Complex regulation of neutrophil-derived MMP-9 secretion in central nervous system tuberculosis

The association between neutrophil percentage-to-albumin ratio (NPAR) and depression among US adults: a cross-sectional study

Inflammation plays an important role in depression, and the neutrophil-to-albumin ratio (NPAR) is a cost-effective and readily available novel biomarker of inflammation. The association between NPAR and depression is unclear; therefore, to assess the relationship between NPAR and depression, we conducted a cross-sectional study of 33,768 participants ≥ 18 years of age from the 2005-2018 NHANES database. NPAR was calculated as Neutrophil percentage (in total WBC count) (%) × 100/Albumin (g/dL). Multivariate logistic regression models were used to test the independent association between NPAR and depression, adjusting for demographic factors, education, smoking status, alcohol consumption, hypertension, diabetes mellitus, body mass index, the ratio of income to poverty, and history of cardiovascular disease. Results showed that NPAR was significantly and positively associated with depression. When NPAR were analyzed as a categorical variable, there was a 20% increase in the prevalence of depression in the quartile with the highest NPAR compared to the quartile with the lowest NPAR (OR 1.20[95% CI 1.06, 1.36]). Smoothed curve fitting and threshold effect analyses also showed a positive association between NPAR and depression, with an inflection point for threshold and saturation effects of 12.65. NPAR was positively associated with the likelihood of developing depression when NPAR > 12.65 (OR 1.06[95% CI 1.04, 1.09]). The results of subgroup analyses and interaction tests indicated that smoking status had a significant effect on the relationship between NPAR and depression (P < 0.05). Our study reveals a positive association between NPAR levels and depression, suggesting that higher NPAR levels are associated with an increased likelihood of developing depression.

Breaking the Cycle: Matrix Metalloproteinase Inhibitors as an Alternative Approach in Managing Tuberculosis Pathogenesis and Progression

Mycobacterium tuberculosis (Mtb) has long posed a significant challenge to global public health, resulting in approximately 1.6 million deaths annually. Pulmonary tuberculosis (TB) instigated by Mtb is characterized by extensive lung tissue damage, leading to lesions and dissemination within the tissue matrix. Matrix metalloproteinases (MMPs) exhibit endopeptidase activity, contributing to inflammatory tissue damage and, consequently, morbidity and mortality in TB patients. MMP activities in TB are intricately regulated by various components, including cytokines, chemokines, cell receptors, and growth factors, through intracellular signaling pathways. Primarily, Mtb-infected macrophages induce MMP expression, disrupting the balance between MMPs and tissue inhibitors of metalloproteinases (TIMPs), thereby impairing extracellular matrix (ECM) deposition in the lungs. Recent research underscores the significance of immunomodulatory factors in MMP secretion and granuloma formation during Mtb pathogenesis. Several studies have investigated both the activation and inhibition of MMPs using endogenous MMP inhibitors (i.e., TIMPs) and synthetic inhibitors. However, despite their promising pharmacological potential, few MMP inhibitors have been explored for TB treatment as host-directed therapy. Scientists are exploring novel strategies to enhance TB therapeutic regimens by suppressing MMP activity to mitigate Mtb-associated matrix destruction and reduce TB induced lung inflammation. These strategies include the use of MMP inhibitor molecules alone or in combination with anti-TB drugs. Additionally, there is growing interest in developing novel formulations containing MMP inhibitors or MMP-responsive drug delivery systems to suppress MMPs and release drugs at specific target sites. This review summarizes MMPs' expression and regulation in TB, their role in immune response, and the potential of MMP inhibitors as effective therapeutic targets to alleviate TB immunopathology.

Potential of Neuroinflammation-Modulating Strategies in Tuberculous Meningitis: Targeting Microglia

Tuberculous meningitis (TBM) is the most severe complication of tuberculosis (TB) and is associated with high rates of disability and mortality. Mycobacterium tuberculosis (M. tb), the infectious agent of TB, disseminates from the respiratory epithelium, breaks through the blood-brain barrier, and establishes a primary infection in the meninges. Microglia are the core of the immune network in the central nervous system (CNS) and interact with glial cells and neurons to fight against harmful pathogens and maintain homeostasis in the brain through pleiotropic functions. However, M. tb directly infects microglia and resides in them as the primary host for bacillus infections. Largely, microglial activation slows disease progression. The non-productive inflammatory response that initiates the secretion of pro-inflammatory cytokines and chemokines may be neurotoxic and aggravate tissue injuries based on damages caused by M. tb. Host-directed therapy (HDT) is an emerging strategy for modulating host immune responses against diverse diseases. Recent studies have shown that HDT can control neuroinflammation in TBM and act as an adjunct therapy to antibiotic treatment. In this review, we discuss the diverse roles of microglia in TBM and potential host-directed TB therapies that target microglia to treat TBM. We also discuss the limitations of applying each HDT and suggest a course of action for the near future.

Association between systemic immune-inflammation index and post-stroke depression: a cross-sectional study of the national health and nutrition examination survey 2005-2020

Background

Less research has linked the Systemic Immune Inflammatory Index (SII) with post-stroke depression (PSD). This study aims to look at any potential connections between SII and PSD.

Methods

The National Health and Nutrition Examination Survey (NHANES), conducted in a population that embodied complete SII and stroke data from 2005 to 2020, was used to perform the current cross-sectional survey. A fitted smoothed curve was used to depict the nonlinear link between SII and PSD, and multiple linear regression analysis demonstrated a positive correlation between SII and PSD.

Results

Multiple linear regression analysis showed that SII and PSD were markedly related [1.11(1.05, 1.17)]. Interaction tests showed that the association between SII and PSD was not statistically different between strata, and age, sex, BMI, income poverty ratio, education level, smoking status, diabetes mellitus, coronary heart disease, and heart failure did not have a significant effect on this positive association (p > 0.05 for interaction). In addition, a nonlinear association between SII and PSD was found using a two-stage linear regression model.

Conclusion

The results of our research support the existence of a significant positive correlation between SII levels and PSD. Further prospective trials are required to comprehend SII, which is for the PSD thoroughly.

