Complement-fixing antibodies to sympathetic and parasympathetic tissues in IDDM. Autonomic brake index and heart-rate variation

Cardiovascular Autonomic Neuropathy and Distal Symmetric Sensorimotor Polyneuropathy: These Two Diabetic Microvascular Complications do not Invariably Co-Exist

Background:

Cardiovascular autonomic neuropathy (CAN) and distal symmetrical sensorimotor polyneuropathy (DSPN) are serious microvascular complications of diabetes mellitus (DM). Their simultaneous development remains disputable. The aim of the present study was to examine the correlation between CAN and the presence/severity of DSPN in DM.

Methods:

Subjects with type 1 (group A: n=51; mean age 40.4 years) and type 2 DM (group B: n=153; mean age 64.6 years) were studied. Evaluation of DSPN was based on neuropathy disability score. Assessment of CAN was based on the battery of 4 standardized cardiovascular autonomic function tests.

Results:

In group A, patients with moderate/severe DSPN exhibited a 12-fold higher likelihood of CAN in univariate analysis (p=0.035). However, significance was lost after adjustment for gender, age, DM duration, and haemoglobin A1c. In group A, likelihood for CAN did not correlate with the presence of mild DSPN in univariate and multivariate analysis. In group B, likelihood of CAN was similar in patients with mild and in those with moderate/severe DSPN compared with patients without DSPN in univariate and multivariate analysis. In between group comparison CAN was similarly distributed in the 2 groups (p for interaction=0.367), in patients with no, mild and moderate/severe DSPN.

Conclusion:

CAN does not always co-exist with degrees of DSPN, ranging from mild to moderate/ severe and is similarly distributed in T1DM and T2DM patients with mild and moderate/severe DSPN and in patients without DSPN.

Association of autoimmunity to autonomic nervous structures with nerve function in patients with type 1 diabetes: a 16-year prospective study

OBJECTIVE We prospectively evaluated the association between autoimmunity to autonomic nervous structures and autonomic neuropathy in type 1 diabetes in relation to clinical variables. RESEARCH DESIGN AND METHODS A cohort of 112 patients with type 1 diabetes was prospectively followed from adolescence (T0) to approximately 4 (T4) and 16 (T16) years later. Standard cardiovascular (CV) tests and neurological examination were performed and related to the presence of circulating antibodies (Ab) to autonomic nervous structures detected at T0 and T4. Quality of life was assessed by a diabetes-specific questionnaire. RESULTS Sixty-six patients (59% of the cohort) were reexamined at T16 (age 31.4 ± 2 years; disease duration 23.4 ± 3.7 years). Nineteen had circulating Ab to autonomic structures. Prevalence of abnormal tests and autonomic symptoms were higher in Ab-positive (68 and 26%, respectively) than Ab-negative (32 and 4%) patients (P < 0.05). Among Ab-positive patients, the relative risk (RR) of having at least one altered CV test was 5.77 (95% CI 1.56-21.33), and an altered deep breathing (DB) test (<15 bpm) was 14.65 (2.48-86.46). Previous glycemic control was the only other predictor (RR 1.06 [1.002-1.13]/mmol/mol HbA1c increase). Presence of Ab carried over a 68% probability of developing an altered CV test; absence of Ab carried a 91% probability of not having an altered DB test and an 89% probability of not having an altered Valsalva ratio. Autonomic neuropathy was independently associated with worse quality of life. CONCLUSIONS Circulating Ab to autonomic structures are associated with the development of autonomic dysfunction in young diabetic patients independent of glycemic control.

Cardiac autonomic neuropathy in patients with diabetes mellitus

Cardiac autonomic neuropathy (CAN) is an often overlooked and common complication of diabetes mellitus. CAN is associated with increased cardiovascular morbidity and mortality. The pathogenesis of CAN is complex and involves a cascade of pathways activated by hyperglycaemia resulting in neuronal ischaemia and cellular death. In addition, autoimmune and genetic factors are involved in the development of CAN. CAN might be subclinical for several years until the patient develops resting tachycardia, exercise intolerance, postural hypotension, cardiac dysfunction and diabetic cardiomyopathy. During its sub-clinical phase, heart rate variability that is influenced by the balance between parasympathetic and sympathetic tones can help in detecting CAN before the disease is symptomatic. Newer imaging techniques (such as scintigraphy) have allowed earlier detection of CAN in the pre-clinical phase and allowed better assessment of the sympathetic nervous system. One of the main difficulties in CAN research is the lack of a universally accepted definition of CAN; however, the Toronto Consensus Panel on Diabetic Neuropathy has recently issued guidance for the diagnosis and staging of CAN, and also proposed screening for CAN in patients with diabetes mellitus. A major challenge, however, is the lack of specific treatment to slow the progression or prevent the development of CAN. Lifestyle changes, improved metabolic control might prevent or slow the progression of CAN. Reversal will require combination of these treatments with new targeted therapeutic approaches. The aim of this article is to review the latest evidence regarding the epidemiology, pathogenesis, manifestations, diagnosis and treatment for CAN.

