Multiplex Immunoassay of Plasma Cytokine Levels in Men with Alcoholism and the Relationship to Psychiatric Assessments

Impulsivity across severe mental disorders: a cross-sectional study of immune markers and psychopharmacotherapy

BACKGROUND

Impulsivity is a transdiagnostic feature linked to severe clinical expression and a potential target for psychopharmacological strategies. Biological underpinnings are largely unknown, but involvement of immune dysregulation has been indicated, and the effects of psychopharmacological agents vary. We investigated if impulsivity was associated with circulating immune marker levels and with a range of psychopharmacological treatment regimens in severe mental disorders.

METHODS

Impulsivity was assessed in a sample (N = 657) of patients with schizophrenia or schizophreniform disorder (SCZ) (N = 116) or bipolar disorder (BD) (N = 159) and healthy participants (N = 382) using the Barratt Impulsiveness Scale (BIS-11) questionnaire. Plasma levels of systemic immune markers (RANTES, IL-1RA, IL-18, IL-18BP, sTNFR-1) were measured by enzyme immunoassays. Patients underwent thorough clinical assessment, including evaluation of psychotropic medication. Associations were assessed using linear regressions.

RESULTS

Impulsivity  was positively associated with SCZ (p < 0.001) and BD (p < 0.001) diagnosis and negatively associated with age (p < 0.05), but not significantly associated with any of the circulating immune markers independently of diagnostic status. Among patients, impulsivity was negatively associated with lithium treatment (p = 0.003) and positively associated with antidepressant treatment (p = 0.011) after controlling for diagnosis, psychotropic co-medications, manic symptoms, and depressive symptoms.

CONCLUSIONS

We report elevated impulsivity across SCZ and BD but no associations to systemic immune dysregulation based on the current immune marker selection. The present study reveals associations between impulsivity in severe mental disorders and treatment with lithium and antidepressants, with opposite directions. Future studies are warranted to determine the causal directionality of the observed associations with psychopharmacotherapy.

Potential Biomarkers of Impulsivity in Mild Traumatic Brain Injury: A Pilot Study

Very few studies have investigated cognition and impulsivity following mild traumatic brain injury (mTBI) in the general population. Furthermore, the neurobiological mechanisms underlying post-TBI neurobehavioral syndromes are complex and remain to be fully clarified. Herein, we took advantage of machine learning based-modeling to investigate potential biomarkers of mTBI-associated impulsivity. Twenty-one mTBI patients were assessed within one-month post-TBI and their data were compared to 19 healthy controls on measures of impulsivity (Barratt Impulsiveness Scale - BIS), executive functioning, episodic memory, self-report cognitive failures and blood biomarkers of inflammation, vascular and neuronal damage. mTBI patients were significantly more impulsive than controls in BIS total and subscales. Serum levels of sCD40L, Cathepsin D, IL-4, Neuropilin-1, IFN-α2, and Copeptin were associated with impulsivity in mTBI patients. Besides showing that mTBI are associated with impulsivity in non-military people, we unveiled different pathophysiological pathways potentially implicated in mTBI-related impulsivity.

Roles and correlations of TIM-3 and LAG-3 with cytokines and chemokines in alcoholic liver disease

BACKGROUND

Dysregulation of immune checkpoint regulators has been reported in alcoholic liver disease (ALD). This study was designed to assess the serum levels of cytokines and chemokines associated with ALD and uncover the possible disease correlations with the soluble TIM-3 and LAG-3.

METHODS

The soluble TIM-3 and LAG-3 levels were measured by enzyme-linked immunoassay, and 14 cytokines and chemokines were measured using Luminex-based multiplex assay in 111 male ALD patients and 45 healthy controls (HCs).

RESULTS

Our results showed that soluble TIM-3 was significantly increased (p < 0.001) while soluble LAG-3 was significantly decreased (p < 0.001) in ALD group compared to HCs. Among the 14 cytokines and chemokines assessed, granulocyte-colony stimulating factor (G-CSF) (p = 0.003) and interferon γ-induced protein (IP)-10 (p < 0.001) were significantly increased, while interleukin (IL)-4 (p = 0.005) and IL-12 (p40) (p = 0.001) were significantly decreased in the ALD group. Kaplan-Meier analysis showed that overall survival decreased in higher TIM-3 level individuals.

CONCLUSIONS

Our results showed that TIM-3, LAG-3, and IP-10 appear to be important for clinical diagnosis of ALD and ALD severity and may represent potential therapeutic targets in ALD.