Effect of Dexamethasone on Adhesion of Human Neutrophils and Concomitant Secretion

Neutrophils play a dual role in protecting the body. They are able to penetrate infected tissues and destroy pathogens there by releasing aggressive bactericidal substances. While into the surrounding tissues, the aggressive products secreted by neutrophils initiate development of inflammatory processes. Invasion of neutrophils into tissues is observed during the development of pneumonia in the patients with lung diseases of various etiologies, including acute respiratory distress syndrome caused by coronavirus disease. Synthetic corticosteroid hormone dexamethasone has a therapeutic effect in treatment of lung diseases, including reducing mortality in the patients with severe COVID-19. The acute (short-term) effect of dexamethasone on neutrophil adhesion to fibrinogen and concomitant secretion was studied. Dexamethasone did not affect either attachment of neutrophils to the substrate or their morphology. Production of reactive oxygen species (ROS) and nitric oxide (NO) by neutrophils during adhesion also did not change in the presence of dexamethasone. Dexamethasone stimulated release of metalloproteinases in addition to the proteins secreted by neutrophils during adhesion under control conditions, and selectively stimulated release of free amino acid hydroxylysine, a product of lysyl hydroxylase. Metalloproteinases play a key role and closely interact with lysyl hydroxylase in the processes of modification of the extracellular matrix. Therapeutic effect of dexamethasone could be associated with its ability to reorganize extracellular matrix in the tissues by changing composition of the neutrophil secretions, which could result in the improved gas exchange in the patients with severe lung diseases.

Mechanosensory feedback loops during chronic inflammation

Epithelial tissues are crucial to maintaining healthy organization and compartmentalization in various organs and act as a first line of defense against infection in barrier organs such as the skin, lungs and intestine. Disruption or injury to these barriers can lead to infiltration of resident or foreign microbes, initiating local inflammation. One often overlooked aspect of this response is local changes in tissue mechanics during inflammation. In this mini-review, we summarize known molecular mechanisms linking disruption of epithelial barrier function to mechanical changes in epithelial tissues. We consider direct mechanisms, such as changes in the secretion of extracellular matrix (ECM)-modulating enzymes by immune cells as well as indirect mechanisms including local activation of fibroblasts. We discuss how these mechanical changes can modulate local immune cell activity and inflammation and perturb epithelial homeostasis, further dysregulating epithelial barrier function. We propose that this two-way relationship between loss of barrier function and altered tissue mechanics can lead to a positive feedback loop that further perpetuates inflammation. We discuss this cycle in the context of several chronic inflammatory diseases, including inflammatory bowel disease (IBD), liver disease and cancer, and we present the modulation of tissue mechanics as a new framework for combating chronic inflammation.

Association between Systemic Immune Inflammation Index and Cognitive Impairment after Acute Ischemic Stroke

Background and Aims: Post-stroke cognitive impairment (PSCI) is one of the major complications after ischemic stroke. PSCI has been shown to be associated with low-grade systemic inflammation. As a novel inflammatory marker, the systemic immune-inflammation (SII) index could reflect clinical outcomes in severe cardiovascular diseases. We therefore performed a prospective study to investigate the correlation between the SII index and the risk of PSCI in patients with ischemic stroke. Methods: We prospectively enrolled 254 patients with ischemic stroke with symptoms onset <72 h. The SII index was detected within 24 h after admission. The Montreal Cognitive Scale (MoCA) was utilized to evaluate cognitive function, and PSCI was defined as a MoCA score of <25 points. Results: During the 3-month follow-up, 70 participants (27.6%) had mild cognitive impairment and 60 (23.6%) had severe cognitive impairment. In binary logistic regression analysis, each one-standard deviation increase in the SII index was significantly associated with the prevalence of PSCI after adjusting for age, sex, and other confounders (odds ratio 2.341; 95% confidence interval, 1.439–3.809, p = 0.001). Similar significant findings were observed when SII was defined as a categorical variable. In addition, the multiple-adjusted spline regression model showed a linear association between the SII index and cognitive impairment (p = 0.003 for linearity). Conclusions: Our study indicated that an increased SII index was closely related to PSCI at 3 months in patients with ischemic stroke. Further research is required to evaluate the efficacy of inflammation management in these patients.

Blood-Brain Barrier Integrity Damage in Bacterial Meningitis: The Underlying Link, Mechanisms, and Therapeutic Targets

Despite advances in supportive care and antimicrobial treatment, bacterial meningitis remains the most serious infection of the central nervous system (CNS) that poses a serious risk to life. This clinical dilemma is largely due to our insufficient knowledge of the pathology behind this disease. By controlling the entry of molecules into the CNS microenvironment, the blood-brain barrier (BBB), a highly selective cellular monolayer that is specific to the CNS's microvasculature, regulates communication between the CNS and the rest of the body. A defining feature of the pathogenesis of bacterial meningitis is the increase in BBB permeability. So far, several contributing factors for BBB disruption have been reported, including direct cellular damage brought on by bacterial virulence factors, as well as host-specific proteins or inflammatory pathways being activated. Recent studies have demonstrated that targeting pathological factors contributing to enhanced BBB permeability is an effective therapeutic complement to antimicrobial therapy for treating bacterial meningitis. Hence, understanding how these meningitis-causing pathogens affect the BBB permeability will provide novel perspectives for investigating bacterial meningitis's pathogenesis, prevention, and therapies. Here, we summarized the recent research progress on meningitis-causing pathogens disrupting the barrier function of BBB. This review provides handy information on BBB disruption by meningitis-causing pathogens, and helps design future research as well as develop potential combination therapies.

The role of neutrophils in the dysfunction of central nervous system barriers

Leukocyte migration into the central nervous system (CNS) represents a central process in the development of neurological diseases with a detrimental inflammatory component. Infiltrating neutrophils have been detected inside the brain of patients with several neuroinflammatory disorders, including stroke, multiple sclerosis and Alzheimer’s disease. During inflammatory responses, these highly reactive innate immune cells can rapidly extravasate and release a plethora of pro-inflammatory and cytotoxic factors, potentially inducing significant collateral tissue damage. Indeed, several studies have shown that neutrophils promote blood-brain barrier damage and increased vascular permeability during neuroinflammatory diseases. Recent studies have shown that neutrophils migrate into the meninges and choroid plexus, suggesting these cells can also damage the blood-cerebrospinal fluid barrier (BCSFB). In this review, we discuss the emerging role of neutrophils in the dysfunction of brain barriers across different neuroinflammatory conditions and describe the molecular basis and cellular interplays involved in neutrophil-mediated injury of the CNS borders.

