Role of basement membrane in EMMPRIN/CD147 induction in rat tracheal epithelial cells

Development of a novel human CD147 knock-in NSG mouse model to test SARS-CoV-2 viral infection

BACKGROUND

An animal model that can mimic the SARS-CoV-2 infection in humans is critical to understanding the rapidly evolving SARS-CoV-2 virus and for development of prophylactic and therapeutic strategies to combat emerging mutants. Studies show that the spike proteins of SARS-CoV and SARS-CoV-2 bind to human angiotensin-converting enzyme 2 (hACE2, a well-recognized, functional receptor for SARS-CoV and SARS-CoV-2) to mediate viral entry. Several hACE2 transgenic (hACE2Tg) mouse models are being widely used, which are clearly invaluable. However, the hACE2Tg mouse model cannot fully explain: (1) low expression of ACE2 observed in human lung and heart, but lung or heart failure occurs frequently in severe COVID-19 patients; (2) low expression of ACE2 on immune cells, but lymphocytopenia occurs frequently in COVID-19 patients; and (3) hACE2Tg mice do not mimic the natural course of SARS-CoV-2 infection in humans. Moreover, one of most outstanding features of coronavirus infection is the diversity of receptor usage, which includes the newly proposed human CD147 (hCD147) as a possible co-receptor for SARS-CoV-2 entry. It is still debatable whether CD147 can serve as a functional receptor for SARS-CoV-2 infection or entry.

RESULTS

Here we successfully generated a hCD147 knock-in mouse model (hCD147KI) in the NOD-scid IL2Rgammanull (NSG) background. In this hCD147KI-NSG mouse model, the hCD147 genetic sequence was placed downstream of the endogenous mouse promoter for mouse CD147 (mCD147), which creates an in vivo model that may better recapitulate physiological expression of hCD147 proteins at the molecular level compared to the existing and well-studied K18-hACE2-B6 (JAX) model. In addition, the hCD147KI-NSG mouse model allows further study of SARS-CoV-2 in the immunodeficiency condition which may assist our understanding of this virus in the context of high-risk populations in immunosuppressed states. Our data show (1) the human CD147 protein is expressed in various organs (including bronchiolar epithelial cells) in hCD147KI-NSG mice by immunohistochemical staining and flow cytometry; (2) hCD147KI-NSG mice are marginally sensitive to SARS-CoV-2 infection compared to WT-NSG littermates characterized by increased viral copies by qRT-PCR and moderate body weight decline compared to baseline; (3) a significant increase in leukocytes in the lungs of hCD147KI-NSG mice, compared to infected WT-NSG mice.

CONCLUSIONS

hCD147KI-NSG mice are more sensitive to COVID-19 infection compared to WT-NSG mice. The hCD147KI-NSG mouse model can serve as an additional animal model for further interrogation whether CD147 serve as an independent functional receptor or accessory receptor for SARS-CoV-2 entry and immune responses.

Reprint of: Extracellular matrix as a biological scaffold material: Structure and function

Biological scaffold materials derived from the extracellular matrix (ECM) of intact mammalian tissues have been successfully used in a variety of tissue engineering/regenerative medicine applications both in preclinical studies and in clinical applications. Although it is recognized that the materials have constructive remodeling properties, the mechanisms by which functional tissue restoration is achieved are not well understood. There is evidence to support essential roles for both the structural and functional characteristics of the biological scaffold materials. This paper provides an overview of the composition and structure of selected ECM scaffold materials, the effects of manufacturing methods upon the structural properties and resulting mechanical behavior of the scaffold materials, and the in vivo degradation and remodeling of ECM scaffolds with an emphasis on tissue function.

Whole-organ tissue engineering: decellularization and recellularization of three-dimensional matrix scaffolds

The definitive treatment for end-stage organ failure is orthotopic transplantation. However, the demand for transplantation far exceeds the number of available donor organs. A promising tissue-engineering/regenerative-medicine approach for functional organ replacement has emerged in recent years. Decellularization of donor organs such as heart, liver, and lung can provide an acellular, naturally occurring three-dimensional biologic scaffold material that can then be seeded with selected cell populations. Preliminary studies in animal models have provided encouraging results for the proof of concept. However, significant challenges for three-dimensional organ engineering approach remain. This manuscript describes the fundamental concepts of whole-organ engineering, including characterization of the extracellular matrix as a scaffold, methods for decellularization of vascular organs, potential cells to reseed such a scaffold, techniques for the recellularization process and important aspects regarding bioreactor design to support this approach. Critical challenges and future directions are also discussed.

