Differential distribution of HLA-DQ beta/DR beta epitopes in the two forms of Guillain-Barré syndrome, acute motor axonal neuropathy and acute inflammatory demyelinating polyneuropathy (AIDP): identification of DQ beta epitopes associated with susceptibility to and protection from AIDP

Guillain-Barré syndrome (GBS), an acute, immune-mediated paralytic disorder affecting the peripheral nervous system, is the most common cause of acute flaccid paralysis in the post-polio era. GBS is classified into several subtypes based on clinical and pathologic criteria, with acute inflammatory demyelinating polyneuropathy (AIDP) and acute motor axonal neuropathy (AMAN) being the most common forms observed. To better understand the pathogenesis of GBS and host susceptibility to developing the disease, the distribution of HLA class II Ags along with the seroreactivity to Campylobacter jejuni were investigated in a population of GBS patients from northern China. Using DNA-based typing methods, 47 patients with AMAN, 25 patients with AIDP, and 97 healthy controls were studied for the distribution of class II alleles. We found that the DQ beta RLD(55-57)/ED(70-71) and DR beta E(9)V(11)H(13) epitopes were associated with susceptibility to AIDP (p = 0.009 and p = 0.004, respectively), and the DQ beta RPD(55-57) epitope was associated with protection (p = 0.05) from AIDP. These DQ beta/DR beta positional residues are a part of pockets 4 (DQ beta 70, 71, DR beta 13), 6 (DR beta 11), and 9 (DQ beta 56, 57, DR beta 9); have been demonstrated to be important in peptide binding and T cell recognition; and are associated with other diseases that have a pathoimmunological basis. Class II HLA associations were not identified with AMAN, suggesting a different immunological mechanism of disease induction in the two forms of GBS. These findings provide immunogenetic evidence for differentiating the two disease entities (AMAN and AIDP) and focuses our attention on particular DR beta/DQ beta residues that may be instrumental in understanding the pathophysiology of AIDP.

Molecular population genetic analysis of Campylobacter jejuni HS:19 associated with Guillain-Barré syndrome and gastroenteritis

Infection with Campylobacter jejuni serotype HS:19 is associated with the development of Guillain-Barré syndrome (GBS). To determine whether a particular HS:19 clone is associated with GBS, multilocus enzyme electrophoresis (MLEE) was used to analyze a worldwide collection of isolates. There were 34 electropherotypes (ETs) in 3 phylogenetic clusters among 83 C. jejuni isolates. Cluster I contained all HS:19 strains, and a single ET (ET4) accounted for most HS:19 strains. HS:19 strains did not occur in any of the other clusters. ET4 contained isolates from different geographic locations, indicating global spread of this clone. Furthermore, ET4 contained isolates from patients with uncomplicated enteritis and GBS, as well as isolates from animal sources. The results of this study show that HS:19 strains comprise a clonal, although not monomorphic, population, which is distinct from non-HS:19 strains within C. jejuni. A unique clone associated with GBS was not identified by use of MLEE.

The effect of quadriceps femoris muscle strengthening exercises on spasticity in children with cerebral palsy

BACKGROUND AND PURPOSE

The Bobath neurodevelopmental treatment approach advised against the use of resistive exercise, as proponents felt that increased effort would increase spasticity. The purpose of this study was to test the premise that the performance of exercises with maximum efforts will increase spasticity in people with cerebral palsy (CP). Spasticity, in the present study, was defined as a velocity-dependent hyperexcitability of the muscle stretch reflex.

SUBJECTS

Twenty-four subjects with the spastic diplegic form of CP (mean age=11.4 years, SD=3.0, range=7-17) and 12 subjects without known neurological impairments (mean age=11.6 years, SD=3.5, range=7-17) were assessed.

METHODS

Knee muscle spasticity was assessed bilaterally using the pendulum test to elicit a stretch reflex immediately before and after 3 different forms of right quadriceps femoris muscle exercise (isometric, isotonic, and isokinetic) during a single bout of exercise training. Pendulum test outcome measures were: (1) first swing excursion, (2) number of lower leg oscillations, and (3) duration of the oscillations.

RESULTS

There were no changes in spasticity following exercise between the 2 groups of subjects.

DISCUSSION AND CONCLUSION

These results do not support the premise that exercises with maximum efforts increase spasticity in people with CP.

Clinical correlates and prognosis in early spindle coma

OBJECTIVE

To determine the prognostic significance of spindle coma (SC) according to etiology and EEG reactivity.

METHODS

We reviewed 15 patients with SC due to various causes within 8 days of coma to determine the prognostic significance of this EEG pattern.

RESULTS

The outcome among survivors was favorable: among 13 survivors, 9 were independent in all activities of daily living (ADLs) at 6 months; 3 were dependent in all ADLs; and one remained in coma. EEG reactivity to noxious stimuli best predicted outcome: All patients (whatever the coma etiology) with EEG reactivity survived; conversely, not all patients without EEG reactivity died.

CONCLUSION

In our patients, EEG reactivity independent of etiology predicted survival, neurological examination did not predict outcome. Most SC survivors had a meaningful recovery achieving all ADLs. From the literature, the cause of SC was predictive of outcome: encephalopathy, seizures and trauma had the best prognosis while hypoxia, CRA and structural lesions carried the worst. Literature review revealed that 23% of patients [56/242] died or remained in a persistent vegetative state (PVS). Best outcomes occurred when SC was due to drugs, encephalopathy or seizures: (0/14 died or were in a PVS). With trauma 15% [25/169] died or were in a PVS). Intermediate outcomes occurred with hypoxia and cardio-respiratory arrest (CRA): 33% [7/21] died or were in a PVS. The gravest outcomes occurred with brain-stem and cerebral infarctions, and tumors: 73% [22/30] died or were in a PVS.