Changes of FSTL1 and MMP-9 levels in patients with acute cerebral infarction and its relationship with hemorrhagic transformation

BACKGROUND

hemorrhagic transformation is a serious complication of acute ischemic stroke, which may lead to poor prognosis and delayed use of anticoagulant therapy.

METHODS

125 patients with cerebral infarction from December 2019 to December 2020 in the Second Affiliated Hospital of Zhejiang University were selected. All patients did not receive intravascular therapy, intravenous thrombolysis and other reperfusion treatment; and the relevant laboratory data were collected within 24 h after admission. At the same time, 15 healthy subjects were selected as the research objects for prospective analysis. Hemorrhagic transformation (HT) was defined as a condition in which computed tomography (CT) did not indicate bleeding at admission, but follow-up magnetic resonance imaging (MRI) or CT showed hemorrhage. The patients were divided into HT group (n = 50) and non-HT group (n = 75) according to whether there was HT after admission. The concentrations of FSTL1 and MMP-9 in peripheral blood of the two groups were detected.

RESULTS

The concentrations of FSTL1 and MMP-9 in acute cerebral infarction (ACI) group were significantly higher than those in control group. However the HT group had a higher concentration of FSTL1 and MMP-9 than the non-HT group. The serum FSTL1 and MMP-9 were independent risk factors for hemorrhagic transformation. The area under the ROC curve of FSTL1 and MMP-9 in diagnosis of HT was 0.809 and 0.856 respectively, and their combined value was 0.923.

CONCLUSION

The high levels of FSTL1 and MMP-9 had strong correlation with HT in ACI patients.

Neutrophil-Mediated Immunopathology and Matrix Metalloproteinases in Central Nervous System - Tuberculosis

Tuberculosis (TB) remains one of the leading infectious killers in the world, infecting approximately a quarter of the world’s population with the causative organism Mycobacterium tuberculosis (M. tb). Central nervous system tuberculosis (CNS-TB) is the most severe form of TB, with high mortality and residual neurological sequelae even with effective TB treatment. In CNS-TB, recruited neutrophils infiltrate into the brain to carry out its antimicrobial functions of degranulation, phagocytosis and NETosis. However, neutrophils also mediate inflammation, tissue destruction and immunopathology in the CNS. Neutrophils release key mediators including matrix metalloproteinase (MMPs) which degrade brain extracellular matrix (ECM), tumor necrosis factor (TNF)-α which may drive inflammation, reactive oxygen species (ROS) that drive cellular necrosis and neutrophil extracellular traps (NETs), interacting with platelets to form thrombi that may lead to ischemic stroke. Host-directed therapies (HDTs) targeting these key mediators are potentially exciting, but currently remain of unproven effectiveness. This article reviews the key role of neutrophils and neutrophil-derived mediators in driving CNS-TB immunopathology.

GSK-3α/β Activity Negatively Regulates MMP-1/9 Expression to Suppress Mycobacterium tuberculosis Infection

Tuberculosis (TB) caused by Mycobacterium tuberculosis (Mtb) infection is the deadliest infectious disease and a global health problem. Macrophages (Mφs) and neutrophils that can phagocytose Mtb represent the first line of immune response to infection. Glycogen synthase kinase-3α/β (GSK-3α/β) represents a regulatory switch in host immune responses. However, the efficacy and molecular mechanisms of how GSK-3α/β interacts with Mtb infection in Mφs remain undefined. Here, we demonstrated that Mtb infection downregulated GSK-3α/β activity and promoted matrix metalloproteinase-1 (MMP-1) and MMP-9 expressions in Mφs derived from acute monocytic human leukemia THP-1 cells (THP-1-Mφs). We confirmed the upregulation of MMP-9 expression in tissues of TB patients compared with patients of chronic inflammation (CI). In THP-1-Mφs and C57BL/6 mice, GSK-3α/β inhibitor SB216763 significantly increased MMP-1/9 production and facilitated Mtb load, while MMP inhibitors blocked MMP-1/9 expression and Mtb infection. Consistently, GSK-3α/β silencing significantly increased MMP-1/9 expression and Mtb infection, while overexpression of GSK-3α/β and constitutive activated GSK-3α/β mutants significantly reduced MMP-1/9 expression and Mtb infection in THP-1-Mφs. MMP-1/9 silencing reduced Mtb infection, while overexpression of MMP-1/9 promoted Mtb infection in THP-1-Mφs. We further found that GSK-3α/β inhibition increased Mtb infection and MMP-1/9 expression was blocked by ERK1/2 inhibitor. Additionally, we showed that protein kinase C-δ (PKC-δ) and mammalian target of rapamycin (mTOR) reduced GSK-3α/β activity and promoted MMP-1/9 production in Mtb-infected THP-1-Mφs. In conclusion, this study suggests that PKC-δ-mTOR axis suppresses GSK-3α/β activation with acceleration of MMP-1/9 expression through phospho-ERK1/2. These results reveal a novel immune escape mechanism of Mtb and a novel crosstalk between these critical signaling pathways in anti-TB immunity.

Nos2-/- mice infected with M. tuberculosis develop neurobehavioral changes and immunopathology mimicking human central nervous system tuberculosis

BACKGROUND

Understanding the pathophysiology of central nervous system tuberculosis (CNS-TB) is hampered by the lack of a good pre-clinical model that mirrors the human CNS-TB infection. We developed a murine CNS-TB model that demonstrates neurobehavioral changes with similar immunopathology with human CNS-TB.

