Intrathecal synthesis of anti-sulfatide IgG is associated with peripheral nerve disease in acquired immunodeficiency syndrome

Compartmentalized intrathecal immunoglobulin synthesis during HIV infection - a model of chronic CNS inflammation?

HIV infects the central nervous system (CNS) during primary infection and persists in resident macrophages. CNS infection initiates a strong local immune response that fails to control the virus but is responsible for by-stander lesions involved in neurocognitive disorders. Although highly active anti-retroviral therapy now offers an almost complete control of CNS viral proliferation, low-grade CNS inflammation persists. This review focuses on HIV-induced intrathecal immunoglobulin (Ig) synthesis. Intrathecal Ig synthesis early occurs in more than three-quarters of patients in response to viral infection of the CNS and persists throughout the course of the disease. Viral antigens are targeted but this specific response accounts for <5% of the whole intrathecal synthesis. Although the nature and mechanisms leading to non-specific synthesis are unknown, this prominent proportion is comparable to that observed in various CNS viral infections. Cerebrospinal fluid-floating antibody-secreting cells account for a minority of the whole synthesis, which mainly takes place in perivascular inflammatory infiltrates of the CNS parenchyma. B-cell traffic and lineage across the blood-brain-barrier have not yet been described. We review common technical pitfalls and update the pending questions in the field. Moreover, since HIV infection is associated with an intrathecal chronic oligoclonal (and mostly non-specific) Ig synthesis and associates with low-grade axonal lesions, this could be an interesting model of the chronic intrathecal synthesis occurring during multiple sclerosis.

Elevated anti-sulfatide antibodies in Guillain-Barré syndrome in T cell depleted at end-stage AIDS

A 38-year-old man developed the Guillain-Barré syndrome (GBS) associated with untreated end-stage AIDS and CD4+ lymphocyte count of 3 cells/mm(3). The patient had serum high titer anti-sulfatide antibodies and responded well to infusion of immunoglobulin. The data suggest that elevated levels of anti-sulfatide antibodies may play a role in the pathogenesis of GBS in this patient, although a direct neurotropic effect of HIV virus cannot be excluded.

[Guillain-Barré syndrome in HIV-infected patients at Bobo-Dioulasso Hospital (Burkina Faso)]

Neurological manifestations of human immunodeficiency virus (HIV) infection are frequent and several associated peripheral neuropathies have been recognized. Among them, Guillain-Barré syndrome (GBS) may occur either early or during the course of the illness. We present a prospective study of 32 consecutive cases of GBS managed over a 5-Year period at Bobo-Dioulasso Hospital where HIV prevalence reaches 20.1p.cent. Male gender predominated (24/32). GBS occurred during the dry season for 65.7p.cent of the patients. Prior infections were found in 84.4p.cent. The motor deficit was paraplegia or tetraplegia. Clinically, paraplegia was associated with transient urinary sphincteric involvement in 24 HIV-infected patients and 3 HIV negative patients. Facial nerve paralysis was found in 3 patients. Among the 32 patients with GBS, 27 were tested positive for HIV. Two patients were infected by HIV1 and HIV2. Cerebrospinal fluid examination showed albumin-cell dissociation and elevated albumin level in 75p.cent of the samples. Autonomic neuropathies were seen in 9 HIV-infected patients. The CD4 counts were above 200/mm3 in 10 among 18 HIV-infected patients. The clinical presentations were more severe in HIV-positive patients with a longer duration of symptoms. HIV-infected patients walked unaided within 51.1 days of peak paralysis. No fatal event occurred. This study indicates clearly that GBS in young adults is strongly associated with HIV infection and should be considered as an indicator of HIV infection in Black Africans. In the tropical context GBS should lead to HIV screening.

Can antiglycolipid antibodies present in HIV-infected individuals induce immune demyelination?

