Chronic nicotine treatment decreases LPS signaling through NF-κB and TLR-4 modulation in the hippocampus

Protective Effect of Galantamine against Doxorubicin-Induced Neurotoxicity

BACKGROUND AND AIMS

Doxorubicin (DOX) causes cognitive impairment (chemobrain) in patients with cancer. While DOX damages the cholinergic system, few studies have focused on the protective effects of cholinergic function on chemobrain. The acetylcholinesterase inhibitor galantamine (GAL) demonstrates neuroprotective properties. We investigated the mechanisms associated with DOX-induced cognitive impairments and the potential protective role of GAL in preventing chemobrain.

MAIN METHODS

Female Wistar rats were divided into control, DOX, GAL, and DOX + GAL groups. The rats in the DOX group were administered DOX (5 mg/kg intraperitoneally twice weekly for two weeks), while those in the GAL group were orally administered GAL (2.5 mg/kg) via oral gavage once daily for 15 days. The combination group (DOX + GAL) received GAL (once daily) and DOX (two times per week) concurrently. The body weights and survival rates were monitored daily. The animals were subjected to behavioral tests to assess the memory function followed by the biochemical estimation of inflammatory markers, including tumor necrosis factor-α (TNF-α), interleukine-1β (IL-1β), and interleukine-6 (IL-6) in rat brain tissue and RT-qPCR.

KEY FINDINGS

DOX caused a reduction in the body weight and survival rate, which was alleviated by GAL concomitant treatment with DOX (DOX + GAL). These groups had reduced body weights and survival rates. DOX-treated animals exhibited an impairment of short-term spatial working memory, manifested as a behavioral alteration in the Y-maze test, the novel object recognition (NOR) test, and the elevated plus-maze (EPM) test. Concurrent treatment with GAL (DOX + GAL) showed improved memory function, as evidenced by an increase in the number of entries and time spent in the novel arm, the time spent exploring the novel object, and the transfer latency in the Y-maze, NOR test, and EPM test, respectively. These findings were also supported by biochemical observations showing the reversal of DOX-induced changes in IL-1β, IL-6, and TNF-α, as well as their relative expression of mRNA in brain tissue following concurrent GAL treatment.

CONCLUSION

GAL appeared to be a neuroprotective agent against neuroinflammation caused by DOX by reducing inflammatory markers in the brain.

Differential Effects of Nicotine, Alcohol, and Coexposure on Neuroimmune-Related Protein and Gene Expression in Corticolimbic Brain Regions of Rats

Nicotine and alcohol co-use is extremely common and their use constitutes two of the most common causes of preventable death, yet the underlying biological mechanisms are largely understudied. Activation of neuroimmune toll-like receptors (TLRs) promotes the induction of proinflammatory cascades and increases alcohol intake in rodents, which further promotes TLRs in the brain; nicotine may decrease central proinflammatory signaling. The current studies sought to determine the effects of nicotine ± alcohol (alone or in combination) on circulating blood plasma and TLR protein/gene expression in addiction-associated corticolimbic brain regions, including the prefrontal cortex-prelimbic (mPFC-PL) and nucleus accumbens core (AcbC). Adult rats were treated with alcohol (0 or 2 g/kg, IG) and exposed to nicotine vapor (0 or 30 mg/mL solution) daily for 2, 14, or 28 days. Plasma studies indicated no effects of independent exposure or coexposure in males. Coexposure decreased plasma nicotine levels versus nicotine-only treated females, yet alcohol and cotinine concentrations were unchanged. By 28 days, the anti-inflammatory cytokine IL-13 was decreased in alcohol-only females. Divergent changes in TLR3 (but not TLR4) protein occurred for independent-drug exposed males (but not coexposure), with reductions in the mPFC-PL after 14 days and increases in the AcbC by 28 days. Gene expression following chronic coexposure suggests nicotine may regionally counteract alcohol-induced inflammation, including increased AcbC-TLR3/4/7 and several downstream markers in females and increased mPFC-PL-TLR3 and -STAT3 (but not IRF3) evident in males with exposure to either drug alone. These findings give further insight into the role of sex and the neuroimmune system in independent exposure and coexposure to nicotine ± alcohol.