METHODS

We injected two Mycobacterium tuberculosis (M.tb) strains, H37Rv and CDC1551, respectively, into two mouse strains, C3HeB/FeJ and Nos2-/- mice, either into the third ventricle or intravenous. We compared the neurological symptoms, histopathological changes and levels of adhesion molecules, chemokines, and inflammatory cytokines in the brain induced by the infections through different routes in different strains.

RESULTS

Intra-cerebroventricular infection of Nos2-/- mice with M.tb led to development of neurological signs and more severe brain granulomas compared to C3HeB/FeJ mice. Compared with CDC1551 M.tb, H37Rv M.tb infection resulted in a higher neurobehavioral score and earlier mortality. Intra-cerebroventricular infection caused necrotic neutrophil-dominated pyogranulomas in the brain relative to intravenous infection which resulted in disseminated granulomas and mycobacteraemia. Histologically, intra-cerebroventricular infection of Nos2-/- mice with M.tb resembled human CNS-TB brain biopsy specimens. H37Rv intra-cerebroventricular infected mice demonstrated higher brain concentrations of inflammatory cytokines, chemokines and adhesion molecule ICAM-1 than H37Rv intravenous-infected mice.

CONCLUSIONS

Intra-cerebroventricular infection of Nos2-/- mice with H37Rv creates a murine CNS-TB model that resembled human CNS-TB immunopathology, exhibiting the worst neurobehavioral score with a high and early mortality reflecting disease severity and its associated neurological morbidity. Our murine CNS-TB model serves as a pre-clinical platform to dissect host-pathogen interactions and evaluate therapeutic agents for CNS-TB.

Enzymatically releasable polyethylene glycol - host defense peptide conjugates with improved activity and biocompatibility

Host defense peptides (HDPs) have been the subject of great interest for the treatment of multidrug-resistant bacterial infections due to their multimodal activity and low induction of resistance. However, aggregation, toxicity, and short biological half-life have limited their applicability for clinical treatment. Many methods have been explored to alleviate these issues, such as polymer (e.g., polyethylene glycol (PEG)) conjugation, but these are often accompanied by reductions in the activity of the HDP. Here, we detail the design of a novel PEG-HDP conjugate incorporating an enzymatic cleavage sequence targeting matrix metalloproteinases (MMPs) that accumulate at sites of inflammation and infection. Addition of the cleavage sequence onto either the N- or the C-terminal region of the parent peptide (peptide 73, a derivative of the HDP aurein 2.2) was explored to determine the location for optimal antimicrobial activity following MMP cleavage; furthermore, the susceptibility of the peptide to MMP cleavage after conjugation to 2 kDa or 5 kDa PEG was examined. The top candidate, L73, utilized an N-terminal cleavage site that was subsequently conjugated to a 2 kDa PEG polymer. Both L73 and the conjugate exhibited no antimicrobial activity in vitro until cleaved by purified MMP, which liberated a peptide fragment with 16- or 63-fold improved activity, respectively, corresponding to a minimum inhibitory concentration (MIC) of 8 μg/mL, comparable to that of peptide 73 (4 μg/mL). Furthermore, PEG conjugation improved the blood compatibility and reduced the aggregation tendency of the HDP in vitro, indicating enhanced biocompatibility. When administered as a single subcutaneous dose (~3.6 mg, or a peptide concentration of 142 mg/kg) in a mouse abscess model of high-density methicillin-resistant Staphylococcus aureus (MRSA) infection, the conjugate displayed strong activity, reducing abscess size and bacterial load by 73.3% and 58-fold, respectively. This activity was completely lost when the cleavage site was rendered resistant to MMPs by the substitution of two d-amino acids, supporting the hypothesis that antimicrobial activity was dependent on cleavage by MMPs, which were shown here to increasingly accumulate at the abscess site up to 18 h post infection. Finally, the conjugate displayed biocompatibility in vivo, with no identifiable toxicity or aggregation.

Doxycycline host-directed therapy in human pulmonary tuberculosis

BACKGROUNDMatrix metalloproteinases (MMPs) are key regulators of tissue destruction in tuberculosis (TB) and may be targets for host-directed therapy. We conducted a phase II double-blind, randomized, controlled trial investigating doxycycline, a licensed broad-spectrum MMP inhibitor, in patients with pulmonary TB.METHODSThirty patients with pulmonary TB were enrolled within 7 days of initiating anti-TB treatment and randomly assigned to receive either 100 mg doxycycline or placebo twice a day for 14 days, in addition to standard care.RESULTSWhole blood RNA-sequencing demonstrated that doxycycline accelerated restoration of dysregulated gene expression in TB towards normality, rapidly down-regulating type I and II interferon and innate immune response genes, and up-regulating B-cell modules relative to placebo. The effects persisted for 6 weeks after doxycycline discontinuation, concurrent with suppressed plasma MMP-1. Doxycycline significantly reduced sputum MMP-1, -8, -9, -12 and -13, suppressed type I collagen and elastin destruction, reduced pulmonary cavity volume without altering sputum mycobacterial loads, and was safe.CONCLUSIONAdjunctive doxycycline with standard anti-TB treatment suppressed pathological MMPs in PTB patients. Larger studies on adjunctive doxycycline to limit TB immunopathology are merited.TRIAL REGISTRATIONClinicalTrials.gov NCT02774993.FUNDINGSingapore National Medical Research Council (NMRC/CNIG/1120/2014, NMRC/Seedfunding/0010/2014, NMRC/CISSP/2015/009a); the Singapore Infectious Diseases Initiative (SIDI/2013/013); National University Health System (PFFR-28 January 14, NUHSRO/2014/039/BSL3-SeedFunding/Jul/01); the Singapore Immunology Network Immunomonitoring platform (BMRC/IAF/311006, H16/99/b0/011, NRF2017_SISFP09); an ExxonMobil Research Fellowship, NUHS Clinician Scientist Program (NMRC/TA/0042/2015, CSAINV17nov014); the UK Medical Research Council (MR/P023754/1, MR/N006631/1); a NUS Postdoctoral Fellowship (NUHSRO/2017/073/PDF/03); The Royal Society Challenge Grant (CHG\R1\170084); the Sir Henry Dale Fellowship, Wellcome Trust (109377/Z/15/Z); and A*STAR.

