Are multiple sclerosis and amyotrophic lateral sclerosis autoimmune disorders of endogenous vasoactive neuropeptides?

The Multifaceted Role of GPCRs in Amyotrophic Lateral Sclerosis: A New Therapeutic Perspective?

Amyotrophic lateral sclerosis (ALS) is a degenerating disease involving the motor neurons, which causes a progressive loss of movement ability, usually leading to death within 2 to 5 years from the diagnosis. Much effort has been put into research for an effective therapy for its eradication, but still, no cure is available. The only two drugs approved for this pathology, Riluzole and Edaravone, are onlyable to slow down the inevitable disease progression. As assessed in the literature, drug targets such as protein kinases have already been extensively examined as potential drug targets for ALS, with some molecules already in clinical trials. Here, we focus on the involvement of another very important and studied class of biological entities, G protein-coupled receptors (GPCRs), in the onset and progression of ALS. This workaimsto give an overview of what has been already discovered on the topic, providing useful information and insights that can be used by scientists all around the world who are putting efforts into the fight against this very important neurodegenerating disease.

Protective Effects of Pituitary Adenylate Cyclase-Activating Polypeptide and Vasoactive Intestinal Peptide Against Cognitive Decline in Neurodegenerative Diseases

Cognitive impairment is one of the major symptoms in most neurodegenerative disorders such as Alzheimer’s (AD), Parkinson (PD), and Huntington diseases (HD), affecting millions of people worldwide. Unfortunately, there is no treatment to cure or prevent the progression of those diseases. Cognitive impairment has been related to neuronal cell death and/or synaptic plasticity alteration in important brain regions, such as the cerebral cortex, substantia nigra, striatum, and hippocampus. Therefore, compounds that can act to protect the neuronal loss and/or to reestablish the synaptic activity are needed to prevent cognitive decline in neurodegenerative diseases. Pituitary adenylate cyclase-activating polypeptide (PACAP) and vasoactive intestinal peptide (VIP) are two highly related multifunctional neuropeptides widely distributed in the central nervous system (CNS). PACAP and VIP exert their action through two common receptors, VPAC1 and VPAC2, while PACAP has an additional specific receptor, PAC1. In this review article, we first presented evidence showing the therapeutic potential of PACAP and VIP to fight the cognitive decline observed in models of AD, PD, and HD. We also reviewed the main transduction pathways activated by PACAP and VIP receptors to reduce cognitive dysfunction. Furthermore, we identified the therapeutic targets of PACAP and VIP, and finally, we evaluated different novel synthetic PACAP and VIP analogs as promising pharmacological tools.

Implications of white matter damage in amyotrophic lateral sclerosis (Review)

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease, which involves the progressive degeneration of motor neurons. ALS has long been considered a disease of the grey matter; however, pathological alterations of the white matter (WM), including axonal loss, axonal demyelination and oligodendrocyte death, have been reported in patients with ALS. The present review examined motor neuron death as the primary cause of ALS and evaluated the associated WM damage that is guided by neuronal‑glial interactions. Previous studies have suggested that WM damage may occur prior to the death of motor neurons, and thus may be considered an early indicator for the diagnosis and prognosis of ALS. However, the exact molecular mechanisms underlying early‑onset WM damage in ALS have yet to be elucidated. The present review explored the detailed anatomy of WM and identified several pathological mechanisms that may be implicated in WM damage in ALS. In addition, it associated the pathophysiological alterations of WM, which may contribute to motor neuron death in ALS, with similar mechanisms of WM damage that are involved in multiple sclerosis (MS). Furthermore, the early detection of WM damage in ALS, using neuroimaging techniques, may lead to earlier therapeutic intervention, using immunomodulatory treatment strategies similar to those used in relapsing‑remitting MS, aimed at delaying WM damage in ALS. Early therapeutic approaches may have the potential to delay motor neuron damage and thus prolong the survival of patients with ALS. The therapeutic interventions that are currently available for ALS are only marginally effective. However, early intervention with immunomodulatory drugs may slow the progression of WM damage in the early stages of ALS, thus delaying motor neuron death and increasing the life expectancy of patients with ALS.

