Evaluation of free radical status in CSF in childhood meningitis

High Concentration of Protein Oxidation Biomarker O-Tyr/Phe Predicts Better Outcome in Childhood Bacterial Meningitis

Neuronal damage in bacterial meningitis (BM) partly stems from the host´s inflammatory response and induced oxidative stress (OS). We studied the association of cerebrospinal fluid (CSF) biomarkers indicating oxidative damage to proteins with course of illness and outcome in childhood BM in Angola. Ortho-tyrosine/phenylalanine (o-Tyr/Phe), 3-chlorotyrosine/para-tyrosine (3Cl-Tyr/p-Tyr), and 3-nitrotyrosine/para-tyrosine (3NO2-Tyr/p-Tyr) concentration ratios were measured in 79 BM admission CSF samples, employing liquid chromatography coupled to tandem mass spectrometry. Besides death, disease outcomes were registered on Day 7 of treatment and one month after discharge (control visit). The outcome was graded according to the modified Glasgow Outcome Scale (GOS), which considers neurological and audiological sequelae. Children with a o-Tyr/Phe ratio below the median were more likely to present focal convulsions and secondary fever during recovery and suboptimal outcome (GOS < 5) on Day 7 and at control visit (odds ratio (OR) 2.85; 95% CI 1.14–7.14 and OR 5.23; 95% CI 1.66–16.52, respectively). Their most common sequela was ataxia on Day 7 and at control visit (OR 8.55; 95% CI 2.27–32.22 and OR 5.83; 95% CI 1.12–30.4, respectively). The association of a higher admission CSF o-Tyr/Phe ratio with a better course and outcome for pediatric BM points to a beneficial effect of OS.

Analysis of Tuberculosis Meningitis Pathogenesis, Diagnosis, and Treatment

Tuberculosis (TB) is the most prevalent infectious disease in the world. In recent years there has been a significant increase in the incidence of TB due to the emergence of multidrug resistant strains of Mycobacterium tuberculosis (M. tuberculosis) and the increased numbers of highly susceptible immuno-compromised individuals. Central nervous system TB, includes TB meningitis (TBM-the most common presentation), intracranial tuberculomas, and spinal tuberculous arachnoiditis. Individuals with TBM have an initial phase of malaise, headache, fever, or personality change, followed by protracted headache, stroke, meningismus, vomiting, confusion, and focal neurologic findings in two to three weeks. If untreated, mental status deteriorates into stupor or coma. Delay in the treatment of TBM results in, either death or substantial neurological morbidity. This review provides latest developments in the biomedical research on TB meningitis mainly in the areas of host immune responses, pathogenesis, diagnosis, and treatment of this disease.

Overview of Brain-to-Gut Axis Exposed to Chronic CNS Bacterial Infection(s) and a Predictive Urinary Metabolic Profile of a Brain Infected by Mycobacterium tuberculosis

A new paradigm in neuroscience has recently emerged - the brain-gut axis (BGA). The contemporary focus in this paradigm has been gut → brain ("bottom-up"), in which the gut-microbiome, and its perturbations, affects one's psychological state-of-mind and behavior, and is pivotal in neurodegenerative disorders. The emerging brain → gut ("top-down") concept, the subject of this review, proposes that dysfunctional brain health can alter the gut-microbiome. Feedback of this alternative bidirectional highway subsequently aggravates the neurological pathology. This paradigm shift, however, focuses upon non-communicable neurological diseases (progressive neuroinflammation). What of infectious diseases, in which pathogenic bacteria penetrate the blood-brain barrier and interact with the brain, and what is this effect on the BGA in bacterial infection(s) that cause chronic neuroinflammation? Persistent immune activity in the CNS due to chronic neuroinflammation can lead to irreversible neurodegeneration and neuronal death. The properties of cerebrospinal fluid (CSF), such as immunological markers, are used to diagnose brain disorders. But what of metabolic markers for such purposes? If a BGA exists, then chronic CNS bacterial infection(s) should theoretically be reflected in the urine. The premise here is that chronic CNS bacterial infection(s) will affect the gut-microbiome and that perturbed metabolism in both the CNS and gut will release metabolites into the blood that are filtered (kidneys) and excreted in the urine. Here we assess the literature on the effects of chronic neuroinflammatory diseases on the gut-microbiome caused by bacterial infection(s) of the CNS, in the context of information attained via metabolomics-based studies of urine. Furthermore, we take a severe chronic neuroinflammatory infectious disease - tuberculous meningitis (TBM), caused by Mycobacterium tuberculosis, and examine three previously validated CSF immunological biomarkers - vascular endothelial growth factor, interferon-gamma and myeloperoxidase - in terms of the expected changes in normal brain metabolism. We then model the downstream metabolic effects expected, predicting pivotal altered metabolic pathways that would be reflected in the urinary profiles of TBM subjects. Our cascading metabolic model should be adjustable to account for other types of CNS bacterial infection(s) associated with chronic neuroinflammation, typically prevalent, and difficult to distinguish from TBM, in the resource-constrained settings of poor communities.