Cytokine Production in Whole Blood Cells Culture of Patients with Alcohol Dependence and Autologous Plasma Oxidative Stress Markers

We studied spontaneous production of a spectrum of proinflammatory cytokines by cultured whole blood cells from men with alcohol dependence at the stage of withdrawal syndrome and oxidative stress markers (carbonylated proteins and TBA-reactive substances) in the plasma of these blood samples. Enhanced production of cytokines by blood cells and increased concentrations of oxidative stress markers in the autologous plasma were revealed in comparison with the corresponding parameters in the control (blood from healthy men). Direct correlations were found between the levels of spontaneous cytokine production by blood cells from subjects with alcohol dependence and the concentration of oxidized proteins and lipids in autologous plasma.

Chronic intermittent ethanol and lipopolysaccharide exposure differentially alter Iba1-derived microglia morphology in the prelimbic cortex and nucleus accumbens core of male Long-Evans rats

Accumulating evidence has linked pathological changes associated with chronic alcohol exposure to neuroimmune signaling mediated by microglia. Prior characterization of the microglial structure-function relationship demonstrates that alterations in activity states occur concomitantly with reorganization of cellular architecture. Accordingly, gaining a better understanding of microglial morphological changes associated with ethanol exposure will provide valuable insight into how neuroimmune signaling may contribute to ethanol-induced reshaping of neuronal function. Here we have used Iba1-staining combined with high-resolution confocal imaging and 3D reconstruction to examine microglial structure in the prelimbic (PL) cortex and nucleus accumbens (NAc) in male Long-Evans rats. Rats were either sacrificed at peak withdrawal following 15 days of exposure to chronic intermittent ethanol (CIE) or 24 hr after two consecutive injections of the immune activator lipopolysaccharide (LPS), each separated by 24 hr. LPS exposure resulted in dramatic structural reorganization of microglia in the PL cortex, including increased soma volume, overall cellular volume, and branching complexity. In comparison, CIE exposure was associated with a subtle increase in somatic volume and differential effects on microglia processes, which were largely absent in the NAc. These data reveal that microglial activation following a neuroimmune challenge with LPS or exposure to chronic alcohol exhibits distinct morphometric profiles and brain region-dependent specificity.

The Impact of Sedentary Lifestyle, High-fat Diet, Tobacco Smoke, and Alcohol Intake on the Hematopoietic Stem Cell Niches

Hematopoietic stem and progenitor cells maintain hematopoiesis throughout life by generating all major blood cell lineages through the process of self-renewal and differentiation. In adult mammals, hematopoietic stem cells (HSCs) primarily reside in the bone marrow (BM) at special microenvironments called “niches.” Niches are thought to extrinsically orchestrate the HSC fate including their quiescence and proliferation. Insight into the HSC niches mainly comes from studies in mice using surface marker identification and imaging to visualize HSC localization and association with niche cells. The advantage of mouse models is the possibility to study the 3-dimensional BM architecture and cell interactions in an intact traceable system. However, this may not be directly translational to human BM. Sedentary lifestyle, unhealthy diet, excessive alcohol intake, and smoking are all known risk factors for various diseases including hematological disorders and cancer, but how do lifestyle factors impact hematopoiesis and the associated niches? Here, we review current knowledge about the HSC niches and how unhealthy lifestyle may affect it. In addition, we summarize epidemiological data concerning the influence of lifestyle factors on hematological disorders and malignancies.

Importance of sex and trauma context on circulating cytokines and amygdalar GABAergic signaling in a comorbid model of posttraumatic stress and alcohol use disorders

Alcohol use disorder (AUD) and anxiety disorders are frequently comorbid and share mechanisms that could be therapeutic targets. To facilitate mechanistic studies, we adapted an inhibitory avoidance-based "2-hit" rat model of posttraumatic stress disorder (PTSD) and identified predictors and biomarkers of comorbid alcohol (ethanol)/PTSD-like symptoms in these animals. Stressed Wistar rats received a single footshock on two occasions. The first footshock occurred when rats crossed into the dark chamber of a shuttle box. Forty-eight hours later, rats received the second footshock in a familiar (FAM) or novel (NOV) context. Rats then received 4 weeks of two-bottle choice (2BC) ethanol access. During subsequent abstinence, PTSD-like behavior responses, GABAergic synaptic transmission in the central amygdala (CeA), and circulating cytokine levels were measured. FAM and NOV stress more effectively increased 2BC drinking in males and females, respectively. Stressed male rats, especially drinking-vulnerable individuals (≥0.8 g/kg average 2-h ethanol intake with >50% ethanol preference), showed higher fear overgeneralization in novel contexts, increased GABAergic transmission in the CeA, and a profile of increased G-CSF, GM-CSF, IL-13, IL-6, IL-17a, leptin, and IL-4 that discriminated between stress context (NOV > FAM > Control). However, drinking-resilient males showed the highest G-CSF, IL-13, and leptin levels. Stressed females showed increased acoustic startle and decreased sleep maintenance, indicative of hyperarousal, with increased CeA GABAergic transmission in NOV females. This paradigm promotes key features of PTSD, including hyperarousal, fear generalization, avoidance, and sleep disturbance, with comorbid ethanol intake, in a sex-specific fashion that approximates clinical comorbidities better than existing models, and identifies increased CeA GABAergic signaling and a distinct pro-hematopoietic, proinflammatory, and pro-atopic cytokine profile that may aid in treatment.