Role of Cholinergic Signaling in Alzheimer's Disease

Acetylcholine, a neurotransmitter secreted by cholinergic neurons, is involved in signal transduction related to memory and learning ability. Alzheimer’s disease (AD), a progressive and commonly diagnosed neurodegenerative disease, is characterized by memory and cognitive decline and behavioral disorders. The pathogenesis of AD is complex and remains unclear, being affected by various factors. The cholinergic hypothesis is the earliest theory about the pathogenesis of AD. Cholinergic atrophy and cognitive decline are accelerated in age-related neurodegenerative diseases such as AD. In addition, abnormal central cholinergic changes can also induce abnormal phosphorylation of ttau protein, nerve cell inflammation, cell apoptosis, and other pathological phenomena, but the exact mechanism of action is still unclear. Due to the complex and unclear pathogenesis, effective methods to prevent and treat AD are unavailable, and research to explore novel therapeutic drugs is various and active in the world. This review summaries the role of cholinergic signaling and the correlation between the cholinergic signaling pathway with other risk factors in AD and provides the latest research about the efficient therapeutic drugs and treatment of AD.

Supplementation of carvacrol attenuates hippocampal tumor necrosis factor-alpha level, oxidative stress, and learning and memory dysfunction in lipopolysaccharide-exposed rats

Background:

Carvacrol is a natural phenolic monoterpene with anti-inflammatory and antioxidant bioactivities. Neuroinflammatory and oxidative stress responses play a crucial role in the pathogenesis of Alzheimer's disease. The present study examined the effect of carvacrol on brain tumor necrosis factor-alpha (TNF-α) level and oxidative stress as well as spatial learning and memory performances in lipopolysaccharide (LPS)-exposed rats.

Materials and Methods:

The rats were treated with either carvacrol (25 and 50 mg/kg) or Tween 80 for 2 weeks. Thereafter, LPS (1 mg/kg) or saline was intraperitoneally administered on days 15–19, 2 h before Morris water maze task, and treatments with carvacrol or Tween 80 were performed 30 min prior to behavioral testing. The level of TNF-α, lipid peroxidation, and total thiol concentration were measured in the hippocampus and cerebral cortex at the end of the experiment.

Results:

It was found that LPS-exposed rats exhibited spatial learning and memory dysfunction, which was accompanied by increased TNF-α level and lipid peroxidation, and decreased total thiol concentration in the hippocampus and/or cortex. Moreover, treatment with carvacrol at a dose of 25 mg/kg attenuated learning and memory impairments, decreased TNF-α and lipid peroxidation level in the hippocampus and cortex, and increased total thiol concentration in the cortex.

Conclusion:

Carvacrol exerts neuroprotective effects against LPS-induced spatial memory deficits through attenuating hippocampal TNF-α level and oxidative stress in rats.

IgM-bearing B cell affinity subpopulations possess differential antigen sensitivity in rainbow trout

The need for accurate assessments of in vitro generated antibody prompted examination of the effect of antigen on secreted antibody concentrations and affinities. It was found that the antigen concentrations commonly employed for in vitro stimulation were able to significantly compromise IgM titer and affinity estimates in rainbow trout. Specifically, IgM titers were underestimated with the high affinity antibodies being specifically blocked. To remedy this, pulsed antigen cultures were employed, and it was found to reveal more accurate IgM antibody titers and affinity estimates. Additionally, pulsed dose responses provided evidence that high antigen concentrations specifically suppressed high affinity B cell induction. Optimal expression of high affinity antibodies required exposure to lower concentrations of antigen. Each affinity subpopulation appeared to possess a graded sensitivity to each dose of antigen, revealing the complex dynamic for differential IgM-bearing B cell induction that is possible during a response. These results reveal not only the need for antigen removal prior to in vitro antibody secretion, but also the possible role of high zone immunological tolerance on IgM affinity maturation in rainbow trout.