The Association Between Systemic Inflammatory Markers and Post-Stroke Depression: A Prospective Stroke Cohort

Objective

Inflammation plays an important role in stroke. Many inflammatory markers in peripheral blood are proved to be associated with stroke severity or prognosis. But few comprehensive models or scales to evaluate the post-stroke depression (PSD) have been reported. In this study, we aimed to compare the level of systemic inflammation markers between PSD and non-PSD patients and explore the association of these inflammatory markers with PSD.

Methods

Totally, 432 ischemic stroke patients were consecutively enrolled in the study and received 1 month follow-up. We used the 17-Hamilton Rating Scale to measure depressive symptoms at 1 month after stroke. With the Hamilton Depression Scale score of >7, patients were diagnosed with PSD. Systemic immune-inflammation index (SII), neutrophil-to-lymphocyte (NLR), platelet-to-lymphocyte (PLR) and derived neutrophil-to-lymphocyte ratio (dNLR) were calculated from the admission blood work.

Results

Finally, 129 patients (30.5%) were diagnosed with PSD at 1 month. PSD patients showed significantly higher levels of SII (501.27 (345.43-782.58) vs 429.60 (315.64-570.98), P=0.001), NLR (2.36 (1.77-3.82) vs 2.17 (1.56-2.80), P=0.010), dNLR (1.67 (1.30-2.51) vs 1.54 (1.16-1.99), P=0.009), PLR (124.65 (95.25-155.15) vs 109.22 (92.38-142.03), P=0.015), especially SII at admission as compared to non-PSD patients. In the logistic analysis, SII value (>547.30) was independently associated with the occurrence of PSD (OR=2.181, 95% CI=1.274-3.732, p =0.004), better than dNLR (OR=1.833, 95% CI=1.071-3.137, p =0.027), PLR (OR= 1.822, 95% CI=1.063-3.122, p =0.029) and NLR (OR =1.728, 95% CI=1.009-2.958, p =0.046).

Conclusion

Increased SII, PLR, dNLR, NLR, particularly SII at admission, are significantly correlated with PSD and may add some prognostic clues to find early discovery of PSD.

The Impact of Obesity on Microglial Function: Immune, Metabolic and Endocrine Perspectives

Increased life expectancy in combination with modern life style and high prevalence of obesity are important risk factors for development of neurodegenerative diseases. Neuroinflammation is a feature of neurodegenerative diseases, and microglia, the innate immune cells of the brain, are central players in it. The present review discusses the effects of obesity, chronic peripheral inflammation and obesity-associated metabolic and endocrine perturbations, including insulin resistance, dyslipidemia and increased glucocorticoid levels, on microglial function.

Evaluation of Peripheral Immune Dysregulation in Alzheimer's Disease and Vascular Dementia

Immune dysregulation has been observed in the brain and blood of patients with Alzheimer's disease (AD). However, a convenient assay to evaluate peripheral immune dysregulation in AD has not been developed, partly due to the inconsistent observations from different studies. We hypothesized that peripheral immune dysregulation may only exist in a subpopulation of AD patients; therefore it may be valuable to identify this subpopulation with a convenient assay. Along this line, we selected 14 candidate genes based on our analysis of microarray data on peripheral blood of AD and other diseases. We used RT-qPCR to examine the expression of these 14 genes in a cohort of 288 subjects, including 74 patients with AD, 64 patients with mild cognitive impairment (MCI), 51 patients with vascular dementia (VaD), and 99 elderly controls with no cognitive dysfunction/impairment. Seven of these 14 genes displayed significant difference in group comparison. Switching from group comparison to individualized evaluation revealed more in-depth information. First, there existed a wide dynamic range for the expression of these immune genes in peripheral blood even within the control group. Second, for the vast majority of the patients (AD, VaD, and MCI patients), the expression of these genes fell within the dynamic range of the control group. Third, a small portion of outliers were observed in the patient groups, more so in the VaD group than that in the AD or MCI groups. This is our first attempt to conduct personalized evaluation of peripheral immune dysregulation in AD and VaD. These findings may be applicable to the identification of peripheral immune dysregulation in AD and VaD patients which may lead to tailored treatment toward those patients.

Human mesenchymal stem cells respond differentially to platelet preparations and synthesize hyaluronic acid in nucleus pulposus extracellular matrix

BACKGROUND CONTEXT

In recent years, autologous platelet-rich plasma (PRP) and bone marrow aspirate concentrate (BMAC) have been used as treatments for disc-related pain. A better understanding of the effects of leukocyte-rich (LR) versus leukocyte poor (LP-) PRP on bone marrow derived human mesenchymal stem/progenitor cells (hMSCs) is likely to improve future research studies, clinical practice and care for patients with chronic discogenic back pain.

PURPOSE

The primary aim of this study is to determine the effects of LR-PRP and LP-PRP on the proliferation and migration of hMSCs in pig nucleus pulposus (NP) extracellular matrix (ECM). The secondary aim is to characterize hMSC-dependent expression of the matrix remodeling enzymes metalloproteinases MMP-2, MMP-3, MMP-9 and tissue inhibitor of metalloproteinases TIMP-2, and to determine whether transplanted hMSCs can synthesize hyaluronic acid (HA).

STUDY DESIGN

Controlled laboratory study.

METHODS

Bone marrow-derived culture expanded hMSCs were seeded onto pig NP and cultured with LR-PRP, LP-PRP or serum/platelet releasate (PR). The same conditions without hMSCs were used as controls. hMSC proliferation, migration and dispersion was assessed via fluorescent microscopy, while HA synthesis, MMP-2, MMP-3, MMP-9, and TIMP-2 protein levels were assessed via enzyme linked immunosorbent assay. All funding was provided by a 501c(3) research foundation and does not have any commercial or sponsorship interests.

RESULTS

LP-PRP and PR cultures resulted in higher hMSC proliferation, migration, dispersion, and MMP-2 expression. LP-PRP cultures resulted in the highest HA production. LR-PRP cultures resulted in lower hMSC proliferation, negligible migration and dispersion, increased MMP-9 expression and lower HA production.

