Correlation of CSF proinflammatory cytokines with MRI in tuberculous meningitis

Alterations of white matter integrity in patients with intracranial tuberculosis: A tract-based spatial statistics study

OBJECTIVE

Intracranial tuberculosis has high mortality and morbidity. Its physiopathologic mechanism, especially neurocognitive mechanism, remains unclear, and there are few studies on white matter in such patients. This study aimed to investigate the white matter abnormalities in patients with intracranial tuberculosis using tract-based spatial statistics (TBSS) method of diffusion tensor imaging (DTI).

METHODS

Fifty patients with intracranial tuberculosis and 49 healthy controls (HCs) were included in this study. Differences in the fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD), and axial diffusivity (AD) between patients and HCs were investigated using TBSS analysis. Partial correlation analysis was performed to explore correlations between DTI values and cognitive functions in patients with intracranial tuberculosis, with age and gender as covariates. Subgroup analysis was also conducted using the same method.

RESULTS

Compared to HCs, patients with intracranial tuberculosis showed a widespread reduction of FA and increase of MD, RD and AD (P < 0.05, TFCE and FWE corrected). Notably, abnormalities in all four metrics were observed in 25 white matter tracts according to the Johns Hopkins University ICBM-DTI-81 White Matter Atlas. Patients with mixed intracranial tuberculosis (mixed-ITB) showed increased AD in a limited range compared with patients with tuberculous meningitis (TBM). With age and gender considered, the MD, RD and AD values in some regions significantly correlated with the cognitive assessment scores.

CONCLUSIONS

The results of this study indicated that patients with intracranial tuberculosis might have widespread abnormalities in the white matter of the brain, which might associate with their cognitive impairment.

Rifampicin and its neuroprotective properties in humans - A systematic review

BACKGROUND

Rifampicin is an antimicrobial drug used in the treatment of mycobacterial and gram-positive bacterial infections. In vitro studies suggest additional rifampicin-associated reduction of neurotoxicity. The aim of this study was to review the evidence for neuroprotective effects of rifampicin in infectious and non-infectious diseases in human studies.

METHODS

A systematic literature search was done in MEDLINE and Embase including studies from 1 Jan 1946/47-20 Jan 2024, in accordance with the preferred reporting items for systematic reviews and meta-analysis (PRISMA) (PROSPERO ID: CRD42022349852). Original articles investigating the effect of rifampicin on infections of the central nervous system (CNS) or on neurodegenerating diseases, were included. Screening, data extraction and risk of bias assessment were done using the Covidence software. Two authors assessed and extracted articles independently and blinded to each other.

RESULTS

1438 articles were identified of which eight were included in the final analysis: Four studies included patients with infectious diseases and four studies with neurodegenerative diseases. A neuroprotective effect of rifampicin was shown in five studies. The studies found reduced inflammatory parameters in the cerebrospinal fluid, improved neurological outcome, less cognitive decline, less brain atrophy or less metabolic decline on imaging as an effect of rifampicin. One RCT showed worsening of cognitive assessment scales in neurodegenerative patients.

CONCLUSION

Current evidence suggests a neuroprotective effect of rifampicin in humans. As evaluation of neuroprotection is not standardized, a consensus definition for evaluation of clinical, radiological, and neuropsychological follow-up after pharmacological intervention would be helpful for future studies assessing neuroprotection.

Brain MRI findings in relation to clinical characteristics and outcome of tuberculous meningitis

Neuroradiological abnormalities in tuberculous meningitis (TBM) are common, but the exact relationship with clinical and inflammatory markers has not been well established. We performed magnetic resonance imaging (MRI) at baseline and after two months treatment to characterise neuroradiological patterns in a prospective cohort of adult TBM patients in Indonesia. We included 48 TBM patients (median age 30, 52% female, 8% HIV-infected), most of whom had grade II (90%), bacteriologically confirmed (71%) disease, without antituberculotic resistance. Most patients had more than one brain lesion (83%); baseline MRIs showed meningeal enhancement (89%), tuberculomas (77%), brain infarction (60%) and hydrocephalus (56%). We also performed an exploratory analysis associating MRI findings to clinical parameters, response to treatment, paradoxical reactions and survival. The presence of multiple brain lesion was associated with a lower Glasgow Coma Scale and more pronounced motor, lung, and CSF abnormalities (p-value <0.05). After two months, 33/37 patients (89%) showed worsening of MRI findings, mostly consisting of new or enlarged tuberculomas. Baseline and follow-up MRI findings and paradoxical responses showed no association with six-month mortality. Severe TBM is characterized by extensive MRI abnormalities at baseline, and frequent radiological worsening during treatment.

