Transketolase and 2′,3′-Cyclic-nucleotide 3′-Phosphodiesterase Type I Isoforms Are Specifically Recognized by IgG Autoantibodies in Multiple Sclerosis Patients

Abstract

The presence of autoantibodies in multiple sclerosis (MuS) is well known, but their target antigens have not been clearly identified. In the present study, IgG autoreactivity to neural antigens of normal human white matter separated by bidimensional electrophoresis was assessed in serum and cerebrospinal fluid of 18 MuS and 20 control patients. Broad IgG autoreactivity was detected by twodimensional immunoblotting in all cases to neural antigens, most of which were identified by mass spectrometry. The comparative analysis of MuS and non-MuS reactive spots showed that a restricted number of neural protein isoforms were specifically recognized by MuS IgG. Almost all MuS patients had cerebrospinal fluid IgG directed to isoforms of one of the oligodendroglial molecules, transketolase, 2,3-cyclic-nucleotide 3-phosphodiesterase type I, collapsin response mediator protein 2, and tubulin ␤4. Interestingly 50% of MuS IgG recognized transketolase, which was mostly localized on oligodendrocytes in human white matter from normal and MuS samples. IgG autoreactivity to cytoskeletal proteins (radixin, sirtuin 2, and actin-interacting protein 1) was prevalent in secondary progressive MuS patients. Among the proteins recognized by serum IgG, almost all MuS patients specifically recognized a restricted number of neuronal/cytoskeletal proteins, whereas 2,3-cyclic-nucleotide 3-phosphodiesterase type I was the oligodendroglial antigen most frequently recognized (44%) by MuS seric IgG. Our immunomics approach shed new light on the autoimmune repertoire present in MuS patients revealing novel oligodendroglial and/or neuronal putative autoantigens with potential important pathogenic and diagnostic implications.

A Novel Unbiased Proteomic Approach to Detect the Reactivity of Cerebrospinal Fluid in Neurological Diseases

“…In particular, many cytoskeletal proteins and proteins regulating the cytoskeletal dynamics showed reactivity with MS-CSF (Table II). In line with previous reports, molecules such as ␣␤-crystallin, enolase, 14 -3-3 protein and GAPDH were also identified (11,15,49) in the MS-CSF, thus validating our experimental approach. Interestingly, 17% of reactive proteins were myelin proteins and molecules from immunological origin (Fig.…”

“…Therefore, it is not surprising that any events that may impair the function of molecules involved in glucose metabolism could lead to significant damage in the integrity and function of neurons or their supporting cells. In this context, it is noteworthy that antibodies to AE, TPI, and GAPDH have been shown to be present in the CSF from MS patients (15,51,52). Besides their glycolytic roles, these enzymes also have other functions.…”

“…These approaches include immunoblotting (16), antigen microarrays (17,18) and proteomic profiling of the CSF (19,20). Although these different experimental paradigms have led to the identification of several molecules including immunoglobulins (11)(12)(13)15), their exact pathophysiological role(s) remain to be determined. Moreover, most of these studies have analyzed the reactivity of CSF to defined brain antigens or have used as detection reagents, secondary antibodies specific for a defined class of immunoglobin, thus precluding an unbiased analysis of CSF reactivity to unselected CNS components.…”

The myelin membrane-associated enzyme 2′,3′-cyclic nucleotide 3′-phosphodiesterase: on a highway to structure and function

“…Together with several other CNS myelin proteins, CNPase is an auto-antigen in MS -a chronic autoimmune disease [11,[38][39][40] . Changes in the expression levels of…”

“…The true physiological relevance of this, however, is unclear, since myelination in CNPase-defi cient mice seems to proceed normally, and the neuronal aberrations appear months later along with the behavioral phenotype [33] . This suggests that in the absence of CNPase, its possible physiological function in process outgrowth may be complemented by currently unknown factors, and the role of CNPase after active myelination could be related to axonal maintenance [33] .In MS, demyelination occurs in the brain and spinal cord, resulting in a wide array of neurological symptoms.Together with several other CNS myelin proteins, CNPase is an auto-antigen in MS -a chronic autoimmune disease [11,[38][39][40] . Changes in the expression levels of…”