High levels of extracellular matrix metalloproteinase inducer are expressed in lymphangioleiomyomatosis

Pulmonary lymphangioleiomyomatosis is pathologically characterized by the proliferation of abnormal smooth muscle-like cells (lymphangioleiomyomatosis cells) that synthesize excess matrix metalloproteinases. Extracellular matrix metalloproteinase inducer is minimally expressed in the healthy lung, but is up-regulated in various lung injuries that are apparently associated with matrix metalloproteinases. We therefore immunohistochemically stained extracellular matrix metalloproteinase inducer in lymphangioleiomyomatosis cells and measured extracellular matrix metalloproteinase inducer in bronchoalveolar lavage fluid using an enzyme-linked immunosorbent assay. We also quantified extracellular matrix metalloproteinase inducer messenger RNA expression in the lung using quantitative reverse transcriptase-polymerase chain reaction. Intense staining for extracellular matrix metalloproteinase inducer in lymphangioleiomyomatosis cells indicated high immunoreactivity. Dual immunofluorescence studies revealed diffuse colocalization between extracellular matrix metalloproteinase inducer and alpha smooth muscle actin, matrix metalloproteinase-2, or matrix metalloproteinase-9. Although levels of extracellular matrix metalloproteinase inducer messenger RNA did not differ in whole lung homogenates from patients with lymphangioleiomyomatosis and healthy controls (1.7 +/- 0.1 versus 1.5 +/- 0.2 SE, not significant; both n = 4), lymphangioleiomyomatosis nodules retrieved by laser capture microdissection expressed 5.1 (+/-1.0 SE)-fold higher levels of extracellular matrix metalloproteinase inducer messenger RNA than lung homogenates (P = .0077, n = 4). Levels of extracellular matrix metalloproteinase inducer were significantly elevated in bronchoalveolar lavage fluid from lymphangioleiomyomatosis patients compared with controls (82.7 +/- 19.5 versus 38.6 +/- 9.0 SE pg/mL, P = .0497; n = 8 and 9, respectively). Increased levels of extracellular matrix metalloproteinase inducer colocalized with increased matrix metalloproteinases in lymphangioleiomyomatosis cells indicate that it potentially functions in pulmonary lymphangioleiomyomatosis.

A soluble factor (EMMPRIN) in exudate influences knee motion after total arthroplasty

Few studies have been conducted to investigate biological factors that affect postoperative knee motion after total knee arthroplasty (TKA). The purpose of this study is to test the hypothesis that range of knee motion (ROM) at 4 weeks after TKA is correlated with the concentration of extracellular matrix metalloproteinase inducer (EMMPRIN) and transforming growth factor (TGF)-beta1 in the exudative fluid harvested from the joint after surgery. A prospective measurement study was conducted with 20 osteoarthritis patients who underwent TKA. At 48 h after surgery, the exudate was harvested from a closed drainage system. Enzyme-linked immunosorbent assay was performed to measure the concentration of TGF-beta1, EMMPRIN, MMP-1, 2, 9, tissue inhibitor of metalloproteinase-1, and Hyalunonan. Knee flexion angle was measured before and at 4 weeks after surgery. There was a significant correlation between the EMMPRIN levels and knee flexion angle (r = 0.557, p = 0.0148). Western blot analysis of the exudate showed a prominent band for EMMPRIN at 27 kDa. On the other hand, there was no correlation between the TGF-beta1 levels and the knee flexion angle. This study showed that EMMPRIN levels after TKA affect the postoperative ROM. As to clinical relevance, EMMPRIN in the exudate after TKA is a promising biological indicator to predict difficulty in restoring postoperative ROM.

Extracellular matrix metalloproteinase inducer (EMMPRIN) and matrix metalloproteinases (MMPs) as regulators of tumor-host interaction in a spontaneous metastasis model in rats

EMMPRIN has a role in invasion and metastasis through the induction of MMPs and the consequent modulation of cell-substrate and cell-cell adhesion processes. The present study evaluates the expression of EMMPRIN protein and MMP-2/9 activity in tumor and parenchymal cells in a spontaneous metastasis model in rats. Moreover, we explore the regulation of EMMPRIN and MMP-9 by tumor-epithelial cell interactions in vitro. By zymography, we observed an increased proMMP-9 expression in both metastasized liver and spleen samples from tumor bearing rats. Immunohistochemical studies showed EMMPRIN-positive tumor cells in tumor biopsies as well as in spleen and liver samples from tumor bearing rats. Interestingly, a significant increase in EMMPRIN expression in hepatic cells was also detected. The regulation of EMMPRIN expression in tumor and liver cells in response to tumor-host interaction was investigated in vitro through a tumor cell line culture on extracellular matrix (ECM) molecules or in co-culture with normal rat liver cells (BRL3A cells). No significant changes in EMMPRIN expression were detected in tumor cells cultured on ECM molecules. On the other hand, EMMPRIN protein and MMP-9 mRNA expression were induced in BRL3A cells. The increase in EMMPRIN expression in BRL3A cells was inhibited by an anti-EMMPRIN antibody. These results reinforce the main role of EMMPRIN mediating tumor-host interactions that may evolve new opportunities for therapeutic interventions.