Sensitivity of the pendulum test for assessing spasticity in persons with cerebral palsy

The sensitivity of the pendulum test to variation in spasticity in persons with spastic cerebral palsy (CP) was tested in 30 participants with CP and 10 participants without CP (controls) (mean age 13.8 years). The participants with CP were classified into three groups, with normal (mean age 15.9 years), mild/moderate (13.0 years), or severe (23.0 years) muscle tone, as assessed clinically using a modified Ashworth scale. Joint motion during the pendulum test was measured with an electrogoniometer. Muscle relaxation was confirmed using surface EMG. Outcome measures from the pendulum test were (1) number of oscillations, (2) duration of oscillations, (3) excursion of the first backward swing, and (4) relaxation index (first swing excursion/difference between the starting and resting angles). Data were assessed using one-way analysis of variance. Outcome measures 1 to 3 differed significantly between control participants and participants with CP (p<0.05). The first swing excursion was the best predictor of the degree of spasticity in persons with CP, being significantly different between all groups (p<0.05). The number of oscillations and their duration differentiated between control participants and all participants with CP (p<0.05) but not between participants with CP who had mild/moderate versus severe spasticity (p>0.05). The relaxation index was not a sensitive measure (p>0.05 between most study groups). We conclude that the pendulum test is a valid tool for assessing spasticity in persons with CP and that the first swing excursion is the most sensitive outcome measure.

TGFbeta trophic factors differentially modulate motor axon outgrowth and protection from excitotoxicity

Transforming growth factor (TGF) beta-like trophic factors have been shown to be protective in acute neuronal injury paradigms. In the current study, we analyzed and compared members of this growing family, including glial cell line-derived neurotrophic factor (GDNF), neurturin, nodal, persephin, and TGFbeta1, for protection against chronic glutamate toxicity. In parallel, we developed a organotypic spinal cord culture system to study the ability of these factors to promote motor axon outgrowth across white matter. Using these systems, we were able to differentiate the neuroprotective effect of the TGFbeta-like factors from their motor axon outgrowth-promoting activity. GDNF, neurturin, persephin, nodal, and TGFbeta1 all protected against excitotoxic motor neuron degeneration. Low amounts of GDNF (1 ng/ml) and high concentrations of neurturin induced vigorous motor axon outgrowth. In contrast, nodal, persephin, and TGFbeta1 did not induce motor axon outgrowth. Both GDNF and neurturin bind to Ret receptor complexes and were capable of activating the MAP kinase pathway. A specific inhibitor of MAP kinase kinase, PD98059, inhibited the motor axon outgrowth-promoting activity of the GDNF but not the neuroprotective activity. Similarly, the specific PI3K inhibitors, LY294002 and wortmannin, were able to inhibit the promotion of motor axon outgrowth by GDNF, but did not affect neuroprotective activity. Our results suggest that the neurite outgrowth-promoting effect of GDNF is mediated through the PI3K and MAP kinase pathways. The neuroprotective effect of GDNF appears to be through a separate pathway.

Physiologic-pathologic correlation in Guillain-Barré syndrome in children

OBJECTIVE

To correlate electrophysiologic patterns with sural nerve pathology in children with Guillain-Barré syndrome (GBS).

BACKGROUND

Based on electrophysiologic and pathologic observations, GBS has been divided into demyelinating and axonal subtypes. The acute motor axonal neuropathy (AMAN) involves predominantly motor nerve fibers with a physiologic pattern suggesting axonal damage, whereas the acute inflammatory demyelinating polyneuropathy (AIDP) involves both motor and sensory nerve fibers with a physiologic pattern suggesting demyelination. In this study, we sought to confirm these observations by correlating sural nerve pathology with electrophysiologic findings in GBS patients.

METHODS

Biopsies of sural nerve from 29 of 50 prospectively studied GBS patients were obtained. Nerves were examined by light and electron microscopy, and with immunocytochemistry for macrophages, lymphocytes, and complement activation products.

RESULTS

Sural nerves from AMAN patients were normal or had only a few (0.1% to 0.7%) degenerating fibers without lymphocytic infiltration or complement activation. One patient with reduced sural sensory nerve action potential classified as acute motor sensory axonal neuropathy (AMSAN) had many degenerating fibers (2.3%) in the sural nerve. All three AIDP patients displayed active demyelination, and in two patients, lymphocytic infiltration and complement activation products were observed on the abaxonal Schwann cell surface.

CONCLUSION

Classification of Guillain-Barré syndrome subtypes based on motor conduction studies correlates closely with pathologic changes seen in sural nerve. In acute motor axonal neuropathy cases, the sural nerve is almost completely spared pathologically. In acute inflammatory demyelinating polyneuropathy cases, macrophage-mediated demyelination and lymphocytic infiltration are common in the biopsies of sural nerves.

Autoantibodies to GM1b and GalNAc-GD1a: relationship to Campylobacter jejuni infection and acute motor axonal neuropathy in China

IgG antibodies to the minor gangliosides GM1b and GalNAc-GD1a frequently are present in sera of Japanese patients with Guillain-Barré syndrome. The relationship between these autoantibodies and Campylobacter jejuni infection, the type of disease (acute motor axonal neuropathy [AMAN], or acute inflammatory demyelinating polyneuropathy [AIDP]) has yet to be established. Sera samples were obtained from 55 Chinese patients with clinically defined Guillain-Barré syndrome. An electrophysiology study showed nine AIDP, 28 had AMAN, and 18 unclassified. C. jejuni serology was positively correlated with anti-GM1b and anti-GalNAc-GD1a IgG antibodies (respective P values, 0.007 and 0.02). The frequencies of positive anti-GM1b and anti-GalNAc-GD1a serology were greater in AMAN (32 and 21%) than in AIDP (11 and 0%), but the differences were not significant. Infection by C. jejuni may induce IgG anti-GM1b antibody in some patients and IgG anti-GalNAc-GD1a antibody in others. A larger population of patients must be studied to show whether there is a definite correlation.