Nuclear factor-kappa B (NF-κB) in pathophysiology of Parkinson disease: Diverse patterns and mechanisms contributing to neurodegeneration

Parkinson's disease (PD), the most common movement disorder, comprises several pathophysiologic mechanisms including misfolded alpha-synuclein aggregation, inflammation, mitochondrial dysfunction, and synaptic loss. Nuclear Factor-Kappa B (NF-κB), as a key regulator of a myriad of cellular reactions, is shown to be involved in such mechanisms associated with PD, and the changes in NF-κB expression is implicated in PD. Alpha-synuclein accumulation, the characteristic feature of PD pathology, is known to trigger NF-κB activation in neurons, thereby propagating apoptosis through several mechanisms. Furthermore, misfolded alpha-synuclein released from degenerated neurons, activates several signaling pathways in glial cells which culminate in activation of NF-κB and production of pro-inflammatory cytokines, thereby aggravating neurodegenerative processes. On the other hand, NF-κB activation, acting as a double-edged sword, can be necessary for survival of neurons. For instance, NF-κB activation is necessary for competent mitochondrial function and deficiency in c-Rel, one of the NF-κB proteins, is known to propagate DA neuron loss via several mechanisms. Despite the dual role of NF-κB in PD, several agents by selectively modifying the mechanisms and pathways associated with NF-κB, can be effective in attenuating DA neuron loss and PD, as reviewed in this paper.

Effect of nicotine on placental inflammation and apoptosis in preeclampsia-like model

AIMS

Placental tissues from patients with preeclampsia (PE) and in the lipopolysaccharide (LPS)-induced PE-like model were used to investigate the implication of placental inflammation and apoptosis in PE. Whether the beneficial effects of nicotine are related to inhibition of placental inflammation and apoptosis in the PE-like model were investigated.

MAIN METHODS

Placental apoptosis was detected in PE patients and the PE-like rat model by TUNEL staining. Changes in the number of CD68⁺ macrophages in placental tissues from PE patients were detected by immunofluorescent staining. The mRNA expression of the pro-inflammatory cytokines tumor necrosis factor alpha (TNF-α), interleukin (IL-1β), MCP-1, and proteins involved in extrinsic or intrinsic apoptosis signaling in the PE-like model was determined by qRT-PCR; immunofluorescent staining was used to detect the expression of TNF-α receptor (TNFR1), MCP-1 and apoptosis-related proteins.

KEY FINDINGS

Placental apoptosis was increased in both PE patients and the PE-like model, more macrophages infiltrated into placenta in PE patients. A significant upregulation in mRNA expression of TNF-α, IL-1β, MCP-1, and caspase 3, caspase 8, caspase 9 was found in the PE-like rats compared to the control animals, the immunoreactivity of placental MCP-1, TNFR1, and apoptosis-related proteins (caspase 3, caspase 8, caspase 9, Bax) was also enhanced; nicotine treatment significantly reversed those changes.

SIGNIFICANCE

Our data suggests that the protective effects of nicotine are associated with inhibiting placenta inflammation and apoptosis, and nicotine might be a potentially therapeutic candidate for preventing preeclampsia.

Nicotine Alleviates Cortical Neuronal Injury by Suppressing Neuroinflammation and Upregulating Neuronal PI3K-AKT Signaling in an Eclampsia-Like Seizure Model

Our previous studies showed that treatment with alpha7 nicotinic acetylcholine receptor (α7nAChR) agonist nicotine could alleviate systemic inflammation and reduce neuronal loss in the hippocampus and seizure severity in eclampsia. In this study, we further investigated whether there is also neuronal damage in the cortex after eclamptic seizure, elucidated the potential mechanisms underlying the neuroprotective roles of nicotine in eclampsia. Retrospective analysis of MRI data of severe preeclampsia (SPE) patients was conducted. A preeclampsia model was established by lipopolysaccharide injection (PE group), and pentylenetetrazol was used to induce eclamptic seizure (E group). α7nAChR agonist nicotine and its antagonist (α-BGT) and PI3K inhibitor wortmannin were used for drug administration. Neuronal damage was detected by Nissl staining, and changes in neuroinflammation, neuronal apoptosis, α7nAChR expression, and PI3K-AKT signaling on cortical neurons were detected by immunohistochemistry and western blotting. MRI images showed that most abnormal signals from the brain of SPE patients were located in the cortex. The neuron survival ratio was lower in the cortex than in the hippocampus within the E group; such ratios in the cortex were significantly lower in the E and PE groups compared with those of the control group. Nicotine markedly decreased the production of inflammatory cytokines and microglial activation in the cortex of the E group. Moreover, nicotine increased p-AKT levels and decreased cleaved caspase-3 levels in cortical neurons. Treatment with α-BGT reversed effects of nicotine. Wortmannin also blocked the anti-neuronal apoptosis action of nicotine. Our results suggest that nicotine protects against neuronal injury in the cortex following eclampsia possibly by inhibiting neuroinflammation and activating neuronal PI3K-AKT pathway.

