IgM ganglioside GM1 antibodies in patients with autoimmune disease or neuropathy, and controls

AIMS

To compare the titre of anti-ganglioside antibodies (AGA) to GM1 ganglioside in patients with central and peripheral neurological disease and pure motor and sensorimotor neuropathy, in patients with classic autoimmune diseases, and controls.

METHODS

AGA to GM1 were measured using an enzyme linked immunosorbent assay (ELISA) technique, highly purified bovine GM1 ganglioside, and sequential dilution of control and test sera. Antibody titre was calculated using the optical density readings of three consecutive serum dilutions multiplied by the dilution factor.

RESULTS

A considerable overlap was evident in the titre of AGA to GM1 in control and test sera. High antibody titres were most frequent in patients with multifocal motor neuropathy with conduction block (MMNCB). Low AGA titre were observed in several patient groups. Compared with the controls, the median titre of AGA to GM1 was significantly higher in patients with multiple sclerosis, rheumatoid arthritis, primary Sjögren's syndrome and systemic lupus erythematosus. In contrast, the median titre in patients with diabetic peripheral neuropathy, motor neurone disease, sensorimotor neuropathy and chronic inflammatory demyelinating polyneuropathy was no different from that in normal control subjects.

CONCLUSIONS

Estimation of AGA to GM1 may be helpful in the diagnosis of MMNCB in patients with a pure motor neuropathy but in few other conditions. Low titre AGA to GM1 are evident in several autoimmune conditions. The pathogenetic importance of AGA to GM1 in patients with neuropathy is not clear.

Endoneurial localisation of microvascular damage in human diabetic neuropathy

Twenty diabetic patients with neuropathy underwent clinical and neurophysiological evaluation together with a detailed morphometric assessment of capillary pathology in endoneurial and epineurial microvascular beds of the sural nerve. Morphological data were compared with ten non-diabetic control subjects. There were no significant differences in control subjects between basement membrane area, endothelial cell area, endothelial cell profile number or luminal area of endoneurial when compared with epineurial capillaries. In contrast, when compared with epineurial capillaries, endoneurial capillaries from diabetic patients demonstrated a significant increase in basement membrane (p < 0.001) and endothelial cell (p < 0.001) area and a significant reduction in luminal area (p < 0.001). There was no significant difference in endothelial cell profile number between endoneurial and epineurial capillaries amongst diabetic patients. Previous studies have demonstrated a good correlation between the degree of microangiopathy and measures of neuropathic severity. In the present study increased endoneurial capillary basement membrane area was significantly related to reduced peroneal nerve conduction velocity (p < 0.001), myelinated fibre density (p < 0.001) and elevated vibration (p < 0.05) and thermal (p < 0.001) perception. Increased endothelial cell area and reduced luminal size were related to a reduced peroneal nerve conduction (p < 0.05, p < 0.01, respectively), reduced myelinated fibre density (p < 0.05, p < 0.01) and elevated thermal perception (p < 0.05, p < 0.001). Epineurial capillary basement membrane, endothelial cell and luminal area failed to relate to measures of neuropathic severity.(ABSTRACT TRUNCATED AT 250 WORDS)

Relationships between haemostatic factors and capillary morphology in human diabetic neuropathy

We have examined haemostatic factors in 15 diabetic patients with peripheral neuropathy and 10 diabetic patients without clinical complications. Plasma and blood viscosity, fibrinogen, factor VIIIc, von Willebrand factor activity, spontaneous platelet aggregation and fibrinolytic activity were not significantly different between diabetic patients without clinical complications and diabetic patients with peripheral neuropathy. Platelet aggregation was enhanced in diabetic patients with neuropathy compared with those without complications. In the 15 patients with neuropathy and 3 without complications, who underwent biopsy of sural nerve, skin and muscle, associations were found between haemostatic variables and measures of nerve capillary pathology, notably: plasma fibrinogen and nerve capillary basement membrane thickness (r = 0.70, p < 0.001); thromboxane B2 production and nerve capillary basement membrane thickness (r = -0.61, p < 0.01); plasma fibrinolytic activity and endoneurial capillary lumen size (r = 0.60, p < 0.01) and endothelial cell outer perimeter (r = 0.65, p < 0.01). The main associations of skin and muscle capillary abnormalities were with measures of in vitro platelet aggregation, and the correlations found with nerve capillary measurements were not echoed in the overlying muscle and skin. The results are supportive of the involvement of haemostatic abnormalities in the pathogenesis of diabetic neuropathy.