CONCLUSIONS

Human bone marrow-derived hMSCs seeded onto pig NP ECM are capable of synthesizing HA, indicating a transition towards a NP cell phenotype. This process was most enhanced by LP-PRP and marked by increased hMSC proliferation, MMP-2 production, HA synthesis and reduced MMP-9 levels.

CLINICAL SIGNIFICANCE

LP-PRP and PR, with or without hMSCs, may provide better outcomes than LR-PRP in lab investigations and clinical trials for discogenic pain. Bone marrow-derived hMSCs may hold promise as a treatment for disc degeneration.

Presentations and outcomes of central nervous system TB in a UK cohort: The high burden of neurological morbidity

OBJECTIVES

Most data for Central Nervous System Tuberculosis (CNS-TB) derive from high-incidence, resource-limited countries. We sought to determine the presentation, management and outcomes of CNS-TB in a low-incidence setting with accessible healthcare.

METHODS

We undertook a retrospective, observational study of CNS-TB in adults at a single tertiary-referral London hospital (2001-2017). Cases were categorised as either TB meningitis (TBM) or TB mass lesions without meningitis (TBML), applying novel criteria for definite, probable, and possible TBML.

RESULTS

We identified sixty-two cases of TBM (37% definite; 31% probable; 32% possible) alongside 14 TBML cases (36% definite; 29% probable; and 36% possible). Clinical presentation was highly variable. Among CSF parameters, hypoglycorrhachia proved most discriminatory for "definite" TBM. Neurosurgical intervention was required for mass-effect or hydrocephalus in 16%. Mortality was higher in TBM versus TBML (16% vs. 0%) but overall morbidity was significant; 33% of TBM and 29% of TBML survivors suffered persisting neurological disability at 12-months. In TBM, hydrocephalus, infarct, basal enhancement and low CSF white cell count were independently associated with worse neurological outcomes.

CONCLUSION

Although mortality was lower than previously reported in other settings, morbidity was significant, highlighting the need for improved CNS-TB diagnostics, therapeutics and interventions to mitigate neurological sequelae.

Neutrophils in Biomaterial-Guided Tissue Regeneration: Matrix Reprogramming for Angiogenesis

Biomaterial-guided in situ tissue regeneration uses biomaterials to stimulate and guide the body's endogenous, regenerative processes to drive functional tissue repair and regeneration. To be successful, cell migration into the biomaterials is essential, which requires angiogenesis to maintain cell viability. Neutrophils, the first cells responding to an implanted biomaterial, are now known to play an integral part in angiogenesis in multiple tissues and exhibit considerable potential for driving angiogenesis in the context of tissue regeneration. In terms of biomaterial-guided in situ tissue regeneration, harnessing the proangiogenic potential of the neutrophil through its robust secretion of matrix metalloproteinase 9 (MMP-9) may provide a mechanism to improve biomaterial performance by initiating matrix reprogramming. This review will discuss neutrophils as matrix reprogrammers and what is currently known about their ability to create a microenvironment that is more conducive for angiogenesis and tissue regeneration through the secretion of MMP-9. It will first review a set of ground-breaking studies in tumor biology and then present an overview of what is currently known about neutrophils and MMP-9 in biomaterial vascularization. Finally, it will conclude with potential strategies and considerations to engage neutrophils in biomaterial-guided angiogenesis and in situ tissue regeneration. Impact statement This review draws attention to a highly neglected topic in tissue engineering, the role of neutrophils in biomaterial-guided tissue regeneration and angiogenesis. Moreover, it highlights their abundant secretion of matrix metalloproteinase 9 (MMP-9) for matrix reprogramming, a topic with great potential yet to be vetted in the literature. It presents strategies and considerations for designing the next generation of immunomodulatory biomaterials. While there is literature discussing the overall role of neutrophils in angiogenesis, there are a limited number of review articles focused on this highly relevant topic in the context of biomaterial integration and tissue regeneration, making this a necessary and impactful article.

How Prostate Cancer Cells Use Strategy Instead of Brute Force to Achieve Metastasis

Akin to many other cancers, metastasis is the predominant cause of lethality in prostate cancer (PCa). Research in the past decade or so has revealed that although metastatic manifestation is a multi-step and complex process that is orchestrated by distinct cellular and molecular mechanisms, the process in itself is an extremely inefficient one. It is now becoming increasingly evident that PCa cells employ a plethora of strategies to make the most of this inefficient process. These strategies include priming the metastatic sites ahead of colonization, devising ways to metastasize to specific organs, outsmarting the host defense surveillance, lying in a dormant state at the metastatic site for prolonged periods, and widespread reprogramming of the gene expression to suit their needs. Based on established, recent, and evolving lines of research, this review is an attempt to understand PCa metastasis from the perspective of military combat, wherein strategic maneuvering instead of brute force often plays a decisive role in the outcome.

Transcriptome profiling of brain myeloid cells revealed activation of Itgal, Trem1, and Spp1 in western diet-induced obesity

Background

Environmental factors are critical in the development of age-related cognitive decline and dementia. A western diet (WD) can cause nutrient deficiency and inflammation that could impact cognition directly. It is increasingly recognized that innate immune responses by brain myeloid cells, such as resident microglia, and infiltrating peripheral monocytes/macrophages may represent an essential link between a WD, cognitive decline, and dementia. Our previous data demonstrated that chronic consumption of a WD induced inflammation through brain myeloid cells in aging mice and a mouse model of Alzheimer’s disease (AD). However, the subtypes of myeloid cells that contribute to the WD-induced inflammation remain unclear.

Methods

C57BL/6J (B6), myeloid cell reporter mice (B6.Ccr2^RFP/+Cx3cr1^GFP/+), and Ccr2-deficient mice (B6.Ccr2^RFP/RFP) were fed a WD or a control chow diet (CD) from 2 to 6 or 12 months of age. CD11b+CD45^lo and CD11b+CD45^hi cells from WD- and CD-fed B6 or Ccr2-deficient mice were characterized using flow cytometry, RNA-sequencing, and immunofluorescence.

