Characterization of Active MMP9 in Chronic Inflammatory Diseases Using a Novel Anti-MMP9 Antibody

Fusobacterium nucleatum elicits subspecies-specific responses in human neutrophils

Fusobacterium nucleatum as a Gram-negative anaerobe plays a key bridging role in oral biofilms. It is involved in periodontal and extraoral diseases, the most prominent being colorectal cancer. Five subspecies are recognised: animalis, fusiforme, nucleatum, polymorphum and vincentii. Subspecies interact with neutrophils constantly patrolling tissues to remove microbial intruders. Neutrophil antimicrobial activities include generation of reactive oxygen species (ROS), formation of neutrophil extracellular traps (NETs) and release of cytokines and neutrophil enzymes. Subspecies-specific differences in immunogenicity have previously been observed in a neutrophil-like cell line but were not investigated in human neutrophils. Additionally, neutrophil responses to planktonic and biofilm-grown F. nucleatum have not been studied to date. The aims of this study were to compare the immunogenicity of planktonic and biofilm-grown F. nucleatum and to investigate potential differences in human neutrophil responses when stimulated with individual F. nucleatum subspecies. Human neutrophils isolated from peripheral blood were stimulated with planktonic and biofilm-grown F. nucleatum subspecies. Generation of ROS and NET formation were quantified by luminescence and fluorescence assays, respectively. Secretion of cytokines (IL-1β, TNF-α, IL-6, IL-8), neutrophil elastase and matrix metalloproteinase-9 was quantified by enzyme-linked immunosorbent assay (ELISA). Neutrophil responses showed biofilm-grown bacteria induced a significantly higher total and intracellular ROS response, as well as shorter time to total ROS release. Biofilm-grown F. nucleatum led to significantly lower IL-1β release. We found significant differences among individual subspecies in terms of total, intracellular ROS and extracellular superoxide. Subspecies polymorphum stimulated the highest mean amount of NET release. Amounts of cytokines released differed significantly among subspecies, while no differences were found in lysosomal enzyme release. Immunogenicity of F. nucleatum in human neutrophils is highly subspecies-specific in vitro with regard to ROS release and cytokine production. Understanding subspecies-specific immunogenicity of F. nucleatum may facilitate the discovery of novel therapeutic targets in F. nucleatum-mediated diseases.

Edaravone Maintains AQP4 Polarity Via OS/MMP9/β-DG Pathway in an Experimental Intracerebral Hemorrhage Mouse Model

Oxidative stress (OS) is the main cause of secondary damage following intracerebral hemorrhage (ICH). The polarity expression of aquaporin-4 (AQP4) has been shown to be important in maintaining the homeostasis of water transport and preventing post-injury brain edema in various neurological disorders. This study primarily aimed to investigate the effect of the oxygen free radical scavenger, edaravone, on AQP4 polarity expression in an ICH mouse model and determine whether it involves in AQP4 polarity expression via the OS/MMP9/β-dystroglycan (β-DG) pathway. The ICH mouse model was established by autologous blood injection into the basal nucleus. Edaravone or the specific inhibitor of matrix metalloproteinase 9 (MMP9), MMP9-IN-1, called MMP9-inh was administered 10 min after ICH via intraperitoneal injection. ELISA detection, neurobehavioral tests, dihydroethidium staining (DHE staining), intracisternal tracer infusion, hematoxylin and eosin (HE) staining, immunofluorescence staining, western blotting, Evans blue (EB) permeability assay, and brain water content test were performed. The results showed that OS was exacerbated, AQP4 polarity was lost, drainage function of brain fluids was damaged, brain injury was aggravated, expression of AQP4, MMP9, and GFAP increased, while the expression of β-DG decreased after ICH. Edaravone reduced OS, restored brain drainage function, reduced brain injury, and downregulated the expression of AQP4, MMP9. Both edaravone and MMP9-inh alleviated brain edema, maintained blood-brain barrier (BBB) integrity, mitigated the loss of AQP4 polarity, downregulated GFAP expression, and upregulated β-DG expression. The current study suggests that edaravone can maintain AQP4 polarity expression by inhibiting the OS /MMP9/β-DG pathway after ICH.

The Effect of Tissue Inhibitor of Metalloproteinases on Scar Formation after Spinal Cord Injury

Spinal cord injury (SCI) often results in permanent loss of motor and sensory function. After SCI, the blood-spinal cord barrier (BSCB) is disrupted, causing the infiltration of neutrophils and macrophages, which secrete several kinds of cytokines, as well as matrix metalloproteinases (MMPs). MMPs are proteases capable of degrading various extracellular matrix (ECM) proteins, as well as many non-matrix substrates. The tissue inhibitor of MMPs (TIMP)-1 is significantly upregulated post-SCI and operates via MMP-dependent and MMP-independent pathways. Through the MMP-dependent pathway, TIMP-1 directly reduces inflammation and destruction of the ECM by binding and blocking the catalytic domains of MMPs. Thus, TIMP-1 helps preserve the BSCB and reduces immune cell infiltration. The MMP-independent pathway involves TIMP-1's cytokine-like functions, in which it binds specific TIMP surface receptors. Through receptor binding, TIMP-1 can stimulate the proliferation of several types of cells, including keratinocytes, aortic smooth muscle cells, skin epithelial cells, corneal epithelial cells, and astrocytes. TIMP-1 induces astrocyte proliferation, modulates microglia activation, and increases myelination and neurite extension in the central nervous system (CNS). In addition, TIMP-1 also regulates apoptosis and promotes cell survival through direct signaling. This review provides a comprehensive assessment of TIMP-1, specifically regarding its contribution to inflammation, ECM remodeling, and scar formation after SCI.