Dilated perivascular spaces and fatigue: is there a link? Magnetic resonance retrospective 3Tesla study

INTRODUCTION

Fatigue (F) is a common, inexplicable, and disabling symptom in multiple sclerosis (MS) patients. The purpose of this study was to evaluate a possible correlation between fatigue and morpho-volumetric features and site of dilated perivascular spaces (dPS), visible on 3T magnetic resonance (MR) in fatigued multiple sclerosis patients (FMS).

METHODS

We studied 82 relapsing remitting (RR) FMS patients and 43 HC, matched for age, sex, and education. F was assessed by the Fatigue Severity Scale (FSS). To evaluate a possible correlation between degree of F and characteristics of dPS, patients were divided in two groups: more (mFMS) (FSS ≥ 5; n = 30) and less fatigued (lFMS) (FSS ≥ 4; n = 52), compared to a matched healthy control (HC) subject group. The MR study was performed with 3T scanner by SpinEcho T1, Fast-SpinEcho DP-T2, FLAIR, and 3D FSPGR T1 sequences. dPS volumes were measured with Medical Image Processing Analysis and Visualization (MIPAV); Global Cerebral Atrophy (GCA), expressed as Brain Parenchymal Fraction (BPF), was assessed by FSL SIENAX.

RESULTS

The t test showed significantly increased dPS number (p = 0.021) in FMS patients (mFMS p = 0.0024 and lFMS p = 0.033) compared to HC. Pearson correlation revealed a significant correlation between dPS number and FSS (r = 0.208 p = 0.051). Furthermore, the chi-squared test confirms the intragroup (HC, mFMS, lFMS) differences about dPS location (p = 0.01) and size (p = 0.0001).

CONCLUSION

Our study confirms that PS in MS patients presents with different volumetric and site characteristics as compared to HC; moreover, F severity significantly correlates with dPS number, site, and size.

Same-sex marriage, autoimmune thyroid gland dysfunction and other autoimmune diseases in Denmark 1989-2008

Autoimmune diseases have been little studied in gay men and lesbians. We followed 4.4 million Danes, including 9,615 same-sex married (SSM) persons, for 47 autoimmune diseases in the National Patient Registry between 1989 and 2008. Poisson regression analyses provided first hospitalization rate ratios (RRs) comparing rates between SSM individuals and persons in other marital status categories. SSM individuals experienced no unusual overall risk of autoimmune diseases. However, the risk of autoimmune thyroid dysfunction was increased, notably Hashimoto's thyroiditis (women(SSM), RR = 2.92; 95% confidence interval (CI) 1.74-4.55) and Graves' disease (men(SSM), RR = 1.88; 95% CI 1.08-3.01). There was also an excess of primary biliary cirrhosis (women(SSM), RR = 4.09; 95% CI 1.01-10.7), and of psoriasis (men(SSM), RR = 2.48; 95% CI 1.77-3.36), rheumatic fever (men(SSM), RR = 7.55; 95% CI 1.87-19.8), myasthenia gravis (men(SSM), RR = 5.51; 95% CI 1.36-14.4), localized scleroderma (men(SSM), RR = 7.16; 95% CI 1.18-22.6) and pemphigoid (men(SSM), RR = 6.56; 95% CI 1.08-20.6), while Dupuytren's contracture was reduced (men(SSM), RR = 0.64; 95% CI 0.39-0.99). The excess of psoriasis was restricted to same-sex married men with HIV/AIDS (men(SSM), RR = 10.5; 95% CI 6.44-15.9), whereas Graves' disease occurred in excess only among same-sex married men without HIV/AIDS (men(SSM), RR = 1.99; 95% CI 1.12-3.22). Lesbians and immunologically competent gay men in same-sex marriage face no unusual overall risk of autoimmune diseases. However, the observed increased risk of thyroid dysfunction in these lesbians and gay men deserves further study.

Association between DPP6 polymorphism and the risk of progressive multiple sclerosis in Northern and Southern Europeans

BACKGROUND

In this study, we investigated the role of the dipeptidyl-peptidase-6 (DPP6) gene in the etiopathogenesis of progressive forms of multiple sclerosis (PrMS). This gene emerged as a candidate gene in a genome-wide association study (GWAS) performed in an Italian sample of PrMS and controls in which two SNPs located in the gene (rs6956703 and rs11767658) showed evidence of association (nominal p-value<10(-4)) (Martinelli-Boneschi et al.) [18]. Moreover, the gene is highly expressed in the central nervous system, and it has been found to be associated with sporadic cases of amyotrophic lateral sclerosis which shares some feature with PrMS.