Autonomic neuropathy in experimental models of diabetes mellitus

Autonomic neuropathy complicates diabetes by increasing patient morbidity and mortality. Surprisingly, considering its importance, development and exploitation of animal models has lagged behind the wealth of information collected for somatic symmetrical sensory neuropathy. Nonetheless, animal studies have resulted in a variety of insights into the pathogenesis, neuropathology, and pathophysiology of diabetic autonomic neuropathy (DAN) with significant and, in some cases, remarkable correspondence between rodent models and human disease. Particularly in the study of alimentary dysfunction, findings in intrinsic intramural ganglia, interstitial cells of Cajal and the extrinsic parasympathetic and sympathetic ganglia serving the bowel vie for recognition as the chief mechanism. A body of work focused on neuropathologic findings in experimental animals and human subjects has demonstrated that axonal and dendritic pathology in sympathetic ganglia with relative neuron preservation represents one of the neuropathologic hallmarks of DAN but it is unlikely to represent the entire story. There is a surprising selectivity of the diabetic process for subpopulations of neurons and nerve terminals within intramural, parasympathetic, and sympathetic ganglia and innervation of end organs, afflicting some while sparing others, and differing between vascular and other targets within individual end organs. Rather than resulting from a simple deficit in one limb of an effector pathway, autonomic dysfunction may proceed from the inability to integrate portions of several complex pathways. The selectivity of the diabetic process appears to confound a simple global explanation (e.g., ischemia) of DAN. Although the search for a single unifying pathogenetic hypothesis continues, it is possible that autonomic neuropathy will have multiple pathogenetic mechanisms whose interplay may require therapies consisting of a cocktail of drugs. The role of multiple neurotrophic substances, antioxidants (general or pathway specific), inhibitors of formation of advanced glycosylation end products and drugs affecting the polyol pathway may be complex and therapeutic elements may have both salutary and untoward effects. This review has attempted to present the background and current findings and hypotheses, focusing on autonomic elements including and beyond the typical parasympathetic and sympathetic nervous systems to include visceral sensory and enteric nervous systems.

Spectral Peak Frequency in Low-Frequency Band in Cross Spectra of Blood Pressure and Heart Rate Fluctuations in Young Type 1 Diabetic Patients

In this study we tested whether joint evaluation of the frequency (fcs) at which maxima of power in the cross-spectra between the variability in systolic blood pressure and inter-beat intervals in the range of 0.06-0.12 Hz occur together with the quantification of baroreflex sensitivity (BRS) may improve early detection of autonomic dysfunction in type 1 diabetes mellitus (T1DM). We measured 14 T1DM patients (age 20.3-24.2 years, DM duration 10.4-14.2 years, without any signs of autonomic neuropathy) and 14 age-matched controls (Co). Finger arterial blood pressure was continuously recorded by Finapres for one hour. BRS and fcs were determined by the spectral method. Receiver-operating curves (ROC) were calculated for fcs, BRS, and a combination of both factors determined as F(z)=1/(1+exp(-z)), z=3.09–0.013*BRS–0.027*fcs. T1DM had significantly lower fcs than Co (T1DM: 88.8±6.7 vs. Co: 93.7±3.8 mHz; p<0.05), and a tendency towards lower BRS compared to Co (T1DM: 10.3±4.4 vs. Co: 14.6±7.1 ms/mm Hg; p=0.06). The ROC for Fz showed the highest sensitivity and specificity (71.4 % and 71.4 %) in comparison with BRS (64.3 % and 71.4 %) or fcs (64.3 % and 64.3 %). The presented method of evaluation of BRS and fcs forming an integrated factor Fz could provide further improvement in the risk stratification of diabetic patients.