Preliminary Evidence for a Relationship between Elevated Plasma TNFα and Smaller Subcortical White Matter Volume in HCV Infection Irrespective of HIV or AUD Comorbidity

Classical inflammation in response to bacterial, parasitic, or viral infections such as HIV includes local recruitment of neutrophils and macrophages and the production of proinflammatory cytokines and chemokines. Proposed biomarkers of organ integrity in Alcohol Use Disorders (AUD) include elevations in peripheral plasma levels of proinflammatory proteins. In testing this proposal, previous work included a group of human immunodeficiency virus (HIV)-infected individuals as positive controls and identified elevations in the soluble proteins TNFα and IP10; these cytokines were only elevated in AUD individuals seropositive for hepatitis C infection (HCV). The current observational, cross-sectional study evaluated whether higher levels of these proinflammatory cytokines would be associated with compromised brain integrity. Soluble protein levels were quantified in 86 healthy controls, 132 individuals with AUD, 54 individuals seropositive for HIV, and 49 individuals with AUD and HIV. Among the patient groups, HCV was present in 24 of the individuals with AUD, 13 individuals with HIV, and 20 of the individuals in the comorbid AUD and HIV group. Soluble protein levels were correlated to regional brain volumes as quantified with structural magnetic resonance imaging (MRI). In addition to higher levels of TNFα and IP10 in the 2 HIV groups and the HCV-seropositive AUD group, this study identified lower levels of IL1β in the 3 patient groups relative to the control group. Only TNFα, however, showed a relationship with brain integrity: in HCV or HIV infection, higher peripheral levels of TNFα correlated with smaller subcortical white matter volume. These preliminary results highlight the privileged status of TNFα on brain integrity in the context of infection.

Chronic cachaça consumption affects the structure of tibial bone by decreasing bone density and density of mature collagen fibers in middle-aged Wistar rats

Several studies have demonstrated that alcohol consumption can decrease bone density and alter its structure. However, most of the studies did not investigate the effects of specific alcoholic beverages. This study determined the effects of chronic consumption of cachaça (a Brazilian beverage containing alcohol) on body weight (BW), tibia bone density and on the tibia collagen density in middle-aged Wistar rats. Rats with 9 months old were submitted for 100 days, to a liquid diet of cachaça diluted in water with a progressive and controlled concentration (10°GL, 15°GL, 20°GL, 25°GL, and 30°GL). Chronic cachaça intake produced a significant decrease in BW and altered bone remodeling, decreasing trabecular bone density. In chronic cachaça-treated group (CT), the production of collagen fibers in bone tissue has predominantly green birefringence. It appears that they are immature fibers that do not exist in the control group, in which there are standard predominantly yellowish mature fibers. In conclusion, chronic cachaça consumption affects the structure of the tibial bone of middle-aged rats by decreasing the bone density and reducing the density of mature collagen fibers.

Osteoblastic differentiation of stem cells induced by graphene oxide-hydroxyapatite-alginate hydrogel composites and construction of tissue-engineered bone

This study aimed to investigate the effect of graphene oxide (GO)-hydroxyapatite (HA)-sodium alginate (SA) composite application in the field of bone tissue engineering. Four scaffold groups were established (SA-HA, SA-HA-0.8%GO, SA-HA-1.0%GO and SA-HA-1.2%GO) and mixed with bone marrow mesenchymal stem cells (BMSCs). Hydrogel viscosity was measured at room temperature, and after freeze-drying and Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) to detect substance crystallinity, the printability of each hydrogel type was measured with a printing grid. Scanning electron microscopy (SEM) was used to observe the internal microstructure of the scaffolds and to evaluate the growth and proliferation of cells on the scaffold. A hollow cylinder was printed to compare the forming effect of the hydrogel bioinks, and cell-hydrogel composites were implanted under the skin of nude mice to observe the effect of the hydrogels on osteogenesis in vivo. Increased GO concentrations led to reduced scaffold degradation rates, increased viscosity, increased printability, increased mechanical properties, increased scaffold porosity and increased cell proliferation rates. In vivo experiments showed that hematoxylin and eosin (HE) staining, Alizarin red staining, alkaline phosphatase staining and collagen type I immunohistochemical staining increased as the implantation time increased. These results demonstrate that GO composites have high printability as bioinks and can be used for bioprinting of bone by altering the ratio of the different components.

