The extracellular matrix protein mindin regulates trafficking of murine eosinophils into the airspace

The Eotaxin-1/CCR3 Axis and Matrix Metalloproteinase-9 Are Critical in Anti-NC16A IgE-Induced Bullous Pemphigoid

Bullous pemphigoid (BP) is the most common autoimmune bullous skin disease of humans and is characterized by eosinophilic inflammation and circulating and tissue-bound IgG and IgE autoantibodies directed against two hemidesmosomal proteins: BP180 and BP230. The noncollagenous 16A domain (NC16A) of BP180 has been found to contain major epitopes recognized by autoantibodies in BP. We recently established the pathogenicity of anti-NC16A IgE through passive transfer of patient-derived autoantibodies to double-humanized mice that express the human high-affinity IgE receptor, FcεRI, and human NC16A domain (FcεRI/NC16A). In this model, anti-NC16A IgEs recruit eosinophils to mediate tissue injury and clinical disease in FcεRI/NC16A mice. The objective of this study was to characterize the molecular and cellular events that underlie eosinophil recruitment and eosinophil-dependent tissue injury in anti-NC16A IgE-induced BP. We show that anti-NC16A IgEs significantly increase levels of key eosinophil chemoattractants, eotaxin-1 and eotaxin-2, as well as the proteolytic enzyme matrix metalloproteinase-9 (MMP-9) in the lesional skin of FcεRI/NC16A mice. Importantly, neutralization of eotaxin-1, but not eotaxin-2, and blockade of the main eotaxin receptor, CCR3, drastically reduce anti-NC16A IgE-induced disease activity. We further show that anti-NC16A IgE/NC16A immune complexes induce the release of MMP-9 from eosinophils, and that MMP-9-deficient mice are resistant to anti-NC16A IgE-induced BP. Lastly, we find significantly increased levels of eotaxin-1, eotaxin-2, and MMP-9 in blister fluids of BP patients. Taken together, this study establishes the eotaxin-1/CCR3 axis and MMP-9 as key players in anti-NC16A IgE-induced BP and candidate therapeutic targets for future drug development and testing.

Eosinophil accumulation in postnatal lung is specific to the primary septation phase of development

Type 2 immune cells and eosinophils are transiently present in the lung tissue not only in pathology (allergic disease, parasite expulsion) but also during normal postnatal development. However, the lung developmental processes underlying airway recruitment of eosinophils after birth remain unexplored. We determined that in mice, mature eosinophils are transiently recruited to the lung during postnatal days 3-14, which specifically corresponds to the primary septation/alveolarization phase of lung development. Developmental eosinophils peaked during P10-14 and exhibited Siglec-Fmed/highCD11c-/low phenotypes, similar to allergic asthma models. By interrogating the lung transcriptome and proteome during peak eosinophil recruitment in postnatal development, we identified markers that functionally capture the establishment of the mesenchymal-epithelial interface (Nes, Smo, Wnt5a, Nog) and the deposition of the provisional extracellular matrix (ECM) (Tnc, Postn, Spon2, Thbs2) as a key lung morphogenetic event associating with eosinophils. Tenascin-C (TNC) was identified as one of the key ECM markers in the lung epithelial-mesenchymal interface both at the RNA and protein levels, consistently associating with eosinophils in development and disease in mice and humans. As determined by RNA-seq analysis, naïve murine eosinophils cultured with ECM enriched in TNC significantly induced expression of Siglec-F, CD11c, eosinophil peroxidase, and other markers typical for activated eosinophils in development and allergic inflammatory responses. TNC knockout mice had an altered eosinophil recruitment profile in development. Collectively, our results indicate that lung morphogenetic processes associated with heightened Type 2 immunity are not merely a tissue "background" but specifically guide immune cells both in development and pathology.