What do we know and we do not know about cardiovascular autonomic neuropathy in diabetes

Cardiovascular autonomic neuropathy (CAN) in diabetes is generally overlooked in practice, although awareness of its serious consequences is emerging. Challenges in understanding the complex, dynamic changes in the modulation of the sympathetic/parasympathetic systems' tone and their interactions with physiologic mechanisms regulating the control of heart rate, blood pressure, and other cardiovascular functions in the presence of acute hyper-or-hypoglycemic stress, other stressors or medication, and challenges with sensitive evaluations have contributed to lower CAN visibility compared with other diabetes complications. Yet, CAN is a significant cause of morbidity and mortality, due to a high-risk of cardiac arrhythmias, silent myocardial ischemia and sudden death. While striving for aggressive risk factor control in diabetes practice seemed intuitive, recent reports of major clinical trials undermine established thinking concerning glycemic control and cardiovascular risk. This review covers current understanding and gaps in that understanding of the clinical implications of CAN and prevention and treatment of CAN.

Autoantibodies to autonomic nerves associated with cardiac and peripheral autonomic neuropathy

OBJECTIVE

This study examines whether autonomic nerve autoantibodies (ANabs) are associated with development of autonomic neuropathy using a prospective study design.

RESEARCH DESIGN AND METHODS

A group of type 1 diabetic patients were followed prospectively with regard to autonomic nerve function on four occasions. At the third examination, 41 patients were tested for ANabs (complement-fixing autoantibodies to the sympathetic ganglion, vagus nerve, and adrenal medulla), and the results were related to cardiac autonomic nerve function (heart rate variation during deep breathing [expiration/inspiration ratio] and heart-rate reaction to tilt [acceleration and brake index]) and to peripheral sympathetic nerve function (vasoconstriction after indirect cooling [vasoconstriction index]).

RESULTS

ANabs were detected in 23 of 41 (56%) patients at the third examination. Compared with patients without ANabs (ANabs-), patients with ANabs (ANabs+) showed significantly higher frequencies of at least one abnormal cardiac autonomic nerve function test at the third examination (17 of 23 [74%] vs. 7 of 18 [39%]; P = 0.03) and fourth examination (15 of 21 [71%] vs. 4 of 16 [25%]; P < 0.01). In contrast, there was no similar difference at the first or second examination. The relative risk for ANabs(+) patients to develop cardiac autonomic neuropathy at follow-up was 7.5 (95% CI 1.72-32.80). The vasoconstriction index was more abnormal in ANabs+ than in ANabs- patients at the fourth examination (median 1.40 [interquartile range 1.58] vs. 0.35 [2.05]; P = 0.01).

CONCLUSIONS

ANabs were associated with future development of cardiac and peripheral autonomic neuropathy in diabetic patients, implying an etiological relationship between nervous tissue autoimmunity and these diabetes complications.

Diabetic Neuropathies

Diabetes mellitus is associated with a wide spectrum of neuropathy syndromes, ranging from a mild asymptomatic distal sensory neuropathy to a severe disabling radiculoplexus neuropathy. As the pathophysiology of these separate conditions is better understood, classification of the various phenotypes becomes important because of treatment implications. Here we provide a short summary of the history of the classification of diabetic neuropathies and try to describe the most common forms classified according to their presumed pathophysiology. We have tried to include epidemiological data where available, as well as histopathology of nerve in several diabetic neuropathies.

Non-obese diabetic mice rapidly develop dramatic sympathetic neuritic dystrophy: a new experimental model of diabetic autonomic neuropathy

To address the pathogenesis of diabetic autonomic neuropathy, we have examined the sympathetic nervous system in non-obese diabetic (NOD) and streptozotocin (STZ)-induced diabetic mice, two models of type 1 diabetes, and the db/db mouse, a model of type 2 diabetes. After only 3 to 5 weeks of diabetes, NOD mice developed markedly swollen axons and dendrites ("neuritic dystrophy") in the prevertebral superior mesenteric and celiac ganglia (SMG-CG), similar to the pathology described in diabetic STZ- and BBW-rat and man. Comparable changes failed to develop in the superior cervical ganglia of the NOD mouse or in the SMG-CG of non-diabetic NOD siblings. STZ-induced diabetic mice develop identical changes, although at a much slower pace and to a lesser degree than NOD mice. NOD-SCID mice, which are genetically identical to NOD mice except for the absence of T and B cells, do not develop diabetes or neuropathology comparable to diabetic NOD mice. However, STZ-treated NOD-SCID mice develop severe neuritic dystrophy, evidence against an exclusively autoimmune pathogenesis for autonomic neuropathy in this model. Chronically diabetic type 2 db/db mice fail to develop neuritic dystrophy, suggesting that hyperglycemia alone may not be the critical and sufficient element. The NOD mouse appears to be a valuable model of diabetic sympathetic autonomic neuropathy with unambiguous, rapidly developing neuropathology which corresponds closely to the characteristic pathology of other rodent models and man.