Results

Ccr2::RFP expressing myeloid cells were significantly increased in brains of WD- compared to CD-fed mice, but were not elevated in Ccr2-deficient WD-fed mice. The percent of CD11b+CD45^hi cells was significantly increased in WD- compared to CD-fed mice. Comparison of RNA-sequencing data with immune cell data in ImmGen supports that CD11b+CD45^hi cells from WD-fed mice are enriched for peripheral monocytes and neutrophils. Ingenuity pathway analysis predicted these cells elicit proinflammatory responses that may be damaging to the brain. Using stringent criteria for gene expression levels between CD11b+CD45^hi and CD11b+CD45^lo cells, we identified approximately 70 genes that we predict are uniquely expressed in infiltrating cells, including Itgal, Trem1, and Spp1 (osteopontin, OPN). Finally, we show a significantly greater number of OPN+IBA1– cells in WD- compared to CD-fed mice that we propose are activated neutrophils based on ImmGen data. OPN+IBA1– cells are not significantly increased in Ccr2-deficient WD-fed mice.

Conclusions

These data further support the model that peripheral myeloid cells enter the brain in response to diet-induced obesity. Elucidating their contribution to age-related cognitive decline and age-related neurodegenerative diseases should offer new avenues for therapeutic intervention in Alzheimer’s disease and related dementias, where diet/obesity are major risk factors.

Electronic supplementary material

The online version of this article (10.1186/s12974-019-1527-z) contains supplementary material, which is available to authorized users.

Matrix metalloproteinases: Expression, regulation and role in the immunopathology of tuberculosis

Mycobacterium tuberculosis (Mtb) leads to approximately 1.5 million human deaths every year. In pulmonary tuberculosis (TB), Mtb must drive host tissue destruction to cause pulmonary cavitation and dissemination in the tissues. Matrix metalloproteinases (MMPs) are endopeptidases capable of degrading all components of pulmonary extracellular matrix (ECM). It is well established that Mtb infection leads to upregulation of MMPs and also causes disturbance in the balance between MMPs and tissue inhibitors of metalloproteinases (TIMPs), thus altering the extracellular matrix deposition. In TB, secretion of MMPs is mainly regulated by NF-κB, p38 and MAPK signalling pathways. In addition, recent studies have demonstrated the immunomodulatory roles of MMPs in Mtb pathogenesis. Researchers have proposed a new regimen of improved TB treatment by inhibition of MMP activity to hinder matrix destruction and to minimize the TB-associated morbidity and mortality. The proposed regimen involves adjunctive use of MMP inhibitors such as doxycycline, marimastat and other related drugs along with front-line anti-TB drugs to reduce granuloma formation and bacterial load. These findings implicate the possible addition of economical and well-tolerated MMP inhibitors to current multidrug regimens as an attractive mean to increase the drug potency. Here, we will summarize the recent advancements regarding expression of MMPs in TB, their immunomodulatory role, as well as their potential as therapeutic targets to control the deadly disease.

The neurocritical care of tuberculous meningitis

Tuberculous meningitis is the most severe form of tuberculosis and often causes critical illness with high mortality. Two primary management objectives are reducing intracranial pressure, and optimising cerebral perfusion, while killing the bacteria and controlling intracerebral inflammation. However, the evidence base guiding the care of critically ill patients with tuberculous meningitis is poor and many patients do not have access to neurocritical care units. Invasive intracranial pressure monitoring is often unavailable and although new non-invasive monitoring techniques show promise, further evidence for their use is required. Optimal management regimens of neurological complications (eg, hydrocephalus and paradoxical reactions) and of hyponatraemia, which frequently accompanies tuberculous meningitis, remain to be elucidated. Advances in the field of tuberculous meningitis predominantly focus on diagnosis, inflammatory processes, and antituberculosis chemotherapy. However, clinical trials are required to provide robust evidence guiding the most effective supportive, therapeutic, and neurosurgical interventions for tuberculous meningitis that will improve morbidity and mortality.

Matrix Metalloproteinases in Pulmonary and Central Nervous System Tuberculosis-A Review

Tuberculosis (TB) remains the single biggest infectious cause of death globally, claiming almost two million lives and causing disease in over 10 million individuals annually. Matrix metalloproteinases (MMPs) are a family of proteolytic enzymes with various physiological roles implicated as key factors contributing to the spread of TB. They are involved in the breakdown of lung extracellular matrix and the consequent release of Mycobacterium tuberculosis bacilli into the airways. Evidence demonstrates that MMPs also play a role in central nervous system (CNS) tuberculosis, as they contribute to the breakdown of the blood brain barrier and are associated with poor outcome in adults with tuberculous meningitis (TBM). However, in pediatric TBM, data indicate that MMPs may play a role in both pathology and recovery of the developing brain. MMPs also have a significant role in HIV-TB-associated immune reconstitution inflammatory syndrome in the lungs and the brain, and their modulation offers potential novel therapeutic avenues. This is a review of recent research on MMPs in pulmonary and CNS TB in adults and children and in the context of co-infection with HIV. We summarize different methods of MMP investigation and discuss the translational implications of MMP inhibition to reduce immunopathology.

Matrix Metalloproteinase-9 (MMP-9) as a Cancer Biomarker and MMP-9 Biosensors: Recent Advances

As one of the most widely investigated matrix metalloproteinases (MMPs), MMP-9 is a significant protease which plays vital roles in many biological processes. MMP-9 can cleave many extracellular matrix (ECM) proteins to regulate ECM remodeling. It can also cleave many plasma surface proteins to release them from the cell surface. MMP-9 has been widely found to relate to the pathology of cancers, including but not limited to invasion, metastasis and angiogenesis. Some recent research evaluated the value of MMP-9 as biomarkers to various specific cancers. Besides, recent research of MMP-9 biosensors discovered various novel MMP-9 biosensors to detect this enzyme. In this review, some recent advances in exploring MMP-9 as a biomarker in different cancers are summarized, and recent discoveries of novel MMP-9 biosensors are also presented.