Alcohol use disorder and circulating cytokines: A systematic review and meta-analysis

There has been emerging interest in the role of the immune system in the pathophysiology of alcohol use disorder (AUD) given alcohol consumption stimulates immune cells to secrete peripheral pro- and anti-inflammatory cytokines. We conducted a systematic review and meta-analysis to determine whether an abnormal inflammatory cytokine profile exists in AUD patients compared to controls and whether cytokine levels were correlated with behavioural and psychiatric variables. Using the PRISMA (Preferred Reporting Items for Systematic reviews and Meta-analyses) guidelines, a comprehensive search of electronic databases (MEDLINE, EMBASE, Web of Science Core Collection and the Cochrane Library) was conducted, for AUD-related terms in combination with cytokine-related terms. Patients had to meet established criteria for AUD and be compared with healthy controls. A critical appraisal was completed using the Newcastle-Ottawa Scale. Twenty-four papers met the inclusionary criteria with 46 serum or plasma cytokines measured without immune stimulation whereby 17 studies had sufficient data for inclusion in the meta-analysis. Collectively, AUD patients had greater cytokine concentrations than control patients g = 0.85 [ 95% CI 0.42, 1.29]. Differences in cytokine concentrations between AUD patients and controls varied within-study by stage of illness (R₍₂₎² = 19.56%). The greatest differences were reported when AUD patients were engaging in active drinking g = 0.96 [0.49, 1.43] or were in alcohol withdrawal g = 1.25 [0.71, 1.80]. Baseline findings were moderated within and between studies by cytokine identity R₍₂₎² = 51.10%; R₍₃₎² = 44.89%. Cytokine concentrations were not significantly correlated with self-reported craving for alcohol, but were with alcohol consumption r = 0.22 [-0.05, 0.46]. The relationship between cytokine concentration and consumption was moderated by cytokine identity (R₍₂₎² = 100.00%; R₍₃₎² = 100.00%), and sample age (R₍₂₎² = 0.00%; R₍₃₎² = 95.76%). There is sufficient evidence to support the presence of an abnormal circulating cytokine profile in AUD which may vary with respect to the different stages of AUD illness.

Decreased motor impulsivity following chronic lithium treatment in male rats is associated with reduced levels of pro-inflammatory cytokines in the orbitofrontal cortex

Lithium's efficacy in reducing both symptom severity in bipolar disorder (BD) and suicide risk across clinical populations may reflect its ability to reduce impulsivity. Changes in immune markers are associated with BD and suicidality yet their exact role in symptom expression remains unknown. Evidence also suggests that lithium may decrease levels of pro-inflammatory cytokines in the periphery and central nervous system, and that such changes are related to its therapeutic efficacy. However, issues of cause and effect are hard to infer from clinical data alone. Here, we investigated the effects of chronic dietary lithium treatment on rats' performance of the 5-Choice Serial Reaction Time Task (5CSRTT), a well-validated operant behavioural task measuring aspects of impulsivity, attention and motivation. Male Long-Evans rats received a diet supplemented with 0.3% LiCl (n = 13), or the equivalent control diet (n = 16), during behavioural testing. Blood and brain tissue samples were assayed for a wide range of cytokines once any changes in impulsivity became significant. After 12 weeks, chronic lithium treatment reduced levels of motor impulsivity, as indexed by premature responses in the 5CSRTT; measures of sustained attention and motivation were unaffected. Plasma levels of IL-1β, IL-10 and RANTES (CCL-5) were reduced in lithium-treated rats at this time point. IL-1β, IL-6 and RANTES were also reduced selectively within the orbitofrontal cortex of lithium-treated rats, whereas cytokine levels in the medial prefrontal cortex and nucleus accumbens were comparable with control subjects. These results are consistent with the hypothesis that lithium may improve impulse control deficits in clinical populations by minimising the effects of pro-inflammatory signalling on neuronal activity, particularly within the orbitofrontal cortex.

A novel method of sacral nerve stimulation for colonic inflammation

BACKGROUND

Vagal nerve stimulation has been reported to treat inflammation with promising results. The aims of our study were to optimize sacral nerve stimulation (SNS) methodologies for colonic inflammation in a rodent model of colitis and to investigate autonomic and cytokine mechanisms.

METHODS

Three major efforts were made in optimizing SNS: (a) to determine the best stimulation duration: SNS-0.5h daily, SNS-1h daily, and SNS-3h daily with the parameters set at 5 Hz, 10 seconds on, 90 seconds off; (b) to determine the best stimulation position: bilateral, bipolar, and unipolar stimulation; (c) to determine the best stimulation parameters: our 5 Hz intermittent stimulation vs 14 Hz-210 μs continuous stimulation. Inflammatory responses were assessed by the disease activity index (DAI), histological analyses, and the myeloperoxidase (MPO) activity. Levels of inflammatory cytokines, norepinephrine (NE), and pancreatic polypeptide (PP) in both plasma and colon tissues were assessed.