Etiology, neurologic correlations, and prognosis in alpha coma

OBJECTIVE

To determine the factors affecting prognosis in alpha coma (AC).

METHODS

Retrospective review of 36 study patients, 36 control coma patients matched for age and etiology, and meta-analysis of 335 cases in the world literature.

RESULTS

Principal causes were cardiorespiratory arrest (CRA) (21 patients); infection, metabolic dysfunction, head trauma (3 each); and drugs, stroke and hypoxia (2 each). Outcome was predicated by EEG reactivity to noxious stimuli. Fourteen of the 15 patients with reactive EEGs, had measurable outcome, 8 awoke - all but two had etiologies other than CRA. Fourteen of 19 patients without EEG reactivity died; two had support discontinued and 3 awoke. Following CRA, 16/21 patients died and 3 had support discontinued. Only 3 patients made a good recovery - all with toxic or metabolic etiologies. Literature meta-analysis of 335 cases showed that overall, AC carried a poor prognosis (76% died). CRA (226 cases) had an 88% mortality; strokes (29 cases), a 90% mortality; hypoxia without cardiac arrest (28 cases), a 61% mortality; drug-induced AC (25 cases), an 8% mortality.

CONCLUSIONS

Although the cause of AC largely predicts outcome, EEG reactivity in AC predicted survival: most patients with reactivity awoke; most of those without, died. Few survivors had meaningful recovery.

Anti-GD1a antibody is associated with axonal but not demyelinating forms of Guillain-Barré syndrome

Immunopathological studies suggest that the target of immune attack is different in the subtypes of Guillain-Barré syndrome (GBS). In acute motor axonal neuropathy (AMAN), the attack appears directed against the axolemma and nodes of Ranvier. In acute inflammatory demyelinating polyneuropathy (AIDP), the attack appears directed against a component of the Schwann cell. However, the nature of the antigenic targets is still not clear. We prospectively studied 138 Chinese GBS patients and found that IgG anti-GD1a antibodies were closely associated with AMAN but not AIDP. With a cutoff titer of greater than 1:100, 60% of AMAN versus 4% of AIDP patients had IgG anti-GD1a antibodies; with a cutoff titer of greater than 1:1,000, 24% of AMAN patients and none of the AIDP patients had IgG anti-GD1a antibodies. In contrast, low levels of IgG anti-GM1 antibodies (> 1:100) were detected in both the AMAN and the AIDP forms (57% vs 35%, NS). High titers of IgG anti-GM1 (>1:1,000) were more common in the AMAN form (24% vs 8%, NS). Serological evidence of recent Campylobacter infection was detected in 81% of AMAN and 50% of AIDP patients, and anti-ganglioside antibodies were common in both Campylobacter-infected and noninfected patients. Our results suggest that IgG anti-GD1a antibodies may be involved in the pathogenesis of AMAN.

Campylobacter jejuni lipopolysaccharides in Guillain-Barré syndrome: molecular mimicry and host susceptibility

OBJECTIVE

This study was designed to determine if the presence of specific ganglioside-like moieties in Campylobacter lipopolysaccharides (LPSs) is related to the development of Guillain-Barré syndrome (GBS), and to discover how frequently such moieties, including GM1, are present in these LPSs.

METHODS

We studied Campylobacter isolates and sera from seven patients with GBS (five acute motor axonal neuropathy, one acute inflammatory demyelinating polyneuropathy, and one Fisher's syndrome), and compared them with similar specimens from patients with Campylobacter enteritis alone.

RESULTS

All GBS patients had antiganglioside antibodies. Anti-GM1 and anti-GD1a titers were significantly elevated in post-Campylobacter GBS, both axonal and demyelinating, compared with normal control subjects or those with uncomplicated Campylobacter diarrhea. Campylobacter isolated from patients with GBS and with enteritis alone had similar ganglioside-like moieties.

CONCLUSIONS

These results indicate that patients who develop GBS respond differently to the ganglioside-like epitopes on Campylobacter than do non-GBS diarrhea patients. Our findings support a role for host susceptibility as a determinant for the outcome following Campylobacter infection. These findings have important implications for the development of vaccines against Campylobacter jejuni.

Molecular mimicry in Guillain-Barré syndrome

Guillain-Barré syndrome (GBS) is the commonest cause of acute flaccid paralysis worldwide. Recent pathological and electrodiagnostic studies indicated that there are different patterns within this syndrome. The demyelinating pattern predominates in North America and Europe, whereas axonal variants of GBS occur more frequently in Northern China. Infection with Campylobacter jejuni is one of the most frequently recognized antecedent events in all variants of GBS. The lipopolysaccharides of these organisms share ganglioside-like epitopes with peripheral nerves, and patients with GBS have antiganglioside antibodies. These observations have given rise to the hypothesis that "molecular mimicry" is the immunopathogenic mechanism of injury to peripheral nerve fibers. With this hypothesis in view, we summarize our experience of GBS as it occurs in Northern China. To explore the role of molecular mimicry in this cohort we sought evidence of preceding Campylobacter infection and correlated this with clinical characteristics and antiganglioside serology. Based on our results we propose a sequence of pathogenic events leading to peripheral nerve injury in GBS.

Human autoimmune neuropathies

Peripheral nerve diseases are among the most prevalent disorders of the nervous system. Because of the accessibility of the peripheral nervous system (PNS) to direct physiological and pathological study, neuropathies have traditionally played a unique role in developing our understanding of basic mechanism of nervous system injury and repair. At present they are providing new insight into the mechanisms of immune injury to the nervous system. A rapidly growing catalogue of PNS disorders are now suspected to be immune-mediated, and in the best understood of these disorders, the molecular and cellular targets of immune attack are known, and the pathophysiology follows directly from the specific immune injury. This review summarizes the immunologically relevant features of the PNS, then considers selected immune-mediated neuropathies, focusing on pathogenetic mechanisms. Finally, the PNS is providing a testing ground for new immunotherapies and approaches to protection and regeneration, including the use of trophic factors. The current status of treatment and implications for future approaches is reviewed.

