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Autoimmunity is the system of immune responses of an organism against its own healthy cells, tissues and other body normal constituents. Any disease resulting from this type of immune response is termed an "autoimmune disease". Prominent examples include celiac disease, post-infectious IBS, diabetes mellitus type 1, Henloch Scholein Pupura (HSP) sarcoidosis, systemic lupus erythematosus (SLE), Sjögren syndrome, eosinophilic granulomatosis with polyangiitis, Hashimoto's thyroiditis, Graves' disease, idiopathic thrombocytopenic purpura, Addison's disease, rheumatoid arthritis (RA), ankylosing spondylitis, polymyositis (PM), dermatomyositis (DM), Alopecia Areata and multiple sclerosis (MS). Autoimmune diseases are very often treated with steroids.
Myelitis is inflammation of the spinal cord which can disrupt the normal responses from the brain to the rest of the body, and from the rest of the body to the brain. Inflammation in the spinal cord, can cause the myelin and axon to be damaged resulting in symptoms such as paralysis and sensory loss. Myelitis is classified to several categories depending on the area or the cause of the lesion; however, any inflammatory attack on the spinal cord is often referred to as transverse myelitis.
Astrogliosis is an abnormal increase in the number of astrocytes due to the destruction of nearby neurons from central nervous system (CNS) trauma, infection, ischemia, stroke, autoimmune responses or neurodegenerative disease. In healthy neural tissue, astrocytes play critical roles in energy provision, regulation of blood flow, homeostasis of extracellular fluid, homeostasis of ions and transmitters, regulation of synapse function and synaptic remodeling. Astrogliosis changes the molecular expression and morphology of astrocytes, in response to infection for example, in severe cases causing glial scar formation that may inhibit axon regeneration.
Neuromyelitis optica spectrum disorders (NMOSD), including neuromyelitis optica (NMO), are autoimmune diseases characterized by acute inflammation of the optic nerve and the spinal cord (myelitis). Episodes of ON and myelitis can be simultaneous or successive. A relapsing disease course is common, especially in untreated patients. In more than 80% of cases, NMO is caused by immunoglobulin G autoantibodies to aquaporin 4 (anti-AQP4), the most abundant water channel protein in the central nervous system. A subset of anti-AQP4-negative cases is associated with antibodies against myelin oligodendrocyte glycoprotein (anti-MOG). Rarely, NMO may occur in the context of other autoimmune diseases or infectious diseases. In some cases, the etiology remains unknown.
Glial fibrillary acidic protein (GFAP) is a protein that is encoded by the GFAP gene in humans. It is a type III intermediate filament (IF) protein that is expressed by numerous cell types of the central nervous system (CNS), including astrocytes and ependymal cells during development. GFAP has also been found to be expressed in glomeruli and peritubular fibroblasts taken from rat kidneys, Leydig cells of the testis in both hamsters and humans, human keratinocytes, human osteocytes and chondrocytes and stellate cells of the pancreas and liver in rats.
Leukodystrophies are a group of usually inherited disorders characterized by degeneration of the white matter in the brain. The word leukodystrophy comes from the Greek roots leuko, "white", dys, "abnormal" and troph, "growth". The leukodystrophies are caused by imperfect growth or development of the myelin sheath, the fatty insulating covering around nerve fibers. Leukodystrophies may be classified as hypomyelinating or demyelinating diseases, depending on whether the damage is present before birth or occurs after. Other demyelinating diseases are usually not congenital and have a toxic or autoimmune cause.
Meningoencephalitis, also known as herpes meningoencephalitis, is a medical condition that simultaneously resembles both meningitis, which is an infection or inflammation of the meninges, and encephalitis, which is an infection or inflammation of the brain.
Chronic inflammatory demyelinating polyneuropathy (CIDP) is an acquired autoimmune disease of the peripheral nervous system characterized by progressive weakness and impaired sensory function in the legs and arms. The disorder is sometimes called chronic relapsing polyneuropathy (CRP) or chronic inflammatory demyelinating polyradiculoneuropathy. CIDP is closely related to Guillain–Barré syndrome and it is considered the chronic counterpart of that acute disease. Its symptoms are also similar to progressive inflammatory neuropathy. It is one of several types of neuropathy.
Gliosis is a nonspecific reactive change of glial cells in response to damage to the central nervous system (CNS). In most cases, gliosis involves the proliferation or hypertrophy of several different types of glial cells, including astrocytes, microglia, and oligodendrocytes. In its most extreme form, the proliferation associated with gliosis leads to the formation of a glial scar.
Multiple sclerosis is an inflammatory demyelinating disease of the CNS in which activated immune cells invade the central nervous system and cause inflammation, neurodegeneration, and tissue damage. The underlying cause is currently unknown. Current research in neuropathology, neuroimmunology, neurobiology, and neuroimaging, together with clinical neurology, provide support for the notion that MS is not a single disease but rather a spectrum.
Multiple sclerosis and other demyelinating diseases of the central nervous system (CNS) produce lesions and glial scars or scleroses. They present different shapes and histological findings according to the underlying condition that produces them.