Neuropathology and pathogenesis of diabetic autonomic neuropathy

Autonomic neuropathy is a significant complication of diabetes resulting in increased patient morbidity and mortality. A number of studies, which have shown correspondence between neuropathologic findings in experimental animals and human subjects, have demonstrated that axonal and dendritic pathology in sympathetic ganglia in the absence of significant neuron loss represents a neuropathologic hallmark of diabetic autonomic neuropathy. A recurring theme in sympathetic ganglia, as well as in the pot-ganglionic autonomic innervation of various end organs, is the involvement of distal portions of axons and nerve terminals by degenerative or dystrophic changes. In both animals and humans, there is a surprising selectivity of the diabetic process for subpopulations of autonomic ganglia, nerve terminals within sympathetic ganglia and end organs, from end organ to end organ, and between vascular and other targets within individual end organs. Although the involvement or autonomic axons in somatic nerves may reflect an ischemic pathogenesis, the selectivity of the diabetic process confounds simple global explanations of diabetic autonomic neuropathy as the result of diminished blood flow with resultant tissue hypoxia. A single unifying pathogenetic hypothesis has not yet emerged from clinical and experimental animal studies, and it is likely that diabetic autonomic neuropathy will be shown to have multiple causative mechanisms, which will interact to result in the variety of presentations of autonomic injury in diabetes. Some of these mechanisms will be shared with aging changes in the autonomic nervous system. The role of various neurotrophic substances and the polyol pathway in the pathogenesis and treatment of diabetic neuropathy likely represents a two-edged sword with both salutary and exacerbating effects. The basic neurobiologic process underlying the diabetes-induced development of neuroaxonal dystrophy, synaptic dysplasia, defective axonal regeneration, and alterations in neurotrophic substance may be mechanistically related.

Effect of NGF and neurotrophin-3 treatment on experimental diabetic autonomic neuropathy

Peripheral neuropathy is a significant complication of diabetes resulting in increased patient morbidity and mortality. Deficiencies of neurotrophic substances (e.g. NGE NT-3, and IGF-I) have been proposed as pathogenetic mechanisms in the development of distal symmetrical sensory diabetic polyneuropathy, and salutary effects of exogenous NGF administration have been reported in animal models. In comparison, relatively little is known concerning the effect of NGF on experimental diabetic sympathetic autonomic neuropathy. We have developed an experimental animal model of diabetic autonomic neuropathy characterized by the regular occurrence of pathologically distinctive dystrophic axons in prevertebral sympathetic ganglia and ileal mesenteric nerves of rats with chronic streptozotocin (STZ)-induced diabetes. Treatment of STZ-diabetic rats for 2-3 months with pharmacologic doses of NGF or NT-3, neurotrophic substances with known effects on the adult sympathetic nervous system, did not normalize established neuroaxonal dystrophy (NAD) in diabetic rats in the prevertebral superior mesenteric ganglia (SMG) and ileal mesenteric nerves as had pancreatic islet transplantation and IGF-I in earlier experiments. NGF treatment of control animals actually increased the frequency of NAD in the SMG. New data suggests that, in adult sympathetic ganglia. NGF may contribute to the pathogenesis of NAD rather than its amelioration, perhaps as the result of inducing intraganglionic axonal sprouts in which dystrophic changes are superimposed. NT-3 administration did not alter the frequency of NAD in diabetic animals, although it resulted in a significant decrease in NAD in control SMG. Although deficiencies of neurotrophic substances may represent the underlying pathogenesis of a variety of experimental neuropathies, delivery of excessive levels of selected substances may produce untoward effects.

Antibodies to glutamic acid decarboxylase and peripheral nerve function in type 1 diabetes

