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Tenascin-C is an extracellular matrix glycoprotein that is specifically and transiently expressed upon tissue injury. Upon tissue damage, tenascin-C plays a multitude of different roles that mediate both inflammatory and fibrotic processes to enable effective tissue repair. In the last decade, emerging evidence has demonstrated a vital role for tenascin-C in cardiac and arterial injury, tumor angiogenesis and metastasis, as well as in modulating stem cell behavior. Here we highlight the molecular mechanisms by which tenascin-C mediates these effects and discuss the implications of mis-regulated tenascin-C expression in driving disease pathology.

In conditions such as neurodegenerative diseases, posttraumatic stress disorder (PTSD), addiction and spinal cord injuries, restricted synaptic plasticity hinders the formation of new neuronal connections, preventing the compensation and treatment of adverse behaviors. Perineuronal nets (PNNs) significantly restrict synaptic plasticity by inhibiting synapse formation. The digestion of PNNs has been associated with short-term cognitive improvements and reduced long-term memory, offering potential therapeutic benefits in PTSD. This study investigates the correlation between PNNs and fear memory processes in extracellular matrix (ECM) mutant mice, particularly focusing on the amygdala-medial prefrontal cortex (mPFC) circuit, which is crucial for fear memory generation and maintenance. Fear conditioning was conducted on mice lacking four key ECM-molecules: brevican, neurocan, tenascin-C and tenascin-R (4x KO). These mice exhibited severe impairments in memory consolidation, as evident by their inability to retrieve previously learned fear memories, coupled with reduced PNN density and disturbed synaptic integrity along their PNNs. Additionally, changes in neural activity in the basolateral amygdala (BL) and reductions in VGAT + synaptic puncta in the amygdala-mPFC circuit were observed. In contrast, tenascin single KOs showed intact fear behavior and memory compared to their control groups. Impaired fear memory consolidation can be advantageous in certain conditions, such as PTSD, making the 4x KO mice an intriguing model for future fear conditioning studies and highlighting brevican, neurocan, Tnc, and Tnr as compelling targets for further investigation. This study underscores the significance of ECM regulation for synaptic organization and the potential of PNN modulation as a therapeutic target for fear memory-related conditions.

The synaptic transmission in the mammalian brain is not limited to the interplay between the pre- and the postsynapse of neurons, but involves also astrocytes as well as extracellular matrix (ECM) molecules. Glycoproteins, proteoglycans and hyaluronic acid of the ECM pervade the pericellular environment and condense to special superstructures termed perineuronal nets (PNN) that surround a subpopulation of CNS neurons. The present study focuses on the analysis of PNNs in a quadruple knockout mouse deficient for the ECM molecules tenascin-C (TnC), tenascin-R (TnR), neurocan and brevican. Here, we analysed the proportion of excitatory and inhibitory synapses and performed electrophysiological recordings of the spontaneous neuronal network activity of hippocampal neurons in vitro . While we found an increase in the number of excitatory synaptic molecules in the quadruple knockout cultures, the number of inhibitory synaptic molecules was significantly reduced. This observation was complemented with an enhancement of the neuronal network activity level. The in vivo analysis of PNNs in the hippocampus of the quadruple knockout mouse revealed a reduction of PNN size and complexity in the CA2 region. In addition, a microarray analysis of the postnatal day (P) 21 hippocampus was performed unravelling an altered gene expression in the quadruple knockout hippocampus.

Pattern recognition underpins innate immunity; the accurate identification of danger, including infection, injury, or tumor, is key to an appropriately targeted immune response. Pathogen detection is increasingly well defined mechanistically, but the discrimination of endogenous inflammatory triggers remains unclear. Tenascin-C, a matrix protein induced upon tissue damage and expressed by tumors, activates toll-like receptor 4 (TLR4)-mediated sterile inflammation. Here we map three sites within tenascin-C that directly and cooperatively interact with TLR4. We also identify a conserved inflammatory epitope in related proteins from diverse families, and demonstrate that its presence targets molecules for TLR detection, while its absence enables escape of innate immune surveillance. These data reveal a unique molecular code that defines endogenous proteins as inflammatory stimuli by marking them for recognition by TLRs. Although detection of pathogens by pattern recognition receptors is increasingly well defined, recognition of endogenous triggers remains poorly understood. By examining the interface between tenascin-C and TLR4, the authors identify a molecular code that identifies endogenous proteins as inflammatory stimuli.

