Serum and CSF cytokines and matrix metalloproteinases in spinal tuberculosis

Immunopathology in human pulmonary tuberculosis: Inflammatory changes in the plasma milieu and impaired host immune cell functions

Host immune response is key for protection in tuberculosis, but the causative agent, Mycobacterium (M.) tuberculosis, manages to survive despite immune surveillance. Key mechanisms of immune protection have been identified, but the role of immunopathology in the peripheral blood of tuberculosis patients remains unclear. Tuberculosis immunopathology in the blood is characterised by patterns of immunosuppression and hyperinflammation. These seemingly contradictory findings and the pronounced heterogeneity made it difficult to interpret the results from previous studies and to derive implications of immunopathology. However, novel approaches based on comprehensive data analyses and revitalisation of an ancient plasma milieu in vitro assay connected inflammation with immunosuppressive factors in tuberculosis. Moreover, interrelations between the aberrant plasma milieu and immune cell pathology were observed. This review provides an overview of studies on changes in plasma milieu and discusses recent findings linking plasma factors to T-cell and monocyte/macrophage pathology in pulmonary tuberculosis patients.

Doxycycline as a Potential MMP-1 Inhibitor for the Treatment of Spondylitis Tuberculosis: A Study in Rabbit Model

Background

Tuberculosis (TB) of the spine is a highly disruptive disease, especially in underdeveloped and developing countries. This condition requires standard TB treatment for 9-18 months, which increases patient risk of drug-resistant TB. Consequently, this raises the concern of adopting additional therapies to shorten the treatment duration, improve the efficacy of anti-TB drugs, and further decrease damage in the affected tissues and organs. Matrix metalloproteinase- (MMP-) 1 is a key regulator of the destruction of the extracellular matrix and associated proteins and is a new potential target for TB treatment research. In the present study, we investigated the effects of doxycycline as an MMP-1 inhibitor in patients with spondylitis TB.

Methods

Seventy-two New Zealand white rabbits with spondylitis TB were divided into 12 different groups based on incubation period (2, 4, 6, and 8 weeks) and doxycycline administration (without, 1 mg/kg body weight (BW), and 5 mg/kg BW). We observed the course of infection through the blood concentration changes and immunohistochemical examination of MMP-1, in addition to BTA staining, culture, polymerase chain reaction (PCR), and histopathological examination.

Results

Treatment with once daily 5 mg/kg BW doxycycline significantly improved the blood MMP-1 level (p < 0.05) compared with the placebo and 1 mg/kg BW doxycycline. A significantly reduced ongoing infection and a higher healing rate were demonstrated in rabbits with a higher doxycycline dose through BTA staining, culture, PCR, and histopathology. Various degrees of vertebral endplates, vertebral body, and intervertebral disc destruction were observed in 32 rabbits with positive histopathological findings, in addition to positive inflammatory cell infiltration, characterized by numerous lymphocytes, macrophages, and epithelial cells, as well as abundant granulation tissue and necrotic substances proximal to the inoculated vertebral area. Bone and intervertebral disc destructions were more apparent in the untreated rabbits.

Conclusion

Our study demonstrated the potential of doxycycline as an adjunctive treatment in spondylitis TB. However, limitations remain regarding the differences in the pathogenesis and virulence of Mycobacterium tuberculosis between rabbit and human systems, sample size, and the dose-dependent effect of doxycycline. Further studies are needed to address these issues.