Protein Oxidation Biomarkers and Myeloperoxidase Activation in Cerebrospinal Fluid in Childhood Bacterial Meningitis

The immunological response in bacterial meningitis (BM) causes the formation of reactive oxygen and nitrogen species (ROS, RNS) and activates myeloperoxidase (MPO), an inflammatory enzyme. Thus, structural oxidative and nitrosative damage to proteins and DNA occurs. We aimed to asses these events in the cerebrospinal fluid (CSF) of pediatric BM patients. Phenylalanine (Phe), para-tyrosine (p-Tyr), nucleoside 2'-deoxiguanosine (2dG), and biomarkers of ROS/RNS-induced protein and DNA oxidation: ortho-tyrosine (o-Tyr), 3-chlorotyrosine (3Cl-Tyr), 3-nitrotyrosine (3NO₂-Tyr) and 8-oxo-2'-deoxyguanosine (8OHdG), concentrations were measured by liquid chromatography coupled to tandem mass spectrometry in the initial CSF of 79 children with BM and 10 without BM. All biomarkers, normalized with their corresponding precursors, showed higher median concentrations (p < 0.0001) in BM compared with controls, except 8OHdG/2dG. The ratios o-Tyr/Phe, 3Cl-Tyr/p-Tyr and 3NO₂-Tyr/p-Tyr were 570, 20 and 4.5 times as high, respectively. A significantly higher 3Cl-Tyr/p-Tyr ratio was found in BM caused by Streptococcus pneumoniae, than by Haemophilus influenzae type b, or Neisseria meningitidis (p = 0.002 for both). In conclusion, biomarkers indicating oxidative damage to proteins distinguished BM patients from non-BM, most clearly the o-Tyr/Phe ratio. The high 3Cl-Tyr/p-Tyr ratio in pneumococcal meningitis suggests robust inflammation because 3Cl-Tyr is a marker of MPO activation and, indirectly, of inflammation.

Role of Oxidative Stress in Tuberculous Meningitis: a Clinico-Radiological Correlation

Central nervous system infection may be associated with oxidative stress and may influence clinical severity and outcome. We report oxidative stress markers in the patients with tuberculous meningitis (TBM) and correlate these with clinico-radiological severity and outcome. Fifty-six patients with TBM diagnosed on the basis of clinical, cerebrospinal fluid (CSF), and magnetic resonance (MRI) were included. Plasma glutathione (GSH), total antioxidant capacity (TAC), and malondialdehyde (MDA) were measured in the patients and 55 matched healthy controls. Hospital death was noted. Disabilities at 3 and 6 months were categorized using the modified Rankin Scale (mRS) as poor (mRS > 2) or good (mRS ≤ 2). The patients had lower levels of GSH (1.49 ± 0.49 vs 2.57 ± 0.39 mg/dL, p ˂ 0.001) and TAC (0.25 ± 0.17 vs 2.20 ± 0.31 mmol Trolox Eq/L, p ˂ 0.001), and higher level of MDA (6.61 ± 1.72 vs 3.09 ± 0.38 nmol/mL, p < 0.001) compared to controls. Total antioxidant capacity correlated with cranial nerve palsy and CSF pleocytosis. Patients with tuberculoma had lower GSH compared to those without. Six patients died in the hospital, and they had lower GSH (p < 0.01) and TAC (p = 0.02) levels compared to those who survived. Thirty-one and 36 patients had a good outcome at 3 and 6 months respectively. The patients with good outcome had higher GSH level.