Antidepressant Effect and Modulation of the Redox System Mediated by Tannic Acid on Lipopolysaccharide-Induced Depressive and Inflammatory Changes in Mice

Depression is an emotional disorder that causes mental and physical changes, and has limited pharmacotherapy. Tannic acid (TA) is a polyphenol with previously described antioxidant and neuroprotective properties. The aim of this study was to evaluate the effects of TA on lipopolysaccharide (LPS)-induced depressive-like behavior, as well as oxidative stress parameters and TNF-α levels in the brains of mice. Animals were pretreated once daily, with TA (30 or 60 mg/kg), fluoxetine (20 mg/kg) or vehicle for 7 days. On the 7th day, the animals received a single injection of LPS (830 μg/kg). After 24 h, open field, forced swimming, tail suspension, and splash tests were conducted. The endotoxin induced depressive-like behavior in these mice and this was attenuated by TA. In the cerebral cortex, hippocampus, and striatum, LPS increased lipid peroxidation and reactive oxygen species production, and this was also prevented by TA administration. TA treatment also prevented a decrease in catalase activity within the striatum. Further, LPS administration caused increased levels of TNF-α in all brain structures, and this was prevented in the cortex by TA treatment. In conclusion, TA shows many neuroprotective properties, with demonstrated antioxidant, anti-inflammatory and antidepressant effects in this animal model of acute depressive-like behavior. Therefore, this compound could provide an alternative therapeutic approach for the treatment of depression.

Pro-inflammatory modification of cancer cells microsurroundings increases the survival rates for rats with low differentiated malignant glioma of brain

RATIONALE

Glioblastoma multiforme (GBM) is one of the most aggressive human brain tumors. The prognosis is unfavorable with a median survival of 15 months. GBM aggressive nature is associated with a special phenotype of cancer cells that develops because of the transforming growth factor β (TGF-β). The study was aimed at providing experimental justification in vivo of a possibility to suppress TGF-β production in a tumor via pro-inflammatory modification of cancer cell microenvironment, using CD45+ mononuclear cells of the red bone marrow.

MATERIALS AND METHODS

The experiment used animals with transplanted C6 glioma. The animals were divided into 4 groups: (I) control (N=60); (II) group of rats (N=30) that received granulocyte colony-stimulating factor (G-CSF) to recruit CD45+ bone marrow mononuclear cells into their systemic circulation (G-CSF group); (III) group of rats (N=30) that received pro-inflammatory therapy to trigger systemic inflammatory reaction by injecting bacterial lipopolysaccharides (LPS) and interferon-γ (IFNγ); (IV) rats (N=30), stimulated with G-CSF, followed by pro-inflammatory therapy. Stereotaxic modeling of a brain tumor in experimental animals, as well as a combination of morphological, immunocytochemical analyses and immunosorbent assay were used.

RESULTS

TGF-β1 production in the tumor tissue resulted being inversely proportional to the intensity of proliferation processes and directly proportional to the size of necrosis areas, peaking on the 28th day of the experiment. Stimulation of experimental animals with G-CSF recruits CD45+ mononuclear stem and progenitor cells into the systemic circulation of experimental animals with C6 glioma, accompanied by intensification of microglial proliferation in the tumor and infiltration of the tumor tissue with microglial cells. Pro-inflammatory therapy against G-CSF stimulation results in polarization of microglia/macrophages population together with intensified antigen presentation, lower production of TGF-β and IL10, increased synthesis of pro-inflammatory cytokines TNFα and IL1 in the tumor lesion and adjacent brain matter, remodeling of tumor matrix and higher survival rates for the experimental animals.