Of the eight clinically defined neuropathies associated with HIV infection, there is compelling evidence that acute and chronic inflammatory demyelinating polyneuropathy (IDPN) have an autoimmune pathogenesis. Many non-HIV infected individuals who suffer from sensory-motor nerve dysfunction have autoimmune indicators. The immunopathogenesis of demyelination must involve neuritogenic components in myelin. The various antigens suspected to play a role in HIV-seronegative IDPN include (i) P2 protein; (ii) sulfatide (GalS); (iii) various gangliosides (especially GM1); (iv) galactocerebroside (GalC); and (v) glycoproteins or glycolipids with the carbohydrate epitope glucuronyl-3-sulfate. These glycoproteins or glycolipids may be individually targeted, or an immune attack may be raised against a combination of any of these epitopes. The glycolipids, however, especially GalS, have recently evoked much interest as mediators of immune events underlying both non-HIV and HIV-associated demyelinating neuropathies. The present review outlines the recent research findings of antiglycolipid antibodies present in HIV-infected patients with and without peripheral nerve dysfunction, in an attempt to arrive at some consensus as to whether these antibodies may play a role in the immunopathogenesis of HIV-associated inflammatory demyelinating polyneuropathy.

High levels in serum, but no signs of intrathecal synthesis of anti-sulfatide antibodies in HIV-1 infected individuals with or without central nervous system complications

Myelin degeneration is commonly found in the central nervous system (CNS) of individuals infected with human immunodeficiency virus type 1 (HIV-1), especially in patients with HIV-1-associated dementia. We analysed cerebrospinal fluid (CSF) and serum samples from 25 HIV-1 infected individuals for the presence of antibodies directed against sulfatide, the major acidic glycosphingolipid in myelin. Nine of the patients had CNS complications, including 3 with HIV-1-associated dementia, and 16 had no neurological symptoms. Elevated titres of anti-sulfatide antibodies were found in serum from 24/25 HIV-1-infected individuals but in none of them in the CSF. Although the vast majority of HIV-1-infected individuals harbour autoantibodies directed against sulfatide in serum, the lack of detectable intrathecal production indicates that anti-sulfatide antibodies are not a major component in the pathogenesis of CNS myelin damage in HIV-1 infection.

Electrospray ionization tandem mass spectrometric analysis of sulfatide. Determination of fragmentation patterns and characterization of molecular species expressed in brain and in pancreatic islets

The sphingolipid sulfatide is a component of myelin and some non-neuronal cells. Antibodies to sulfatide occur in some patients with autoimmune neuropathies and in patients with insulin-dependent diabetes mellitus (IDDM) caused by immunologic destruction of insulin-secreting pancreatic islet beta-cells. Distinct sulfatide molecular species may differ in immunogenicity, and facile means to identify sulfatide species in islets and other tissues obtainable in only small amounts could be useful. Electrospray ionization mass spectrometry (ESI/MS) permits structural determination of small quantities of phospholipids and is applied here to sulfatide analysis. We find that sulfatide standards are readily analyzed by negative ion ESI/MS, and tandem mass spectra of individual species exhibit some ions common to all species and other ions that reflect distinct fatty acid substituents in different sulfatide molecules. A signature ion cluster resulting from cleavage directed by the alpha-hydroxy group of sulfatide species with a hydroxylated fatty acid substituent identifies such species. Sulfatide profiles in tissue lipid extracts can be obtained by ESI/MS/MS scanning for common sulfatide ions and for ions reflecting fatty acid substituents. Islets are demonstrated to contain sulfatide and to exhibit a profile of species different from that of brain.

Glycosphingolipids as potential diagnostic markers and/or antigens in neurological disorders

Glycosphingolipids are most abundant in the nervous system within which are developmental, regional, structural and cellular differences regarding their composition. The are shedded to the cerebrospinal fluid and thus potential markers for pathogenic alterations in the brain, such as developmental abnormalities, demyelination, gliosis, neuronal cell destruction. The glycosphingolipids have also been found to be antigens in autoimmune processes involving the nervous system, in particular in peripheral neuropathies like Guillain Barré syndrome, multifocal motor neuropathy etc. The immune response might have been triggered by infectious agents with an antigen epitope which mimic the glycosphingolipid or by a primary nerve tissue damage leading to release of glycosphingolipids. There is a series of support for a clinical significance of cerebrospinal fluid glycosphingolipid determinations and the presence of anti-glycosphingolipid antibodies but this has to be further explored. This paper is a mini review of the state of the art and discuss methodological aspects and improvements that might help to explore the relevance of glycosphingolipids in neurological disorders.