KEY RESULTS

Both SNS-1h and SNS-3h significantly ameliorated intestinal inflammation; SNS-1h was superior to SNS-3h. Bipolar but not bilateral or unipolar stimulation improved the inflammation in colitis. SNS with 5 Hz intermittent stimulation but not the 14 Hz continuous SNS was better for treating colitis in rats. SNS with the optimized stimulation parameters increased vagal activity and decreased sympathetic activity. CONCLUSION & INFERENCES: Bipolar stimulation for 1 hour daily using intermittent 5 Hz parameters is most effective in improving colonic inflammation in TNBS-treated rats by inhibiting pro-inflammatory cytokines and increasing anti-inflammatory cytokines via the modulation of the autonomic function.

Inflammatory Biomarkers, Microbiome, Depression, and Executive Dysfunction in Alcohol Users

Alcohol-related disorders (ARD) are highly prevalent among Latin American-Caribbean countries. Mental disorders are common comorbidities in individuals with ARD. However, the etiology of the association between ARD and mental disorders remains unclear. We examined the association of inflammatory cytokines, microbiome, and other biomakers with measures of depression, social anxiety, and executive functions. We observed a significant increase in cytokine and chemokine expression levels in saliva and plasma in the alcohol group (AG) samples. Also, the salivary bacterial composition in the AG revealed an abundance of Prevotella. Depression symptomatology was markedly higher in the AG, but social anxiety levels were negligible. AG also exhibited executive dysfunctions, which negatively correlated with increased plasma levels of pro-inflammatory cytokines and increased salivary concentrations of Prevotella bacteria. Our study suggests that chronic alcohol use correlates with executive dysfunction, immune system dysregulation, and dysbiosis of the salivary microbiota. Additional studies are needed to understand the role of the microbiome and inflammation in alcohol use and mental comorbidities.

Inflammation-related biomarkers in major psychiatric disorders: a cross-disorder assessment of reproducibility and specificity in 43 meta-analyses

Inflammation is a natural defence response of the immune system against environmental insult, stress and injury, but hyper- and hypo-inflammatory responses can trigger diseases. Accumulating evidence suggests that inflammation is involved in multiple psychiatric disorders. Using inflammation-related factors as biomarkers of psychiatric disorders requires the proof of reproducibility and specificity of the changes in different disorders, which remains to be established. We performed a cross-disorder study by systematically evaluating the meta-analysis results of inflammation-related factors in eight major psychiatric disorders, including schizophrenia (SCZ), bipolar disorder (BD), autism spectrum disorder (ASD), major depression disorder (MDD), post-trauma stress disorder (PTSD), sleeping disorder (SD), obsessive-compulsive disorder (OCD) and suicide. A total of 43 meta-analyses involving 704 publications on 44 inflammation-related factors were included in the study. We calculated the effect size and statistical power for every inflammation-related factor in each disorder. Our analyses showed that well-powered case-control studies provided more consistent results than underpowered studies when one factor was meta-analysed by different researchers. After removing underpowered studies, 30 of the 44 inflammation-related factors showed significant alterations in at least one disorder based on well-powered meta-analyses. Eleven of them changed in patients of more than two disorders when compared with the controls. A few inflammation-related factors showed unique changes in specific disorders (e.g., IL-4 increased in BD, decreased in suicide, but had no change in MDD, ASD, PTSD and SCZ). MDD had the largest number of changes while SD has the least. Clustering analysis showed that closely related disorders share similar patterns of inflammatory changes, as genome-wide genetic studies have found. According to the effect size obtained from the meta-analyses, 13 inflammation-related factors would need <50 cases and 50 controls to achieve 80% power to show significant differences (p < 0.0016) between patients and controls. Changes in different states of MDD, SCZ or BD were also observed in various comparisons. Studies comparing first-episode SCZ to controls may have more reproducible findings than those comparing pre- and post-treatment results. Longitudinal, system-wide studies of inflammation regulation that can differentiate trait- and state-specific changes will be needed to establish valuable biomarkers.

Effects of extracorporeal fucosylation of CD44 on the homing ability of rabbit bone marrow mesenchymal stem cells

BACKGROUND

The aim of the study was to investigate the effects of extracorporeal fucosylation of CD44 on the homing ability of rabbit bone marrow mesenchymal stem cells (BMSCs).

METHODS

The rabbit BMSCs were extracorporeal fucosylated using alpha-(1,3)-fucosyltransferase VI (FTVI), then the positive rate of sialyl-LewisX (sLe^X) and the binding rate of E-selectin were detected by flow cytometry, as well as the fluid adhesion of rabbit BMSCs were detected by the parallel flow chamber adhesion test. Then BMSCs were constructed to stably express enhanced green fluorescent protein (EGFP) and were injected intravenously into the model rabbits with tibial fractures. After 6 weeks of injection, the levels of stromal cell-derived factor (SDF-1) and monocyte chemoattractant protein-1 (MCP-1) in rabbit serum and damaged bone tissues were detected. The positive rate of EGFP expressions was detected by immunohistochemistry staining.