Autoimmune mechanisms have been implicated in the pathophysiology of diabetic neuropathy. We studied the association between glutamic acid decarboxylase (GAD65) and islet cell (IA-2) autoantibodies as well as autoantibodies to the autonomic nervous system and peripheral nerve function in recent onset type 1 diabetes. Thirty-seven patients (27 females and 10 males) enrolled 2-22 months after diagnosis. Humoral factors, glycemic control, and peripheral nerve function were measured annually for 3 yr. Patients with high GAD65Ab had worse glycemic control and higher insulin requirements. Patients with high GAD65Ab had slower motor nerve conduction velocities in the median, ulnar, and peroneal nerves (P < 0.025 for each nerve). The mean motor nerve conduction velocity Z scores at the time of the third evaluation was 0.341 +/- 0.25 for the low GAD65Ab patients and -0.600 +/- 0.25 for the high GAD65Ab patients (P < 0.01). Similar differences between the low and high GAD65Ab groups were observed for F wave latencies, thermal threshold detection, and cardiovascular autonomic function. The composite peripheral nerve function Z scores in the low GAD65Ab patients were 0.62 +/- 11, 0.71 +/- 0.19, and 0.21 +/- 0.14 at the first, second, and third evaluations, significantly different from those in the high GAD65Ab patients in whom they were -0.35 +/- 0.15, -0.46 +/- 0.18, and -0.42 +/- 0.16 (P < 0.001). In summary, GAD65Ab in patients with recent onset type 1 diabetes are associated with worse glycemic control and slightly worse peripheral nerve function. Although the latter remained within normal limits and none of the patients had clinical neuropathy, the GAD65Ab-related differences in composite peripheral nerve function were highly significant (P < 0.001) and could not be attributed to GAD65Ab-related differences in glycemic control.

Effect of streptozotocin-induced diabetes on NGF, P75(NTR) and TrkA content of prevertebral and paravertebral rat sympathetic ganglia

Diabetic autonomic neuropathy results in significant morbidity and mortality. Both diabetic humans and experimental animals show neuroaxonal dystrophy of autonomic nerve terminals, particularly in the prevertebral superior mesenteric ganglia (SMG) and celiac ganglia (CG) which innervate the hyperplastic/hypertrophic diabetic small intestine. Previously, investigators suggested that disturbances in ganglionic nerve growth factor (NGF) content or transport might play a pathogenetic role in diabetic autonomic pathology. To test this hypothesis, we measured NGF content and NGF receptor expression, p75(NTR) (low affinity neurotrophin receptor) and trkA (high affinity NGF receptor), in control and diabetic rat SMG, CG and superior cervical ganglia (SCG). Surprisingly, rather than a decrease, we observed an approximate doubling of NGF content in the diabetic SMG and CG, a result which reflects increased NGF content in the hyperplastic diabetic alimentary tract. No change in NGF content was detected in the diabetic SCG which is relatively spared in experimental diabetic autonomic neuropathy. NGF receptor expression was not consistently altered in any of the autonomic ganglia. These observations suggest that increased NGF content in sympathetic ganglia innervating the diabetic alimentary tract coupled with intact receptor expression may produce aberrant axonal sprouting and neuroaxonal dystrophy.

Insulin-like growth factor I reverses experimental diabetic autonomic neuropathy

Recent studies have suggested a role for neurotrophic substances in the pathogenesis and treatment of diabetic neuropathy. In this study, the effect of insulin-like growth factor I (IGF-I) on diabetic sympathetic autonomic neuropathy was examined in an experimental streptozotocin-induced diabetic rat model. Two months of IGF-I treatment of chronically diabetic rats with established neuroaxonal dystrophy (the neuropathological hallmark of the disease) involving the superior mesenteric ganglion and ileal mesenteric nerves resulted in nearly complete normalization of the frequency of neuroaxonal dystrophy in both sites without altering the severity of diabetes. Treatment with low-dose insulin (to control for the transient glucose-lowering effects of IGF-I) failed to affect the frequency of ganglionic or mesenteric nerve neuroaxonal dystrophy or the severity of diabetes. The striking improvement in the severity of diabetic autonomic neuropathy shown with IGF-I treatment in these studies and the fidelity of the rat model to findings in diabetic human sympathetic ganglia provide promise for the development of new clinical therapeutic strategies.

Prevalence of autoantibodies to autonomic nervous tissue structures in Type 1 diabetes mellitus

AIMS

The pathogenesis of diabetic autonomic neuropathy is multifactorial, but recent studies have suggested a link between the presence of autoantibodies to nervous tissue structures and severe, symptomatic autonomic neuropathy. The present study was designed to examine the true prevalence of these autoantibodies in a large clinic-based population of Type 1 diabetic patients compared to nondiabetic controls.

METHODS

The presence of complement fixing autoantibodies to vagus nerve (CF-VN), sympathetic ganglion (CF-SG) and adrenal medulla (CF-ADM) was assessed by immunofluorescence in a large cohort of patients (n = 394) of varying duration of Type 1 DM (median 28 years, range 6 months to 73 years) and 160 age and sex-matched nondiabetic control subjects.

RESULTS

All three autoantibodies were frequently detected in Type 1 DM (CF-VN, 22.1%; CF-SG, 30.7%; CF-ADM, 13.2%) but only rarely in healthy control subjects (4.4%, 4.4% and 3.1%, respectively; P < 0.0005 for all). There was no association between any of the autoantibodies and retinopathy (fundoscopy), peripheral somatic neuropathy (biothesiometry) or nephropathy (urinary albumin-creatinine ratio).

