Chemical neuroimmunology: health in a nutshell bidirectional communication between immune and stress (limbic-hypothalamic-pituitary-adrenal) systems

Increased Levels of Beta-Endorphin and Noradrenaline after a Brief High-Impact Multidimensional Rehabilitation Program in Multiple Sclerosis

Finding new solutions for the management of multiple sclerosis (MS) is crucial: further research is needed to study the effect of non-pharmacological interventions on the symptoms and the course of the disease, especially on lifestyle. Benefits from a proper lifestyle are evident not only on a clinical level but also on immune and neuro-endocrine systems. A brief high-impact multidimensional rehabilitation program (b-HIPE) was proposed for a sample of people with MS (pwMS) with a medium level of disease disability. We tested the change on clinical parameters and quality of life (QoL) after participation in B-HIPE. We furthermore decided to measure beta-endorphin and catecholamines concentrations pre- and post-participation in the b-HIPE program, due to the relationship between these hormones and the immune system in neurodegenerative diseases. Our results showed that after the b-HIPE program, an improvement of clinical parameters and QoL occurred. Moreover, we found higher levels of beta-endorphin and noradrenaline after participation in the program. These findings highlight the importance of implementing lifestyle interventions in the clinical management of MS. Furthermore, we hypothesize that the B-HIPE program increased beta-endorphin and noradrenaline levels, helping to reduce the inflammation related to MS disease.

Evolutionary Significance of the Neuroendocrine Stress Axis on Vertebrate Immunity and the Influence of the Microbiome on Early-Life Stress Regulation and Health Outcomes

Stress is broadly defined as the non-specific biological response to changes in homeostatic demands and is mediated by the evolutionarily conserved neuroendocrine networks of the hypothalamus-pituitary-adrenal (HPA) axis and the sympathetic nervous system. Activation of these networks results in transient release of glucocorticoids (cortisol) and catecholamines (epinephrine) into circulation, as well as activation of sympathetic fibers innervating end organs. These interventions thus regulate numerous physiological processes, including energy metabolism, cardiovascular physiology, and immunity, thereby adapting to cope with the perceived stressors. The developmental trajectory of the stress-axis is influenced by a number of factors, including the gut microbiome, which is the community of microbes that colonizes the gastrointestinal tract immediately following birth. The gut microbiome communicates with the brain through the production of metabolites and microbially derived signals, which are essential to human stress response network development. Ecological perturbations to the gut microbiome during early life may result in the alteration of signals implicated in developmental programming during this critical window, predisposing individuals to numerous diseases later in life. The vulnerability of stress response networks to maladaptive development has been exemplified through animal models determining a causal role for gut microbial ecosystems in HPA axis activity, stress reactivity, and brain development. In this review, we explore the evolutionary significance of the stress-axis system for health maintenance and review recent findings that connect early-life microbiome disturbances to alterations in the development of stress response networks.

Transcriptional regulation of corticotropin-releasing hormone gene in stress response

As a central player of the hypothalamic-pituitary-adrenal (HPA) axis, the corticotropin -releasing hormone (CRH) neurons in the hypothalamic paraventricular nucleus (PVN) determine the state of HPA axis and play a key role in stress response. Evidence supports that during stress response the transcription and expression of CRH was finely tuned, which involved cis-element-transcriptional factor (TF) interactions and epigenetic mechanisms. Here we reviewed recent progress in CRH transcription regulation from DNA methylation to classic TFs regulation, in which a number of paired receptors were involved. The imbalance of multiple paired receptors in regulating the activity of CRH neurons indicates a possible molecular network mechanisms underlying depression etiology and directs novel therapeutic strategies of depression in the future.

Precision active pharmaceutical ingredients are the goal

Understanding and exploiting molecular mechanisms in biology is central to chemical biology. Chemical biology studies of biological macromolecules are now in a perfect continuum with molecular level and nanomolecular level mechanistic studies involving whole organisms. The potential opportunity presented by such studies is the design and creation of genuine precision active pharmaceutical ingredients (APIs; including DNA, siRNA, smaller-molecule bioactives) that demonstrate exceptional levels of disease target specificity and selectivity. This article covers the best of my personal and collaborative academic research work using an organic chemistry and chemical biology approach towards understanding biological molecular recognition processes, work that appears to be leading to the generation of novel precision APIs with genuine potential for the treatments of major chronic diseases that afflict globally.