Tuberculous meningitis

Tuberculosis remains a global health problem, with an estimated 10.4 million cases and 1.8 million deaths resulting from the disease in 2015. The most lethal and disabling form of tuberculosis is tuberculous meningitis (TBM), for which more than 100,000 new cases are estimated to occur per year. In patients who are co-infected with HIV-1, TBM has a mortality approaching 50%. Study of TBM pathogenesis is hampered by a lack of experimental models that recapitulate all the features of the human disease. Diagnosis of TBM is often delayed by the insensitive and lengthy culture technique required for disease confirmation. Antibiotic regimens for TBM are based on those used to treat pulmonary tuberculosis, which probably results in suboptimal drug levels in the cerebrospinal fluid, owing to poor blood-brain barrier penetrance. The role of adjunctive anti-inflammatory, host-directed therapies - including corticosteroids, aspirin and thalidomide - has not been extensively explored. To address this deficit, two expert meetings were held in 2009 and 2015 to share findings and define research priorities. This Review summarizes historical and current research into TBM and identifies important gaps in our knowledge. We will discuss advances in the understanding of inflammation in TBM and its potential modulation; vascular and hypoxia-mediated tissue injury; the role of intensified antibiotic treatment; and the importance of rapid and accurate diagnostics and supportive care in TBM.

Temporal changes of oxidative stress markers in Escherichia coli K1-induced experimental meningitis in a neonatal rat model

Despite advances in antimicrobial therapy and advanced critical care neonatal bacterial meningitis has a mortality rate of over 10% and induces neurological sequelae in 20-50% of cases. Escherichia coli K1 (E. coli K1) is the most common gram-negative organism causing neonatal meningitis and is the second most common cause behind group B streptococcus. We previously reported that an E. coli K1 experimental meningitis infection in neonatal rats resulted in habituation and aversive memory impairment and a significant increase in cytokine levels in adulthood. In this present study, we investigated the oxidative stress profile including malondialdehyde (MDA) levels, carbonyl protein formation, myeloperoxidase activity (MPO) activity, superoxide dismutase (SOD) activity and catalase (CAT) activity 6, 12, 24, 48, 72 and 96h after E. coli K1 experimental meningitis infection. In addition, sulfhydryl groups, nitrite and nitrate levels and activity of the mitochondrial respiratory chain enzymes were also measured in the frontal cortex and hippocampus of neonatal rats. The results from this study demonstrated a significant increase in MDA, protein carbonyls and MPO activity and a simultaneous decrease in SOD activity in the hippocampus of the neonatal meningitis survivors but the same was not observed in frontal cortex. In addition, we also observed a significant increase in complex IV activity in the hippocampus and frontal cortex of meningitis survivor rats. Thus, the results from this study reaffirmed the possible role of oxidative stress, nitric oxide and its related compounds in the complex pathophysiology of E. coli K1-induced bacterial meningitis.

Oxidative stress in children with bacterial meningitis

Bacterial meningitis is a common cause of morbidity and mortality in children. The oxidative stress in bacterial meningitis is barely determined. Forty children with bacterial meningitis were studied for their oxidants and antioxidants status in serum and cerebrospinal fluid. Fever (95%) was commonest presentation followed by seizure and vomiting. Neck rigidity and Kernig's sign were present in 37.5% and 27.5% cases, respectively. Plasma and cerebrospinal fluid malondialdehyde, protein carbonyl and nitrite levels were significantly raised in cases (p < 0.001). Plasma and cerebrospinal fluid ascorbic acid, glutathione and superoxide dismutase levels were significantly decreased in children with septic meningitis (p < 0.001). Significantly elevated malondialdehyde, nitrite and protein carbonyl levels reflect increased oxidative stress, whereas decreased concentrations of glutathione, ascorbic acid and superoxide dismutase indicates utilization of the antioxidants in septic meningitis. Thus, changes in oxidants and antioxidants observed suggest production of reactive oxygen species and their possible role in pathogenesis of septic meningitis.