A bigenic mouse model of FSGS reveals perturbed pathways in podocytes, mesangial cells and endothelial cells

Focal segmental glomerulosclerosis is a major cause of end stage renal disease. Many patients prove unresponsive to available therapies. An improved understanding of the molecular basis of the disease process could provide insights leading to novel therapeutic approaches. In this study we carried out an RNA-seq analysis of the altered gene expression patterns of podocytes, mesangial cells and glomerular endothelial cells of the bigenic Cd2ap+/-, Fyn-/- mutant mouse model of FSGS. In the podocytes we observed upregulation of many genes related to the Tgfβ family/pathway, including Gdnf, Tgfβ1, Tgfβ2, Snai2, Vegfb, Bmp4, and Tnc. The mutant podocytes also showed upregulation of Acta2, a marker of smooth muscle and associated with myofibroblasts, which are implicated in driving fibrosis. GO analysis of the podocyte upregulated genes identified elevated protein kinase activity, increased expression of growth factors, and negative regulation of cell adhesion, perhaps related to the observed podocyte loss. Both podocytes and mesangial cells showed strong upregulation of aldehyde dehydrogenase genes involved in the synthesis of retinoic acid. Similarly, the Cd2ap+/-, Fyn-/- mesangial cells, as well as podocytes in other genetic models, and the glomeruli of human FSGS patients, all show upregulation of the serine protease Prss23, with the common thread suggesting important functionality. Another gene with strong upregulation in the Cd2ap+/-, Fyn-/- mutant mesangial cells as well as multiple other mutant mouse models of FSGS was thrombospondin, which activates the secreted inactive form of Tgfβ. The Cd2ap+/-, Fyn-/- mutant endothelial cells showed elevated expression of genes involved in cell proliferation, angioblast migration, angiogenesis, and neovasculature, all consistent with the formation of new blood vessels in the diseased glomerulus. The resulting global definition of the perturbed molecular pathways in the three major cell types of the mutant glomerulus provide deeper understanding of the molecular pathogenic pathways.

Investigation of mindin levels in hypertensive patients with left ventricular hypertrophy and QRS fragmentation on electrocardiography

PURPOSE

Mindin was associated with diabetic nephropathy, podocyte injury, colitis, allergic asthma, liver ischaemia and reperpusion injury and ischaemic brain injury. On the other hand, it was reported as a protective factor against obesity, cardiac hypertrophy, fibrosis and remodelling. Fragmented QRS complexes (fQRS) are markers of altered ventricular depolarisation owing to a prior myocardial scar and fibrosis. In this study, we aimed to investigate mindin levels in hypertensive patients with left ventricular hypertrophy and fQRS on electrocardiography.

METHODS

This observational case-control study enrolled 70 (36 female) hypertensive patients with fQRS and 38 (23 female) hypertensive control patients. All patients were evaluated by transthoracic echocardiography. Mindin levels were measured by the enzyme-linked immunosorbent assay (ELISA). Clinical, echocardiographic and laboratory data were compared between patient and control groups.

RESULTS

There was no significant difference between patient and control groups in terms of clinical, echocardiographic and routine laboratory parameters. The mindin levels were significantly higher in the patient group than controls (11.3 (7.21-19.31) vs 4.15 (2.86-6.34); p < .001). Multiple logistic regression analyses defined increased mindin levels as an independent predictor for the presence of fQRS (Odds ratio: 1.733; p = .034). Mindin levels >6.74 predicted the presence of fQRS with a sensitifity of 84.3% and specificity of 79.9% on receiver operating characteristic (ROC) curve analysis (The area under the curve:0.889; Confidence Interval: 0.827-0.951; p < .001).

CONCLUSION

Mindin expressin is upregulated in hypertensive patients with fQRS complexes. In contrary to previous studies, increased mindin levels may be associated with myocardial fibrosis.

Eosinophils Mediate Tissue Injury in the Autoimmune Skin Disease Bullous Pemphigoid

Eosinophils are typically associated with unique inflammatory settings, including allergic inflammation and helminth infections. However, new information suggests that eosinophils contribute more broadly to inflammatory responses and participate in local immune regulation and the tissue remodeling/repair events linked with a variety of diseases. Eosinophilic infiltration has long been a histologic hallmark of bullous pemphigoid (BP), a subepidermal autoimmune blistering disease characterized by autoantibodies directed against basement membrane protein BP180. However, the exact role of eosinophils in disease pathogenesis remains largely unknown. We show here that eosinophils are necessary for IgE autoantibody-mediated BP blister formation in a humanized IgE receptor mouse model of BP. Disease severity is IgE dose dependent and correlates with the degree of eosinophil infiltration in the skin. Furthermore, IgE autoantibodies fail to induce BP in eosinophil-deficient mice, confirming that eosinophils are required for IgE-mediated tissue injury. Thus, eosinophils provide the cellular link between IgE autoantibodies and skin blistering in this murine model of BP. These findings suggest a role for eosinophils in autoimmune disease and have important implications for the treatment of BP and other antibody-mediated inflammatory and autoimmune diseases.

