Serum matrix metalloproteinase-9 and tissue inhibitor of metalloproteinase-1 levels in non-herpetic acute limbic encephalitis

Identification of TIMP1 as an inflammatory biomarker associated with temporal lobe epilepsy based on integrated bioinformatics and experimental analyses

BACKGROUND

Epilepsy is the second most prevalent neurological disease. Although there are many antiseizure drugs, approximately 30% of cases are refractory to treatment. Temporal lobe epilepsy (TLE) is the most common epilepsy subtype, and previous studies have reported that hippocampal inflammation is an important mechanism associated with the occurrence and development of TLE. However, the inflammatory biomarkers associated with TLE are not well defined.

METHODS

In our study, we merged human hippocampus datasets (GSE48350 and GSE63808) through batch correction and generally verified the diagnostic roles of inflammation-related genes (IRGs) and subtype classification according to IRGs in epilepsy through differential expression, random forest, support vector machine, nomogram, subtype classification, enrichment, protein‒protein interaction, immune cell infiltration, and immune function analyses. Finally, we detected the location and expression of inhibitor of metalloproteinase-1 (TIMP1) in epileptic patients and kainic acid-induced epileptic mice.

RESULTS

According to the bioinformatics analysis, we identified TIMP1 as the most significant IRG associated with TLE, and we found that TIMP1 was mainly located in cortical neurons and scantly expressed in cortical gliocytes by immunofluorescence staining. We detected decreased expression of TIMP1 by quantitative real-time polymerase chain reaction and western blotting.

CONCLUSION

TIMP1, the most significant IRG associated with TLE, might be a novel and promising biomarker to study the mechanism of epilepsy and guide the discovery of new drugs for its treatment.

Serum matrix metallopeptidase-9 and tissue inhibitor of metalloproteinase-1 levels in autoimmune encephalitis

OBJECTIVE

Some pediatric patients with autoimmune encephalitis (AE) experience sequelae in spite of immunotherapy. In this study, we aimed to evaluate the association of serum matrix metallopeptidase-9 (MMP-9) and tissue inhibitor of metalloproteinase-1 (TIMP-1) levels with the neurological prognosis of AE.

METHODS

We retrospectively included 13 patients with AE who had been referred to Saitama Children's Medical Center from February 2011 to May 2019. We compared serum MMP-9 levels, TIMP-1 levels, and MMP-9/TIMP-1 ratio in the acute period (within 30 days from the onset of AE) and subacute period (30-day period following the acute period). We also compared these biomarker levels between patients with (group A) and without sequelae (group B). Sequelae were evaluated at discharge or the last visit.

RESULTS

Group A (median age, 7.8 years; range, 5.3-10.7 years) and group B (median age, 13.3 years; range, 11.1-15.4 years) had 6 patients each; 1 patient was excluded because the time of AE onset was unknown. In the acute period, there were no significant differences in MMP-9 levels, TIMP-1 levels, and MMP-9/TIMP-1 ratio between groups A and B. In the subacute period, serum MMP-9/TIMP-1 ratio was higher in group A than in group B (p < 0.01). There were no significant differences in MMP-9 and TIMP-1 levels between groups A and B.

CONCLUSIONS

Patients with sequelae of AE showed a high MMP-9/TIMP-1 ratio in the subacute period. Our study demonstrates that elevation of serum MMP-9/TIMP-1 ratio in the subacute period may be a predictive factor of sequelae of AE.

Severe anti-GAD antibody-associated encephalitis after stem cell transplantation

BACKGROUND

General features of anti-glutamic acid decarboxylase (GAD) antibody-associated limbic encephalitis are seizures, cognitive impairment, and imaging findings at the medial temporal lobes. We report a patient affected with remarkably severe anti-GAD antibody-positive encephalitis after hematopoietic stem cell transplantation (HSCT).

CASE REPORT

A 5-year-old girl received HSCT due to pineoblastoma. Thirteen months after HSCT, she showed seizure clustering and altered mental status. Her anti-GAD antibody level was high, 65,100 U/mL (reference range < 1.5 U/mL). Her disease was diagnosed as autoimmune encephalitis and she received intravenous immunoglobulin (IVIG) and methylprednisolone. After the therapy, she partially recovered. Encephalitis later relapsed, however, and she showed extremely high anti-GAD antibody, 27 months after HSCT. Although lesions were located in the temporal and occipital lobes by MRI at 5 days after the relapse, very severe whole brain encephalitis was revealed at 13 days after the relapse. Seizures and abnormal encephalogram were resistant to IVIG and methylprednisolone. After plasma exchange, these findings were resolved. MRI revealed diffuse cerebral atrophy, 57 months after the relapse. No relapse has occurred for the past 5 years with decreased anti-GAD antibody after starting bimonthly administration of IVIG.