METHODS

We genotyped 19 SNPs selected using a direct and tagging approach in 244 Italian PrMS and 225 controls, and we measured the expression levels of the gene in 13 PrMS cases and 25 controls.

RESULTS

Five out of 19 SNPs were found to be associated with the disease (adjusted p<0.05), and they have been tested in an independent sample of 179 primary progressive MS and 198 controls from Northern Europe. None of the SNPs was replicated, but combined analysis confirmed the presence of association for rs2046748 (p=2.5×10(-3),OR=1.82, 95%CI=1.24-2.69).

CONCLUSIONS

These results, inflated by the limited sample size determined by the rarity of this condition, suggest a possible role of this gene in the susceptibility to PrMS, at least in Southern Europeans. Moreover, DPP6 was over-expressed in PrMS patients compared to controls.

Olfactory ensheathing cell transplantation into spinal cord prolongs the survival of mutant SOD1(G93A) ALS rats through neuroprotection and remyelination

Amyotrophic lateral sclerosis (ALS) is a progressively fatal, incurable, neurodegenerative disorder. In this study, we investigated whether olfactory ensheathing cells (OEC) transplantation could provide protection to motor neurons and enable remyelination in mutant SOD1(G93A) transgenic rats with ALS. Seventy-two rats were divided into four groups: SOD1(G93A) rats (n = 20); medium+SOD1(G93A) rats (n = 20); OECs+SOD1(G93A) rats (n = 24); and another eight wild-type rats were used as controls. About 5 μL (1 × 10(5)) OECs in DF12 medium was injected into the dorsal funiculus of the thoracic spinal cord at a predetermined depth. Survival analysis revealed a significant increase in the survival time in OEC+SOD1(G93A) rats. Body weight records and inclined board test showed a significant difference between OEC+SOD1(G93A) and SOD1(G93A) from the onset at 7 days to 11 days (P < 0.05). Four weeks following transplantation, motor neuron counts in the ventral horn of the spinal cord noted a significant motor neuron loss in SOD1(G93A) rats when compared with wild-type rats (P < 0.001), and much less neuronal loss and collapse was noted in OEC+SOD1(G93A) rats when compared with SOD1(G93A) rats(P < 0.001); immunohistochemistry and Western blot analysis of choline acetyltransferase supported the motor neuron count. Images of confocal microscope indicated that the transplanted OECs had survived for more than 4 weeks and migrated 4.2 mm through the spinal cord. Evidence of remyelination of transplanted OEC was captured with triple fluorescence labeling of green fluorescent protein, neurofilament, and myelin basic protein and was further confirmed by Western blot analysis of MPB. In conclusion, the transplanted OECs could serve as a source of neuroprotection and remyelination to modify the ALS microenvironment.

History and physiology of immune privilege

Immune privilege is the condition in which selected immune responses are suppressed or excluded in certain organs, such as the eye. Immune privilege in the eye was described over 130 years ago, but its significance was not appreciated until the early 1950s. Investigations beginning in the 1970s ushered in a new era and revealed that ocular immune privilege is due to anatomical, physiological, and immunoregulatory processes that prevent the induction and expression of immune-mediated inflammation. It is widely believed that immune privilege is an adaptation for reducing immune-mediated injury to ocular cells that have limited or no capacity for regeneration.

Autoimmune diseases in women with Turner's syndrome

OBJECTIVE

In terms of number of X chromosomes, women with Turner's syndrome cytogenetically resemble men. An increased risk of autoimmune diseases has been observed among women with Turner's syndrome. This study was undertaken to investigate whether the autoimmune disease profile in women with Turner's syndrome is characterized by diseases with a female or male predominance.

METHODS

Using the Danish Cytogenetic Central Register, the Danish National Patient Register, and the Danish Civil Registration System, we estimated relative risk of 46 different autoimmune diseases in a cohort of 798 Danish women with Turner's syndrome followed up for 12,461 person-years between 1980 and 2004. Standardized incidence ratios (SIRs) of first hospitalization for autoimmune disease and 95% confidence intervals (95% CIs) were used as measures of relative risk.