Oxidative stress in children with neurocysticercosis

BACKGROUND

Free radicals can cause neuronal injury and play an important role in pathogenesis of neurocysticercosis. This study was done to evaluate oxidative stress (antioxidants and oxidants) in cerebrospinal fluid (CSF) of children with neurocysticercosis and to observe their correlation with the type of seizure and outcome.

METHODS

Forty consecutive confirmed cases of neurocysticercosis were evaluated for their markers of reactive oxygen species, that is, oxidants (malondialdehyde, protein carbonyl and nitrite) and antioxidant (superoxide dismutase, glutathione peroxidase, ceruloplasmin, ascorbic acid, copper and zinc) concentrations in CSF. An equal number of children, age and sex matched with an idiopathic generalized tonic-clonic seizure, were studied as controls.

RESULTS

Generalized tonic-clonic seizure (65%) was the most common presentation, and a single ring-enhancing lesion in the parietal lobe was the most common finding in cranial imaging. Oxidants such as malondialdehyde, protein carbonyl and nitrite in CSF were significantly elevated (P < 0.001), whereas antioxidants such as superoxide dismutase, glutathione peroxidase, ceruloplasmin, ascorbic acid, copper and zinc levels were significantly lower (P < 0.001) in children with neurocysticercosis than in controls. There were insignificant differences in oxidant and antioxidant value in CSF in relation to the type of seizure, number and location of lesion in cerebral cortex and antiepileptic therapy.

CONCLUSION

The significantly elevated malondialdehyde, nitrite and protein carbonyl values reflect increased oxidative stress, whereas decreased concentrations of glutathione peroxidase, ascorbic acid, zinc, copper, ceruloplasmin and superoxide dismutase point toward utilization of the antioxidants in neurocysticercosis. The observed changes in oxidants and antioxidants suggest the production of reactive oxygen species such as superoxide, hydrogen peroxides and hydroxyl radicals and their possible role in pathogenesis of neurocysticercosis.

Brief Clinical Report: EVALUATION OF ANTIOXIDANT STATUS IN CHILDREN WITH ACUTE BACTERIAL MENINGITIS AND ENCEPHALITIS

Antioxidant status was investigated in children with acute bacterial meningitis and encephalitis to investigate the possible role of free radicals in children with meningitis and encephalitis. Our study included 16 children with acute bacterial meningitis, 13 with encephalitis, and 17 control subjects. Serum ceruloplasmin, uric acid, albumin, bilirubin superoxide dismutase (SOD), catalase, and glutathione peroxidase (GPx) levels were studied in all subjects within 6 h of admission. There was a statistically significant difference between the groups for all parameters except for serum uric acid. All antioxidant activities except for albumin level were increased in the study groups. Albumin level was higher in the control group than those of meningitis and encephalitis groups. When the values of meningitis and encephalitis were compared, there was a statistically significant difference between the groups for serum SOD, GPx, ceruloplasmin, and albumin. In conclusion, our study showed that serum SOD, GPx, catalase, and ceruloplasmin were higher in children with acute bacterial meningitis and serum SOD, GPx, catalase, ceruloplasmin, and total bilirubin levels were increased in children with encephalitis. These findings suggest that antioxidant status was almost similar in both acute bacterial meningitis and encephalitis conditions in childhood.

Oxidant and antioxidant parameters in the treatment of meningitis

The aim of this study was to assess the effects of meningitis treatment on the serum and cerebrospinal-fluid oxidant and antioxidant status in children with bacterial meningitis. Forty children with bacterial meningitis, at ages ranging from 4 months to 12 years (mean age, 4 years), were enrolled in the study. Within 8 hours after admission (before treatment) and 10 days after clinical and laboratory indications of recovery (after treatment), cerebrospinal fluid and venous blood were collected. Thirty-seven healthy children (mean age, 4 years) were enrolled as control subjects, and only venous blood was collected. Serum total oxidant status, lipid hydroperoxide, oxidative stress index, uric acid, albumin, and ceruloplasmin levels were lower in the patient group after treatment (P<0.05). Serum total antioxidant capacity levels, vitamin C, total bilirubin, and catalase concentrations were not significantly altered by treatment (P>0.05). However, cerebrospinal fluid total oxidant status, lipid hydroperoxide, and oxidative stress index levels were higher, and cerebrospinal fluid total antioxidant capacity levels were lower after treatment than before treatment (P<0.05). In conclusion, we demonstrated that serum oxidative stress was lower, and cerebrospinal fluid oxidative stress was higher, after rather than before treatment in children with bacterial meningitis.