CONCLUSIONS

Our results on this large cohort establish the extensive presence of autonomic nervous tissue autoantibodies in Type 1 DM. Their role in reflecting, causing or predicting autonomic neuropathy remains to be determined.

Autonomic function and autoantibodies to autonomic nervous structures, glutamic acid decarboxylase and islet tyrosine phosphatase in adolescent patients with IDDM

Recent studies have linked autoimmunity to nervous tissue structures and diabetic autonomic neuropathy, but data on the early stage of IDDM and on the natural history of this association are not available. For this reason, we investigated autonomic nervous function, and the presence of autoantibodies to sympathetic and parasympathetic nervous structures, to glutamic acid decarboxylase (GAD) and tyrosine phosphatase (IA-2/ICA512) in 85 adolescents with insulin-dependent diabetes mellitus (IDDM) (mean age 14.7+/-1.6 yr, mean duration of diabetes 6.8+/-3.5 yr), and 45 age and sex-matched healthy subjects. Nervous tissues autoantibodies were detected using an indirect immunofluorescent complement-fixation technique, with monkey adrenal gland, rabbit cervical ganglia and vagus nerve as substrates. GAD and IA-2/ICA512 autoantibodies were detected by radioimmunoprecipitation assay. Seven patients (8%) had anti-vagus nerve autoantibodies, 7 other patients (8%) had anti-cervical ganglia autoantibodies, while all controls were negative (P < 0.05). Anti-adrenal medulla antibodies were detected in 16 patients (19%) and in 2 control subjects (P<0.02). None of the patients had autonomic symptoms. When patients were divided according to the presence or absence of autoantibodies, values of the cardiovascular tests (deep breathing, 30:15 ratio, Valsalva ratio) were similar in the two groups and similar to those in healthy subjects. However, when considered together, patients positive for one or more autoantibody showed a trend for lower values of deep breathing test and 30:15 ratio test, compared with healthy control subjects, which failed to reach conventional significance values (P=0.17 and P=0.07, respectively). No correlation was found between cardiovascular parameters and metabolic control or diabetes duration. There was no association between autoimmunity to nervous tissue structures and presence of GAD and IA-2/ICA512 Ab, and no correlation between these two autoantibodies and values of cardiovascular tests. Our data indicate that autonomic dysfunction is not a characteristic of young diabetic patients, but that autoantibodies against autonomic nervous structures are present during the first 1 to 15 yr of diabetes. GAD and tyrosine phosphatase appear to be excluded as target autoantigens within autonomic structures. Follow-up studies are required to evaluate future autonomic dysfunction and symptoms in these patients, and to establish whether the subtle autonomic dysfunction detected and/or the nervous tissue autoantibodies, are predictive of the development of this complication.

[Cardiovascular and pupillary autonomic and somatosensory neuropathy in chronic diseases with autoimmune phenomena. A comparative study of patients with Crohn disease, ulcerative colitis, systemic lupus erythematosus, progressive systemic sclerosis and type I diabetes mellitus]

BACKGROUND

During the last years, examination of autonomic nervous function and of autonomic neuropathy has attracted attention not only in diabetes mellitus research but also in other areas of internal medicine. However, patients with various chronic diseases with autoimmune phenomenons have never been investigated in a comparative study with standardized examination techniques. Hence, the aim of the study was to examine the prevalence and the severity of autonomic neuropathy in patients with the following chronic diseases.

PATIENTS AND METHODS

We investigated 28 patients with Crohn's disease (CD: age: 32.4 +/- 2.0 y), 17 patients with ulcerative colitis (UC: 39.7 +/- 3.6 y), 39 patients with systemic lupus erythematosus (SLE: 34.9 +/- 2.0 y), 38 patients with progressive systemic sclerosis (pSS; 51.5 +/- 2.4 y) and 65 patients with insulin-dependent diabetes mellitus (IDDM: 35.5 +/- 1.6 y). Cardiovascular autonomic (cANP), pupillary autonomic (pANP), and sensorimotor (ssNP) neuropathy were assessed by standardized techniques.

RESULTS

Prevalence rates for cANP, pANP and ssNP were found to be 0%, 19%, and 7% in CD, 6%, 25%, and 18% in UC, 5%, 29%, and 10% in SLE, 11%, 16%, and 32% in pSS, and 26%, 66%, and 29% in IDDM, respectively.