Intrinsic disorder in spondins and some of their interacting partners

Spondins, which are proteins that inhibit and promote adherence of embryonic cells so as to aid axonal growth are part of the thrombospondin-1 family. Spondins function in several important biological processes, such as apoptosis, angiogenesis, etc. Spondins constitute a thrombospondin subfamily that includes F-spondin, a protein that interacts with Aβ precursor protein and inhibits its proteolytic processing; R-spondin, a 4-membered group of proteins that regulates Wnt pathway and have other functions, such as regulation of kidney proliferation, induction of epithelial proliferation, the tumor suppressant action; M-spondin that mediates mechanical linkage between the muscles and apodemes; and the SCO-spondin, a protein important for neuronal development. In this study, we investigated intrinsic disorder status of human spondins and their interacting partners, such as members of the LRP family, LGR family, Frizzled family, and several other binding partners in order to establish the existence and importance of disordered regions in spondins and their interacting partners by conducting a detailed analysis of their sequences, finding disordered regions, and establishing a correlation between their structure and biological functions.

Transcriptome-Wide Expression Profiling in Skin Fibroblasts of Patients with Joint Hypermobility Syndrome/Ehlers-Danlos Syndrome Hypermobility Type

Joint hypermobility syndrome/Ehlers–Danlos syndrome hypermobility type (JHS/EDS-HT), is likely the most common systemic heritable connective tissue disorder, and is mostly recognized by generalized joint hypermobility, joint instability complications, minor skin changes and a wide range of satellite features. JHS/EDS-HT is considered an autosomal dominant trait but is still without a defined molecular basis. The absence of (a) causative gene(s) for JHS/EDS-HT is likely attributable to marked genetic heterogeneity and/or interaction of multiple loci. In order to help in deciphering such a complex molecular background, we carried out a comprehensive immunofluorescence analysis and gene expression profiling in cultured skin fibroblasts from five women affected with JHS/EDS-HT. Protein study revealed disarray of several matrix structural components such as fibrillins, tenascins, elastin, collagens, fibronectin, and their integrin receptors. Transcriptome analysis indicated perturbation of different signaling cascades that are required for homeostatic regulation either during development or in adult tissues as well as altered expression of several genes involved in maintenance of extracellular matrix architecture and homeostasis (e.g., SPON2, TGM2, MMP16, GPC4, SULF1), cell-cell adhesion (e.g., CDH2, CHD10, PCDH9, CLDN11, FLG, DSP), immune/inflammatory/pain responses (e.g., CFD, AQP9, COLEC12, KCNQ5, PRLR), and essential for redox balance (e.g., ADH1C, AKR1C2, AKR1C3, MAOB, GSTM5). Our findings provide a picture of the gene expression profile and dysregulated pathways in JHS/EDS-HT skin fibroblasts that correlate well with the systemic phenotype of the patients.

Genes of innate immunity and the biological response to inhaled ozone

Ambient ozone has a significant impact on human health. We have made considerable progress in understanding the fundamental mechanisms that regulate the biological response to ozone. It is increasingly clear that genes of innate immunity play a central role in both infectious and noninfectious lung disease. The biological response to ambient ozone provides a clinically relevant environmental exposure that allows us to better understand the role of innate immunity in noninfectious airways disease. In this brief review, we focus on (1) specific cell types in the lung modified by ozone, (2) ozone and oxidative stress, (3) the relationship between genes of innate immunity and ozone, (4) the role of extracellular matrix in reactive airways disease, and (5) the effect of ozone on the adaptive immune system. We summarize recent advances in understanding the mechanisms that ozone contributes to environmental airways disease.