Inflammatory Markers Combined With Metalloproteinase-9, Neopterin, and S100B Concentrations May Indicate the Pathogenesis of Central Nervous System Diseases in Children

The identification of central nervous system inflammation etiology leads to adjusted therapy. We analyzed the potential inflammatory and neuro-axonal damage markers in children. Our target was to correlate the findings with a disease's course or a sequalae risk and assess their clinical usefulness. The study included 96 children with symptoms of central nervous system inflammation who underwent diagnostics. The research group involved 24 children with autoimmune disorders and 31 with neuroinfection. The control group included patients with both etiologies excluded. We analyzed the results of routine laboratory tests together with chosen serum (neopterin, interleukin [IL]-1β, IL-6) and CSF (metalloproteinase [MMP]-9, S100B protein) markers. In the whole cohort, CSF MMP-9 correlated with CSF cytosis and serum IL-6 and CRP. In the undivided neuroinflammatory group, CSF S100B correlated with serum IL-6 and IgM concentrations. CSF cytosis was associated with CSF MMP-9 and serum neopterin levels. Among the infective patients, IL-6 was linked with increased CSF MMP-9. We conclude that astroglial protein S100B, neopterin, and cytokine concentrations may enable predicting long-term consequences, whereas CSF MMP-9 concentration may reflect the actual central nervous system injury regardless of etiology.

Evaluation of host biomarkers for monitoring treatment response in spinal tuberculosis: A 12-month cohort study

BACKGROUND

Monitoring treatment response is an important precaution in spinal tuberculosis (TB), particularly when the condition was clinically diagnosed rather than bacteriologically confirmed and when drug susceptibility testing was not performed. Conventional monitoring measures have limitations and there is a need for favourable alternatives. Therefore, this study aimed to investigate changes in immune biomarkers over the course of treatment for spinal TB and to compare these responses to the conventional monitoring measure, erythrocyte sedimentation rate (ESR).

METHODS

Patients with spinal TB were recruited from a tertiary hospital in the Western Cape, South Africa, and provided blood samples at 0, 3, 6, 9 and 12 months of TB treatment. Blood samples were analysed for ESR, using standard techniques, and for 19 cytokines, using a multiplex platform. Changes in ESR and cytokine levels were investigated using a mixed model ANOVA and Least Significant Difference post-hoc testing.

RESULTS

Twenty-six patients with spinal TB were included in the study although only fifteen remained in follow-up at 12 months. Seven biomarkers changed significantly over the course of treatment (CRP, Fibrinogen, IFN-γ, Ferritin, VEGF-A, ApoA1 and NCAM, p < 0.01) with a further three showing a strong trend towards change (CCL1, CXCL9 and GDF-15, 0.05 ≥ p ≤ 0.06). Responsive biomarkers could be approximately grouped according to patterns of progressive, initial or delayed change. ESR performed similarly to CRP, Fibrinogen and IFN-γ with all showing significant decreases between 0, 6 and 12- months of treatment. Individual ESR responses were variable.

DISCUSSION

Individual ESR responses may be unreliable and support the investigation of multi-marker approaches to evaluating treatment response in spinal TB. Biomarkers of treatment response identified in the current study require validation in a larger study, which may also incorporate aspects such as evaluating biomarkers within the first week of treatment and the inclusion of a healthy control group.

Central Inflammatory Cytokines in Tuberculous Meningitis: A Systematic Review and Meta-analysis