Molecular mimicry is defined as the theoretical possibility that sequence similarities between foreign and self-peptides are sufficient to result in the cross-activation of autoreactive T or B cells by pathogen-derived peptides. Despite the prevalence of several peptide sequences which can be both foreign and self in nature, a single antibody or TCR can be activated by just a few crucial residues which stresses the importance of structural homology in the theory of molecular mimicry. Upon the activation of B or T cells, it is believed that these "peptide mimic" specific T or B cells can cross-react with self-epitopes, thus leading to tissue pathology (autoimmunity). Molecular mimicry is a phenomenon that has been just recently discovered as one of several ways in which autoimmunity can be evoked. A molecular mimicking event is, however, more than an epiphenomenon despite its low statistical probability of occurring and these events have serious implications in the onset of many human autoimmune disorders.
Pituicytes are glial cells of the posterior pituitary. Their main role is to assist in the storage and release of neurohypophysial hormones.
Inflammatory demyelinating diseases (IDDs), sometimes called Idiopathic (IIDDs) due to the unknown etiology of some of them, are a heterogenous group of demyelinating diseases - conditions that cause damage to myelin, the protective sheath of nerve fibers - that occur against the background of an acute or chronic inflammatory process. IDDs share characteristics with and are often grouped together under Multiple Sclerosis. They are sometimes considered different diseases from Multiple Sclerosis, but considered by others to form a spectrum differing only in terms of chronicity, severity, and clinical course.
Glial scar formation (gliosis) is a reactive cellular process involving astrogliosis that occurs after injury to the central nervous system. As with scarring in other organs and tissues, the glial scar is the body's mechanism to protect and begin the healing process in the nervous system.
Papillary tumors of the pineal region (PTPR) were first described by A. Jouvet et al. in 2003 and were introduced in the World Health Organization (WHO) classification of Central Nervous System (CNS) in 2007. Papillary Tumors of the Pineal Region are located on the pineal gland which is located in the center of the brain. The pineal gland is located on roof of the diencephalon. It is a cone shaped structure dorsal to the midbrain tectum. The tumor appears to be derived from the specialized ependymal cells of the subcommissural organ. Papillary tumors of the central nervous system and particularly of the pineal region are very rare and so diagnosing them is extremely difficult.
Multiple sclerosis (MS) can be pathologically defined as the presence of distributed glial scars (scleroses) in the central nervous system that must show dissemination in time (DIT) and in space (DIS) to be considered MS lesions.
Chronic relapsing inflammatory optic neuropathy (CRION) is a form of recurrent optic neuritis that is steroid responsive and dependent. Patients typically present with pain associated with visual loss. CRION is a clinical diagnosis of exclusion, and other demyelinating, autoimmune, and systemic causes should be ruled out. Early recognition is crucial given risks for severe visual loss and because it is treatable with immunosuppressive treatment such as steroids or B-cell depleting therapy. Relapse that occurs after reducing or stopping steroids is a characteristic feature. In 2022 CRION has been included as a subgroup of optic neuritis in an international consensus classification.
MOG antibody disease (MOGAD) or MOG antibody-associated encephalomyelitis (MOG-EM) is an inflammatory demyelinating disease of the central nervous system. Serum anti-myelin oligodendrocyte glycoprotein antibodies are present in up to half of patients with an acquired demyelinating syndrome and have been described in association with a range of phenotypic presentations, including acute disseminated encephalomyelitis, optic neuritis, transverse myelitis, and neuromyelitis optica.
Several biomarkers for diagnosis of multiple sclerosis, disease evolution and response to medication are under research. While most of them are still under research, there are some of them already well stablished:
References
- 1 2 Boyan Fang el al., Autoimmune Glial Fibrillary Acidic Protein Astrocytopathy. A Novel Meningoencephalomyelitis, November 2016, JAMA Neurol. 2016;73(11):1297-1307. doi : 10.1001/jamaneurol.2016.2549
- ↑ Y. Long et al., Autoimmune glial fibrillary acidic protein astrocytopathy in Chinese patients: a retrospective study, 29 November 2017, https://doi.org/10.1111/ene.13531
- ↑ Patel N M, Bronder J, Motta M, Morris N. Mystery Case: A 23-year-old man with headaches, confusion, and lower extremity weakness. Neurology. 2018;92(18):863-867. https://n.neurology.org/content/92/18/863/tab-article-info
- ↑ Iorio R, Damato V, Evoli A, et al, Clinical and immunological characteristics of the spectrum of GFAP autoimmunity: a case series of 22 patients, J Neurol Neurosurg Psychiatry 2018;89:138-146.
- ↑ Shan F, Long Y, Qiu W. Autoimmune Glial Fibrillary Acidic Protein Astrocytopathy: A Review of the Literature. Front Immunol. 2018 Dec 5;9:2802. doi: 10.3389/fimmu.2018.02802. PMID 30568655, PMCID PMC6290896, doi : 10.3389/fimmu.2018.02802
- ↑ Eoin Flanagan et al., Specificity of glial fibrillary acidic protein IgG autoantibody (GFAP-IgG) for Autoimmune Meningoencephalomyelitis Diagnosis, Neurology, April 18, 2017; 88 (16 Supplement)
- ↑ Yang X. et al., Treatment of Autoimmune Glial Fibrillary Acidic Protein Astrocytopathy: Follow-Up in 7 Cases, Neuroimmunomodulation 2017;24:113-119, https://doi.org/10.1159/000479948
- ↑ Patel N M, Bronder J, Motta M, Morris N. Mystery Case: A 23-year-old man with headaches, confusion, and lower extremity weakness. Neurology. 2018;92(18):863-867. https://n.neurology.org/content/92/18/863/tab-article-info