The Function of the Hypothalamic-Pituitary-Adrenal Axis During Experimental Autoimmune Encephalomyelitis: Involvement of Oxidative Stress Mediators

Lipid metabolism is dysregulated in endocrine glands upon autoimmune demyelination

Disturbance in neuroendocrine signaling has been consistently documented in multiple sclerosis (MS), a chronic autoimmune disorder of the central nervous system (CNS) representing the main cause of non-traumatic brain injury among young adults. In fact, MS patients display altered hormonal levels and psychiatric symptoms along with the pathologic hallmarks of the disease, which include demyelination, neuroinflammation and axonal injury. In addition, we have recently shown that extensive transcriptional changes take place in the hypothalamus of mice upon the MS model experimental autoimmune encephalomyelitis (EAE). We also detected structural and functional aberrancies in endocrine glands of EAE animals. Specifically, we described the hyperplasia of adrenal glands and the atrophy of ovaries at disease peak. To further expand the characterization of these phenotypes, here we profiled the transcriptomes of both glands by means of RNA-seq technology. Notably, we identified fatty acid and cholesterol biosynthetic pathways as the most dysregulated molecular processes in adrenals and ovaries, respectively. Furthermore, we demonstrated that key genes encoding neuropeptides and hormone receptors undergo distinct expression dynamics in the hypothalamus along disease progression. Altogether, our results corroborate the dysfunction of the neuroendocrine system as a major pathological event of autoimmune demyelination and highlight the crosstalk between the CNS and the periphery in mediating such disease phenotypes.

Oxidative Stress Markers in Multiple Sclerosis

The pathogenesis of multiple sclerosis (MS) is not completely understood, but genetic factors, autoimmunity, inflammation, demyelination, and neurodegeneration seem to play a significant role. Data from analyses of central nervous system autopsy material from patients diagnosed with multiple sclerosis, as well as from studies in the main experimental model of multiple sclerosis, experimental autoimmune encephalomyelitis (EAE), suggest the possibility of a role of oxidative stress as well. In this narrative review, we summarize the main data from studies reported on oxidative stress markers in patients diagnosed with MS and in experimental models of MS (mainly EAE), and case-control association studies on the possible association of candidate genes related to oxidative stress with risk for MS. Most studies have shown an increase in markers of oxidative stress, a decrease in antioxidant substances, or both, with cerebrospinal fluid and serum/plasma malonyl-dialdehyde being the most reliable markers. This topic requires further prospective, multicenter studies with a long-term follow-up period involving a large number of patients with MS and controls.

Preventive effects of melatonin on periodontal tissue destruction due to psychological stress in rats with experimentally induced periodontitis

OBJECTIVE AND BACKGROUND

Psychological stress is a potential modifiable environmental risk factor causally related to the exacerbation of periodontitis and other chronic inflammatory diseases. This animal study aimed to investigate comprehensively the preventive efficacy of systemic melatonin administration on the possible effects of restraint stress on the periodontal structures of rats with periodontitis.

METHODS

Forty-eight male Sprague Dawley rats were randomly divided into six groups: control, restraint stress (S), S-melatonin (S-Mel), experimental periodontitis (Ep), S-Ep, and S-Ep-Mel. Periodontitis was induced by placing a 3.0 silk suture in a sub-paramarginal position around the cervix of the right and left lower first molars of the rats and keeping the suture in place for 5 weeks. Restraint stress was applied simultaneously by ligation. Melatonin and carriers were administered to the control, S, Ep, and S-Ep groups intraperitoneally (10 mg/body weight/day, 14 days) starting on day 21 following ligation and subjection to restraint stress. An open field test was performed on all groups on day 35 of the study. Periodontal bone loss was measured via histological sections. Histomorphometric and immunohistochemical (RANKL and OPG) evaluations were performed on right mandibular tissue samples and biochemical (TOS (total oxidant status), TAS (total antioxidant status), OSI (oxidative stress index), IL-1β, IL-10, and IL-1β/IL-10) evaluations were performed on left mandibular tissue samples.

RESULTS

Melatonin significantly limited serum corticosterone elevation related to restraint stress (p < .05). Restraint stress aggravated alveolar bone loss in rats with periodontitis, while systemic melatonin administration significantly reduced stress-related periodontal bone loss. According to the biochemical analyses, melatonin significantly lowered IL-1β/IL-10, OSI (TOS/TAS), and RANKL/OPG rates, which were significantly elevated in the S-Ep group.

CONCLUSION

Melatonin can significantly prevent the limited destructive effects of stress on periodontal tissues by suppressing RANKL-related osteoclastogenesis and oxidative stress.

