Deficiency of the metabolic enzyme SCHAD in pancreatic ß-cells promotes amino acid-sensitive hypoglycemia.

Congenital hyperinsulinism of infancy (CHI) can be caused by a deficiency of the ubiquitously expressed enzyme short-chain 3-hydroxyacyl-CoA dehydrogenase (SCHAD). To test the hypothesis that SCHAD-CHI arises from a specific defect in pancreatic ß-cells, we created genetically engineered ß-cell-specific (ß-SKO) or hepatocyte-specific (L-SKO) SCHAD knockout mice. While L-SKO mice were normoglycemic, plasma glucose in ß-SKO animals was significantly reduced in the random-fed state, after overnight fasting, and following refeeding. The hypoglycemic phenotype was exacerbated when the mice were fed a diet enriched in leucine, glutamine, and alanine. Intraperitoneal injection of these three amino acids led to a rapid elevation in insulin levels in ß-SKO mice compared to controls. Consistently, treating isolated ß-SKO islets with the amino acid mixture potently enhanced insulin secretion compared to controls in a low-glucose environment. RNA sequencing of ß-SKO islets revealed reduced transcription of ß-cell identity genes and upregulation of genes involved in oxidative phosphorylation, protein metabolism, and Ca2+ handling. The ß-SKO mouse offers a useful model to interrogate the intra-islet heterogeneity of amino acid sensing given the very variable expression levels of SCHAD within different hormonal cells, with high levels in ß- and δ-cells and virtually absent α-cell expression. We conclude that the lack of SCHAD protein in ß-cells results in a hypoglycemic phenotype characterized by increased sensitivity to amino acid-stimulated insulin secretion and loss of ß-cell identity.

Serum levels of matrix metalloproteinases: implications in clinical neurology.

Matrix metalloproteinases (MMPs) are zinc-dependent enzymes involved in remodeling extracellular matrix and cell-matrix interactions. A pathogenic role of MMPs in neurological disorders is likely. This paper focuses on serological clinical aspects only. In multiple sclerosis, higher serum MMP-3 is seen during relapses. Lower serum MMP-8 and -9 levels correlate with fewer contrast-enhanced T(2)-weighted MRI lesions, and serum MMP-9 can be used in monitoring treatment. In myasthenia gravis, serum MMP-2, -3, and -9 levels are elevated in both generalized and ocular diseases. A proportion of the patients have markedly increased serum MMP-3. In acute stroke, higher serum MMP-9 correlates with larger infarct volume, stroke severity, and worse functional outcome, and serum MMP-3 is significantly lower than in several other neurological disorders and healthy controls. In amyotrophic lateral sclerosis, serum MMP-2 correlates with disease progression, and both serum MMP-1 and -2 are elevated. In Alzheimer's disease, serum MMP-3, -9, and -10 are elevated. In migraine, serum MMP-2 is elevated, and also MMP-9 in those patients with migraine without aura. MMP-9 is implicated in the pathogenesis of experimental epilepsy. A pathogenic role of MMPs in these conditions could be related to their ability to degrade extracellular matrix. MMPs may also facilitate autoimmunity.

Heat-shock proteins in clinical neurology.

Heat-shock proteins (HSPs) are antigen-presenting protein-aggregation-preventing chaperones, induced by cellular stress in eukaryotic cells. In this review, we focus on recent HSP advances in neurological disorders. In myasthenia gravis, patients responding to immunosuppressive therapy have reduced serum HSP-71 antibodies. Generalized and ocular myasthenia gravis patients have elevated serum HSP-70 antibodies, indicating common pathogenic mechanisms. In Guillain-Barré syndrome, HSP-70 antibodies are elevated in serum and cerebrospinal fluid, and serum levels are higher than in myasthenia gravis and multiple sclerosis. In multiple sclerosis, serum HSP-27 antibodies are elevated during relapses providing disease activation marker, while α,ß-crystallin expression in brain lesions indicates remission phase initiation. In acute stroke, serum HSP-27 antibodies are elevated irrespective of stroke type and duration. In epilepsy, HSP-27 is induced in patients' astrocytes and cerebral blood vessel walls, and α,ß-crystallin is expressed in epileptic foci. In neurodegenerative disorders such as Alzheimer dementia and Parkinson's disease, HSPs are upregulated in brain tissue, and α,ß-crystallin modulates superoxide dismutase-1 (SOD-1) tissue accumulation in familial amyotrophic lateral sclerosis. HSPs play an important role in antigen-presentation and tolerance development. Antibody-mediated interference with their function alters immune responses causing neuropathology. The role of HSPs in clinical neurology should be the subject of future investigation.