CONCLUSION

This may be the first case of severe and recurrent anti-GAD antibody-associated autoimmune encephalitis after HSCT with specific MRI findings. No relapse has occurred since starting maintenance IVIG.

The Deacetylase HDAC6 Mediates Endogenous Neuritic Tau Pathology

The initiating events that promote tau mislocalization and pathology in Alzheimer's disease (AD) are not well defined, partly because of the lack of endogenous models that recapitulate tau dysfunction. We exposed wild-type neurons to a neuroinflammatory trigger and examined the effect on endogenous tau. We found that tau re-localized and accumulated within pathological neuritic foci, or beads, comprised of mostly hypo-phosphorylated, acetylated, and oligomeric tau. These structures were detected in aged wild-type mice and were enhanced in response to neuroinflammation in vivo, highlighting a previously undescribed endogenous age-related tau pathology. Strikingly, deletion or inhibition of the cytoplasmic shuttling factor HDAC6 suppressed neuritic tau bead formation in neurons and mice. Using mass spectrometry-based profiling, we identified a single neuroinflammatory factor, the metalloproteinase MMP-9, as a mediator of neuritic tau beading. Thus, our study uncovers a link between neuroinflammation and neuritic tau beading as a potential early-stage pathogenic mechanism in AD.

Open study of pranlukast add-on therapy in intractable partial epilepsy

Innovative treatments of epileptic seizures are needed to improve the outcome of epilepsy. We studied the effect of pranlukast on seizure outcome in patients with intractable partial epilepsy. An open study was conducted to evaluate the clinical efficacy of 24-week pranlukast add-on therapy in 50 patients with intractable partial seizures. Serum concentrations of matrix metalloproteinase (MMP)-9 were determined using Biotrak Activity Assay System. Cytokines in cerebrospinal fluid (CSF) were measured by the BioPlex (BioRad) system and soluble TNF receptor1 (sTNFR1) in CSF was measured by the ELISA. Surface markers of lymphocytes in CSF were examined by cell-sorter. Seizure-free rate (SFR) was 13.6%, responder rate (RR) was 47.7%, and aggravation rate (AR) was 18.2% at the 13-24 week period after starting pranlukast. In patients with increased serum MMP-9 before pranlukast therapy (baseline), comparison of paired serum levels showed a significant decrease after pranlukast therapy. Baseline CSF levels of IL-1β and IL-6 were elevated in patients compared with disease controls. Of four patients with paired data, three (including a responder to pranlukast) showed decreased pro-inflammatory cytokines (IL-1β, IL-6, and TNFα), and four showed decreased sTNFR1, after pranlukast treatment, and only a responder had markedly decreased frequency of CD8+ T cells in CSF. Pranlukast reduces seizure frequencies probably by pleiotropic effects including normalization of MMP-9 in sera, reduced leakage of pro-inflammatory cytokines into CNS, and inhibition of extravasation of leucocytes from brain capillaries. Further investigations by double-blind control study and animal models are warranted.

MMP-9/TIMP-1 imbalance induced in human dendritic cells by Porphyromonas gingivalis

Matrix metalloproteinase-9 (MMP-9) cleaves collagen, allowing leukocytes to traffic toward the vasculature and the lymphatics. When MMP-9 is unregulated by tissue inhibitor of metalloproteinase-1 (TIMP-1), this can lead to tissue destruction. Dendritic cells (DCs) infiltrate the oral mucosa increasingly in chronic periodontitis, characterized by infection with several pathogens including Porphyromonas gingivalis. In this study, human monocyte-derived DCs were pulsed with different doses of lipopolysaccharide of P. gingivalis 381 and of Escherichia coli type strain 25922, as well as whole live isogenic fimbriae-deficient mutant strains of P. gingivalis 381. Levels of induction of MMP-9 and TIMP-1, as well as interleukin-10 (IL-10), which reportedly inhibits MMP-9 induction, were measured by several approaches. Our results reveal that lipopolysaccharide of P. gingivalis, compared with lipopolysaccharide from E. coli type strain 25922, is a relatively potent inducer of MMP-9, but a weak inducer of TIMP-1, contributing to a high MMP-9/TIMP-1 ratio.Whole live P. gingivalis strain 381, major fimbriae mutant DPG-3 and double mutant MFB were potent inducers of MMP-9, but minor fimbriae mutant MFI was not. MMP-9 induction was inversely proportional to IL-10 induction. These results suggest that lipopolysaccharide and the minor and the major fimbriae of P. gingivalis may play distinct roles in induction by DCs of MMP-9, a potent mediator of local tissue destruction and leukocyte trafficking.