CYBA allelic variants are associated with severity and recovery in Guillain-Barré syndrome.

BACKGROUND AND AIMS: Guillain-Barré syndrome (GBS) is a rare, acute neuropathy characterized by ascending muscle weakness. Age, axonal GBS variants, and antecedent Campylobacter jejuni infection are associated with severe GBS, but the detailed mechanisms of nerve damage are only partly explored. Pro-inflammatory myeloid cells express NADPH oxidases (NOX) that generate tissue-toxic reactive oxygen species (ROS) that are implicated in neurodegenerative diseases. This study analyzed the impact of variants of the gene encoding the functional NOX subunit CYBA (p22phox ) on acute severity, axonal damage, and recovery in adult GBS patients. METHODS: Extracted DNA from 121 patients was genotyped for allelic variation at rs1049254 and rs4673 within CYBA using real-time quantitative polymerase chain reaction. Serum neurofilament light chain was quantified by single molecule array. Patients were followed for severity and motor function recovery for up to 13 years. RESULTS: CYBA genotypes linked to reduced formation of ROS, i.e. rs1049254/G and rs4673/A, were significantly associated with unassisted ventilation, shorter time to normalization of serum neurofilament light chain and shorter time to regained motor function. Residual disability at follow-up was confined to patients carrying CYBA alleles associated with high formation of ROS. INTERPRETATION: These findings implicate NOX-derived ROS in GBS pathophysiology and CYBA alleles as biomarkers of severity.

Impact of CYBA genotypes on severity and progression of multiple sclerosis.

BACKGROUND AND PURPOSE: The NOX2 enzyme of myeloid cells generates reactive oxygen species (ROS) that have been implicated in the pathology of multiple sclerosis (MS). We aimed to determine the impact of genetic variation within CYBA, which encodes the functional CYBA/p22phox subunit of NOX2, on MS severity and progression. METHODS: One hundred three MS patients with up to 49 (median = 17) years follow-up time from first MS diagnosis were genotyped at the single nucleotide polymorphisms rs1049254 and rs4673 within CYBA. Results were matched with disease severity and time to diagnosis of secondary progressive MS (SPMS). NOX2-mediated formation of ROS was measured by chemiluminescence in blood myeloid cells from healthy donors (n = 55) with defined genotypes at rs1049254 and rs4673. RESULTS: The rs1049254/G and rs4673/A CYBA alleles were associated with reduced formation of ROS and were thus defined as low-ROS alleles. Patients carrying low-ROS alleles showed reduced multiple sclerosis severity score (p = 0.02, N = 103, linear regression) and delayed onset of SPMS (p = 0.02, hazard ratio [HR] = 0.46, n = 100, log-rank test). In a cohort examined after 2005, patients carrying low-ROS CYBA alleles showed >20 years longer time to secondary progression (p = 0.003, HR = 0.29, n = 59, log-rank test). CONCLUSIONS: These results implicate NOX2 in MS, in particular for the development of secondary progressive disease, and point toward NOX2-reductive therapy aiming to delay secondary progression.

Leukocyte oxygen radical production determines disease severity in the recurrent Guillain-Barré syndrome.

BACKGROUND: The recurrent Guillain-Barré syndrome (RGBS) is characterized by at least two GBS episodes with intervening remission. In a previous study of monophasic GBS, we reported that the magnitude of oxygen radical production ("respiratory burst") in peripheral blood leukocytes was inversely correlated to disease severity. The present study sought to establish a similar correlation in patients with RGBS. METHODS: Oxygen radical production in leukocytes was induced by formyl-Met-Leu-Phe (fMLF), Trp-Lys-Tyr-Met-Val-Met-NH2 (WKYMVM), or phorbol myristate acetate (PMA) and assessed by quantifying superoxide anion formed by the leukocyte NADPH oxidase. RESULTS: Disease severity, assessed using the MRC score, was negatively correlated to superoxide anion production triggered by fMLF or WKYMVM (p = 0.001 and 0.002, respectively; n = 10). Superoxide anion production also was significantly lower in RGBS patients with incomplete recovery after stimulation with fMLF (p = 0.004) or WKYMVM (p = 0.003). CONCLUSION: We conclude that a lower respiratory burst in leukocytes is strongly associated with a severe course of RGBS.

Oxygen radical production in leukocytes and disease severity in multiple sclerosis.

This study investigated the relationship between the formation of NADPH oxidase-dependent oxygen radicals in peripheral blood leukocytes ('respiratory burst') and disease severity in patients with multiple sclerosis (MS). Oxygen radical production was induced by formyl-Met-Leu-Phe (fMLF), Trp-Lys-Tyr-Met-Val-Met-NH2 (WKYMVM) or phorbol myristate acetate (PMA) and was assessed by quantifying superoxide anion, i.e. the initial radical formed by the NADPH oxidase. Disease severity was evaluated using the Multiple Sclerosis Severity Score (MSSS). In patients with severe disease, the production of superoxide anion was significantly lower for all three inducers of radical formation (p=0.04-0.004). Our findings are supportive of a protective role of oxygen radicals in autoimmunity.

Oxygen radical production and severity of the Guillain--Barré syndrome.

The NADPH oxidase-dependent formation of reactive oxygen species ("oxygen radicals") by phagocytic cells constitutes an important part of the innate immune defence against microorganisms. Recent studies in animal models imply that a deficient function of the NADPH oxidase may be linked to the development of autoimmunity, but a link between oxygen radical production and severity of autoimmune disease in humans has not been established. We have examined the oxygen radical production in peripheral blood leukocytes from patients with the Guillain-Barré syndrome (GBS). Leukocytes from GBS patients in a stationary phase 1-5 years after their acute episode were activated by the formyl peptide receptor (FPR) ligand formyl-Met-Leu-Phe (fMLF) or the closely related formyl peptide like receptor 1 (FPRL1) ligand Trp-Lys-Tyr-Met-Val-Met-NH2 (WKYMVM). The patients were dichotomized according to severity by 1) the requirement of intensive care unit treatment and 2) the ability to walk independently after 3 months. Our data show that the amount of superoxide release following challenge with either of the two agonists fMLF and WKYMVM was significantly lower in patients requiring intensive care unit treatment or unable to walk after 3 months. Results obtained with the global activator phorbol myristate acetate, as well as with fMLF in TNF alpha-primed leukocytes, suggested that the deficiency of oxygen radical production in patients with severe GBS was the result of a specific deficiency of radical production in response to FPR/FPRL1 ligands rather than an inherent deficiency of NADPH oxidase function.