RESULTS

After fucosylation, the positive rate of sLe^X and the binding rate of E-selectin were significantly higher than those in the no fucosylated group. The results of fluorescence microscopy showed that BMSCs with stable expression of EGFP were successfully constructed. The results of ELISA and Western Blot showed that the secretion of SDF-1 and MCP-1 and the expression of SDF-1 and MCP-1 protein in BMSCs treatment group processed by fucosylated were significantly higher than those in BMSCs treatment group processed by no fucosylated. The results of immunohistochemical staining showed that the positive rate of EGFP expression was also significantly increased, which indicated that the BMSCs at the injured bone tissues were significantly increased and helpful in the repair of bone injury.

CONCLUSIONS

Extracorporeal fucosylation of CD44 molecules can significantly enhance the homing ability of rabbit BMSCs, which may be achieved by SDF-1 and MCP-1 regulation.

Time course of microglia activation and brain and blood cytokine/chemokine levels following chronic ethanol exposure and protracted withdrawal in rats

Alcohol produces complex effects on the immune system. Moderate alcohol use (1-2 drinks per day) has been shown to produce anti-inflammatory responses in human blood monocytes, whereas, the post mortem brains of severe alcoholics show increased immune gene expression and activated microglial markers. The present study was conducted to evaluate the time course of alcohol effects during exposure and after withdrawal, and to determine the relationship between microglial and cytokine responses in brain and blood. Forty-eight adult, male Wistar rats were exposed to chronic ethanol vapors, or air control, for 5 weeks. Following ethanol/air exposure blood and brains were collected at three time points: 1) while intoxicated, following 35 days of air/vapor exposure; 2) following 24 h of withdrawal from exposure, and 3) 28 days after withdrawal. One hemisphere of the brain was flash-frozen for cytokine analysis, and the other was fixed for immunohistochemical analysis. The ionized calcium-binding adapter molecule 1 (Iba-1) was used to evaluate microglia activation at the three time points, and rat cytokine/chemokine Magnetic Bead Panels (Millipore) were used to analyze frontal cortex tissue lysate and serum. Ethanol induced a significant increase in Iba-1 that peaked at day 35, remained significant after 1 day of withdrawal, and was elevated at day 28 in frontal cortex, amygdala, and substantia nigra. Ethanol exposure was associated with a transient reduction of the serum level of the major pro- and anti-inflammatory cytokines and chemokines and a transient increase of effectors of sterile inflammation. Little or no changes in these molecules were seen in the frontal cortex except for HMG1 and fractalkine that were reduced and elevated, respectively, at day 28 following withdrawal. These data show that ethanol exposure produces robust microglial activation; however, measures of inflammation in the blood differ from those in the brain over a protracted time course.

Compounding effect of vitamin D3 diet, supplementation, and alcohol exposure on macrophage response to mycobacterium infection

Vitamin D₃ is known to be a key component in the defense against Mycobacterium tuberculosis (Mtb) infection through the regulation of cytokine and effector molecules. Conversely, alcohol exposure has been recognized as an immune dysregulator. Macrophages were extracted from D₃ deficient and sufficient diet mice and supplemented with D₃ or exposed to ethanol during ex vivo infection using M. bovis BCG, as a surrogate for Mtb. Results of our study indicate that while exogenous supplementation or alcohol exposure did alter immune response, in vivo diet was the greatest determinant of cytokine and effector molecule production. Alcohol exposure was found to profoundly dysregulate primary murine macrophages, with ethanol-exposed cells generally characterized as hyper- or hyporesponsive. Exogenous D₃ supplementation had a normative effect for diet deficient host, however supplementation was not sufficient to compensate for the effects of diet deficiency. Vitamin D₃ sufficient diet resulted in reduced cell cytotoxicity for the majority of time points. Results provide insight into the ramifications of both the individual and combined health risks of D₃ deficiency or alcohol exposure. Given the clinical relevance of D₃ deficiency and alcohol use comorbidities, outcomes of this study have implications in therapeutic approaches for the treatment of tuberculosis disease.