Total antioxidant/oxidant status in meningism and meningitis

The objective of this study was to investigate the antioxidant/oxidant status of serum and cerebrospinal fluid in children with meningismus and acute bacterial meningitis. Twenty-three children (age range, 0.75 to 9 years) with fever and meningeal signs that required analysis of the cerebrospinal fluid, but no cytologic or biochemical evidence of meningitis in their serum and cerebrospinal fluid, constituted the meningismus group. Thirty-one children (age range, 0.5 to 10 years) with acute bacterial meningitis constituted the meningitis group. Twenty-nine healthy children (age range, 0.5 to 11 years) were recruited as control subjects. Antioxidant status (ascorbic acid, albumin, thiol, uric acid, total bilirubin, total antioxidant capacity, catalase and ceruloplasmin concentrations) and oxidant status (lipid hydroperoxide and total oxidant status) were measured. The serum antioxidant status was lower, and oxidant status levels higher in both meningitis and meningismus subjects than in the control children (P < 0.001). Cerebrospinal fluid oxidant status was lower in the meningitis group than in the meningismus group (P < 0.05). These results indicate that serum antioxidant status was lower, and serum oxidant status was higher in children in the meningismus and meningitis groups, whereas cerebrospinal fluid oxidant status was higher in the meningismus group than in the meningitis group.

A comparative study of nitric oxide, glutathione, and glutathione peroxidase activities in cerebrospinal fluid from children with convulsive diseases/children with aseptic meningitis

It has been reported that active oxygen and/or free radicals are produced in the central nervous system (CNS) compartment in patients with bacterial meningitis, so it is supposed that the levels of endogenous antioxidative scavengers in the cerebrospinal fluid (CSF) are elevated as an adaptive reaction to bacterial meningitis, which exerts severe stress on the human body. We assumed that they are also elevated in patients with convulsive diseases. Nitric oxide (NO) and endogenous antioxidative scavengers (glutathione (GSH), glutathione peroxidase (GPX), (total) superoxide dismutase (T-SOD), manganese superoxide dismutase (Mn-SOD), and catalase) were measured in CSF from a group of child patients with various neurological diseases and a control group. NO, GSH, and GPX activities in CSF from the patients with convulsive diseases were significantly higher than in those with aseptic meningitis or in the controls. Furthermore, all parameters in CSF from patients with bacterial meningitis were significantly higher than in any other group. The present study suggests that oxidative stress may be associated with the pathophysiology of convulsion and that its clinical attenuation will lead to improvement in the prognosis for convulsive diseases.

Brief clinical study: Lipid peroxidation and antioxidant status in children with acute purulent meningitis and encephalitis

In this study, lipid peroxidation and antioxidant status were investigated in children with acute bacterial meningitis and encephalitis. The aim was to determine whether there was a possible role of free radicals in meningitis and encephalitis in childhood. Our study included 16 children with acute bacterial meningitis, 13 with encephalitis, and 17 control subjects. Serum malondialdehyde (MDA), reduced glutathione (GSH), vitamin C, vitamin E, beta-carotene, and retinol levels were studied in all subjects within 6 h of admission. There was a statistically significant difference for serum MDA, GSH, and vitamin C between the groups. Serum MDA and vitamin C levels were higher, and serum GSH levels were lower in the study groups compared to the control group. Vitamin C levels were similar in both the encephalitis and control groups, but they were significantly lower in the children with encephalitis than the meningitis group. In conclusion, our study showed that serum MDA and GSH levels were affected in children with both meningitis and encephalitis, but vitamin C level was affected only in children with meningitis. Serum vitamin E, beta-carotene, and retinol levels were not changed in childhood meningitis and encephalitis.