CONCLUSIONS

Pro-inflammatory inflammatory modification of cancer cell microenvironment suppresses TGFβ production in a tumor and increases survival rates of the rats with transplanted poorly differentiated malignant brain glioma.

κ-opioid receptor agonists may alleviate intestinal damage in cardiopulmonary bypass rats by inhibiting the NF-κB/HIF-1α pathway

The aims of the present study were to investigate the protective effect of a κ-opioid receptor (KOR) agonist on intestinal barrier dysfunction in rats during cardiopulmonary bypass (CPB), as well as to examine the role of NF-κB and the transcription factor hypoxia-inducible factor-1α (HIF-1α) signaling pathway in the regulatory mechanism. A total of 50 rats were randomly divided into five groups, with 10 rats in each group: Sham surgery group (group Sham), CPB surgery group (group CPB), KOR agonist + CPB (group K), KOR agonist + specific KOR antagonist + CBP (group NK) and KOR agonist + NF-κB pathway specific inhibitor + CPB (group NF). Intestinal microcirculation was evaluated to determine intestinal barrier dysfunction in rats following CPB surgery. Hematoxylin and eosin (H&E) staining was used to observe intestinal tissue injury in the rats. ELISA was used to detect the inflammatory factors interleukin (IL)-1β, IL-6, IL10 and tumor necrosis factor-α, and the oxidative stress factors superoxidase dismutase, malondialdehyde and nitric oxide in serum. In addition, ELISA was used to investigate the serum levels of the intestinal damage markers D-lactic acid, diamine oxidase and intestinal fatty acid-binding protein. Western blotting was used to investigate the protein expression levels of tight junction proteins zonula occludens-1 and claudin-1. Furthermore, immunohistochemistry was used to examine intestinal injuries and western blotting was used to detect expression levels of NF-κB/HIF-1α signaling pathway-related proteins. H&E staining results suggested that the KOR agonist alleviated intestinal damage in the CPB model rats. This effect was reversed by the addition of a KOR antagonist. Further investigation of inflammatory and oxidative stress factors using ELISA revealed that the KOR agonist reduced the inflammatory and oxidative stress responses in the intestinal tissues of the CPB model rats. The ELISA results of intestinal damage markers and western blotting results of tight junction protein expression suggested that KOR agonist treatment may alleviate intestinal injury in CPB model rats. In addition, the western blotting and immunohistochemistry results suggested that KOR agonists may decrease the expression levels of NF-κB, p65 and HIF-1α in CPB. Collectively, the present results suggested that KOR agonists are able to ameliorate the intestinal barrier dysfunction in rats undergoing CPB by inhibiting the expression levels of NF-κB/HIF-1α signaling pathway-related proteins.

Short-term PM2.5 exposure induces sustained pulmonary fibrosis development during post-exposure period in rats

Up to now, while some toxicological studies have identified pulmonary fibrosis immediately induced by long-term PM_2.5 exposure, there has been no evidence indicating, whether short-term exposure can lead to post-exposure development of pulmonary fibrosis. Here, we treated rats with PM_2.5 for 1 month (10 times), followed by normal feeding for 18 months. ¹⁸F-FDG intake, which is linked with the initiation and development of pulmonary fibrosis in living bodies, was found to gradually increase in lung following exposure through micro PET/CT imaging. Histolopathological examination revealed continuous deterioration of pulmonary injury post-exposure. Collagen deposition and hydroxyproline content continued to increase all along in the post-exposure duration, indicating pulmonary fibrosis development. Chronic and persistent induction of pulmonary inflammatory gene expression (Tnf, Il1b, Il6, Ccl2, and Icam1), epithelial mesenchymal transition (EMT, reduction of E-cadherin and elevation of fibronectin) and RelA/p65 upregulation, as well as serum inflammatory cytokine production, were also found in PM_2.5-treated rats. Pulmonary oxidative stress, manifested by increase of MDA and decrease of GSH and SOD, was induced during exposure but disappeared in later post-exposure duration. These results suggested that short-term PM_2.5 exposure could lead to sustained post-exposure pulmonary fibrosis development, which was mediated by oxidative-stress-initiated NF-κB/inflammation/EMT pathway.