Experimental Autoimmune Encephalomyelitis Influences GH-Axis in Female Rats

Inflammation, demyelination, and axonal damage to the central nervous system (CNS) are the hallmarks of multiple sclerosis (MS) and its representative animal model, experimental autoimmune encephalomyelitis (EAE). There is scientific evidence for the involvement of growth hormone (GH) in autoimmune regulation. Previous data on the relationship between the GH/insulin like growth factor-1 (IGF-1) axis and MS/EAE are inconclusive; therefore, the aim of our study was to investigate the changes in the GH axis during acute monophasic EAE. The results show that the gene expression of Ghrh and Sst in the hypothalamus does not change, except for Npy and Agrp, while at the pituitary level the Gh, Ghrhr and Ghr genes are upregulated. Interestingly, the cell volume of somatotropic cells in the pituitary gland remains unchanged at the peak of the disease. We found elevated serum GH levels in association with low IGF-1 concentration and downregulated Ghr and Igf1r expression in the liver, indicating a condition resembling GH resistance. This is likely due to inadequate nutrient intake at the peak of the disease when inflammation in the CNS is greatest. Considering that GH secretion is finely regulated by numerous central and peripheral signals, the involvement of the GH/IGF-1 axis in MS/EAE should be thoroughly investigated for possible future therapeutic strategies, especially with a view to improving EAE disease.

The Model of Interstitial Cystitis for Evaluating New Molecular Strategies of Interstitial Regeneration in Humans

Given the recent evidence in the clinical application of regenerative medicine, mostly on integumentary systems, we focused our interests on recent bladder regeneration approaches based on mesenchymal stem cells (MSCs), platelet-rich plasma (PRP), and hyaluronic acid (HA) in the treatment of interstitial cystitis/bladder pain syndrome (IC/BPS) in humans. IC/BPS is a heterogeneous chronic disease with not-well-understood etiology, characterized by suprapubic pain related to bladder filling and urothelium dysfunction, in which the impairment of immunological processes seems to play an important role. The histopathological features of IC include ulceration of the mucosa, edema, denuded urothelium, and increased detection of mast cells and other inflammatory cells. A deeper understanding of the molecular mechanism underlying this disease is essential for the selection of the right therapeutic approach. In fact, although various therapeutic strategies exist, no efficient therapy for IC/BPS has been discovered yet. This review gives an overview of the clinical and pathological features of IC/BPS, with a particular focus on the molecular pathways involved and a special interest in the ongoing few investigational therapies in IC/BPS, which use new regenerative medicine approaches, and their synergetic combination. Good knowledge of the molecular aspects related to stem cell-, PRP-, and biomaterial-based treatments, as well as the understanding of the molecular mechanism of this pathology, will allow for the selection of the right and best use of regenerative approaches of structures involving connective tissue and epithelia, as well as in other diseases.

Electroacupuncture ameliorates cardiac dysfunction in myocardial ischemia model rats: a potential role of the hypothalamic-pituitary-adrenal axis

OBJECTIVE

To verify the hypothesis that electroacupuncture inhibits the hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis regulating the expression of glial fibrillary acidic protein (GFAP) in the hippocampus of acute myocardial ischemia (AMI) rats.

METHODS

Sixty-six healthy male Sprague-Dawley rats were randomly divided into five groups: Sham, AMI (Model), electroacupuncture at Shenmen (HT7)-Tongli (HT5) segment (EA), non-acupoint electroacupuncture (Control), and Model + corticosterone (Model + CORT). AMI was induced occlusion of the left anterior descending coronary artery, followed by 3 d of electroacupuncture at Shenmen (HT7)-Tongli (HT5) segment. In the Control group, electroacupuncture was applied at points lying 5 and 10 mm from the base of the tail. The AMI + CORT group was injected with CORT (20 mg/kg) in saline. Hemorheology, electrocardiography (ECG), hematoxylin and eosin staining, and expression of glycogen phosphorylase BB (GPBB) and heart-type fatty acid-binding protein (H-FABP) were used to assess cardiac function. The effects of adrenocorticotropic hormone (ACTH) and CORT were evaluated by enzyme-linked immunosorbent assay. Protein expression in the Sham and Model groups were screened by tandem mass tag-based quantitative proteomics analysis. Protein expression was evaluated by Western blotting (vimentin and GFAP) and immunofluorescence staining (GFAP).

RESULTS

Compared with the Sham group, the hemorheology indicators, heart rate, ECG-ST segment elevation, and GPBB and H-FABP levels were higher in Model rats. The EA group showed reductions in these indicators compared with the Model group. Similarly, in Model rats, the expression of ACTH and CORT were significantly increased compared with the Sham group. The EA group also showed reduced expression of ACTH and CORT. Importantly, proteomics analysis showed that vimentin was differentially expressed in Model rats. Compared with the Sham group, vimentin and GFAP expression in the hippocampus was increased in the Model group but decreased in the AMI + EA group. Additionally, intraperitoneal injection of CORT aggravated the expression of GPBB, H-FABP and GFAP.