No formal agreement exists regarding central inflammatory cytokine aberrations in tuberculosis (TB). We undertook a systematic review and meta-analysis of studies comparing cytokine levels in cerebrospinal fluid (CSF) from patients with TB compared with controls. We searched PubMed, Scopus, and Web of Science for articles published up to June 22, 2021. Studies were included in the meta-analysis if they assessed unadjusted levels of cytokines in unstimulated CSF samples and drew the comparison(s) between any of the following pairs: patients with TB versus controls without central nervous system (CNS) infection and meningitis, patients with TB versus patients with meningitis of etiologies other than Mycobacterium tuberculosis, HIV-infected patients with TB versus HIV-uninfected patients with TB, and HIV-infected patients with TB versus HIV-infected patients without TB. The primary outcome was the difference in mean CSF inflammatory cytokine levels between each of the 2 groups mentioned. The standardized mean difference was chosen to measure effect using a restricted maximum-likelihood estimator random-effects model. Of 1170 records identified, 40 studies were included in the meta-analysis. We calculated effect sizes for 30 different cytokines. About half of the studies took place in South Africa and India (18 out of 40 studies). Studies were mostly (92.5%) on patients with tuberculous meningitis (TBM), with only 3 articles of patients with neurotuberculosis and spinal TB. The quality of studies was rated as low to moderate and high with a 1.2:1 ratio. Compared with controls without CNS infection and meningitis, interferon-gamma (IFNγ), interleukin (IL)-12p40, IL-17F, IL-1β, IL-2, IL-4, IL-6, IL-8, sIL-2R, transforming growth factor beta (TGFβ), TGFβ1, and tumor necrosis factor alpha (TNFα) were increased in patients with TBM. Compared with patients with meningitis of etiologies other than M. tuberculosis or combined meningitis and nonmeningitis patients, patients with TBM had higher CSF concentrations of IFNγ, IL-13, and sIL-2R, whereas levels of IL-12p70, IL-15, IL-1Ra, IL-5, IL-7, IL-9, and sTNFR55 were decreased. Compared with patients with meningitis of bacterial etiologies other than M. tuberculosis, CSF levels of IFNγ and sIL-2R were increased in patients with TBM, whereas levels of IL-1Ra, IL-13, IL-17, and TNF R55-BP were decreased. Patients with TBM were not different from patients with CM for most CSF cytokines assessed, but IFNγ and IL-1β were increased. TNFα, IL-1β, IL-1Ra, IL-8, IFNγ, sIL-2R, IL-13, and IL-17 were higher in patients with TBM than those with viral or aseptic meningitis. Compared with HIV-negative patients with TBM, IFNγ, IL-10, IL-12p70, and IL-5 were decreased in HIV-positive patients with TBM, whereas IL-1β, TNFα, and IL-2 were increased. Elevated TNFα, IL-1β, IFNγ, IL-6, IL-17, and IFNα2 were found in HIV-positive patients with TBM compared with their counterparts without TBM. This study should be considered an explorative meta-analytic review, leading us to offer the best TBM-associated central inflammatory cytokines. Our study could prepare a panel of central cytokines as a potential aid in diagnosing TBM and its differentiation from meningitis of other etiologies.

Candidate Biomarkers to Distinguish Spinal Tuberculosis From Mechanical Back Pain in a Tuberculosis Endemic Setting

Background

Spinal tuberculosis (TB) may have a variable, non-specific presentation including back pain with- or without- constitutional symptoms. Further tools are needed to aid early diagnosis of this potentially severe form of TB and immunological biomarkers may show potential in this regard. The aim of this study was to investigate the utility of host serum biomarkers to distinguish spinal TB from mechanical back pain.

Methods

Patients with suspected spinal TB or suspected mechanical back pain were recruited from a tertiary hospital in the Western Cape, South Africa, and provided a blood sample for biomarker analysis. Diagnosis was subsequently confirmed using bacteriological testing, advanced imaging and/or clinical evaluation, as appropriate. The concentrations of 19 host biomarkers were evaluated in serum samples using the Luminex platform. Receiver Operating Characteristic (ROC) curves and General Discriminant Analysis were used to identify biomarkers with the potential to distinguish spinal TB from mechanical back pain.

Results

Twenty-six patients with spinal TB and 17 with mechanical back pain were recruited. Seven out of 19 biomarkers were significantly different between groups, of which Fibrinogen, CRP, IFN-γ and NCAM were the individual markers with the highest discrimination utility (Area Under Curve ROC plot 0.88-0.99). A five-marker biosignature (CRP, NCAM, Ferritin, CXCL8 and GDF-15) correctly classified all study participants after leave-one-out cross-validation.

Conclusion

This study identified host serum biomarkers with the potential to diagnose spinal TB, including a five-marker biosignature. These preliminary findings require validation in larger studies.