Nicotine attenuates concanavalin A-induced liver injury in mice by regulating the α7-nicotinic acetylcholine receptor in Kupffer cells

Nicotine, a potent parasympathomimetic alkaloid, manifests anti-inflammatory properties by activating nicotinic acetylcholine receptors (nAChRs). In this study, we evaluated the effects of nicotine on concanavalin A (ConA)-induced autoimmune hepatitis. Nicotine (0.5 and 1 mg/kg) was intraperitoneally administered to BALB/c mice and mice were intravenously injected with ConA (15 mg/kg) to induce hepatitis. The results showed that nicotine treatment ameliorated pathological lesions in livers and significantly suppressed the expression of pro-inflammatory cytokines in the livers. Such effects were mediated by inhibiting the nuclear factor-kappa B (NF-κB) signaling in livers. Interestingly, nicotine inhibited the ConA-induced inflammatory response in primary cultured Kupffer cells (KCs) but did not alter the proliferation of splenocytes. The protective effects of nicotine against ConA-induced hepatitis were abolished in KC-depleted mice, indicating the requirement of KCs in this process. Additionally, the expression of α7-nAChR on KCs was dramatically increased by nicotine treatment, and the protective effects of nicotine on ConA-induced liver injury were significantly suppressed by treatment with methyllycaconitine (MLA), a specific α7-nAChR antagonist. Consistently, in primary cultured KCs, the activation of NF-κB signaling was also regulated by nicotine treatment. This study suggests that nicotine increases α7-nAChR-mediated cholinergic activity in KCs resulting in decrease of ConA-induced autoimmune hepatitis through inhibiting NF-κB signaling.

Time Course of Hemodynamic Responses to Different Doses of Lipopolysaccharide in Unanesthetized Male Rats

Lipopolysaccharide (LPS) administration is a well-known method to induce systemic inflammation widely used for investigating new therapeutic strategies for sepsis treatment, which is characterized by clinical manifestations such as tachycardia and hypotension. However, there are different doses of LPS used in several studies, and the hemodynamic responses were not always well characterized. Thus, the present study aimed to evaluate the arterial pressure, heart rate, heart rate variability, and baroreflex function from rats, over time, to different doses of LPS. Femoral artery and vein catheters were inserted into anesthetized Wistar-Hannover male rats for arterial pressure recording and LPS administration, respectively. On the next day, the arterial pressure was recorded before and after (90, 180, and 360 min) LPS injection (0.06, 20, 30, and 40 mg/kg). All doses of LPS tested increased the heart rate and decreased baroreflex sensitivity over time. In addition, while LPS administration of 20, 30, and 40 mg/kg increased the mean arterial pressure over time, 0.06 mg/kg decreased the mean arterial pressure at 360 min, as compared to baseline values. Furthermore, high doses of LPS decreased the power of the HF band of the cardiac interval spectrum over time, and the higher dose increased the power of the LF band. Our data indicate that high doses of LPS promote hypertensive response over time, while a low dose decreases arterial pressure. Moreover, the changes in heart rate variability and baroreflex function elicited by LPS may be not associated with arterial pressure response produced by the endotoxemia.

Stepwise targeted matching strategy from in vitro to in vivo based on ultra-high performance liquid chromatography tandem mass spectrometry technology to quickly identify and screen pharmacodynamic constituents

The study of in vivo pharmacodynamic constituents (PCs) of traditional Chinese medicine (TCM) is important for providing new clues for TCM applications in clinical therapies in modern medicine. However, detecting and identifying PCs from complex biological samples remain a challenge. In this study, a practical and novel stepwise targeted matching and longitudinal analysis strategy from in vitro to in vivo was developed. This strategy combined with ultra-high performance liquid chromatography tandem mass spectrometry was applied to quickly discover PCs in TCM. This approach was developed based on a core perception that all drugs taken orally might be transformed progressively and orderly from the intestinal tract, liver, and blood to the target organ. Based on this core perception, stepwise targeted matching was orderly and efficiently accomplished by multiple screening processes that were based on a stepwise enriched in-house library. Ginseng (Panax ginseng) was set as the example of herbal medicine for validating the reliability and availability of this approach. By applying this novel strategy to the stepwise screening of metabolites, we successfully identified 113 metabolites, among which 59 compounds were defined as prototypes. Based on the in vivo metabolites, network pharmacology analysis was applied to screen the PCs of ginseng and clarified the action mechanism of ginseng for the treatment of Alzheimer's disease (AD). A total of 27 herbal constituents and 64 related targets shared commonly by compounds and AD were integrated via target network pharmacology analysis. These results demonstrated that this original approach will greatly improve high-throughput screening of metabolites and PCs on AD. It also can explicate the mechanism of action of TCM. Furthermore, this strategy is practicable to identify metabolites and screen PCs in other herbal medicines.