Synthesis, F-18 radiolabeling, and microPET evaluation of 3-(2,4-dichlorophenyl)-N-alkyl-N-fluoroalkyl-2,5-dimethylpyrazolo[1,5-a]pyrimidin-7-amines as ligands of the corticotropin-releasing factor type-1 (CRF1) receptor

A series of 3-(2,4-dichlorophenyl)-N-alkyl-N-fluoroalkyl-2,5-dimethylpyrazolo[1,5-a]pyrimidin-7-amines were synthesized and evaluated as potential positron emission tomography (PET) tracers for the corticotropin-releasing factor type-1 (CRF1) receptor. Compounds 27, 28, 29, and 30 all displayed high binding affinity (⩽1.2 nM) to the CRF1 receptor when assessed by in vitro competition binding assays at 23 °C, whereas a decrease in affinity (⩾10-fold) was observed with compound 26. The logP7.4 values of [(18)F]26-[(18)F]29 were in the range of ∼2.2-2.8 and microPET evaluation of [(18)F]26-[(18)F]29 in an anesthetized male cynomolgus monkey demonstrated brain penetrance, but specific binding was not sufficient enough to differentiate regions of high CRF1 receptor density from regions of low CRF1 receptor density. Radioactivity uptake in the skull, and sphenoid bone and/or sphenoid sinus during studies with [(18)F]28, [(18)F]28-d8, and [(18)F]29 was attributed to a combination of [(18)F]fluoride generated by metabolic defluorination of the radiotracer and binding of intact radiotracer to CRF1 receptors expressed on mast cells in the bone marrow. Uptake of [(18)F]26 and [(18)F]27 in the skull and sphenoid region was rapid but then steadily washed out which suggests that this behavior was the result of binding to CRF1 receptors expressed on mast cells in the bone marrow with no contribution from [(18)F]fluoride.

A pilot study evaluating presurgery neuroanatomical biomarkers for postoperative cognitive decline after total knee arthroplasty in older adults

BACKGROUND

Total knee arthroplasty improves quality of life but is associated with postoperative cognitive dysfunction in older adults. This prospective longitudinal pilot study with a parallel control group tested the hypotheses that (1) nondemented adults would exhibit primary memory and executive difficulties after total knee arthroplasty, and (2) reduced preoperative hippocampus/entorhinal volume would predict postoperative memory change, whereas preoperative leukoaraiosis and lacunae volumes would predict postoperative executive dysfunction.

METHODS

Surgery (n = 40) and age-education-matched controls with osteoarthritis (n = 15) completed pre- and postoperative (3 weeks, 3 months, and 1 yr) memory and cognitive testing. Hypothesized brain regions of interest were measured in patients completing preoperative magnetic resonance scans (surgery, n = 31; control, n = 12). Analyses used reliable change methods to identify the frequency of cognitive change at each time point.

RESULTS

The incidence of postoperative memory difficulties was shown with delay test indices (i.e., story memory test: 3 weeks = 17%, 3 months = 25%, 1 yr = 9%). Postoperative executive difficulty with measures of inhibitory function (i.e., Stroop Color Word: 3 weeks = 21%, 3 months = 22%, 1 yr = 9%). Hierarchical regression analysis assessing the predictive interaction of group (surgery, control) and preoperative neuroanatomical structures on decline showed that greater preoperative volumes of leukoaraiosis/lacunae were significantly contributed to postoperative executive (inhibitory) declines.

CONCLUSIONS

This pilot study suggests that executive and memory declines occur in nondemented adults undergoing orthopedic surgery. Severity of preoperative cerebrovascular disease may be relevant for understanding executive decline, in particular.

Stress resilience and vulnerability: the association with rearing conditions, endocrine function, immunology, and anxious behavior

BACKGROUND

The current study explored the underlying behavioral, endocrine, and immune markers of vulnerability to stress-induced depression, and the impact of rearing environments on adult functioning.