Matrix metalloproteinases in myasthenia gravis.

INTRODUCTION: Myasthenia gravis (MG) is an autoimmune disease with weakness in striated musculature due to anti-acetylcholine receptor (AChR) antibodies or muscle specific kinase at the neuromuscular junction. A subgroup of patients has periocular symptoms only; ocular MG (OMG). Matrix metalloproteinases (MMP) are increased in several autoimmune diseases, including generalized MG (GMG), and have been suggested to play a role in immune cell infiltration, basement membrane breakdown and autoimmune pathogenesis. METHODS: Total levels of MMP2, MMP3 and MMP9 were measured in serum by ELISA. RESULTS: The MG patients had increased serum levels of MMP2 (median values 200.7 vs. 159.7 ng/ml, p < 0.001) and MMP9 (median values 629.6 vs. 386.4 ng/ml, p < 0.001) compared to controls. A subgroup of patients had increased MMP3 concentration (p = 0.001). The differences were not dependent on presence of AChR antibodies. No difference was observed between GMG and OMG patients with regard to MMP2 (p = 0.598), MMP3 (p = 0.450) and MMP9 (p = 0.271). DISCUSSION: The increased MMP levels in our MG patients group and the lack of dependence on anti-AChR antibodies suggest that MMP2, MMP3 and MMP9 play a role in the development of MG. The similarities between GMG and OMG support OMG as a systemic disease.

Patient-reported outcome after treatment for definite Lyme neuroborreliosis.

OBJECTIVE: To chart patient-reported outcome measures (PROMs) in Norwegian patients treated for definite neuroborreliosis (NB). MATERIAL AND METHODS: Adult patients treated for definite NB 1-10 years earlier supplied demographics, symptoms and treatment during NB, and answered validated questionnaires; Fatigue Severity Scale (FSS), Hospital Anxiety and Depression Scale (HADS), health-related quality of life questionnaire (RAND-36), and Patient Health Questionnaire (PHQ-15). RESULTS: A higher proportion of NB-treated persons reported severe fatigue, defined as FSS score ≥ 5, than in Norwegian normative data, but when removing persons with confounding fatigue associated comorbidities (n = 69) from the analyses, there was no difference between groups. Physical health-related quality of life (RAND-36 PCS), mean FSS score, proportions of persons reporting moderate or severe somatic symptom burden (PHQ-15 score ≥ 10), anxiety (HADS-A ≥ 8), or depression (HADS-D ≥ 8) did not differ between NB-treated persons and reference scores. Mental health-related quality of life (RAND-36 MCS) was poorer than in normative data (47.1 vs. 53.3), but associated with anxiety, depression and current moderate or severe somatic symptom burden, and not with NB characteristics. CONCLUSIONS: Results on validated PROM questionnaires measuring fatigue, anxiety, depression, self-reported somatic symptom burden, and physical health-related quality did not differ between persons treated for definite NB 1-10 years earlier and reference scores. NB-treated persons tended to report a slightly poorer mental health-related quality of life than found in normative data, but when adjusting for confounders the causative connection is questionable. Overall, the long-term prognosis of definite NB seems to be good.

Myasthenia gravis sera have no effect on cardiomyocytes in vitro.

Myasthenia gravis (MG) is an autoimmune disorder primarily caused by circulating autoantibodies targeting the nicotinic acetylcholine receptor. Several studies have suggested a link between MG and heart disease. Girardi heart cells were treated with MG sera, measuring cytotoxic effects using flow cytometry, adenylate kinase (AK) release and evaluating morphology. MG sera did not induce morphological changes in the cells. AK release from cells treated with MG sera did not exceed controls and flow cytometric examination did not reveal any increase in dead or apoptotic cells. We conclude that MG sera have no cytotoxic effect in our heart cell culture system.