Combination of TLR8 and TLR4 agonists reduces the degrading effects of nicotine on DC-NK mediated effector T cell generation

The magnitude of immune responses to vaccination is a critical factor in determining protection from disease. It is known that cigarette smoke dampens the immune system and increases the risk of vaccine-preventable diseases. We reported that nicotine, the immunosuppressive component of cigarette smoke, disrupts the differentiation and functional properties of DC, which are pivotal in the initiation of immune response to vaccines. We also reported that TLR agonists act in synergy and boost DC maturation, DC-NK crosstalk and ultimately naïve T cell polarization into effector Th1 and Tc1 cells. Here, we investigated whether the combination of TLR agonists could diminish the degrading effects of nicotine on DC-NK mediated effector T cell generation. We found that none of TLR agonists, single or combined, were able to diminish completely the adverse effects of nicotine on DC. However, TLR3, TLR4, and TLR8 agonists acted as the most effective adjuvants to increase the expression levels of antigen-presenting, costimulatory molecules and production of cytokines by nicotine-exposed DC (nicDC). When combined, TLR3 + 8 and TLR4 + 8 synergistically optimized nicDC maturation and IFN-γ secretion from nicotine-exposed NK (nicNK) during co-cultures. Interestingly, in contrast to DC-NK-T, co-cultures of nicDC-nicNK-T treated with TLR3 + 8 or TLR4 + 8 agonists produced a similar frequency of effector memory Th1 and Tc1 cells. However, the effector cells from TLR4 + 8 followed by TLR3 + 8 treated nicDC-nicNK-T co-cultures produced significantly more IFN-γ when compared with aluminum salt treated co-culture. Our data suggest that addition of appropriate TLR agonists to vaccine formulation could potentially augment the immune response to vaccination in smokers.

Comparison of the effect of three licorice varieties on cognitive improvement via an amelioration of neuroinflammation in lipopolysaccharide-induced mice

BACKGROUND/OBJECTIVES

Neuroinflammation plays critical role in neurodegenerative disorders, such as Alzheimer's disease (AD). We investigated the effect of three licorice varieties, Glycyrhiza uralensis, G. glabra, and Shinwongam (SW) on a mouse model of inflammation-induced memory and cognitive deficit.

MATERIALS/METHODS

C57BL/6 mice were injected with lipopolysaccharide (LPS; 2.5 mg/kg, intraperitoneally) and orally administrated G. uralensis, G. glabra, and SW extract (150 mg/kg/day). SW, a new species of licorice in Korea, was combined with G. uralensis and G. glabra. Behavioral tests, including the T-maze, novel object recognition and Morris water maze, were carried out to assess learning and memory. In addition, the expressions of inflammation-related proteins in brain tissue were measured by western blotting.

RESULTS

There was a significant decrease in spatial and objective recognition memory in LPS-induced cognitive impairment group, as measured by the T-maze and novel object recognition test; however, the administration of licorice ameliorated these deficits. In addition, licorice-treated groups exhibited improved learning and memory ability in the Morris water maze. Furthermore, LPS-injected mice had up-regulated pro-inflammatory proteins, such as inducible nitric oxide synthase (iNOS), cyclooxygenase-2, interleukin-6, via activation of toll like receptor 4 (TLR4) and nuclear factor-kappa B (NFκB) pathways in the brain. However, these were attenuated by following administration of the three licorice varieties. Interestingly, the SW-administered group showed greater inhibition of iNOS and TLR4 when compared with the other licorice varieties. Furthermore, there was a significant increase in the expression of brain-derived neurotrophic factor (BDNF) in the brain of LPS-induced cognitively impaired mice that were administered licorice, with the greatest effect following SW treatment.