METHOD

Adult Sprague-Dawley rats (n=195) were reared in either Maternal Separation (MS), Early Weaning and Isolation (EWI), or Non-Handled (NH) conditions. Anxiety behavior was assessed using the emergence test at mean postnatal day (PND) 60. Stress-induced depressive behavior was measured at mean PND 86 using an intermittent cold water swim stress and swim escape test (SET) paradigm. Immediately following the SET, and in a sample of naïve controls (N=31), trunk blood was collected to assay for serum corticosterone (CORT) and spleens were removed for determination of Concanavalin A (Con-A) stimulated T-cell proliferation.

RESULTS

Stress vulnerable rats (top tertile of SET swim time) were characterised by increased anxiety-like behavior, greater post-stress CORT concentrations, and a significantly higher Con-A induced T-cell proliferative response compared to stress resilient rats (bottom tertile of SET swim time). The EWI rearing condition was a contributing factor in predicting total swim escape time, however MS was not. MS offspring did have double the basal level of CORT than NH offspring, suggestive of a hyperfunctioning HPA axis.

CONCLUSION

The swim stress animal model enabled observation of stress vulnerability and resilience; results point towards the existence of distinct behavioral, endocrine, and immunological profiles of the vulnerable and resilient animal, which may have important implications for mental health and stress research.

Inflammation and neuropeptides: the connection in diabetic wound healing

Abnormal wound healing is a major complication of both type 1 and type 2 diabetes, with nonhealing foot ulcerations leading in the worst cases to lower-limb amputation. Wound healing requires the integration of complex cellular and molecular events in successive phases of inflammation, cell proliferation, cell migration, angiogenesis and re-epithelialisation. A link between wound healing and the nervous system is clinically apparent as peripheral neuropathy is reported in 30-50% of diabetic patients and is the most common and sensitive predictor of foot ulceration. Indeed, a bidirectional connection between the nervous and the immune systems and its role in wound repair has emerged as one of the focal features of the wound-healing dogma. This review provides a broad overview of the mediators of this connection, which include neuropeptides and cytokines released from nerve fibres, immune cells and cutaneous cells. In-depth understanding of the signalling pathways in the neuroimmune axis in diabetic wound healing is vital to the development of successful wound-healing therapies.

Chronic mild stress impairs cognition in mice: from brain homeostasis to behavior

Exposure to chronic stress in rodents and psychosocial stress in humans has been shown to alter cognitive functions and has been linked to the pathophysiology of mood disorders. The purpose of the present study was to investigate effects and possible mechanisms of a chronic mild stress (CMS) procedure on cognitive behaviors in Swiss albino mice using the object recognition test (ORT) and object location test (OLT). Results showed that CMS exposure impaired cognitive performance and produced amnesia of acquired information in both ORT and OLT. Furthermore, the cognitive impairment was coexistent with increased plasma levels of interleukin-1beta (IL-1beta), interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha), as well as with enhanced plasma levels of corticosterone (CORT), corticotrophin-releasing hormone (CRH) and adrenocorticotrophic hormone (ACTH). In addition, severe neuronal cell damage was found, as bromodeoxyuridine (BrdU) positive cells and the expression of brain derived neurotrophic factor (BDNF) in dentate gyrus (DG) of hippocampus were decreased after 5 weeks CMS procedure. Taken together, these findings indicated that CMS exposure-induced impairment of cognitive behaviors might be attributed to the stress-related alterations in brain homeostasis that were reflected in changes in the neuroimmune and neuroendocrine systems as well as in neurogenesis.

Stress susceptibility predicts the severity of immune depression and the failure to combat bacterial infections in chronically stressed mice

Chronic psychological stress has been suggested to play a role in disorders in which the immune system unexpectedly fails to respond in a protective manner. Chronic combined acoustic and restraint stress compromises the anti-bacterial defense mechanisms of female BALB/c mice. The immunodeficiency is characterized by an apoptotic loss of lymphocytes, reduced ex vivo-inducibility of TNF but increased inducibility of IL10, reduced T-cell proliferation, and impaired phagocyte functions. Stressed mice develop depression-like behavior that was monitored by a stress severity score (SSS). Besides a strain (BALB/c>CBA) and gender (male>female) dependent susceptibility to chronic stress, inbred mice have an individual coping ability. Importantly, the individual SSS strongly correlates with Escherichia coli dissemination after infection as well as with IL10-inducibility and circulating corticosterone levels of each animal.

