 days induced cognitive impairment and neuroinflammation (e.g., increased interleukin-6 levels, 151 ± 2.3% [mean ± SD] vs. 100 ± 9.0%, P = 0.035, n = 6) in young but not in adult mice. Anesthesia with 3% sevoflurane for 2 h daily for 1 day and 9% desflurane for 2 h daily for 3 days induced neither cognitive impairment nor neuroinflammation. Finally, an enriched environment and antiinflammatory treatment (ketorolac) ameliorated the sevoflurane-induced cognitive impairment.

CONCLUSIONS

: Anesthesia-induced cognitive impairment may depend on developmental stage, anesthetic agent, and number of exposures. These findings also suggest the cellular basis and the potential prevention and treatment strategies for anesthesia-induced cognitive impairment, which may ultimately lead to safer anesthesia care and better postoperative outcomes for children.

Ischemic stroke and traumatic brain injury: the role of the kallikrein-kinin system

Acute ischemic stroke and traumatic brain injury are a major cause of mortality and morbidity. Due to the paucity of therapies, there is a pressing clinical demand for new treatment options. Successful therapeutic strategies for these conditions must target multiple pathophysiological mechanisms occurring at different stages of brain injury. In this respect, the kallikrein-kinin system is an ideal target linking key pathological hallmarks of ischemic and traumatic brain damage such as edema formation, inflammation, and thrombosis. In particular, the kinin receptors, plasma kallikrein, and coagulation factor XIIa are highly attractive candidates for pharmacological development, as kinin receptor antagonists or inhibitors of plasma kallikrein and coagulation factor XIIa are neuroprotective in animal models of stroke and traumatic brain injury. Nevertheless, conflicting preclinical evaluation as well as limited and inconclusive data from clinical trials suggest caution when transferring observations made in animals into the human situation. This review summarizes current evidence on the pathological significance of the kallikrein-kinin system during ischemic and traumatic brain damage, with a particular focus on experimental data derived from animal models. Experimental findings are also compared with human data if available, and potential therapeutic implications are discussed.