High Level of Soluble CD146 In Cerebrospinal Fluid Might be a Biomarker of Severity of Anti-N-Methyl-D-Aspartate Receptor Encephalitis

Background

Disruption of the blood–brain barrier (BBB) is an important pathophysiological process of anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis. A recent multi-center study showed that soluble (s) CD146 is a potential biomarker for monitoring early BBB damage and central nervous system inflammation, but little is known about sCD146 in anti-NMDAR encephalitis.

Method

Twenty-three anti-NMDAR encephalitis patients and seventeen controls with non-inflammatory neurological diseases were recruited. sCD146 and inflammatory cytokines in cerebrospinal fluid (CSF) and serum were detected by ELISA. Modified Rankin scale (mRS) scores were used to assess the neurological status of each patient. A follow-up review was completed three months after discharge.

Results

sCD146 levels in the CSF of patients with the acute stage anti-NMDAR encephalitis were significantly increased compared with controls and accompanied by increases in TNF-α, IL-6 and IL-10. CSF sCD146 was positively correlated with neuroinflammatory factors in the CSF and with mRS score. Three months after effective treatment, CSF sCD146 in patients was significantly decreased but remained significantly different compared with the controls.

Conclusion

Our data suggested that higher expression of CSF sCD146 correlated with more serious neurological damage. Therefore, levels of CSF sCD146 may represent a promising indicator for monitoring disease and optimizing clinical treatment decisions in the early stages of anti-NMDAR encephalitis.

Matrix Metalloproteinase Inspired Therapeutic Strategies for Bone Diseases

Matrix Metalloproteinases (MMPs), as a family of zinc-containing enzymes, show the function of decomposing Extracellular Matrix (ECM) and participate in the physiological processes of cell migration, growth, inflammation, and metabolism. Clinical and experimental studies have indicated that MMPs play an essential role in tissue injury and repair as well as tumor diagnosis, metastasis, and prognosis. An increasing number of researchers have paid attention to their functions and mechanisms in bone health and diseases. The present review focuses on MMPs-inspired therapeutic strategies for the treatment of bone-related diseases. We introduce the role of MMPs in bone diseases, highlight the MMPs-inspired therapeutic options, and posit MMPs as a trigger for smart cell/drug delivery.

Effect of Dexmedetomidine Hydrochloride on perioperative inflammation and postoperative lung infection in patients with spinal tuberculosis

Objective

To explore the effect of dexmedetomidine hydrochloride on perioperative inflammation and postoperative lung infection in patients with spinal tuberculosis.

Method

A double-blind control observation was conducted in spinal tuberculosis patients with the use of general anesthesia during the operation. A total of 171 spinal tuberculosis patients who received endotracheal intubation for general anesthesia in Henan University of Chinese Medicine from January 2017 to April 2019 were included. The concentration changes in serum TNF-α and IL-6 were recorded at one hour, six hour and one day after the operation. The incidence of postoperative pulmonary complications of patients were also evaluated.

Results

The results showed that in the experimental group compared with the control group, serum TNF-α and IL-6 concentrations one hour, six hour and one day after the operation were significantly lower (P<0.05). The rate of postoperative pulmonary complications was lower in the experimental group than that in the control group (P<0.05).

Conclusion

Dexmedetomidine hydrochloride has obvious anti-inflammatory effects and can reduce the incidence of pulmonary complications after surgery.