Evidence for genetic correlation between human cerebral white matter microstructure and inflammation

White matter microstructure is affected by immune system activity via the actions of circulating pro-inflammatory cytokines. Although white matter microstructure and inflammatory measures are significantly heritable, it is unclear if overlapping genetic factors influence these traits in humans. We conducted genetic correlation analyses of these traits using randomly ascertained extended pedigrees from the Genetics of Brain Structure and Function Study (N = 1862, 59% females, ages 18-97 years; 42 ± 15.7). White matter microstructure was assessed using fractional anisotropy (FA) calculated from diffusion tensor imaging (DTI). Circulating levels (pg/mL) of pro-inflammatory cytokines (IL-6, IL-8, and TNFα) phenotypically associated with white matter microstructure were quantified from blood serum. All traits were significantly heritable (h² ranging from 0.41 to 0.66 for DTI measures and from 0.18 to 0.30 for inflammatory markers). Phenotypically, higher levels of circulating inflammatory markers were associated with lower FA values across the brain (r = -.03 to r = -.17). There were significant negative genetic correlations between most DTI measures and IL-8 and TNFα, although effects for TNFα were no longer significant when covarying for body mass index. Genetic correlations between DTI measures and IL-6 were not significant. Understanding the genetic correlation between specific inflammatory markers and DTI measures may help researchers focus questions related to inflammatory processes and brain structure.

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.

CXCR7 antagonism prevents axonal injury during experimental autoimmune encephalomyelitis as revealed by in vivo axial diffusivity

Background

Multiple Sclerosis (MS) is characterized by the pathological trafficking of leukocytes into the central nervous system (CNS). Using the murine MS model, experimental autoimmune encephalomyelitis (EAE), we previously demonstrated that antagonism of the chemokine receptor CXCR7 blocks endothelial cell sequestration of CXCL12, thereby enhancing the abluminal localization of CXCR4-expressing leukocytes. CXCR7 antagonism led to decreased parenchymal entry of leukocytes and amelioration of ongoing disease during EAE. Of note, animals that received high doses of CXCR7 antagonist recovered to baseline function, as assessed by standard clinical scoring. Because functional recovery reflects axonal integrity, we utilized diffusion tensor imaging (DTI) to evaluate axonal injury in CXCR7 antagonist- versus vehicle-treated mice after recovery from EAE.

Methods

C57BL6/J mice underwent adoptive transfer of MOG-reactive Th1 cells and were treated daily with either CXCR7 antagonist or vehicle for 28 days; and then evaluated by DTI to assess for axonal injury. After imaging, spinal cords underwent histological analysis of myelin and oligodendrocytes via staining with luxol fast blue (LFB), and immunofluorescence for myelin basic protein (MBP) and glutathione S-transferase-π (GST-π). Detection of non-phosphorylated neurofilament H (NH-F) was also performed to detect injured axons. Statistical analysis for EAE scores, DTI parameters and non-phosphorylated NH-F immunofluorescence were done by ANOVA followed by Bonferroni post-hoc test. For all statistical analysis a p < 0.05 was considered significant.

Results

In vivo DTI maps of spinal cord ventrolateral white matter (VLWM) axial diffusivities of naïve and CXCR7 antagonist-treated mice were indistinguishable, while vehicle-treated animals exhibited decreased axial diffusivities. Quantitative differences in injured axons, as assessed via detection of non-phosphorylated NH-F, were consistent with axial diffusivity measurements. Overall, qualitative myelin content and presence of oligodendrocytes were similar in all treatment groups, as expected by their radial diffusivity values. Quantitative assessment of persistent inflammatory infiltrates revealed significant decreases within the parenchyma of CXCR7 antagonist-treated mice versus controls.

Conclusions

These data suggest that CXCR7 antagonism not only prevents persistent inflammation but also preserves axonal integrity. Thus, targeting CXCR7 modifies both disease severity and recovery during EAE, suggesting a role for this molecule in both phases of disease.