CONCLUSION

The study demonstrated patients with IDDM to have the highest prevalence rates of cANP and pANP. Patients with other chronic diseases, particularly SLE, pSS and UC, had high prevalence rates of pANP. This may be due to alterations of structures of the central nervous system in these patients. cANP was rare in patients with inflammatory bowel disease and ssNP was found very often in patients with pSS, probably due to local fibrotic lesions. The various disease groups differ in the pattern and severity of autonomic and sensorimotor neuropathy, which indicates that different structures and neuropathogenic mechanisms may be involved.

Autoantibodies against sympathetic ganglia and evidence of cardiac sympathetic dysinnervation in newly diagnosed and long-term IDDM patients

To investigate the presence of autoantibodies against sympathetic nervous tissue and their correlation with cardiac sympathetic dysinnervation in insulin-dependent diabetes mellitus (IDDM), 20 newly diagnosed (age 26 +/- 6 years) and 48 long-term IDDM patients (age 40 +/- 13 years, duration of diabetes 22 +/- 12 years) without myocardial perfusion abnormalities (normal 99mTC-methoxyisobutylisonitrile uptake) were assessed for myocardial 123I-metaiodo benzylguanidine (123I-MIBG) uptake and complement-fixing sympathetic ganglia (CF-SG) autoantibodies. Both groups of patients were also studied for islet cell antibodies (ICA) and ECG-based cardiac autonomic neuropathy. Eighty control subjects (age 18-49 years) were investigated for CF-SG autoantibodies. Eight newly diagnosed (40%) and 12 long-term (25%) IDDM patients exhibited CF-SG autoantibodies, compared to 4 control subjects (5%; p < 0.01, p < 0.05). In long-term diabetic patients, the reduction of global but not of regional myocardial 123I-MIBG uptake correlated with CF-SG autoantibodies (r = 0.34, p = 0.02). Newly diagnosed diabetic patients did not show an association between CF-SG autoantibodies and global or regional myocardial 123I-MIBG uptake. ECG-based cardiac autonomic neuropathy (> or = two of five cardiac reflex tests abnormal) was present in 22 and absent in 26 long-term IDDM patients, of whom 9 (41%) and 3 (12%), respectively were positive for CF-SG autoantibodies (p = 0.02). Only 1 newly diagnosed IDDM patient demonstrated ECG-based cardiac autonomic neuropathy and was also positive for CF-SG autoantibodies. Although they are somewhat suggestive, results concerning autoantibodies against sympathetic nervous tissue and cardiac sympathetic dysinnervation do not strongly support the view that autoimmune mechanisms play a major role in the pathogenesis of cardiac sympathetic neuropathy in IDDM.

The neuronal toxic factor in serum of type 1 diabetic patients is a complement-fixing autoantibody

Type 1 diabetes is an autoimmune disease resulting in destruction of pancreatic beta cells. Many of the pancreatic beta cell autoantigens are also neuronal cell components. Using adrenergic neuroblastoma cells, we have previously demonstrated that humoral mechanisms may contribute to the development of diabetic neuropathy in Type 1 patients. We hypothesize that the toxic factor in Type 1 diabetic serum is an immunoglobulin. When neuroblastoma cells were exposed to immunoglobulins precipitated from serum of Type 1 diabetes patients with neuropathy, cell growth was significantly inhibited by day 5 (3.8 +/- 2.4 x 10(5) cells) compared to cells cultured with immunoglobulins from control (8.2 +/- 2.3 x 10(5) cells) or Type 2 diabetic serum (7.0 +/- 3.0 x 10(5) cells). The inhibitory effect (3.2 +/- 0.9 x 10(5) cells) could be removed from Type 1 diabetic serum by affinity precipitation with protein A-agarose (8.0 +/- 0.8 x 10(5) cells). Mild heat denaturing of the serum reversed the inhibitory effect (3.8 +/- 0.9 vs 1.4 +/- 1.4 x 10(5) cells), indicating a requirement for complement. Immunofluorescent labelling with anti-IgG secondary antibody of cells exposed to Type 1 diabetic serum indicated recognition of a membrane-bound antigen. The studies in this report support the hypothesis that autoimmune neuronal destruction may contribute to the development of diabetic autonomic neuropathy in patients with Type 1 diabetes.