Quantitative proteomics of cerebrospinal fluid using tandem mass tags in dogs with recurrent epileptic seizures

This prospective study included four dog groups (group A: healthy dogs, groups B: dogs with idiopathic epilepsy under antiepileptic medication (AEM), C: idiopathic epilepsy dogs without AEM administration, D: dogs with structural epilepsy). The purpose of the study was to compare the proteomic profile among the four groups. Samples were analyzed by a quantitative Tandem Mass Tags approach using a Q-Exactive-Plus mass-spectrometer. Identification and relative quantification were performed using Proteome Discoverer, and data were analyzed using R. Gene ontology terms were analyzed based on Canis lupus familiaris database. Data are available via ProteomeXchange with identifier PXD018893. Eighteen proteins were statistically significant among the four groups (P < 0.05). MMP2 and EFEMP2 appeared down-regulated whereas HP and APO-A1 were up-regulated (groups B, D). CLEC3B and PEBP4 were up-regulated whereas APO-A1 was down-regulated (group C). IGLL1 was down-regulated (groups B, C) and up-regulated (group D). EFEMP2 was the only protein detected among the four groups and PEBP4 was significantly different among the epileptic dogs. Western blot and SPARCL immunoassay were used to quantify HP abundance change, validating proteomic analysis. Both, showed good correlation with HP levels identified through proteomic analysis (r = 0.712 and r = 0.703, respectively). SIGNIFICANCE: The proteomic analysis from CSF of dogs with epileptic seizures could reflect that MMP2, HP and APO-A1 may contribute to a blood-brain barrier disruption through the seizure-induced inflammatory process in the brain. MMP2 change may indicate the activation of protective mechanisms within the brain tissue. Antiepileptic medication could influence several cellular responses and alter the CSF proteome composition.

Mycobacterium tuberculosis infection increases the number of osteoclasts and inhibits osteoclast apoptosis by regulating TNF-α-mediated osteoclast autophagy

Osteoarticular tuberculosis, a chronic inflammatory disease characterized by Mycobacterium tuberculosis (M.tb) infection, has become a serious problem in China. The present study was conducted to determine the mechanism of action of tumor necrosis factor (TNF)-α in the pathogenesis of osteoarticular tuberculosis. The number of osteoclasts in osteoarticular tuberculosis tissue samples was detected by tartrate-resistant acid phosphatase staining. Autophagy and apoptosis of osteoclasts were detected by western blotting, reverse transcription-quantitative PCR, transmission electron microscopy and TUNEL staining. The results showed that autophagy and the number of osteoclasts increased in the lesions of patients with osteoarticular tuberculosis compared with osteoarthritis samples. Moreover, activation of osteoclast autophagy inhibited the apoptosis of osteoclasts infected with M.tb, and increased the expression level of TNF-α. The results showed that TNF-α enhanced the autophagic activity of M.tb-infected osteoclasts and inhibited cell apoptosis. These findings indicated that M.tb infection induced osteoclast production and inhibited osteoclast apoptosis by regulating TNF-α-mediated osteoclast autophagy, revealing a new mechanism for TNF-α in the pathogenesis of osteoarticular tuberculosis.

Hesperidin methyl chalcone alleviates spinal tuberculosis in New Zealand white rabbits by suppressing immune responses

Objective: Spinal tuberculosis (ST) refers to tuberculosis resulted from infections of Mycobacterium tuberculosis (Mtb) in the spinal cord. Hesperidin methyl chalcone (HMC) is a flavonoid derivative from citrus fruits with anti-inflammatory properties. We aimed to investigate the efficacy of HMC in treating ST in New Zealand white rabbit model. Design and Setting: Rabbits were infected in the sixth lumbar vertebral bodies with or without Mtb strain H37Rv followed by treatments with HMC. Outcome Measures: 10 weeks post treatments, the adjacent vertebral tissues were examined by hematoxylin-eosin staining. The expression levels of transcription factor κB (NF-κB) p65 and monocyte chemoattractant protein-1 (MCP-1/CCL2) in lymphocytes were determined using reverse transcription quantitative real-time PCR (RT-qPCR), Western blot and enzyme-linked immunosorbent assays (ELISA). The serum levels of interleukin (IL)-2, IL-4, IL-10 as well as interferon (IFN)-γ were also assessed using ELISA. Western blot was used to determine the effects of HMC on the phosphorylation of IKKα/β, p65, and IκBα in the signal transduction of NF-κB pathways. Results: HMC significantly attenuated the granulation in adjacent vertebral bone tissues. The expression of p65, IL-4, IL-10, and MCP-1 was reduced. The NF-κB pathway was suppressed, in which the phosphorylation of IκBα, IKKα/β, and p65 was inhibited whereas the relative level of IκBα was increased. Conclusion: HMC could serve as a therapeutic option to effectively inhibit granulomas formation through downregulation of MCP-1, IL-4, IL-10, and NF-κB in the treatment of ST.