Lyme neuroborreliosis: do we treat according to guidelines?

Evidence-based guidelines, published in 2010, equate the efficacy of oral and intravenous antibiotics and recommend treatment duration of 2 weeks in early Lyme neuroborreliosis (LNB) without encephalitis or myelitis. Further, the Norwegian health authorities give a general advice to choose oral rather than intravenous administration when proven effective, due to lower costs, fewer risks, and reduced patient inconvenience. In this study we aimed to chart LNB treatment practice in Norway and compare it to these recommendations. Adult patients diagnosed with definite LNB between 2007 and 2013 in 11 different hospitals in the four health regions in Norway were invited to answer a questionnaire regarding duration and administration of antibiotic treatment. A total of 253 patients answered. Median age at diagnosis was 59 years (range 19-83), and 125 (49%) were women. Duration of treatment was 1 week in 7 (3%) patients, 2 weeks in 81 (32%), 3 weeks in 62 (25%), 4 weeks in 48 (19%), 5 weeks in 12 (5%), ≥6 weeks in 29 (12%), and unknown in 14 (6%). Treatment was given orally in 77 (30%) patients, intravenously in 110 (44%), both orally and intravenously in 65 (26%), and unknown in one. Treatment practices differed between the health regions (p = 0.002). During the study period, there were no significant time trend neither with respect to proportion of patients treated for only 2 weeks (OR 0.899, p = 0.109) nor with respect to proportion of patients treated exclusively with oral antibiotics (OR 1.131, p = 0.074). In conclusion, there seem to be a gap between evidence-based recommendations and treatment practice of LNB in Norway.

Anti-Heat Shock Protein 70 antibody levels are increased in myasthenia gravis and Guillain-Barré syndrome.

Myasthenia gravis (MG) is an autoimmune disorder where patients develop autoantibodies towards skeletal muscle proteins (e.g. acetylcholine receptor and muscle specific kinase), causing weakness in striated muscles. Ocular MG (OMG) represents a subtype of (MG) affecting only the periocular muscles. The pathogenesis of this phenotype remains unclear. Heat Shock Protein 70 (Hsp70) plays a role in immune regulation. Antibodies against this protein are associated with several autoimmune diseases, and its biological significance has been shown in vivo. We have therefore examined the concentration of anti-Hsp70 antibodies in sera from 35 OMG patients and 94 patients with generalized MG (GMG) using ELISA assays. The antibody concentrations were compared to those in patients with multiple sclerosis (MS), Guillain-Barré syndrome (GBS) and to healthy controls. MG patients had significantly higher anti-Hsp70 antibody concentrations than both MS patients and healthy controls. GBS patients had higher antibody levels than all other groups. No difference in antibody levels was found when comparing OMG and GMG. Our results suggest that patients with MG and GBS have a previous or current increased exposure to Hsp70 antigens. The similarity between GMG and OMG strengthens the hypothesis that OMG represents a systemic disease, similar to GMG.

Morphological effects of myasthenia gravis patient sera on human muscle cells.

Myasthenia gravis (MG) is caused primarily by autoantibodies against the nicotinic acetylcholine receptor (AChR), but autoantibodies to other muscle proteins may be present. Many of these proteins have structural or signalling functions, the disruption of which may affect muscle cell morphology or viability. In order to investigate the role of such autoantibodies in MG, we examined the effect of MG patient sera, of different autoantibody composition and obtained at different stages of disease severity, on primary human muscle cells. Sera from MG patients induced changes in cell morphology from typical elongated cells to an irregular phenotype, caused the formation of inclusion bodies and intracellular vesicles, and led to a disordered arrangement of actin microfilaments. Sera from the most severely affected patients also induced cell death, which did not occur via classic apoptosis. The effects were not complement-mediated and were dose- and time-dependent. As the effects observed in the cell culture system correlated with disease severity, a greater understanding of the individual factors responsible for these effects may improve our understanding of MG pathogenesis and be of value in the assessment of disease in individual patients.