Endoneurial capillary abnormalities in mild human diabetic neuropathy

Microvascular factors have been implicated in the pathogenesis of human diabetic neuropathy. The extent of microangiopathy was assessed in 15 diabetic patients with clinically mild neuropathy and compared with eight age matched control subjects. Endoneurial capillary density was reduced (p less than 0.04) and correlated significantly with reduced myelinated fibre density (p less than 0.01). Both basement membrane area (p less than 0.0001) and endothelial cell profile number per capillary (p less than 0.002) were significantly increased in diabetic patients and correlated significantly with both neurophysiological and neuropathological measures of neuropathic severity. There was no evidence of endothelial cell hypertrophy as assessed by either cross sectional endothelial cell area or a reduction in luminal size. Furthermore, the percentage of closed vessels did not differ between diabetic patients and control subjects and failed to relate to measures of neuropathic severity. It was concluded that microvascular abnormalities are prominent in patients with clinically mild human diabetic neuropathy, and that these data provide further support for the role of endoneurial capillary disease in the development of this condition.

Skin epidermal thickness and vascular density in type 1 diabetes

Epidermal skin thickness and vascular density were assessed in skin biopsies obtained from the dorsum of the foot in 28 Type 1 diabetic patients and 17 normal control subjects, matched for age. Epidermal skin thickness did not differ significantly between control subjects (74 +/- 4 (+/- SE) microns) and diabetic patients (78 +/- 4 microns). It was not related to the duration of diabetes and presence of complications. Neither small (capillary) nor large (arteriole/venule) vessel densities differed significantly between control subjects (59 +/- 6 mm-2 and 19 +/- 2 mm-2) and diabetic patients (65 +/- 4 mm-2 and 22 +/- 3 mm-2). Vessel densities were unrelated to the duration of diabetes and presence of complications.

Neutrophil aldose reductase activity as a potential marker for neuropathy and cataract in diabetes

Aldose reductase activity can be measured in the neutrophil and it has been proposed that this may be a marker for risk of complications in diabetes. We have studied aldose reductase activity in neutrophil, nerve, and lens in diabetic patients undergoing sural nerve biopsy or cataract extraction. A correlation was demonstrated between lens and neutrophil aldose reductase activity (r = 0.53, p = 0.01) but no correlations were demonstrated between nerve aldose reductase activities and nerve morphometry, nerve function or neutrophil aldose reductase activity. No significant difference was found between neutrophil aldose reductase activities in groups of patients with severe neuropathy, or cataract, or no complications (24 (interquartile range 16-32) vs 24 (16-40) vs 24 (16-40) nmol NADPH min-1 10(8)-cells-1). In a group of 56 Type 1 diabetic patients screened within 6 years of diagnosis, multiple regression analysis failed to show any relationship between neutrophil aldose reductase activity and abnormalities of neurophysiological function. These results suggest that neutrophil aldose reductase activity cannot be used as a marker for the development of cataract or neuropathy in diabetes.

The relationship between sural nerve morphometric findings and measures of peripheral nerve function in mild diabetic neuropathy

The morphological findings in sural nerve biopsy specimens from 15 diabetic patients with mild neuropathy were compared with control biopsies from eight non-neuropathic, non-diabetic subjects, and correlations were sought with electrophysiological studies and quantitative sensory tests for vibration, thermal, and current perception thresholds. Myelinated fibre density was reduced compared with control biopsies (4042 +/- 2090 (+/- SD) vs 6800 +/- 1100 mm-2; p less than 0.01). A strong correlation existed between myelinated fibre density and sural sensory conduction velocity (r = 0.84, p less than 0.001), sural action potential amplitude (r = 0.74, p less than 0.001), peroneal motor conduction velocity (r = 0.58, p less than 0.02), and median sensory amplitude (r = 0.64, p less than 0.01) but there was no correlation between myelinated fibre density and any quantitative sensory test. We conclude that conventional electrophysiological tests in the lower limb are reliable surrogate measures for structural abnormalities in early diabetic neuropathy.