Onset of feedback reactions underlying vertebrate rod photoreceptor light adaptation

Light adaptation in vertebrate photoreceptors is thought to be mediated through a number of biochemical feedback reactions that reduce the sensitivity of the photoreceptor and accelerate the kinetics of the photoresponse. Ca2+ plays a major role in this process by regulating several components of the phototransduction cascade. Guanylate cyclase and rhodopsin kinase are suggested to be the major sites regulated by Ca2+. Recently, it was proposed that cGMP may be another messenger of light adaptation since it is able to regulate the rate of transducin GTPase and thus the lifetime of activated cGMP phosphodiesterase. Here we report measurements of the rates at which the changes in Ca2+ and cGMP are followed by the changes in the rates of corresponding enzymatic reactions in frog rod outer segments. Our data indicate that there is a temporal hierarchy among reactions that underlie light adaptation. Guanylate cyclase activity and rhodopsin phosphorylation respond to changes in Ca2+ very rapidly, on a subsecond time scale. This enables them to accelerate the falling phase of the flash response and to modulate flash sensitivity during continuous illumination. To the contrary, the acceleration of transducin GTPase, even after significant reduction in cGMP, occurs over several tens of seconds. It is substantially delayed by the slow dissociation of cGMP from the noncatalytic sites for cGMP binding located on cGMP phosphodiesterase. Therefore, cGMP-dependent regulation of transducin GTPase is likely to occur only during prolonged bright illumination.

Differential distribution of HLA alleles in two forms of Guillain-Barré syndrome

Guillain-Barré syndrome in northern China occurs in two forms: acute inflammatory demyelinating polyneuropathy (AIDP) and acute motor axonal neuropathy (AMAN). AMAN and AIDP have an immunologic basis, and some cases are associated with preceding Campylobacter jejuni infection. The distribution of allelic forms of the histocompatibility genes HLA-DPB1, DQB1, DRB1, DRB3, DRB4, and DRB5 was examined by DNA-based technology in 34 control, 12 AIDP, and 31 AMAN cases. In AIDP patients, the DRB1*1301 allele showed a significant increase (18% vs. 0%, P = .055). In AMAN patients, alleles DRB1*1301-03 and DRB1*1312, taken collectively, were increased (19% vs. 0%, P = .009), but by itself, the DRB1*1301 allele was not increased, as in AIDP patients. With a larger number of persons, more definitive statements will be possible; however, the differential distribution of DR13 allelic forms between AIDP and AMAN cases may suggest that there are different immunologic mechanisms operating at the molecular level of these diseases.

Patterns of recovery in the Guillain-Barre syndromes

Clinical, electrodiagnostic, and pathologic studies indicate that the Guillain-Barre syndromes (GBSs) include both primary demyelinating and primary axonal forms. The axonal forms are usually thought to have a poorer prognosis, with less chance for rapid or complete recovery. In northern China, epidemics of one axonal form, acute motor axonal neuropathy (AMAN), occur annually in the summer. Autopsy studies in some fatal cases have demonstrated wallerian-like degeneration of motor roots and motor fibers in the peripheral nerves. Recovery of such patients would require axonal regeneration along the entire length of the nerve fiber. In a 2-year prospective study of GBS at a single hospital in northern China, 42 patients were classified as having either AMAN (32 patients), acute inflammatory demyelinating polyneuropathy (AIDP) (8 patients), or as undetermined (2 patients) by electrodiagnostic criteria. Their recoveries were monitored clinically. The recovery times of AMAN and AIDP patients were similar: the median time to regain the ability to walk 5 meters with assistance was 31 days for patients classified as having AMAN and 32 days for those classified as having AIDP. These rapid recovery times are incompatible with severe wallerian degeneration of the ventral roots and motor nerve fibers. The rapid recoveries observed in AMAN patients could be explained by relatively quickly reversible immune-mediated changes at nodes of Ranvier in motor fibers, by degeneration and regeneration of intramuscular motor nerve terminals, or both.

Motor nerve terminal degeneration provides a potential mechanism for rapid recovery in acute motor axonal neuropathy after Campylobacter infection

We investigated the possible mechanisms of paralysis and recovery in a patient with the acute motor axonal neuropathy (AMAN) pattern of the Guillain-Barré syndrome. The AMAN pattern of GBS is characterized clinically by acute paralysis without sensory involvement and electrodiagnostically by low compound motor action potential amplitudes, suggesting axonal damage, without evidence of demyelination. Many AMAN patients have serologic or culture evidence of recent Campylobacter jejuni infection. Pathologically, the most severe cases are characterized by wallerian-like degeneration of motor axons affecting the ventral roots as well as peripheral nerves, but some fatal cases have only minor changes in the roots and peripheral nerves, and some paralyzed patients with the characteristic electrodiagnostic findings of AMAN recover rapidly. The mechanism of paralysis and recovery in such cases has been uncertain. A 64-year-old woman with culture-proven Campylobacter upsaliensis diarrhea developed typical features of AMAN. She improved quickly following plasmapheresis. Her serum contained IgG anti-GM1 antibodies. The lipopolysaccharide of the organism bound peanut agglutinin. This binding was blocked by cholera toxin, suggesting that the organism contained the Gal(beta1-3)GalNAc epitope of GM1 in its lipopolysaccharide. Motor-point biopsy showed denervated neuromuscular junctions and reduced fiber numbers in intramuscular nerves. In contrast, the sural nerve biopsy was normal and skin biopsy showed normal dermal and epidermal innervation. In AMAN the paralysis may reflect degeneration of motor nerve terminals and intramuscular axons. In addition, the anti-GM1 antibodies, which can bind at nodes of Ranvier, might produce failure of conduction. These processes are potentially reversible and likely to underlie the capacity for rapid recovery that characterizes some cases of AMAN.