Identification of critical genes and metabolic pathways in rheumatoid arthritis and osteoporosis toward drug repurposing

BACKGROUND

Rheumatoid arthritis (RA) and osteoporosis (OP) are considered to be complex diseases. In recent studies, a positive association between RA and OP has been reported triggering growing research interest. This study aims to investigate the drugs related to critical genes in RA and OP, using bioinformatics approaches, toward drug repurposing.

METHOD

RA and OP genes were identified. The RA-OP PPI network was constructed and analyzed using the STRING and Cytoscape, respectively. Hub genes and modules were extracted and enriched Gene Ontology, through the WebGestalt and g:Profiler. The identification of the drugs related to critical genes using the DGIDB, and extracted the miRNAs using miRWalk and miRNet.

RESULTS

By network clustering, five significant modules were obtained that have important roles in the immune system. IL6, TNF, IL1B, STAT3, TGFB1, TP53, HIF1A, CCL2, IL10, and MMP9 were found as the top 10 hub genes in the RA-OP network. Hub genes were shown to have implications in inflammatory response, significant functions in cytokine receptor binding, and localized mostly in extracellular space. By investigating the drugs related to hub genes, 16 drugs were identified as repurposing candidate drugs. The 10 drugs included Hydroxychloroquine, Infliximab, Adalimumab, Etanercept, Certolizumab, Cyclosporine, Diacerein, Gevokizumab, Canakinumab, and Olokizumab proposed for OP. Also, six drugs including Pirfenidone, Pentoxifylline, Vadimezan, Rilonacept, Metelimumab, and Siltuximab have important roles in inflammatory control and were proposed for both RA and OP.

CONCLUSIONS

The results of the present study can provide novel insights into the pathogenesis and treatment of RA and OP.

Gram-negative anaerobes elicit a robust keratinocytes immune response with potential insights into HS pathogenesis

Hidradenitis Suppurativa (HS) is a chronic autoinflammatory skin disease with activated keratinocytes, tunnel formation and a complex immune infiltrate in tissue. The HS microbiome is polymicrobial with an abundance of commensal gram-positive facultative (GPs) Staphylococcus species and gram-negative anaerobic (GNA) bacteria like Prevotella, Fusobacterium and Porphyromonas with increasing predominance of GNAs with disease severity. We sought to define the keratinocyte response to bacteria commonly isolated from HS lesions to probe pathogenic relationships between HS and the microbiome. Type strains of Prevotella nigrescens, Prevotella melaninogenica, Prevotella intermedia, Prevotella asaccharolytica, Fusobacterium nucleatum, as well as Staphylococcus aureus and the normal skin commensal Staphylococcus epidermidis were heat-killed and co-incubated with normal human keratinocytes. RNA was collected and analysed using RNAseq and RT-qPCR. The supernatant was collected from cell culture for protein quantification. Transcriptomic profiles between HS clinical samples and stimulated keratinocytes were compared. Co-staining of patient HS frozen sections was used to localize bacteria in lesions. A mouse intradermal injection model was used to investigate early immune recruitment. TLR4 and JAK inhibitors were used to investigate mechanistic avenues of bacterial response inhibition. GNAs, especially F. nucleatum, stimulated vastly higher CXCL8, IL17C, CCL20, IL6, TNF and IL36γ transcription in normal skin keratinocytes than the GPs S. epidermidis and S. aureus. Using RNAseq, we found that F. nucleatum (and Prevotella) strongly induced the IL-17 pathway in keratinocytes and overlapped with transcriptome profiles of HS patient clinical samples. Bacteria were juxtaposed to activated keratinocytes in vivo, and F. nucleatum strongly recruited murine neutrophil and macrophage migration. Both the TLR4 and pan-JAK inhibitors reduced cytokine production. Detailed transcriptomic profiling of healthy skin keratinocytes exposed to GNAs prevalent in HS revealed a potent, extensive inflammatory response vastly stronger than GPs. GNAs stimulated HS-relevant genes, including many genes in the IL-17 response pathway, and were significantly associated with HS tissue transcriptomes. The close association of activated keratinocytes with bacteria in HS lesions and innate infiltration in murine skin cemented GNA pathogenic potential. These novel mechanistic insights could drive future targeted therapies.

Matrix metalloproteinase 9: An emerging biomarker for classification of adherent vestibular schwannoma

Background

The progression of vestibular schwannoma (VS) is intricately linked with interactions between schwannoma cells and the extracellular matrix. Surgical resection of VS is associated with substantial risks as tumors are adherent to the brainstem and cranial nerves. We evaluate the role of matrix metalloproteinase 9 (MMP9) in VS and explore its potential as a biomarker to classify adherent VS.

Methods

Transcriptomic analysis of a murine schwannoma allograft model and immunohistochemical analysis of 17 human VS were performed. MMP9 abundance was assessed in mouse and human schwannoma cell lines. Transwell studies were performed to evaluate the effect of MMP9 on schwannoma invasion in vitro. Plasma biomarkers were identified from a multiplexed proteomic analysis in 45 prospective VS patients and validated in primary culture. The therapeutic efficacy of MMP9 inhibition was evaluated in a mouse schwannoma model.

Results

MMP9 was the most highly upregulated protease in mouse schwannomas and was significantly enriched in adherent VS, particularly around tumor vasculature. High levels of MMP9 were found in plasma of patients with adherent VS. MMP9 outperformed clinical and radiographic variables to classify adherent VS with outstanding discriminatory ability. Human schwannoma cells secreted MMP9 in response to TNF-α which promoted cellular invasion and adhesion protein expression in vitro. Lastly, MMP9 inhibition decreased mouse schwannoma growth in vivo.

Conclusions

We identify MMP9 as a preoperative biomarker to classify adherent VS. MMP9 may represent a new therapeutic target in adherent VS associated with poor surgical outcomes that lack other viable treatment options.