RETRACTED: NAD(P)H:quinone oxidoreductase 1 protects lungs from oxidant-induced emphysema in mice

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of the Authors. Since learning of potential discrepancies between the raw data from the animal pulmonary physiology laboratory at Duke that were used to calculate the in vivo pulmonary mechanics and the re-exported machine-generated raw data, some studies published elsewhere have been replicated successfully. However it is not possible to replicate this study as the NQO1-deficient mice on the C57BL/6 background are no longer available from the NCI. The authors recognize that previous work to identify differences in alveolar size can vary dependent on background strain when comparing inbred mouse strains (Soutiere SE et al Resp Physiol Neurobiol 2004;140(3)183–91 doi: 10.1016/j.resp.2004.02.003). Because of the prolonged period of time required to successfully backcross NQO1-deficient animals onto C57BL/6J background and the time required to repeat studies presented in this manuscript the authors think it does not seem feasible to conduct replicate studies in a reasonable timeline. Therefore, the most appropriate course of action is to retract the report as it is the authors' goal to maintain accuracy of the scientific record to the best of their ability. The authors offer sincere apologies to the scientific community.

Extracellular Matrix Protein Mindin is Required for the Complete Allergic Response to Fungal-Associated Proteinase

Asthma remains an important cause of morbidity and mortality with an incidence that continues to rise. Despite the importance of this disease, the mechanisms by which the host develops allergic airways disease remain poorly understood. The development of allergic airways disease appears to be contingent on activation of both the innate and adaptive immune system, but little is known about the cross-talk between these two systems. The extracellular matrix protein mindin (Spondin 2) has been previously demonstrated to have functional roles in both the innate and adaptive immunological responses. Previous work supports that pulmonary challenge with fungal-associated allergenic proteinase (FAP) induces an innate allergic response. We hypothesized that mindin would modify the biological response to FAP. Saline or FAP was administered by oropharyngeal aspiration to C57BL/6 wild type or mindin-null mice every 4 days for a total of five exposures. FAP exposed C57BL/6 mice developed enhanced airway hyperresponsiveness (AHR) to methacholine challenge and increased neutrophils and eosinophils in the bronchoalveolar lavage as compared to saline exposed controls. These responses were significantly reduced in mindin-null mice exposed to FAP. FAP challenge was associated with a broad induction of cytokines (IL-1β, TNFα, Th1, Th2, and IL-17), chemokines, and growth factors, which were reduced in mindin-null mice exposed to FAP. RNA expression in lung monocytes for representative M1 and M2 activation markers were increased by FAP, but were independent of mindin. Our observations support that challenge with FAP results in activation of both innate and adaptive immune signaling pathways in a manner partially dependent on mindin. These findings suggest a potential role for the extracellular matrix protein mindin in cross-talk between the innate and adaptive immune systems.

Role of mindin in diabetic nephropathy

A number of studies have shown that proinflammatory cytokines have important roles in determining the development of microvascular diabetic complications, including nephropathy. Inflammatory biomarkers should be useful for diagnosis or monitoring of diabetic nephropathy. Mindin (spondin 2) is a member of the mindin-/F-spondin family of secreted extracellular matrix (ECM) proteins. Recent studies showed that mindin is essential for initiation of innate immune response and represents a unique pattern-recognition molecule in the ECM. Previously, we demonstrated that the levels of urinary mindin in patients with type 2 diabetes were higher than those in healthy individuals. We propose that urinary mindin is a potent biomarker for the development of diabetic nephropathy.

The role of the extracellular matrix protein mindin in airway response to environmental airways injury

BACKGROUND

Our previous work demonstrated that the extracellular matrix protein mindin contributes to allergic airways disease. However, the role of mindin in nonallergic airways disease has not previously been explored.

OBJECTIVES

We hypothesized that mindin would contribute to airways disease after inhalation of either lipopolysaccharide (LPS) or ozone.

METHODS

We exposed C57BL/6J and mindin-deficient (-/-) mice to aerosolized LPS (0.9 μg/m3 for 2.5 hr), saline, ozone (1 ppm for 3 hr), or filtered air (FA). All mice were evaluated 4 hr after LPS/saline exposure or 24 hr after ozone/FA exposure. We characterized the physiological and biological responses by analysis of airway hyperresponsiveness (AHR) with a computer-controlled small-animal ventilator (FlexiVent), inflammatory cellular recruitment, total protein in bronchoalveolar lavage fluid (BALF), proinflammatory cytokine profiling, and ex vivo bronchial ring studies.