Acute motor axonal neuropathy: an antibody-mediated attack on axolemma

The acute motor axonal neuropathy (AMAN) form of the Guillain-Barre syndrome is a paralytic disorder of abrupt onset characterized pathologically by motor nerve fiber degeneration of variable severity and by sparing of sensory fibers. There is little demyelination or lymphocytic inflammation. Most cases have antecedent infection with Campylobacter jejuni and many have antibodies directed toward GM1 ganglioside-like epitopes, but the mechanism of nerve-fiber injury has not been defined. In 7 fatal cases of AMAN, immunocytochemistry demonstrated the presence of IgG and the complement activation product C3d bound to the axolemma of motor fibers. The most frequently involved site was the nodal axolemma, but in more severe cases IgG and C3d were found within the periaxonal space of the myelinated internodes, bound to the outer surface of the motor axon. These results suggest that AMAN is a novel disorder caused by an antibody- and complement-mediated attack on the axolemma of motor fibers.

Immune attack on the Schwann cell surface in acute inflammatory demyelinating polyneuropathy

The localization, mode of action, and roles of complement in the Guillain-Barre syndrome have been controversial. We used high-resolution immunocytochemistry to localize complement activation products in early stages of the acute inflammatory demyelinating polyneuropathy (AIDP) pattern of Guillain-Barre syndrome. Three AIDP subjects who were autopsied had had symptoms for 3 to 9 days at the time of death. Immunocytochemistry was performed on etched, epoxy resin-embedded sections, and the next thin section was compared by electron microscopy (thick/thin sections). Many fibers had a rim of the complement activation marker C3d and the terminal complement complex neoantigen C5b-9 along the outer surface of the Schwann cells. Ultrastructural analysis of these C3d-positive fibers showed mild vesicular changes of the outermost myelin lamellae. Vesicular degeneration was seen before the invasion of macrophages into the myelin, and was the predominant change in the subject with symptoms for 3 days. C3d staining was not found on myelin membranes. The results suggest that at least some forms of AIDP are complement mediated. We speculate that complement is activated by antibody bound to epitopes on the outer surface of the Schwann cell and that the resulting complement activation initiates the vesiculation of myelin.

Early nodal changes in the acute motor axonal neuropathy pattern of the Guillain-Barré syndrome

The axonal patterns of Guillain-Barré syndrome, associated in many cases with antecedent Campylobacter jejuni infection, are now recognized as frequent causes of acute flaccid paralysis in some regions of the world. This study examined ultrastructurally the PNS of seven cases of the acute motor axonal neuropathy form of Guillain-Barré syndrome. In this disorder previous studies of advanced cases have found Wallerian-like degeneration of motor fibres in the spinal roots and peripheral nerves, with little lymphocytic inflammation or demyelination. The present study was focused on identifying early changes and establishing the sequence of changes. By electron microscopy the earliest and mildest changes consisted of lengthening of the node of Ranvier with distortion of the paranodal myelin, and in some instances with breakdown of the outermost myelin terminal loops. At this stage many nodes had overlying macrophages which extended their processes through the Schwann cell basal lamina covering the node and apposed the axolemma. Macrophage processes then extended beneath the myelin terminal loops, and the whole macrophage entered the periaxonal space at the paranode. Macrophage processes dissected the axon from the adaxonal Schwann cell plasmalemma and the macrophages advanced into the internodal periaxonal space, where they typically surrounded a condensed-appearing axon. At this stage the adaxonal Schwann cell cytoplasm regularly degenerated and disappeared, so that the periaxonal space was bounded by the innermost myelin lamella, and the axolemma of many fibres could not be seen. The internodal myelin sheath and the abaxonal Schwann cell cytoplasm remained normal. This arrangement appeared to be stable for some time, but in many fibres the axon subsequently underwent Wallerian-like degeneration. By interfering with impulse conduction, these nodal and periaxonal changes may explain paralysis in some pathologically mild cases. In addition, at early stages, these changes may be reversible, thus explaining the rapid recovery of some patients who become paralysed with acute motor axonal neuropathy. These observations, taken together with previous studies, suggest that acute motor axonal neuropathy is an antibody- and complement-mediated disorder in which the relevant epitopes are present on the nodal and internodal axolemma.

Pathology of the motor-sensory axonal Guillain-Barré syndrome

The concept of a severe motor-sensory neuropathy of acute onset caused by an immune attack on the axon ("axonal" Guillain-Barré syndrome) has been advanced primarily based on electrodiagnostic and limited pathological data, but remains controversial. At autopsy some cases demonstrate unusually severe inflammatory demyelinating neuropathy. There are conflicting data about whether antecedent Campylobacter jejuni infection is associated with "axonal" Guillain-Barré syndrome. We report 4 individuals from Hebei Province, China, who died 7, 7, 18, and 60 days after onset of a syndrome diagnosed clinically as Guillain-Barré syndrome. High titers of antibodies recognizing C. jejuni, consistent with recent infection, were found in the 2 patients tested. At autopsy the 3 with early disease had ongoing wallerian-like degeneration of fibers in the ventral and dorsal roots and in the peripheral nerves, with only minimal demyelination or lymphocytic infiltration. All 3 had numerous macrophages in the periaxonal space of myelinated internodes, and rare intraaxonal macrophages as well. Examination of the patient having the syndrome for 60 days confirmed the extensive loss of large fibers in the spinal roots and nerves, and the paucity of demyelination and remyelination. These observations confirm predictions that some patients with severe motor-sensory Guillain-Barré syndrome, as defined clinically, have predominantly axonal lesions of both motor and sensory fibers, even in the early stages of the disease, and that axonal Guillain-Barré syndrome can follow C. jejuni infection. The pathology supports the possibility that such cases of motor-sensory axonal Guillain-Barré syndrome represent the most severe end of a spectrum of immune attack directed toward epitopes on the axon.