Tolerating the Unwelcome Guest; How the Host Withstands Persistent Mycobacterium tuberculosis

Our understanding of the host response to infections has historically focused on “resistance” mechanisms that directly control pathogen replication. However, both pathogen effectors and antimicrobial immune pathways have the capacity to damage host tissue, and the ability to tolerate these insults can also be critical for host survival. These “tolerance” mechanisms may be equally as important as resistance to prevent disease in the context of a persistent infection, such as tuberculosis, when resistance mechanisms are ineffective and the pathogen persists in the tissue for long periods. Host tolerance encompasses a wide range of strategies, many of which involve regulation of the inflammatory response. Here we will examine general strategies used by macrophages and T cells to promote tolerance in the context of tuberculosis, and focus on pathways, such as regulation of inflammasome activation, that are emerging as common mediators of tolerance.

Matrix metalloproteinase inhibitors enhance the efficacy of frontline drugs against Mycobacterium tuberculosis

Mycobacterium tuberculosis (Mtb) remains a grave threat to world health with emerging drug resistant strains. One prominent feature of Mtb infection is the extensive reprogramming of host tissue at the site of infection. Here we report that inhibition of matrix metalloproteinase (MMP) activity by a panel of small molecule inhibitors enhances the in vivo potency of the frontline TB drugs isoniazid (INH) and rifampicin (RIF). Inhibition of MMP activity leads to an increase in pericyte-covered blood vessel numbers and appears to stabilize the integrity of the infected lung tissue. In treated mice, we observe an increased delivery and/or retention of frontline TB drugs in the infected lungs, resulting in enhanced drug efficacy. These findings indicate that targeting Mtb-induced host tissue remodeling can increase therapeutic efficacy and could enhance the effectiveness of current drug regimens.

Mycobacterium tuberculosis (Mtb) continues to be the leading cause of death from a single infectious agent worldwide, leading to 1.8 million deaths in 2015. The long treatment required (6–9 months), with all of its incumbent problems, can promote the emergence of multidrug-resistant (MDR) TB strains, so strategies to shorten the treatment duration are in dire need. Mtb’s success as a pathogen hinges on its ability to remodel the host tissue, characterized by extracellular matrix (ECM) deposition and leaky vascularization. Here we report that inhibition of matrix metalloproteinases (MMPs) significantly enhances the potency of frontline TB antibiotics. These MMP inhibitors increase the relative proportion of healthy blood vessels versus leaky dysfunctional vessels at the infection site, and enhance drug delivery and/or retention. Our study highlights the potential of targeting Mtb-induced host tissue remodeling to enhance the efficacy of current frontline antibiotics. It also suggests an alternative therapeutic strategy to repair the leaky blood vessels in TB granulomas to enhance drug delivery. Repurposing of MMP inhibitors may hold the key to shortening TB treatments and combating the emergence of MDR strains.

Matrix metalloproteinase-9 activity and a downregulated Hedgehog pathway impair blood-brain barrier function in an in vitro model of CNS tuberculosis

Central nervous system tuberculosis (CNS TB) has a high mortality and morbidity associated with severe inflammation. The blood-brain barrier (BBB) protects the brain from inflammation but the mechanisms causing BBB damage in CNS TB are uncharacterized. We demonstrate that Mycobacterium tuberculosis (Mtb) causes breakdown of type IV collagen and decreases tight junction protein (TJP) expression in a co-culture model of the BBB. This increases permeability, surface expression of endothelial adhesion molecules and leukocyte transmigration. TJP breakdown was driven by Mtb-dependent secretion of matrix metalloproteinase (MMP)-9. TJP expression is regulated by Sonic hedgehog (Shh) through transcription factor Gli-1. In our model, the hedgehog pathway was downregulated by Mtb-stimulation, but Shh levels in astrocytes were unchanged. However, Scube2, a glycoprotein regulating astrocyte Shh release was decreased, inhibiting Shh delivery to brain endothelial cells. Activation of the hedgehog pathway by addition of a Smoothened agonist or by addition of exogenous Shh, or neutralizing MMP-9 activity, decreased permeability and increased TJP expression in the Mtb-stimulated BBB co-cultures. In summary, the BBB is disrupted by downregulation of the Shh pathway and breakdown of TJPs, secondary to increased MMP-9 activity which suggests that these pathways are potential novel targets for host directed therapy in CNS TB.

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.

Epigenetic Regulation of Matrix Metalloproteinase-1 and -3 Expression in Mycobacterium tuberculosis Infection

In pulmonary tuberculosis (TB), the inflammatory immune response against Mycobacterium tuberculosis (Mtb) is associated with tissue destruction and cavitation, which drives disease transmission, chronic lung disease, and mortality. Matrix metalloproteinase (MMP)-1 is a host enzyme critical for the development of cavitation. MMP expression has been shown to be epigenetically regulated in other inflammatory diseases, but the importance of such mechanisms in Mtb-associated induction of MMP-1 is unknown. We investigated the role of changes in histone acetylation in Mtb-induced MMP expression using inhibitors of histone deacetylases (HDACs) and histone acetyltransferases (HAT), HDAC siRNA, promoter-reporter constructs, and chromatin immunoprecipitation assays. Mtb infection decreased Class I HDAC gene expression by over 50% in primary human monocyte-derived macrophages but not in normal human bronchial epithelial cells (NHBEs). Non-selective inhibition of HDAC activity decreased MMP-1/-3 expression by Mtb-stimulated macrophages and NHBEs, while class I HDAC inhibition increased MMP-1 secretion by Mtb-stimulated NHBEs. MMP-3 expression, but not MMP-1, was downregulated by siRNA silencing of HDAC1. Inhibition of HAT activity also significantly decreased MMP-1/-3 secretion by Mtb-infected macrophages. The MMP-1 promoter region between −2,001 and −2,942 base pairs from the transcriptional start site was key in control of Mtb-driven MMP-1 gene expression. Histone H3 and H4 acetylation and RNA Pol II binding in the MMP-1 promoter region were increased in stimulated NHBEs. In summary, epigenetic modification of histone acetylation via HDAC and HAT activity has a key regulatory role in Mtb-dependent gene expression and secretion of MMP-1 and -3, enzymes which drive human immunopathology. Manipulation of epigenetic regulatory mechanisms may have potential as a host-directed therapy to improve outcomes in the era of rising TB drug resistance.