Morphological abnormalities in the sural nerve from patients with peripheral vascular disease

The present paper has been written in order to determine the morphological alterations in the sural nerve from patients with chronic arteriosclerotic occlusive disease. Eight patients with Peripheral Vascular Disease (PVD) and six age-matched control subjects were studied. Morphometric data revealed two groups of patients, one of them with mild disease (n = 5), and the other one with severe damage (n = 3), consisting in loss of myelinated fibres and increase in the number of small fibres (p less than 0.05). Teased nerve fibres and electron microscopic studies also showed two types of patients, with respect to the myelin or the axonal alterations. The unmyelinated fibre population was affected equally in both groups. In conclusion, this study supports the idea that ischemia is able to cause structural alterations in the peripheral nerve, and that it can play a role in the development of neuropathy.

Hypoxic neuropathy: relevance to human diabetic neuropathy

Clinical and neurophysiological studies were conducted in 47 patients with chronic obstructive airways disease and compared with 46 age-matched control subjects. Symptomatic neuropathy was reported in 13% and ankle jerks were absent in 45% of hypoxic patients. Peroneal and median nerve conduction velocities and median and sural sensory nerve amplitudes were significantly reduced in hypoxic patients (p less than 0.01). Six hypoxic patients underwent biopsy of the sural nerve, soleus muscle and overlying skin. Nerve glucose, sorbitol, fructose and myo-inositol concentrations were normal. Detailed light and electronmicroscopy revealed both nerve fibre and microvascular pathology. Segmental demyelination (32%) and unmyelinated fibre degeneration were found to be prominent lesions. The sural nerve perineurium was thickened due to an increase in the number of perineurial lamellae and an increase in intraperineurial space. Basement membrane thickening was observed in capillaries of nerve, muscle and skin. Endothelial cell hyperplasia and hypertrophy were observed in nerve and muscle capillaries but not in skin capillaries. In conclusion, this study has provided neurological, neurophysiological and neuropathological evidence of a neuropathy in hypoxic patients with chronic obstructive airways disease. These findings may be of relevance to some aspects of the aetiology of human diabetic neuropathy.

Microangiopathy in human diabetic neuropathy: relationship between capillary abnormalities and the severity of neuropathy

Clinical, electrophysiological and ultrastructural morphometric observations were made in 5 diabetic non-neuropathic patients, 5 diabetic patients with mild neuropathy and 11 diabetic patients with severe neuropathy. Capillary abnormalities were assessed in simultaneous nerve, muscle and skin biopsies and compared with results from 6 age-matched, non-diabetic control subjects. Nerve capillaries demonstrated markedly greater pathology than skin and muscle capillaries. Endoneurial capillary density was significantly reduced in severely neuropathic diabetic patients (p less than 0.01) when compared with control subjects. Capillary basement membrane (p less than 0.002), endothelial cell (p less than 0.003) and total diffusion barrier (endothelial cell, pericyte, basement membrane) (p less than 0.001) thickness were significantly increased, and oxygen diffusing capacity was significantly reduced (p less than 0.001) in the nerves of patients with severe diabetic neuropathy when compared to control subjects. Endothelial cell profile number and luminal perimeter were significantly increased in asymptomatic (p less than 0.01), (p less than 0.05) and severely neuropathic (p less than 0.001), (p less than 0.05) diabetic patients respectively. However, endothelial cell outer perimeter, a measure of capillary size, showed no significant increase in diabetic patients when compared with control subjects. An association was observed between neurophysiological and neuropathological measures of neuropathic severity. There was no significant correlation between the duration of diabetes and HbA1 levels with capillary pathology or with neuropathic severity. Very few abnormalities of muscle and skin correlated with neuropathic severity. However, all measures of nerve capillary pathology correlated significantly with neurophysiological and neuropathological measures of neuropathic severity.