Guillain-Barré syndrome in northern China. The spectrum of neuropathological changes in clinically defined cases

The pathology of the Guillain-Barré syndrome remains controversial, and autopsied cases available for study by contemporary techniques are uncommon. Large numbers of cases clinically diagnosed as Guillain-Barré syndrome occur in northern China. In this study we examined the neuropathological changes in 12 autopsied cases from Hebei Province, China. Eleven died early in the course of their disease. In all cases tissue was specially handled and fixed for electron microscopy and for immunocytochemistry. Three of these 12 cases had typical acute inflammatory demyelinating polyneuropathy (AIDP) with lymphocytic infiltration and macrophage-mediated demyelination, reproducing the pathological picture most often reported in Guillain-Barré syndrome in North America, Europe, and Australia. Six cases had predominantly axonal involvement, characterized by Wallerian-like degeneration of nerve fibres, with only minimal demyelination and with minimal inflammation in five. Three cases, even though paralysed at the time of death, had only very mild changes in the spinal roots and sciatic nerves. Within the group of six predominantly axonal cases, there were important differences both in the severity of the abnormalities and in the classes of fibres involved. Three cases had extensive Wallerian-like degeneration of sensory as well as motor fibres [acute motor-sensory axonal neuropathy (AMSAN)], while in the other three cases the fibre degeneration affected the motor nerve fibres almost exclusively. These latter cases establish a structural basis for the clinical and electrophysiological picture termed the acute motor axonal neuropathy (AMAN) pattern. In both the AMAN and the AMSAN patterns, a prominent feature was the presence of macrophages within the periaxonal space, surrounding or displacing the axon, and surrounded by an intact myelin sheath. These studies show that the early pathological changes in cases clinically diagnosed as the Guillain-Barré syndrome are diverse and not restricted to the well-known pattern of AIDP, and that the predominant pathological patterns may differ in different parts of the world. The differences in pathological findings between acute inflammatory demyelinating polyneuropathy and the axonal patterns are likely to reflect differences in the pathogenetic mechanisms. The periaxonal macrophages in the axonal patterns suggest that an important epitope may be localized to the axolemma or periaxonal space. The mild cases indicate that severe paralysis can occur early in Guillain-Barré syndrome without prominent structural changes along the nerve, suggesting that physiological block or nerve terminal changes may be implicated.

Guillain-Barré syndrome in northern China. Relationship to Campylobacter jejuni infection and anti-glycolipid antibodies

Guillain-Barré syndrome has been considered to be primarily an acute inflammatory demyelinating polyneuropathy (AIDP). Our experience with Guillain-Barré syndrome in northern China differs from the traditional concept. Electrophysiologically and pathologically, most of our patients have motor axonal degeneration with minimal cellular inflammation, which we have termed 'acute motor axonal neuropathy' (AMAN). The current studies were undertaken to characterize prospectively the clinical, electrophysiological, and serological features of Guillain-Barré syndrome, defined clinically, in northern China. In 1991 and 1992, we characterized by electrodiagnostic criteria 129 Chinese patients with Guillain-Barré syndrome. The AMAN form was present in 65% of patients, the AIDP form in 24% and 11% were unclassifiable. For the 38 patients who presented from January to October, 1992, we performed serological assays for antibodies to Campylobacter jejuni and to glycolipids. Of these 38 patients, 55% had AMAN, 32% had AIDP and 13% were unclassifiable. Sixty-six percent of the 38 had serological evidence of recent C. jejuni infection as compared with 16% of village controls (P = 0.001). Seventy-six percent of AMAN patients and 42% of AIDP patients were seropositive. IgG anti-GM1 antibodies were more frequent in Guillain-Barré syndrome patients compared with village controls (42% versus 6%; P < 0.01). However, no statistically significant correlations were found between the pattern of disease, AMAN or AIDP, anti-glycolipid antibodies, or C. jejuni antibodies. Based on electrophysiological criteria, Guillain-Barré syndrome in northern China can be divided into two predominant forms: AIDP and AMAN. The AMAN form is more common and predominates in the yearly summer outbreaks of Guillain-Barré syndrome.(ABSTRACT TRUNCATED AT 250 WORDS)

Prolactin-immunoglobulin G complexes from human serum act as costimulatory ligands causing proliferation of malignant B lymphocytes

Several lines of evidence indicate that immunoglobulin-bound prolactin found in human serum is not a conventional complex between an anti-prolactin antibody and prolactin but a different type of association of prolactin with the Fab portion of IgG heavy chains. The complex of prolactin with IgG was purified from serum by anti-human prolactin affinity chromatography and was shown to contain close to 1 mole of N epsilon-(gamma-glutamyl)lysine crosslinks per mole of complex, a characteristic feature in structures crosslinked by transglutaminase. Interestingly, the complex caused a proliferation of cells from a subset of patients with chronic lymphocytic leukemia, while it was inactive in a cell proliferation prolactin bioassay. By contrast, human prolactin stimulated the proliferation of cells in the bioassay but had no effect on the complex-responsive cells from the patients. Competition studies with prolactin and free Fc fragment of IgG demonstrated a necessity for engaging both the prolactin and the immunoglobulin receptors for proliferation. More importantly, competition for the growth response by free prolactin and IgG suggests both possible reasons for the slow growth of this neoplasm as well as avenues for control of the disease.

The clinical correlates of high-titer IgG anti-GM1 antibodies

Serum IgG anti-GM1 antibodies have been reported to occur in a variety of disorders, including Guillain-Barré syndrome and chronic polyneuropathies. Of over 5,000 serums tested in our laboratory, high titers of selective IgG anti-GM1 antibodies (> 1:1,000) and without binding to sulfatide were found in 35 patients. Clinical correlation revealed that almost all patients had axonal, motor neuropathies. One subgroup was comprised of individuals with an acute motor neuropathy, described either as an acute axonal Guillain-Barré-like syndrome that was occasionally associated with a prodrome of Campylobacter jejuni enteritis or as Chinese paralysis syndrome. A second group of patients had chronic asymmetric lower motor neuron (LMN) syndromes with no conduction block or other evidence of demyelination. The presence of selective high-titer IgG anti-GM1 antibody reactivity in serum is uncommon but when present is strongly associated with acute axonal motor neuropathies or chronic asymmetric LMN syndromes.