Incidence of delayed graft function (DGF) increases due to the decline in donor kidney quality and the increased use of marginal allografts, while the promising biomarkers for early DGF prediction are lacking. Previous analyses showed that Tenascin-C (TNC) was associated with acute kidney injury; however, its correlation with DGF is unclear. This study aimed to evaluate the ability of TNC to predict DGF. This prospective study included 36 perioperative kidney transplant recipients. Serum and urine samples were collected at regular intervals before and during the 10 days after transplantation to measure TNC and other conventional biomarkers. Pre-implantation graft renal biopsies were analyzed using Remuzzi and TNC staining scores. These data were then combined with clinical risk factors to construct a DGF prediction model. In recipients with DGF, sTNC levels peaked on postoperative day 4, and were associated with increased risk of composite events (DGF and rehospitalization). uTNC levels were significantly higher in recipients without DGF, peaking at 8 hours postoperatively. sTNC levels at postoperative day 4 and TNC immunohistochemical scores were identified as independent risk factors for DGF. Incorporating the above two factors into a model comprising recipient age, cholesterol levels, donor cold ischemia time, and surgery duration significantly improved its ability to predict DGF, with the area under the curve increasing from 0.6790 to 0.9321. This study highlights the TNC levels in perioperative kidney transplant recipients and their correlation with DGF. sTNC levels and TNC immunohistochemical staining scores may serve as potential biomarker predicting DGF.

The kidney tubules constitute two-thirds of the cells of the kidney and account for the majority of the organ’s metabolic energy expenditure. Acute tubular injury (ATI) is observed across various types of kidney diseases and may significantly contribute to progression to kidney failure. Non-invasive biomarkers of ATI may allow for early detection and drug development. Using the SomaScan proteomics platform on 434 patients with biopsy-confirmed kidney disease, we here identify plasma biomarkers associated with ATI severity. We employ regional transcriptomics and proteomics, single-cell RNA sequencing, and pathway analysis to explore biomarker protein and gene expression and enriched biological pathways. Additionally, we examine ATI biomarker associations with acute kidney injury (AKI) in the Kidney Precision Medicine Project (KPMP) ( n  = 44), the Atherosclerosis Risk in Communities (ARIC) study ( n  = 4610), and the COVID-19 Host Response and Clinical Outcomes (CHROME) study ( n  = 268). Our findings indicate 156 plasma proteins significantly linked to ATI with osteopontin, macrophage mannose receptor 1, and tenascin C showing the strongest associations. Pathway analysis highlight immune regulation and organelle stress responses in ATI pathogenesis. Acute tubular injury (ATI) significantly contributes to many kidney diseases. Here, the authors identify several immune response and cellular stress plasma proteins linked to ATI severity and acute kidney injury, which may aid in non-invasive ATI assessment.

The bursa of Fabricius (BF) is a unique primary lymphoid organ critical for B cell development in its specialized follicular microenvironment. Although the role of the follicular medulla required for B cell maturation is well characterized, the cellular components and function of the ontogenetically later emerging cortex remain less understood. Here, we combined immunocytochemistry, RNAscope, cell culture, and embryo manipulation techniques to investigate the origin and structure of the cortical compartment. Immunostaining of adult BF revealed a heterogeneous B cell distribution in the cortex, with chB6+/CXCR4 high cells in the outer region and CXCR4 low/dim cells adjacent to the cortico-medullary border. The cortex is supported by CXCL12+/desmin+/vimentin+ mesenchymal reticular cells producing extracellular matrix (ECM), including tenascin-C, which is enriched in the CXCR4 low/dim region. Embryonic expression of tenascin-C coincides with the accumulation of CXCR4+ B cell precursors in the presumptive cortical compartment. Functional studies demonstrate that tenascin-C inhibits embryonic CXCR4+ B cell migration, with overexpression disrupting follicle formation. These findings highlight tenascin-C as a key regulator of B cell migration in the embryonic BF and emphasize the importance of a tenascin-C-free mesenchymal environment for the homing of CXCR4 + B cell precursors during development. In adults, the complementary expression patterns of tenascin-C and CXCR4 molecules suggest that downregulation of CXCR4 is required for B cell migration through the CXCL12-tenascin-C-rich cortex before exiting the BF.