CONCLUSIONS

Our results suggested that electroacupuncture may protect against cardiac injury induced by AMI through regulation of HPA axis hyperactivity, and that hippocampal GFAP may play an important role in the regulation.

Revisiting the Pathogenesis of Type 1 Diabetes: Importance of Neural Input to Pancreatic Islets and the Therapeutic Capability of Stem Cell Educator TM Therapy to Restore Their Integrity

Type 1 diabetes (T1D) is an autoimmune disease with a shortage of islet β cells. To date, the etiology of T1D remains elusive. Increasing clinical evidence and animal studies demonstrate that autoimmune cells are directed against the nervous system of pancreatic islets, contributing to the development of T1D. Therefore, it highlights the necessity to explore novel clinical approaches to fundamentally correct the T1D autoimmunity not only focusing on islet β cells but also on protecting the islet nervous system. This allows the restoration of the integrity of islet innervation and the normal islet β-cell function. To address these issues, we developed a novel technology designated the Stem Cell Educator ^TM therapy, based on immune education by human cord-blood-derived multipotent stem cells (CB-SC). International amulticenter clinical trials demonstrated its clinical safety and efficacy to treat T1D and other autoimmune diseases. Stem Cell Educator ^TM therapy may have the potential to revolutionize the treatment of T1D, without the safety and ethical concerns associated with conventional immune and/or stem cell-based therapies.

Oxidative Stress in Depression: The Link with the Stress Response, Neuroinflammation, Serotonin, Neurogenesis and Synaptic Plasticity

Depression is a prevalent, complex, and highly debilitating disease. The full comprehension of this disease is still a global challenge. Indeed, relapse, recurrency, and therapeutic resistance are serious challenges in the fight against depression. Nevertheless, abnormal functioning of the stress response, inflammatory processes, neurotransmission, neurogenesis, and synaptic plasticity are known to underlie the pathophysiology of this mental disorder. The role of oxidative stress in disease and, particularly, in depression is widely recognized, being important for both its onset and development. Indeed, excessive generation of reactive oxygen species and lack of efficient antioxidant response trigger processes such as inflammation, neurodegeneration, and neuronal death. Keeping in mind the importance of a detailed study about cellular and molecular mechanisms that are present in depression, this review focuses on the link between oxidative stress and the stress response, neuroinflammation, serotonergic pathways, neurogenesis, and synaptic plasticity's imbalances present in depression. The study of these mechanisms is important to lead to a new era of treatment and knowledge about this highly complex disease.

The role of plasma cortisol in dementia, epilepsy, and multiple sclerosis: A Mendelian randomization study

BACKGROUND

Many clinical studies have shown a correlation between plasma cortisol and neurological disorders. This study explored the causal relationship between plasma cortisol and dementia, epilepsy and multiple sclerosis based on Mendelian randomization (MR) method.

METHODS

Data were taken from the summary statistics of a genome-wide association study, FinnGen consortium and United Kingdom Biobank. Dementia, epilepsy, and multiple sclerosis were used as outcomes, and genetic variants associated with plasma cortisol were used as instrumental variables. The main analysis was performed using the inverse variance weighted method, and the results were assessed according to the odds ratio (OR) and 95% confidence interval. Heterogeneity tests, pleiotropy tests, and leave-one-out method were conducted to evaluate the stability and accuracy of the results.

RESULTS

In two-sample MR analysis, the inverse variance weighted method showed that plasma cortisol was associated with Alzheimer's disease (AD) [odds ratio (95% confidence interval) = 0.99 (0.98-1.00), P = 0.025], vascular dementia (VaD) [odds ratio (95% confidence interval) = 2.02 (1.00-4.05), P = 0.049)], Parkinson's disease with dementia (PDD) [odds ratio (95% confidence interval) = 0.24 (0.07-0.82), P = 0.023] and epilepsy [odds ratio (95% confidence interval) = 2.00 (1.03-3.91), P = 0.042]. There were no statistically significant associations between plasma cortisol and dementia with Lewy bodies (DLB), frontotemporal dementia (FTD) and multiple sclerosis.

CONCLUSION

This study demonstrates that plasma cortisol increase the incidence rates of epilepsy and VaD and decrease the incidence rates of AD and PDD. Monitoring plasma cortisol concentrations in clinical practice can help prevent diseases, such as AD, PDD, VaD and epilepsy.