Isoliquiritigenin attenuates spinal tuberculosis through inhibiting immune response in a New Zealand white rabbit model

Spinal tuberculosis (ST) is the tuberculosis caused by Mycobacterium tuberculosis (Mtb) infections in spinal curds. Isoliquiritigenin 4,2′,4′-trihydroxychalcone, ISL) is an anti-inflammatory flavonoid derived from licorice (Glycyrrhiza uralensis), a Chinese traditional medicine. In this study, we evaluated the potential of ISL in treating ST in New Zealand white rabbit models. In the model, rabbits (n=40) were infected with Mtb strain H37Rv or not in their 6^th lumbar vertebral bodies. Since the day of infection, rabbits were treated with 20 mg/kg and 100 mg/kg of ISL respectively. After 10 weeks of treatments, the adjacent vertebral bone tissues of rabbits were analyzed through Hematoxylin-Eosin staining. The relative expression of Monocyte chemoattractant protein-1 (MCP-1/CCL2), transcription factor κB (NF-κB) p65 in lymphocytes were verified through reverse transcription quantitative real-time PCR (RT-qPCR), western blotting and enzyme-linked immunosorbent assays (ELISA). The serum level of interleukin (IL)-2, IL-4, IL-10 and interferon γ (IFN-γ) were evaluated through ELISA. The effects of ISL on the phosphorylation of IκBα, IKKα/β and p65 in NF-κB signaling pathways were assessed through western blotting. In the results, ISL has been shown to effectively attenuate the granulation inside adjacent vertebral tissues. The relative level of MCP-1, p65 and IL-4 and IL-10 were retrieved. NF-κB signaling was inhibited, in which the phosphorylation of p65, IκBα and IKKα/β were suppressed whereas the level of IκBα were elevated. In conclusion, ISL might be an effective drug that inhibited the formation of granulomas through downregulating MCP-1, NF-κB, IL-4 and IL-10 in treating ST.

Immunological recovery in patients with pulmonary tuberculosis after intensive phase treatment

Objectives

This study aimed to examine the change and significance of immune parameters in patients with sputum smear-positive pulmonary tuberculosis (TB) after 2 months of intensive phase anti-TB treatment.

Methods

The immune parameters of 232 cases of sputum smear-positive pulmonary TB were detected before and after 2 months of intensive phase anti-TB treatment and compared with 50 cases from healthy volunteers (controls). The T lymphocyte cell population in peripheral blood was detected using flow cytometry. Serum levels of interleukin (IL)-1β, soluble interleukin-2 receptor, IL-6, and tumour necrosis factor-α were measured by ELISA.

Results

After 2 months of intensive phase anti-TB treatment, a reduction in the percentage of CD4+ T cells showed a significant restoration similar to that of controls. Moreover, after intensive anti-TB treatment, serum levels of IL-1β, soluble interleukin-2 receptor, IL-6, and tumour necrosis factor-α were significantly decreased compared with before treatment. Additionally, serum levels of IL-1β and IL-6 showed a diminished recovery compared with controls.

Conclusions

Our findings suggest immunological recovery in patients with pulmonary TB after intensive phase treatment. Therefore, serum cytokine levels are considered potential host biomarkers for monitoring the response of treatment for pulmonary TB.