Glutamic acid decarboxylase antibodies, autonomic nerve antibodies and autonomic neuropathy in diabetic patients

To clarify whether GAD-ab are associated with diabetic autonomic neuropathy and/or complement fixing antibodies against sympathetic ganglia, adrenal medulla, and vagus nerve, we examined 133 diabetic patients (95 with IDDM). GAD-ab were determined by a radioligand binding assay using in vitro expression of recombinant GAD-65 whereas sympathetic ganglia antibodies, adrenal medulla antibodies, vagus nerve, and ICA were evaluated by indirect immunofluorescence assays. Autonomic nerve function was evaluated by objective tests (heart rate reactions to deep breathing and to tilt). In the total material of 133 patients, GAD-ab were detected in 36 patients, all of whom had IDDM. The frequency of GAD-ab was similar (38%) in IDDM patients with and without signs of autonomic neuropathy (21 of 55 vs 15 of 40). In addition, there were no significant associations between GAD-ab and autonomic nerve antibodies; GAD-ab were detected in 9 of 21 (43%) of patients with and in 27 of 112 (24%) of patients without sympathetic ganglia antibodies, in 5 of 15 (33%) of patients with and 31 of 118 (26%) without adrenal medulla antibodies, and in 5 of 15 (33%) with and 31 of 118 (26%) of patients without vagus nerve antibodies. The frequency of ICA, however, was significantly increased in patients with sympathetic ganglia antibodies compared with those without sympathetic ganglia antibodies (10 of 21 [48%] vs 21 of 112 [19%]; p < 0.01). In conclusion, GAD-ab were neither associated with disturbed autonomic nerve function nor with antibodies against autonomic nerve structures.

Autoantibodies to nervous tissue structures are associated with autonomic neuropathy in type 1 (insulin-dependent) diabetes mellitus

There is evidence that the immune system may play a role in the pathogenesis of autonomic neuropathy in Type 1 (insulin-dependent) diabetes mellitus. In the present study, we investigated the presence of autoantibodies to sympathetic and parasympathetic nervous structures and their correlation with other conventional autoantibodies in well-characterised diabetic populations, with or without diabetic neuropathy, and normal subjects. An indirect immunofluorescent complement-fixation technique was used, with monkey adrenal gland, rabbit cervical ganglia and vagus nerve as substrates. Of the patients with symptomatic autonomic neuropathy 33% were positive for at least one autoantibody (20% anti-sympathetic ganglia, 10% anti-vagus nerve and 13% anti-adrenal medulla). The frequency of having one or more antibodies to nervous tissues and the prevalence of anti-cervical ganglia antibodies were significantly higher in the neuropathic patients than in the diabetic control subjects with disease of similar duration and in the normal subjects (p < 0.05). Of the patients without complications with diabetes of shorter duration 33% were also positive for at least one autoantibody (13% anti-ganglia, 13% anti-vagus nerve and 13% anti-adrenal medulla). No correlation was found with other tissue autoantibodies, including islet cell antibodies. Our data indicate that nervous tissue autoantibodies are associated with symptomatic autonomic neuropathy. Anti-sympathetic ganglia and anti-vagus nerve antibodies seem to be more disease-specific. Patients with diabetes of shorter duration who were positive for these autoantibodies may represent pre-neuropathic patients.

Autonomic nerve antibodies and autonomic nerve function in type 1 and type 2 diabetic patients

Complement-fixing adrenal medulla (CF-ADM), sympathetic ganglion (CF-SG), and vagal (CF-V) nerve antibodies were determined in diabetic patients. Among 74 patients with Type 1 diabetes, CF-ADM was detected in 7 (10%) cases, CF-SG in 14 (19%) cases, and CF-V in 8 (11%) cases. Among 38 patients with Type 2 diabetes, CF-ADM was detected in 5 (13%) cases, CF-SG in 4 (11%) cases, and CF-V in 6 (16%) cases. There were associations between autonomic nerve antibodies and autonomic nerve function. CF-ADM and/or CF-SG were significantly (P less than 0.002) less prevalent in Type 1 diabetic patients with autonomic neuropathy than in those without [5/44 (11%) vs. 14/30 (47%)] and, in agreement with this, the brake index, a sign of parasympathetic and sympathetic autonomic nerve function, was significantly (P less than 0.005) higher (more normal) in these patients (-0.56 +/- 0.13 vs. -1.04 +/- 0.12). In Type 2 diabetic patients, the E/I ratio, an index of parasympathetic nerve function, was significantly (P less than 0.03) lower (more abnormal) in those with CF-V than in those without (-1.81 +/- 0.17 vs. -1.20 +/- 0.11). In conclusion, the frequency of sympathetic nerve antibodies was decreased in Type 1 diabetic patients with autonomic neuropathy, while in Type 2 diabetic patients parasympathetic nerve antibodies were related to severe parasympathetic neuropathy.