[Update on anti-N-methyl-D-aspartate receptor encephalitis]. / Update Anti-N-Methyl-D-Aspartat-Rezeptor-Enzephalitis.

Autoimmune encephalitis is a group of autoimmune inflammatory disorders affecting both grey and white matter of the central nervous system. Encephalitis with autoantibodies against the N­methyl-D-aspartate receptor (NMDA-R) is the most frequent autoimmune encephalitis syndrome presenting with a characteristic sequence of psychiatric and neurological symptoms. Treatment necessitates a close interdisciplinary cooperation. This article provides an update on the current knowledge on diagnostic standards, pathogenesis, and treatment strategies for anti-NMDA-R encephalitis from psychiatric and neurological perspectives.

Anti-cytokine autoantibodies in postherpetic neuralgia.

BACKGROUND: The mechanisms by which varicella zoster virus (VZV) reactivation causes postherpetic neuralgia (PHN), a debilitating chronic pain condition, have not been fully elucidated. Based on previous studies identifying a causative role for anti-cytokine autoantibodies in patients with opportunistic infections, we explored this possibility in PHN. METHODS: Sera from herpes zoster (HZ) patients without and with PHN (N = 115 and 83, respectively) were examined for the presence of autoantibodies against multiple cytokines, and other known autoantigens. In addition, a cohort of patients with complex regional pain syndrome or neuropathic pain was tested for autoantibodies against selected cytokines. Antibody levels against VZV, Epstein Barr virus, and herpes simplex virus-2 were also measured in the HZ and PHN patients. Patient sera with high levels of anti-cytokine autoantibodies were functionally tested for in vitro neutralizing activity. RESULTS: Six PHN subjects demonstrated markedly elevated levels of single, autoantibodies against interferon-α, interferon-γ, GM-CSF, or interleukin-6. In contrast, the HZ and the pain control group showed low or no autoantibodies, respectively, against these four cytokines. Further analysis revealed that one PHN patient with high levels of anti-interleukin-6 autoantibodies had a markedly depressed antibody level to VZV, potentially reflecting poor T cell immunity against VZV. In vitro functional testing revealed that three of the five anti-cytokine autoantibody positive PHN subjects had neutralizing autoantibodies against interferon-α, GM-CSF or interleukin-6. In contrast, none of the HZ patients without PHN had neutralizing autoantibodies. CONCLUSIONS: These results suggest the possibility that sporadic anti-cytokine autoantibodies in some subjects may cause an autoimmune immunodeficiency syndrome leading to uncontrolled VZV reactivation, nerve damage and subsequent PHN.

Local and systemic cytokine expression in patients with postherpetic neuralgia.

BACKGROUND: Postherpetic neuralgia (PHN) is the painful complication of a varicella zoster virus reactivation. We investigated the systemic and local gene expression of pro- and anti-inflammatory cytokine expression in patients with PHN. METHODS: Thirteen patients with PHN at the torso (Th4-S1) were recruited. Skin punch biopsies were obtained from the painful and the contralateral painless body area for intraepidermal nerve fiber density (IENFD) and cytokine profiling. Additionally, blood was withdrawn for systemic cytokine expression and compared to blood values of healthy controls. We analyzed the gene expression of selected pro- and anti-inflammatory cytokines (tumor necrosis factor-alpha [TNF] and interleukins [IL]-1ß, IL-2, and IL-8). RESULTS: IENFD was lower in affected skin compared to unaffected skin (p<0.05), while local gene expression of pro- and anti-inflammatory cytokines did not differ except for two patients who had 7fold higher IL-6 and 10fold higher IL-10 gene expression in the affected skin compared to the contralateral unaffected skin sample. Also, the systemic expression of cytokines in patients with PHN and in healthy controls was similar. CONCLUSION: While the systemic and local expression of the investigated pro- and anti-inflammatory cytokines was not different from controls, this may have been influenced by study limitations like the low number of patients and different disease durations. Furthermore, other cytokines or pain mediators need to be considered.

Clinical Neuropathology practice guide 4-2013: post-herpes simplex encephalitis: N-methyl-Daspartate receptor antibodies are part of the problem.

Classic herpes simplex virus encephalitis (HSVE) is an acute viral infection that usually follows a monophasic disease course; however some patients, mainly children, experience a relapse within weeks or months after the initial event. In a subset of these patients a viral reactivation is unlikely because the CSF PCR for HSV is negative, repeated MRI does not show new necrotic lesions, and the symptoms are refractory to antiviral therapy. These patients often develop choreoathetosis variably accompanied by behavioral changes and seizures, and a postinfectious immune-mechanism has been postulated. Recent studies demonstrated that 7% of patients with HSVE harbor NR1 N-methyl-D-aspartate receptor (NMDAR) IgG antibodies. Moreover, a child with post- HSVE choreoathetosis was found to have NMDAR antibodies; the patient did not improve with antiviral therapy but recovered after aggressive immunotherapy. Based on these findings, evidence is increasing that a subgroup of post-HSVE represents a separate disease entity, which in fact is anti-NMDAR encephalitis. Patients with relapsing HSVE or prolonged atypical symptoms, who have negative CSF PCR for HSV should routinely be tested for NMDAR IgG antibodies in CSF and serum. It is important to be aware of this differential diagnosis because patients respond to immunotherapy.

Propentofylline, a CNS glial modulator does not decrease pain in post-herpetic neuralgia patients: in vitro evidence for differential responses in human and rodent microglia and macrophages.

There is a growing body of preclinical evidence for the potential involvement of glial cells in neuropathic pain conditions. Several glial-targeted agents are in development for the treatment of pain conditions. Here we report the failure of a glial modulating agent, propentofylline, to decrease pain reported in association with post-herpetic neuralgia. We offer new evidence to help explain why propentofylline failed in patients by describing in vitro functional differences between rodent and human microglia and macrophages. We directly compared the proinflammatory response induced by lipopolysaccharide (LPS) with or without propentofylline using rat postnatal microglia, rat peritoneal macrophages, human fetal microglia, human peripheral macrophages and human immortalized THP-1 cells. We measured tumor necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1ß) and nitrite release (as an indicator of nitric oxide (NO)) as downstream indicators. We found that LPS treatment did not induce nitrite in human microglia, macrophages or THP-1 cells; however LPS treatment did induce nitrite release in rat microglia and macrophages. Following LPS exposure, propentofylline blocked TNF-α release in rodent microglia with all the doses tested (1-100 µM), and dose-dependently decreased TNF-α release in rodent macrophages. Propentofylline partially decreased TNF-α (35%) at 100 µM in human microglia, macrophages and THP-1 macrophages. Propentofylline blocked nitrite release from LPS stimulated rat microglia and inhibited nitrite in LPS-stimulated rat macrophages. IL-1ß was decreased in LPS-stimulated human microglia following propentofylline at 100 µM. Overall, human microglia were less responsive to LPS stimulation and propentofylline treatment than the other cell types. Our data demonstrate significant functional differences between cell types and species following propentofylline treatment and LPS stimulation. These results may help explain the differential behavioral effects of propentofylline observed between rodent models of pain and the human clinical trial.