RESULTS

The overall risk of autoimmune disease among women with Turner's syndrome was twice that among Danish women in general (SIR 2.1 [95% CI 1.6-2.7]). For autoimmune diseases with a female predominance, the SIR among women with Turner's syndrome was 1.7 (95% CI 1.2-2.4), whereas the SIR for autoimmune diseases with a male predominance among these women was 3.9 (95% CI 2.5-5.8). Associations were strongest for Hashimoto thyroiditis (SIR 14.6 [95% CI 6.7-27.1]), a strongly female-predominant condition, and type 1 diabetes mellitus (SIR 4.1 [95% CI 2.5-6.3]).

CONCLUSION

Women with Turner's syndrome are at excess risk of autoimmune diseases, notably autoimmune diseases characterized by male predominance.

Chemical modification of class II G protein-coupled receptor ligands: frontiers in the development of peptide analogs as neuroendocrine pharmacological therapies

Recent research and clinical data have begun to demonstrate the huge potential therapeutic importance of ligands that modulate the activity of the secretin-like, Class II, G protein-coupled receptors (GPCRs). Ligands that can modulate the activity of these Class II GPCRs may have important clinical roles in the treatment of a wide variety of conditions such as osteoporosis, diabetes, amyotrophic lateral sclerosis and autism spectrum disorders. While these receptors present important new therapeutic targets, the large glycoprotein nature of their cognate ligands poses many problems with respect to therapeutic peptidergic drug design. These native peptides often exhibit poor bioavailability, metabolic instability, poor receptor selectivity and resultant low potencies in vivo. Recently, increased attention has been paid to the structural modification of these peptides to enhance their therapeutic efficacy. Successful modification strategies have included d-amino acid substitutions, selective truncation, and fatty acid acylation of the peptide. Through these and other processes, these novel peptide ligand analogs can demonstrate enhanced receptor subtype selectivity, directed signal transduction pathway activation, resistance to proteolytic degradation, and improved systemic bioavailability. In the future, it is likely, through additional modification strategies such as addition of circulation-stabilizing transferrin moieties, that the therapeutic pharmacopeia of drugs targeted towards Class II secretin-like receptors may rival that of the Class I rhodopsin-like receptors that currently provide the majority of clinically used GPCR-based therapeutics. Currently, Class II-based drugs include synthesized analogs of vasoactive intestinal peptide for type 2 diabetes or parathyroid hormone for osteoporosis.

RANTES release contributes to the protective action of PACAP38 against sodium nitroprusside in cortical neurons

Pituitary adenylate cyclase activating polypeptide (PACAP), a promising neuroprotective peptide, plays an important role during development of the nervous system and in regeneration after injury. PACAP directly promotes survival via multiple signaling systems in neurons. This neuropeptide also has immuno-modulatory properties and can regulate the expression of various inflammatory mediators such as chemokines in nonneuronal cells. Chemokines and their G protein-coupled receptors are widely distributed in the brain, suggesting important functions for these inflammatory proteins in the CNS. The ability of brain endothelial cells and glia to release chemokines has been well documented, whether neurons are also a source for these mediators is unclear. The objective of this study is to determine whether PACAP38 affects expression of regulated on activation normal T expressed and secreted (RANTES) and macrophage inflammatory protein 1-alpha (MIP-1alpha) in cultured neurons and if these chemokines contribute to the neuroprotective effect of PACAP38. The data show that incubation of neuronal cultures with both PACAP38 and sodium nitroprusside (SNP) reduces the neuronal cell death evoked by SNP alone. PACAP38 dose-dependently increases immunodetectable levels of both RANTES and MIP-1alpha released in the media by cultured neurons. Co-treatment with a neutralizing antibody to RANTES decreases the PACAP38-mediated protection against SNP. Although RANTES treatment of neurons increased MIP-1alpha levels in the media and MIP-1alpha supports neuronal survival in unstressed cultures, MIP-1alpha does not protect neurons from SNP-induced toxicity. Furthermore, co-treatment with a MIP-1alpha neutralizing antibody did not affect PACAP38-induced protection against SNP. These results show that the protective effect of PACAP38 on cultured neurons is mediated, in part, by release of RANTES. The ability of PACAP to directly enhance neuronal survival through multiple intracellular signaling pathways as well as via the release of neuroprotective mediators such as RANTES highlights its utility as a potential therapeutic agent for the treatment of neurodegenerative diseases.