Peripheral TNFα elevations in abstinent alcoholics are associated with hepatitis C infection

Substantial evidence supports the view that inflammatory processes contribute to brain alterations in HIV infection. Mechanisms recently proposed to underlie neuropathology in Alcohol Use Disorder (AUD) include elevations in peripheral cytokines that sensitize the brain to the damaging effects of alcohol. This study included 4 groups: healthy controls, individuals with AUD (abstinent from alcohol at examination), those infected with HIV, and those comorbid for HIV and AUD. The aim was to determine whether inflammatory cytokines are elevated in AUD as they are in HIV infection. Cytokines showing group differences included interferon gamma-induced protein 10 (IP-10) and tumor necrosis factor α (TNFα). Follow-up t-tests revealed that TNFα and IP-10 were higher in AUD than controls but only in AUD patients who were seropositive for Hepatitis C virus (HCV). Specificity of TNFα and IP-10 elevations to HCV infection status was provided by correlations between cytokine levels and HCV viral load and indices of liver integrity including albumin/globulin ratio, fibrosis scores, and AST/platelet count ratio. Because TNFα levels were mediated by HCV infection, this study provides no evidence for elevations in peripheral cytokines in "uncomplicated", abstinent alcoholics, independent of liver disease or HCV infection. Nonetheless, these results corroborate evidence for elevations in IP-10 and TNFα in HIV and for IP-10 levels in HIV+HCV co-infection.

The efficacy of (+)-Naltrexone on alcohol preference and seeking behaviour is dependent on light-cycle

Circadian rhythm affects drug-induced reward behaviour and the innate immune system. Peaks in reward-associated behaviour and immune responses typically occur during the active (dark) phase of rodents. While the role of the immune system, specifically, Toll-like receptor 4 (TLR4, an innate immune receptor) in drug-induced reward is becoming increasingly appreciated, it is unclear whether its effects vary according to light-cycle. Therefore, the aim of this study was to characterise the effects of the phase of the light-cycle and the state of the innate immune system on alcohol reward behaviour and subsequently determine whether the efficacy of targeting the immune component of drug reward depends upon the light-cycle. This study demonstrates that mice exhibit greater alcohol-induced conditioned place preference and alcohol two-bottle choice preference during the dark cycle. This effect overlapped with elevations in reward-, thirst- and immune-related genes. Administration of (+)-Naltrexone, a TLR4 antagonist, reduced immune-related gene mRNA expression and alcohol preference with its effects most pronounced during the dark cycle. However, (+)-Naltrexone, like other TLR4 antagonists exhibited off-target side effects, with a significant reduction in overall saccharin intake - an effect likely attributable to a reduction in tyrosine hydroxylase (Th) mRNA expression levels. Collectively, the study highlights a link between a time-of-day dependent influence of TLR4 on natural and alcohol reward-like behaviour in mice.

Maternal Diet, Metabolic State, and Inflammatory Response Exert Unique and Long-Lasting Influences on Offspring Behavior in Non-Human Primates

Nutritional status influences brain health and gestational exposure to metabolic disorders (e.g. obesity and diabetes) increases the risk of neuropsychiatric disorders. The aim of the present study was to further investigate the role of maternal Western-style diet (WSD), metabolic state, and inflammatory factors in the programming of Japanese macaque offspring behavior. Utilizing structural equation modeling, we investigated the relationships between maternal diet, prepregnancy adiposity, third trimester insulin response, and plasma cytokine levels on 11-month-old offspring behavior. Maternal WSD was associated with greater reactive and ritualized anxiety in offspring. Maternal adiposity and third trimester macrophage-derived chemokine (MDC) exerted opposing effects on offspring high-energy outbursts. Elevated levels of this behavior were associated with low maternal MDC and increased prepregnancy adiposity. This is the first study to show that maternal MDC levels influence offspring behavior. We found no evidence suggesting maternal peripheral inflammatory response mediated the effect of maternal diet and metabolic state on aberrant offspring behavior. Additionally, the extent of maternal metabolic impairment differentially influenced chemokine response. Elevated prepregnancy adiposity suppressed third trimester chemokines, while obesity-induced insulin resistance augmented peripheral chemokine levels. WSD also directly increased maternal interleukin-12. This is the first non-human primate study to delineate the effects of maternal diet and metabolic state on gestational inflammatory environment and subsequent offspring behavior. Our findings give insight to the complex mechanisms by which diet, metabolic state, and inflammation during pregnancy exert unique influences on offspring behavioral regulation.

Midkine in the mouse ventral tegmental area limits ethanol intake and Ccl2 gene expression

Midkine (MDK) is a cytokine and neurotrophic factor that is more highly expressed in the brains of alcoholics and in mice predisposed to drink large amounts of ethanol, suggesting that MDK may regulate ethanol consumption. Here we measured ethanol consumption in male and female Mdk knockout (-/-) mice using the two-bottle choice and the drinking in the dark (DID) tests. We found that Mdk -/- mice consumed significantly more ethanol than wild-type controls in both tests. To determine if MDK acts in the ventral tegmental area (VTA) to regulate ethanol consumption, we delivered lentivirus expressing a Mdk shRNA into the VTA of male C57BL/6J mice to locally knockdown Mdk and performed the DID test. Mice expressing a Mdk shRNA in the VTA consumed more ethanol than mice expressing a control non-targeting shRNA, demonstrating that the VTA is one site in the brain through which MDK acts to regulate ethanol consumption. Since MDK also controls the expression of inflammatory cytokines in other organs, we examined gene expression of interleukin-1 beta (Il1b), tumor necrosis factor alpha (Tnfα) and the chemokine (C-C motif) ligand 2 (Ccl2) in the VTA of Mdk -/- mice and in mice expressing Mdk shRNA in the VTA. Expression of Ccl2 was elevated in the VTA of Mdk -/- mice and in mice expressing Mdk shRNA in the VTA. These results demonstrate that MDK functions in the VTA to limit ethanol consumption and levels of CCL2, a chemokine known to increase ethanol consumption.