Secretion of specific nonphosphorylated and phosphorylated rat prolactin isoforms at different stages of the estrous cycle

The biological activity and immunoreactivity of serum prolactin (PRL) has been shown to fluctuate throughout the estrous cycle of the rat. Since the 24-kDa nonphosphorylated and phosphorylated isoforms from several species have also been shown to differ in their biological and immunoreactivities, we have investigated the possibility that the 24-kDa monomer isoform profile varied throughout the estrous cycle of the rat. The PRL isoform profile was assessed in homogenates of pituitaries and in short-term incubation media. Comparisons between homogenates, which always contained isoforms 1, 2, 3, and 3' (numbered according to increasing acidity), and media showed nonproportional release of the isoforms at all stages. Of great interest were the release of isoform 1 (a nonphosphorylated form) only at estrus and the lack of release of isoform 3' (a phosphorylated form) only in the afternoon of proestrus. This lack of release of 3' was accompanied by a marked increase in the release of isoform 2 (the unmodified polypeptide). These results suggest a unique function for isoform 1 during estrus and a role for increased isoform 2 and absent isoform 3' during the proestrus surge of PRL. Moreover, they suggest that fluctuations in the biological activity and immunoreactivity of serum PRL during the estrous cycle could be due, at least in part, to fluctuations in the isoform profile.

Acute motor axonal neuropathy: a frequent cause of acute flaccid paralysis in China

In northern China, annual epidemics of acute-onset flaccid paralysis diagnosed clinically as Guillain-Barré syndrome have been recognized for at least 20 years. On the basis of an historical analysis of more than 3,200 patients, distinctive features include most cases occurring during the summer months among children and young adults, most of whom reside in rural areas. Of 90 patients with acute flaccid paralysis, 88 had a distinctive pattern that shares clinical and cerebrospinal fluid findings with demyelinating Guillain-Barré syndrome, but that differs from Guillain-Barré syndrome physiologically and pathologically. The clinical course is marked by rapidly progressive ascending tetraparesis, often with respiratory failure, but without fever, systemic illness, or sensory involvement. Cerebrospinal fluid is acellular, and elevations of protein content occur in the second or third week of illness. Electrodiagnostic studies show normal motor distal latencies and limb conduction velocities, but reduced compound muscle action potential amplitudes. Sensory nerve action potentials and, when elicitable, F waves are within the range of normal. Recovery is usually good. Autopsy studies have shown Wallerian-like degeneration of motor fibers. These studies establish that this is a distinctive syndrome, distinguishable from poliomyelitis and demyelinating Guillain-Barré syndrome.

Prolactin isoform 2 as an autocrine growth factor for GH3 cells

Because PRL has growth factor activities in several tissues, we have asked whether it also has autocrine growth factor activity in pituitary GH3 cells. GH3 cells were grown at increasing densities in the presence or absence of antirat PRL (polyclonal and monoclonal) or nonspecific antibodies. Cell proliferation increased with increasing cell density, as did the concentration of PRL in the medium. Antirat PRL, but not control antibody, markedly inhibited but did not eliminate cell proliferation, and this effect was diminished with increasing PRL concentration in the medium. PRL receptors were demonstrated on 40-50% of the cells by indirect immunofluorescence using a specific antirat PRL receptor monoclonal antibody. Cell surface PRL was colocalized to the same 40-50% of the cells and copatched or cocapped along with the receptors. Absence or presence of PRL receptors did not correlate with stage of the cell cycle, as judged by ethidium bromide dual labeling. Cell surface PRL was found to be on PRL-containing cells. These data have fulfilled four criteria necessary for establishment of a substance as a secreted autocrine growth factor: 1) the factor must be secreted; 2) in log growth phase, increased cell proliferation should occur at increased cell densities; 3) the cells must display a receptor for the factor; and 4) there must be a growth response to the factor. Thus we have established that PRL is an autocrine growth factor for at least 40-50% of the GH3 cell population. This, to our knowledge, is the first example of autocrine growth factor activity of a major hormone normotopically expressed.

50 kD prolactin binding protein in schizophrenics on neuroleptic medication

Serum samples from 15 age-matched normal male subjects and 15 male schizophrenic patients on neuroleptic medication were subjected to immunoprecipitation with anti-human prolactin (PRL) and analysis of the immunoprecipitate by two-dimensional gel electrophoresis. We report the unexpected immunoprecipitation of large amounts of an approximately 50 kD protein in 12/15 of the schizophrenic patients. Preliminary analyses suggest that this 50 kD protein may be an IgG heavy chain. Since total levels of IgG and each of the IgG subclasses are the same in the normal and schizophrenic group, the increased amount of the 50 kD protein in the schizophrenics is clearly specific to anti PRL precipitation. Since the anti-PRL does not directly recognize either the 50 kD protein or any immunoglobulin light chains in the precipitate, we suggest that the 50 kD protein is precipitated because it is bound to PRL. Perhaps immunoglobulin binding of PRL is a mechanism used to compensate for chronically elevated PRL levels during neuroleptic treatment.