Chronic Ouabain Prevents Radiation-Induced Reduction in the α2 Na,K-ATPase Function in the Rat Diaphragm Muscle

The damaging effect of ionizing radiation (IR) on skeletal muscle Na,K-ATPase is an open field of research. Considering a therapeutic potential of ouabain, a specific ligand of the Na,K-ATPase, we tested its ability to protect against the IR-induced disturbances of Na,K-ATPase function in rat diaphragm muscle that co-expresses the α1 and α2 isozymes of this protein. Male Wistar rats (n = 26) were subjected to 6-day injections of vehicle (0.9% NaCl) or ouabain (1 µg/kg/day). On the fourth day of injections, rats were exposed to one-time total-body X-ray irradiation (10 Gy), or a sham irradiation. The isolated muscles were studied 72 h post-irradiation. IR decreased the electrogenic contribution of the α2 Na,K-ATPase without affecting its protein content, thereby causing sarcolemma depolarization. IR increased serum concentrations of ouabain, IL-6, and corticosterone, decreased lipid peroxidation, and changed cellular redox status. Chronic ouabain administration prevented IR-induced depolarization and loss of the α2 Na,K-ATPase electrogenic contribution without changing its protein content. This was accompanied with an elevation of ouabain concentration in circulation and with the lack of IR-induced suppression of lipid peroxidation. Given the crucial role of Na,K-ATPase in skeletal muscle performance, these findings may have therapeutic implications as countermeasures for IR-induced muscle pathology.

The neuroprotective effects of icariin on ageing, various neurological, neuropsychiatric disorders, and brain injury induced by radiation exposure

Epimedium brevicornum Maxim, a Traditional Chinese Medicine, has been used for the treatment of impotence, sinew and bone disorders, “painful impediment caused by wind-dampness,” numbness, spasms, hypertension, coronary heart disease, menopausal syndrome, bronchitis, and neurasthenia for many years in China. Recent animal experimental studies indicate that icariin, a major bioactive component of epimedium may effectively treat Alzheimer’s disease, cerebral ischemia, depression, Parkinson’s disease, multiple sclerosis, as well as delay ageing. Our recent study also suggested that epimedium extract could exhibit radio-neuro-protective effects and prevent ionizing radiation-induced impairment of neurogenesis. This paper reviewed the pharmacodynamics of icariin in treating different neurodegenerative and neuropsychiatric diseases, ageing, and radiation-induced brain damage. The relevant molecular mechanisms and its anti-neuroinflammatory, anti-apoptotic, anti-oxidant, as well as pro-neurogenesis roles were also discussed.

Effect of the renin-angiotensin system on the exacerbation of adrenal glucocorticoid steroidogenesis in diabetic mice: Role of angiotensin-II type 2 receptor

Prior investigation shows an increase in the activity of both hypothalamus-pituitary-adrenal (HPA) axis and the renin-angiotensin system (RAS) in diabetic patients. Moreover, activation of angiotensin-II type 1 receptor (AT₁) has been associated with adrenal steroidogenesis. This study investigates the role of RAS on the overproduction of corticosterone in diabetic mice. Diabetes was induced by intravenous injection of alloxan into fasted Swiss-webster mice. Captopril (angiotensin-converting enzyme inhibitor), Olmesartan (AT₁ receptor antagonist), CGP42112A (AT₂ receptor agonist) or PD123319 (AT₂ receptor antagonist) were administered daily for 14 consecutive days, starting 7 days post-alloxan. Plasma corticosterone was evaluated by ELISA, while adrenal gland expressions of AT₁ receptor, AT₂ receptor, adrenocorticotropic hormone receptor MC2R, pro-steroidogenic enzymes steroidogenic acute regulatory protein (StAR), and 11β-hydroxysteroid dehydrogenase type 1 (11βHSD1) were assessed using immunohistochemistry or western blot. Diabetic mice showed adrenal gland overexpression of AT₁ receptor, MC2R, StAR, and 11βHSD1 without altering AT₂ receptor levels, all of which were sensitive to Captopril or Olmesartan treatment. In addition, PD123319 blocked the ability of Olmesartan to reduce plasma corticosterone levels in diabetic mice. Furthermore, CGP42112A significantly decreased circulating corticosterone levels in diabetic mice, without altering the overexpression of MC2R and StAR in the adrenal glands. Our findings revealed that inhibition of both angiotensin synthesis and AT₁ receptor activity reduced the high production of corticosterone in diabetic mice via the reduction of MC2R signaling expression in the adrenal gland. Furthermore, the protective effect of Olmesartan on the overproduction of corticosterone by adrenals in diabetic mice depends on both AT₁ receptor blockade and AT₂ receptor activation.