Neural substrates, experimental evidences and functional hypothesis of acupuncture mechanisms

OBJECTIVES

Although acupuncture therapy has demonstrated itself to be effective in several clinical areas, the underlying mechanisms of acupuncture in general and the analgesic effect in particular are, however, still not clearly delineated. We, therefore, have studied acupuncture analgesic effect through fMRI and proposed a hypothesis, based on the obtained result, which will enlighten the central role of the brain in acupuncture therapy.

METHODS

The proposed model, termed as a broad sense hypothalamus-pituitary-adrenal (BS-HPA) axis, was based on our observed neuroimaging results. The model incorporates the stress-induced HPA axis model together with neuro-immune interaction including the cholinergic anti-inflammatory model.

RESULTS

The obtained results coupled with accumulating evidence suggest that the central nervous system is essential for the processing of these effects via its modulation of the autonomic nervous system, neuroimmune system and hormonal regulation.

CONCLUSIONS

Based on our fMRI study, it appears that understanding the effects of acupuncture within a neuroscience-based framework is vital. Further, we have proposed the broad sense-HPA axis hypothesis which incorporates the experimental results.

Role of depression and inflammation in incident coronary heart disease events

Inflammatory biomarkers and depression have been proposed as novel coronary heart disease (CHD) risk markers. However, prospective studies have rarely assessed these 2 candidate CHD risk markers simultaneously in predicting incident CHD events. Therefore, although depression and elevated inflammatory biomarkers frequently covary, it is unclear how these risk markers relate to each other and to CHD event onset. The elucidation of these causal pathways has important clinical implications for patients who are depressed and/or have elevated inflammatory biomarkers. In this review, the publications examining the relations among depression, inflammation, and CHD events are discussed.

Neuroendocrine and cytokine profile of chronic mild stress-induced anhedonia

A bidirectional relationship exists between depression and cardiovascular disease. Patients with major depression are more likely to develop cardiac events, and patients with myocardial infarction and heart failure are more likely to develop depression. A feature common to both clinical syndromes is activation of proinflammatory cytokines and stress hormones, including the hypothalamic-pituitary-adrenal axis and the renin-angiotensin-aldosterone system. In the present study we examined the hypothesis that exposure to chronic mild stress (CMS), an experimental model of depression that induces anhedonia in rats, is sufficient to activate the production of proinflammatory cytokines and stress hormones that are detrimental to the heart and vascular system. Four weeks of exposure of male, Sprague-Dawley rats to mild unpredictable environmental stressors resulted in anhedonia which was operationally defined as a reduction in sucrose intake without a concomitant effect on water intake. Humoral assays indicated increased plasma levels of tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), plasma renin activity, aldosterone, and corticosterone in the CMS exposed rats. Tissue TNF-alpha and IL-1beta were increased in the hypothalamus, and TNF-alpha was increased in the pituitary gland. These humoral responses to CMS, associated with anhedonia as an index of depression in the rat, are likely to be associated with neurohumoral mechanisms that may contribute to adverse cardiac events. The findings provide a basis for examining more directly the interactions among the central, endocrine, and immune systems in depression associated with heart disease.

Structure-activity studies on the corticotropin releasing factor antagonist astressin, leading to a minimal sequence necessary for antagonistic activity

Corticotropin Releasing Factor (CRF) antagonists are considered promising for treatment of stress-related illnesses such as major depression and anxiety-related disorders. We report here the design, synthesis and biological evaluation of 91 truncated astressin analogues in order to deduce the pharmacophoric amino acid residues. Such truncated peptides may serve as valuable lead structures for the development of new small, non-peptide-based CRF antagonists. N-Terminal truncation of astressin led to active CRF antagonists that are substantially reduced in size and are selectively active at the human CRF receptor type 1 in vitro and in vivo. Subsequently, an alanine scan in combination with further truncated derivatives led to the proposal of a new pharmacophoric model of peptide-based CRF antagonists. It was found that the astressin(27-41)C sequence is the shortest active CRF antagonist. The first eight N-terminal amino acid residues were found to be an important structural determinant and were replaceable by alanine residues, thus enhancing the alpha-helical propensity. A covalent structural constraint is of utmost importance for the preorganization of the C-terminal amino acid residues. The C-terminal heptapeptide sequence, however, was found to be crucial for the antagonistic activity, since substitution or deletion of any residue led to inactive compounds.