Prolactin (PRL) processing by kallikrein: production of the 21-23.5K PRL-like molecules and inferences about PRL storage in mature secretory granules

We have previously described a series of C-terminally-clipped forms of PRL, the 21-23.5K PRL-like molecules (PLMs). Because we noted estrogen (E2) induction of PLMs and E2 also induces a pituitary glandular kallikrein, we have investigated the possibility that processing of PRL by kallikrein is responsible for the production of the PLMs. Subcellular fractionation of pituitaries from control or E2-treated female rats showed total kallikrein to be concentrated 1- to 4-fold and 6- to 20-fold in the granules (vs. original homogenate) from control and E2-treated animals, respectively. Cleavage of purified PRL by kallikrein resulted in the formation of large quantities of a number of the PLMs. Incubation of secretory granules derived from control or E2-treated animals under the same conditions showed no cleavage of PRL in the absence of a limiting granule membrane and a small production of the PLMs in the presence of a granule membrane. Production in the latter instance was slightly greater in granules derived from E2-treated animals. Addition of purified kallikrein to secretory granules from control or E2-treated animals in the presence or absence of granule membranes, resulted in the additional production of large amounts of only the smallest PLM (PLM 9), indicating a lack of cleavage of the two most C-terminal sites for the enzyme. Increasing the concentration of beta-mercaptoethanol to 0.64 M, to ensure monomerization of the granule PRL, had no effect on endogenous kallikrein activity of the number of products resulting from the addition of exogenous kallikrein to granules. In summary: 1) purified kallikrein can cleave purified PRL to form products which run with the same isoelectric point and mol wt values as the PLMs; 2) kallikrein is present in PRL secretory granules; 3) some PLM production occurs in a membrane-bound secretory granule fraction, but none occurs after removal of the membrane; this intragranular production, like cleavage of purified PRL with purified kallikrein, is dependent on the presence of a detergent and a reducing agent; 4) cleavage of granular PRL by exogenous kallikrein is limited to a single site and the more C-terminal sites are protected; and 5) protection of the C-terminus is not removed by intermolecular and intramolecular disulfide bond reduction. We conclude: 1) that pituitary glandular kallikrein is a strong candidate for the enzyme responsible for the production of the PLMs, and 2) that there is some element of PRL storage, other than intermolecular disulfide bonds, which involves the C-terminus of the molecule.

Biosynthesis of the secreted 24 K isoforms of prolactin

PRL exists within the mammotroph population in a number of different molecular forms. Several of these forms are best described as isoforms, as they have the same mol wt (24 K), but differ in their net charges. In this study we have used in vitro translation assays to ascertain the number of 24 K translation products of normal pituitary messenger RNA (mRNA), and, finding only one, have used both in vitro translation assays and subcellular fractionation to determine the intracellular site of the posttranslational modification of this single translation product. Translation of mRNA from normal pituitary tissue or GH3 cells resulted in the apparent production of a number of pre-PRLs, but in only a single rough microsome-processed form of PRL, 24 K isoform 2. Longer term translation assays utilizing a variety of isotopes failed to show any evidence for rough microsomal posttranslational modification of isoform 2. Subcellular fractionation, using a discontinuous sucrose gradient, however, produced a membrane-bound large secretory granule fraction which, when isolated, contained essentially only isoform 2, and which had the capacity to convert isoform 2 to isoforms 3 and 3' by posttranslational phosphorylation.

Mammotroph autoregulation: the differential roles of the 24K isoforms of prolactin

In this study we have attempted to determine which of the secreted 24K isoforms was responsible for autocrine regulation of PRL secretion by comparing the isoforms synthesized and secreted by normal cells, which do autoregulate, with those synthesized and secreted by GH3 cells, which do not normally autoregulate. Comparable numbers of cells were washed free of serum and then extracted into Tris-buffered saline by sonication and detergent treatment. Proteins present in these cell extracts and in samples of culture medium were then precipitated with cold acetone (-20 C; 48 h) and subsequently dissolved in urea-lysis buffer for 2-dimensional (2-D) electrophoresis. The 2-D patterns for normal cells showed four 24K PRL isoforms inside the cells and three 24K PRL isoforms (designated 2, 3, and 3') secreted into the medium. The 2-D patterns for GH3 cells showed very little intracellular storage of PRL, but what was present was identified as 24K PRL isoform 2. The GH3 cells secreted large amounts of only 24K PRL isoform 2. Preparations of PRL containing only isoforms 1,2, and 3 (at a total radioimmunoassayable concentration of 5 micrograms/ml PRL) were capable of inducing autoregulation in GH3 cells, as evidence by decreased secretion of prelabeled intracellular PRL. Initiation of autoregulation in GH3 cells caused granulation and the intracellular production of isoform 3. Since a) a preparation containing isoforms 1, 2, and 3 was found to induce autoregulation in GH3 cells, b) isoform 1 is not a secreted form, and c) isoform 2 does not cause autoregulation (at least in GH3 cells), it is deduced that isoform 3 is an autocrine form of PRL. Since initiation of autoregulation in GH3 cells caused those cells to produce isoform 3, it is further deduced that the autoregulatory defect in GH3 cells lies in the actual lack of production of isoform 3 and not in an inherent inability of these cells to produce isoform 3.

Production and secretion of the 21-23.5 kDa prolactin-like molecules

We recently described the presence of a series of prolactin (PRL)-like molecules (PLMs) in the rat pituitary gland and showed that their formation was not due to artifactual proteolysis of 24 kDa PRL during extraction or to degradation of PRL in lysosomes. In this study we have found (1) in vitro translation of pituitary cell RNA to result in the production of only 24 kDa monomer isoform 2 and no PLMs, (2) that secretion of newly synthesized PLMs is differently regulated than at least a proportion of newly synthesized monomers, (3) that secretion of newly synthesized PLMs occurs after at least a 6 h delay, (4) that cysteamine (a) inhibits the release of the PLMs, (b) causes an increase in their amount versus isoform 2, and (c) causes an intracellular accumulation of pleiomorphic, immature secretory granules, and (5) that cells grown under degranulating culture conditions do not contain PLMs. These results, using normal anterior pituitary cells in primary culture, demonstrate the potential for differential release of the PLMs versus monomer PRL in vivo and are consistent with the production of the PLMs from 24 kDa monomer isoform 2 during secretory granule condensation.