Mitochondrial ROS induced by chronic ethanol exposure promote hyper-activation of the NLRP3 inflammasome

Alcohol use disorders are common both in the United States and globally, and are associated with a variety of co-morbid, inflammation-linked diseases. The pathogenesis of many of these ailments are driven by the activation of the NLRP3 inflammasome, a multi-protein intracellular pattern recognition receptor complex that facilitates the cleavage and secretion of the pro-inflammatory cytokines IL-1β and IL-18. We hypothesized that protracted exposure of leukocytes to ethanol would amplify inflammasome activation, which would help to implicate mechanisms involved in diseases associated with both alcoholism and aberrant NLRP3 inflammasome activation. Here we show that long-term ethanol exposure of human peripheral blood mononuclear cells and a mouse macrophage cell line (J774) amplifies IL-1β secretion following stimulation with NLRP3 agonists, but not with AIM2 or NLRP1b agonists. The augmented NRLP3 activation was mediated by increases in iNOS expression and NO production, in conjunction with increases in mitochondrial membrane depolarization, oxygen consumption rate, and ROS generation in J774 cells chronically exposed to ethanol (CE cells), effects that could be inhibited by the iNOS inhibitor SEITU, the NO scavenger carboxy-PTIO, and the mitochondrial ROS scavenger MitoQ. Chronic ethanol exposure did not alter K⁺ efflux or Zn²⁺ homeostasis in CE cells, although it did result in a lower intracellular concentration of NAD⁺. Prolonged administration of acetaldehyde, the product of alcohol dehydrogenase (ADH) mediated metabolism of ethanol, mimicked chronic ethanol exposure, whereas ADH inhibition prevented ethanol-induced IL-1β hypersecretion. Together, these results indicate that increases in iNOS and mitochondrial ROS production are critical for chronic ethanol-induced IL-1β hypersecretion, and that protracted exposure to the products of ethanol metabolism are probable mediators of NLRP3 inflammasome hyperactivation.

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Chronic ethanol exposure amplifies NLRP3 inflammasome-induced IL-1β secretion.

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NO and mitochondrial ROS mediate chronic ethanol-augmented IL-1β secretion.

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Alcohol dehydrogenase-generated metabolites cause NLRP3 inflammasome over-activation.

Effects of Adolescent Intermittent Alcohol Exposure on the Expression of Endocannabinoid Signaling-Related Proteins in the Spleen of Young Adult Rats

Intermittent alcohol exposure is a common pattern of alcohol consumption among adolescents and alcohol is known to modulate the expression of the endocannabinoid system (ECS), which is involved in metabolism and inflammation. However, it is unknown whether this pattern may have short-term consequences on the ECS in the spleen. To address this question, we examined the plasma concentrations of metabolic and inflammatory signals and the splenic ECS in early adult rats exposed to alcohol during adolescence. A 4-day drinking in the dark (DID) procedure for 4 weeks was used as a model of intermittent forced-alcohol administration (20%, v/v) in female and male Wistar rats, which were sacrificed 2 weeks after the last DID session. First, there was no liver damage or alterations in plasma metabolic parameters. However, certain plasma inflammatory signals were altered according to sex and alcohol exposition. Whereas fractalkine [chemokine (C-X3-C motif) ligand 1] was only affected by sex with lower concentration in male rats, there was an interaction between sex and alcohol exposure in the TNF-α and interleukin-6 concentrations and only female rats displayed changes. Regarding the mRNA and protein expression of the ECS, the receptors and endocannabinoid-synthesizing enzymes were found to be altered with area-specific expression patterns in the spleen. Overall, whereas the expression of the cannabinoid receptor CB₁ and the nuclear peroxisome proliferator-activated receptor PPARα were lower in alcohol-exposed rats compared to control rats, the CB₂ expression was higher. Additionally, the N-acyl-phosphatidylethanolamine-specific phospholipase D expression was high in female alcohol-exposed rats and low in male alcohol-exposed rats. In conclusion, intermittent alcohol consumption during adolescence may be sufficient to induce short-term changes in the expression of splenic endocannabinoid signaling-related proteins and plasma pro-inflammatory cytokines in young adult rats with a strong sexual dimorphism. The potential impact of these alterations in early adulthood remains to be elucidated.