CONCLUSIONS

The three licorice varieties ameliorated the inflammation-induced cognitive dysfunction by down-regulating inflammatory proteins and up-regulating BDNF. These results suggest that licorice, in particular SW, could be potential therapeutic agents against cognitive impairment.

Chronic inhalation of e-cigarette vapor containing nicotine disrupts airway barrier function and induces systemic inflammation and multiorgan fibrosis in mice

Electronic (e)-cigarettes theoretically may be safer than conventional tobacco. However, our prior studies demonstrated direct adverse effects of e-cigarette vapor (EV) on airway cells, including decreased viability and function. We hypothesize that repetitive, chronic inhalation of EV will diminish airway barrier function, leading to inflammatory protein release into circulation, creating a systemic inflammatory state, ultimately leading to distant organ injury and dysfunction. C57BL/6 and CD-1 mice underwent nose only EV exposure daily for 3-6 mo, followed by cardiorenal physiological testing. Primary human bronchial epithelial cells were grown at an air-liquid interface and exposed to EV for 15 min daily for 3-5 days before functional testing. Daily inhalation of EV increased circulating proinflammatory and profibrotic proteins in both C57BL/6 and CD-1 mice: the greatest increases observed were in angiopoietin-1 (31-fold) and EGF (25-fold). Proinflammatory responses were recapitulated by daily EV exposures in vitro of human airway epithelium, with EV epithelium secreting higher IL-8 in response to infection (227 vs. 37 pg/ml, respectively; P < 0.05). Chronic EV inhalation in vivo reduced renal filtration by 20% ( P = 0.017). Fibrosis, assessed by Masson's trichrome and Picrosirius red staining, was increased in EV kidneys (1.86-fold, C57BL/6; 3.2-fold, CD-1; P < 0.05), heart (2.75-fold, C57BL/6 mice; P < 0.05), and liver (1.77-fold in CD-1; P < 0.0001). Gene expression changes demonstrated profibrotic pathway activation. EV inhalation altered cardiovascular function, with decreased heart rate ( P < 0.01), and elevated blood pressure ( P = 0.016). These data demonstrate that chronic inhalation of EV may lead to increased inflammation, organ damage, and cardiorenal and hepatic disease.

Cardiovascular effects of linalyl acetate in acute nicotine exposure

Backgroud

Smoking is a risk factor for cardiovascular diseases as well as pulmonary dysfunction. In particular, adolescent smoking has been reported to have a higher latent risk for cardiovascular disease. Despite the risk to and vulnerability of adolescents to smoking, the mechanisms underlying the effects of acute nicotine exposure on adolescents remain unknown. This study therefore evaluated the mechanism underlying the effects of linalyl acetate on cardiovascular changes in adolescent rats with acute nicotine exposure.

Methods

Parameters analyzed included heart rate (HR), systolic blood pressure, lactate dehydrogenase (LDH) activity, vascular contractility, and nitric oxide levels.

Results

Compared with nicotine alone, those treated with nicotine plus 10 mg/kg (p = 0.036) and 100 mg/kg (p = 0.023) linalyl acetate showed significant reductions in HR. Moreover, the addition of 1 mg/kg (p = 0.011), 10 mg/kg (p = 0.010), and 100 mg/kg (p = 0.011) linalyl acetate to nicotine resulted in significantly lower LDH activity. Nicotine also showed a slight relaxation effect, followed by a sustained recontraction phase, whereas nicotine plus linalyl acetate or nifedipine showed a constant relaxation effect on contraction of mouse aorta (p < 0.001). Furthermore, nicotine-induced increases in nitrite levels were decreased by treatment with linalyl acetate (p < 0.001).

Conclusions

Taken together, our findings suggest that linalyl acetate treatment resulted in recovery of cell damage and cardiovascular changes caused by acute nicotine-induced cardiovascular disruption. Our evaluation of the influence of acute nicotine provides potential insights into the effects of environmental tobacco smoke and suggests linalyl acetate as an available mitigating agent.