RESULTS

After inhalation of LPS, mindin-/- mice demonstrated significantly reduced total cell and neutrophil recruitment into the airspace compared with their wild-type counterparts. Mindin-/- mice also exhibited reduced proinflammatory cytokine production and lower AHR to methacholine challenge by FlexiVent. After inhalation of ozone, mice had no detectible differences in cellular inflammation or total BALF protein dependent on mindin. However, mindin-/- mice were protected from increased proinflammatory cytokine production and AHR compared with their C57BL/6J counterparts. After ozone exposure, bronchial rings derived from mindin-/- mice demonstrated reduced constriction in response to carbachol.

CONCLUSIONS

These data demonstrate that the extracellular matrix protein mindin modifies the airway response to both LPS and ozone. Our data support a conserved role of mindin in production of proinflammatory cytokines and the development of AHR in two divergent models of reactive airways disease, as well as a role of mindin in airway smooth muscle contractility after exposure to ozone.

Cardiac-specific mindin overexpression attenuates cardiac hypertrophy via blocking AKT/GSK3β and TGF-β1-Smad signalling

AIMS

Mindin is a secreted extracellular matrix protein, an integrin ligand, and an angiogenesis inhibitor, other examples of which are all key players in the progression of cardiac hypertrophy. However, its function during cardiac hypertrophy remains unclear. This study was aimed to identify the effect of mindin on cardiac hypertrophy and the underlying mechanisms.

METHODS AND RESULTS

A significant down-regulation of mindin expression was observed in human failing hearts. To further investigate the role of mindin in cardiac hypertrophy, we used cultured neonatal rat cardiomyocytes with gain and loss of mindin function and cardiac-specific Mindin-overexpressing transgenic (TG) mice. In cultured cardiomyocytes, mindin negatively regulated angiotensin II (Ang II)-mediated hypertrophic growth, as detected by [(3)H]-Leucine incorporation, cardiac myocyte area, and hypertrophic marker protein levels. Cardiac hypertrophy in vivo was produced by aortic banding (AB) or Ang II infusion in TG mice and their wild-type controls. The extent of cardiac hypertrophy was evaluated by echocardiography as well as by pathological and molecular analyses of heart samples. Mindin overexpression in the heart markedly attenuated cardiac hypertrophy, fibrosis, and left ventricular dysfunction in mice in response to AB or Ang II. Further analysis of the signalling events in vitro and in vivo indicated that these beneficial effects of mindin were associated with the interruption of AKT/glycogen synthase kinase 3β (GSK3β) and transforming growth factor (TGF)-β1-Smad signalling.

CONCLUSION

The present study demonstrates for the first time that mindin serves as a novel mediator that protects against cardiac hypertrophy and the transition to heart failure by blocking AKT/GSK3β and TGF-β1-Smad signalling.

Mindin is upregulated during colitis and may activate NF-κB in a TLR-9 mediated manner

AIM: To investigate the regulation of mindin expression and the signaling pathway involved during inflammation.

METHODS: C57BL/6 mice were treated with 3% dextran sulfate sodium (DSS) in drinking water for 6 d to induce acute colitis, and then the colon was harvested for histological analysis or for RNA isolation. mRNA expression of mindin and nuclear factor (NF)-κB p65 was analyzed by quantitative real time polymerase chain reaction (RT-PCR) and mindin expression construct was confirmed by Western blotting. Mouse macrophage and intestinal epithelial lineage cells were stimulated with different cytokines and toll-like receptor (TLR) ligands, before pNF-κB-luciferase activity was assessed using the Dual-Luciferase reporter assay system.

RESULTS: mRNA expression of mindin was upregulated 4.7 ± 1.1 fold compared with the baseline during DSS-induced intestinal inflammation in the mice. Stimulation with CpG-ODN (a known TLR-9 ligand) induced 4.2 ± 0.3 fold upregulation of mindin expression in RAW 264.7 cells. Full-length of mindin was cloned from cDNA of mouse mesenteric lymph node, then the pCMV-Mindin-Flag expression vector was established and the protein expression level was confirmed. Transfection of the mindin construct and stimulation with CpG-ODN significantly increased the NF-κB-luciferase activity by 2.5 ± 0.3 and 4.5 ± 0.5 fold in RAW264.7 and CMT93 cells, respectively (P < 0.01).

CONCLUSION: Mindin expression is upregulated during intestinal inflammation and may induce NF-κB promoter activation in a TLR-9 mediated manner.