Inhibition of Tissue Matrix Metalloproteinases Interferes with Mycobacterium tuberculosis-Induced Granuloma Formation and Reduces Bacterial Load in a Human Lung Tissue Model

Granulomas are hallmarks of pulmonary tuberculosis (TB) and traditionally viewed as host-protective structures. However, recent evidence suggest that Mycobacterium tuberculosis (Mtb) uses its virulence factors to stimulate the formation of granuloma. In the present study, we investigated the contribution of matrix metalloproteinases (MMPs), host enzymes that cause degradation of the extracellular matrix, to granuloma formation and bacterial load in Mtb-infected tissue. To this end, we used our lung tissue model for TB, which is based on human lung-derived cells and primary human monocyte-derived macrophages. Global inhibition of MMPs in the Mtb-infected tissue model reduced both granuloma formation and bacterial load. The infection caused upregulation of a set of MMPs (MMP1, 3, 9, and 12), and this finding could be validated in lung biopsies from patients with non-cavitary TB. Data from this study indicate that MMP activation contributes to early TB granuloma formation, suggesting that host-directed, MMP-targeted intervention could be considered as adjunct therapy to TB treatment.

RETRACTED: The in vitro and in vivo effects of microRNA-133a on intervertebral disc destruction by targeting MMP9 in spinal tuberculosis

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor-in-Chief. Concern was raised about the reliability of the Western blot results in Figure 4 A+C, which appear to have a similar phenotype as seen in many other publications, as detailed here: https://pubpeer.com/publications/0D0667F09124C7911264C51064AF20; and here: https://docs.google.com/spreadsheets/d/1r0MyIYpagBc58BRF9c3luWNlCX8VUvUuPyYYXzxWvgY/edit#gid=262337249. The journal requested that the corresponding author comment on these concerns and provide the raw data. The authors did not respond to this request and therefore the Editor-in-Chief decided to retract the article.

Profiling of metalloprotease activities in cerebrospinal fluids of patients with neoplastic meningitis

Background

Neoplastic invasion into leptomeninges and subarachnoid space, resulting in neoplastic meningitis (NM) is a fatal complication of advanced solid and hematological neoplasms. Identification of malignant involvement of the cerebrospinal fluid (CSF) early in the disease course has crucial prognostic and therapeutic implications, but remains challenging. As indicators of extracellular matrix (ECM) degradation and breakdown of the blood–brain-barrier, Matrix Metalloproteases (MMPs) and A Disintegrin and Metalloproteases (ADAMs) are potential analytes for cerebral pathophysiology and metastatic dissemination of tumor cells into the CSF.

Methods

We compared protease activities in CSF samples from patients with NM and control individuals using FRET-based metalloprotease substrates with distinct enzyme selectivity profiles in a real-time, multiplex approach termed “proteolytic activity matrix assay” (PrAMA). Protease activity dynamics can be tracked by fluorescence changes over time. By simultaneously monitoring a panel of 5 FRET-substrate cleavages, a proteolytic signature can be identified and analyzed to infer the activities of multiple specific proteases. Distinct patterns of substrate cleavage comparing disease vs. control samples allow rapid, reproducible and sensitive discrimination even in small volumes of CSF.

Results

Individual substrate cleavage rates were linked to distinct proteases, and PrAMA computational inference implied increased activities of MMP-9, ADAM8 and ADAM17 (4–5-fold on average) in CSF samples from NM patients that were inhibitable by the metalloprotease inhibitor batimastat (BB-94). The activities of these proteases correlated with blood–brain barrier impairment. Notably, CSF cell counts were not found to directly reflect the protease activities observed in CSF samples from NM patients; this may explain the frequent clinical observation of negative cytology in NM patients.

Conclusion

PrAMA analysis of CSF samples is a potential diagnostic method for sensitive detection of NM and may be suitable for the clinical routine.

Electronic supplementary material

The online version of this article (doi:10.1186/s12987-017-0070-5) contains supplementary material, which is available to authorized users.