Tenascin-C (TNC), a matricellular protein, is upregulated in brain parenchyma after experimental subarachnoid hemorrhage (SAH). Recent studies emphasize that early brain injury (EBI) should be overcome to improve post-SAH outcomes. The aim of this study was to investigate effects of TNC knockout (TNKO) on neuronal apoptosis and neuroinflammation, both of which are important constituents of EBI after SAH. C57BL/6 wild-type (WT) mice or TNKO mice underwent sham or filament perforation SAH modeling. Twenty-five WT mice and 25 TNKO mice were randomly divided into sham+WT ( n  = 10), sham+TNKO ( n  = 8), SAH+WT ( n  = 15), and SAH+TNKO ( n  = 17) groups. Beam balance test, neurological score, terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling staining, immunostaining of Toll-like receptor 4 (TLR4), and Western blotting were performed to evaluate neurobehavioral impairments, neuronal apoptosis, and neuroinflammation at 24 h post-SAH. Deficiency of TNC significantly alleviated post-SAH neurobehavioral impairments and neuronal apoptosis. The protective effects of TNKO on neurons were associated with the inhibition of a caspase-dependent apoptotic pathway, which was at least partly mediated by TLR4/nuclear factor-κB/interleukin-1β and interleukin-6 signaling cascades. This study first provided the direct evidence that TNC causes post-SAH neuronal apoptosis and neuroinflammation, potentially leading to the development of a new molecular targeted therapy against EBI.

Dermal fibroblasts and cutaneous nerves are important players in skin diseases, while their reciprocal roles during skin inflammation have not been characterized. Here we identify an inflammation-induced subset of papillary fibroblasts that promotes aberrant neurite outgrowth and psoriasiform skin inflammation by secreting the extracellular matrix protein tenascin-C (TNC). Single-cell analysis of fibroblast lineages reveals a Tnc + papillary fibroblast subset with pro-axonogenesis and neuro-regulation transcriptomic hallmarks. TNC overexpression in fibroblasts boosts neurite outgrowth in co-cultured neurons, while fibroblast-specific TNC ablation suppresses hyperinnervation and alleviates skin inflammation in male mice modeling psoriasis. Dermal γδT cells, the main producers of type 17 pathogenic cytokines, frequently contact nerve fibers in mouse psoriasiform lesions and are likely modulated by postsynaptic signals. Overall, our results highlight the role of an inflammation-responsive fibroblast subset in facilitating neuro-immune synapse formation and suggest potential avenues for future therapeutic research. Local cues for hyperinnervation in chronic skin diseases are not fully understood. Here, the authors show that a distinct subset of dermal papillary fibroblasts promote neurite outgrowth and facilitate neuron-immune interactions through extracellular matrix remodeling in a mouse model of psoriasis

Background Diabetic cardiomyopathy (DCM) is a complex condition linked to diabetes, characterized by cardiac and vascular dysfunction, frequently concomitant with heart failure with preserved ejection fraction. The extracellular matrix glycoprotein Tenascin-C (TNC) has been found to be upregulated under diabetic conditions. However, the potential contributory role of TNC in the progression of DCM remains largely unclear. This study was designed to elucidate the role of TNC in the pathogenesis of DCM. Methods Diabetes was induced in adult male wild-type (WT) and TNC knockout (TNC-KO) mice, through the administration of streptozotocin (50 mg/kg) for five consecutive days. At 18 weeks cardiac and aortic vascular function was evaluated using echocardiography and wire myography. Myocardium and plasma samples were collected for biochemical, histological, and molecular analyses. Cardiomyocytes and cardiac fibroblasts were used to investigate the impact of diabetes on TNC expression, inflammation, myocardial stiffness and function. Additionally, transcriptomic analysis of cardiac tissue by RNA-sequencing was conducted. Plasma TNC levels were assessed by enzyme-linked immunosorbent assay in cohorts of heart failure patients and type 2 diabetes mellitus. Results TNC-KO diabetic mice showed preserved left ventricular systolic and diastolic function, significantly reduced cardiac fibrosis and mitigated endothelial dysfunction compared to WT diabetic animals. Compared with cardiomyocytes of diabetic WT animals, cardiomyocytes of TNC-KO mice developed less stiffness (Fpassive). Additionally, exposing mouse cardiomyocytes and human cardiac fibroblasts to high glucose stress (30 mM) led to a significant increase in TNC expression. Conversely, recombinant human TNC promoted pro-inflammatory and oxidative stress markers in cardiomyocytes. The role of TNC in fibrosis and DCM was found to involve pathways related to p53 signaling and Serpin1k, Ccn1, Cpt1a, and Slc27a1, as identified by RNA sequencing analysis. Additionally, plasma TNC levels were significantly elevated in patients with heart failure, irrespective of diabetes status, compared to healthy individuals. Conclusions Our findings indicate that in diabetes, TNC contributes to cardiac contractile dysfunction, myocardial fibrosis, oxidative stress, inflammation, and metabolic disturbances in diabetic mouse heart. These results implicate the potential of TNC inhibition as a novel therapeutic approach for treating DCM. Graphical abstract