Matrix Metalloproteinases (MMP-2 and MMP-9) and Cyclooxygenase-2 (COX-2) Expressions in Vocal Fold Polyps

The Role of Cytokines in Modulating Vocal Fold Fibrosis: A Contemporary Review

OBJECTIVES

Vocal fold (VF) scarring and laryngeal stenosis are a significant clinical challenge. Excessive scar formation causes low voice quality or even life-threatening obstructions. Cytokines are thought to modulate multiple steps of the establishment of VF fibrosis, but there is no systematic report regarding their role in modulating VF fibrosis. This review aims to investigate the role of cytokines in modulating vocal fold fibrosis.

STUDY DESIGN

Literature review.

METHODS

This review searched for all relevant peer publications in English for the period 2009 to 2019 in the PubMed database using search terms: "laryngeal stenosis," "vocal fold scarring," and "cytokines." A thorough investigation of the methods and results of the reviewed studies was performed.

RESULTS

Comprehensive research in various studies, including analyses of prostaglandin E2 (PGE2), granulocyte-macrophage colony-stimulating factor (GM-CSF), hepatocyte growth factor (HGF), basic fibroblast growth factor (bFGF), transforming growth factor-β3 (TGF-β3), and interleukin-10 (IL-10), supports cytokine therapy for VF scarring and laryngeal stenosis to some extent. A few clinical studies on this topic support the conclusion that HGF and bFGF can be selected as effective drugs, and no serious side effects were found.

CONCLUSIONS

This review describes the potential of cytokines for modulating the process of VF fibrogenesis, although cytokines are still an unproven treatment method. As no ideal drugs exist, cytokines may be considered the candidate treatment for preventing VF fibrogenesis. Laryngoscope, 131:139-145, 2021.

Expression of a disintegrin and metalloproteinase-33 protein in vocal fold polyps

BACKGROUND

This study aimed to evaluate the association of a disintegrin and metalloproteinase-33 protein ('ADAM-33') expression in vocal polyp formation and to determine its correlation with clinical characteristics.

METHODS

Medical charts and histological sections of 32 patients diagnosed with vocal polyps who underwent surgery were analysed. Controls were histopathologically normal vocal fold tissues obtained from 36 patients who underwent surgery for laryngeal squamous cell carcinoma. Immunohistochemical staining was performed to detect ADAM-33 expression in epithelial cells, stroma and vessels.

RESULTS

All epithelial, stromal and vascular staining scores were significantly greater in polyp tissue than in controls (p < 0.001). Stromal ADAM-33 staining scores were higher in vocal polyp patients with a symptom duration of less than six months (p < 0.05). Vocal overuse or the presence of reflux symptoms, sinonasal symptoms or allergy did not affect ADAM-33 immunostaining scores (p = 0.05).

CONCLUSION

In this study, ADAM-33 immunostaining was significantly increased in vocal polyps. Therefore, over-expression of this protein may be associated with vocal polyp pathogenesis.

Characteristics of Expression of Matrix Metalloproteinases (MMP-2 and MMP-9) in Glottic Squamous Cell Carcinoma and Benign Vocal Fold Lesions

Objectives

The aim of this study was to investigate expression profile of matrix metalloproteinases (MMP-2 and MMP-9) in glottic squamous cell carcinoma (SCC) and benign vocal fold lesions (BVFLs) and to correlate it with clinical and pathological features.

Methods

The immunohistochemical expression of MMP-2 and MMP-9 was investigated in specimens taken from 217 patients group, including vocal fold polyps (n=39), recurrent respiratory papillomatosis (n=30), laryngeal keratosis (n=36), glottic SCC (n=112), and the normal tissue of vocal fold (n=12, control group). The expression of MMP-2 and MMP-9, both in epithelium and stroma cells, was graded on a semiquantitative scale, ranging from 0 (no expression) to 18 points (high expression).

Results

Expressions of both, MMP-2 and MMP-9 were significantly higher in the glottic SCC group comparing with BVFL group. Significant higher expression of parenchymal MMP-2 (P<0.001) and stromal MMP-9 (P=0.01) was revealed in the group of moderate/poorly differentiated glottic SCC comparing with well differentiated glottic SCC group. Expression of stroma MMP-2 was found to be correlated with nodal metastasis (P=0.030). Expressions of both, MMP-2 and MMP-9 were not correlated with clinical stage, tumor T value, smoking, alcohol use, age in the glottic SSC patients group. The MMP-2 stroma value of 11.2 points was determined as the optimum point (limiting value) for separating BVFL and glottic SCC patient groups.

Conclusion

Our results suggest that expressions of both MMP-2 and MMP-9 are up-regulated already in the development of BVFL, the next determinant step is concerned with occurrence of malignization. Limiting value of stroma MMP-2 demonstrates prognostic importance of MMP-2 in glottic SCC carcinogenesis.

Lipopolysaccharide responsiveness in vocal fold fibroblasts

Background

Vocal fold fibroblast’s (VFF) strategic location in the lamina propria and their ability to respond to external stimuli by producing inflammatory molecules suggest their possible direct involvement in innate immunity. Toll-like receptors (TLRs) are an essential signaling component to this response, as they allow for recognition of various microorganisms, leading to subsequent induction of pro-inflammatory genes. The objective of this study was to elucidate the role of VFF in the host immune response and subsequent influence on inflammatory cytokine secretion.

Methods

VFF derived from polyp, scar, and normal tissue were treated with 5 μg/ml lipopolysaccharide (LPS). TLR1 through 9, CD14, and MD-2 were measured during stable conditions by polymerase chain reaction (PCR). Expression of TLR4 and IL-1R type-1 genes were quantified after 24 hrs LPS stimulation by reverse transcription-PCR. LPS responsiveness was determined by NF-κB nuclear translocation as measured by subunit p65 expression in nucleus with immunocytochemistry. Downstream effects were confirmed with immunoassay measuring IL-8 concentrations in supernatant after 8 hrs.

Results

All VFFs constitutively expressed TLR1 to 6, TLR9, CD14, and MD-2 mRNA. Polyp VFF exhibited significantly higher TLR4 transcript levels (p < 0.001) in comparison to scar and normal VFF. LPS stimulated scar and polyp VFF exhibited increased levels of p65 in the nucleus (p < 0.01) and secreted greater IL-8 protein (p < 0.0001) compared to normal VFF.

Conclusion

VFF constitutively express genes for the receptors essential to the host immune response. Scar and polyp VFF produced greater LPS responsiveness resulting in over-activated inflammatory patterns. These findings support VFF role in the pathogenesis of inflammatory vocal fold disorders and suggests their presence in the wound bed could lead to chronic inflammation.

Cyclooxygenase-2 signaling in vocal fold fibroblasts

OBJECTIVES/HYPOTHESIS

Inflammation and its role in a coordinated fibroplastic response, which disrupts the structure of the vocal folds following injury, is critical. Cyclooxygenase-2 (COX-2) is an important enzyme involved in both inflammation and fibrosis; in addition, it is a prime target for therapeutic intervention. We sought to study this pathway in vocal fold fibroblasts to provide a foundation for future interventional studies.

STUDY DESIGN

In vitro.

METHODS

Human vocal fold fibroblasts were incubated with IL-1 beta to determine the effects on COX-2 signaling, along with upstream regulatory mechanisms and downstream mediators of wound healing. In vitro methods to assess mRNA expression, as well as intracellular and secreted protein (sodium dodecyl sulfate polyacrylamide gel electrophoresis and enzyme-linked immunosorbent assay) were employed.

RESULTS

IL-1 beta regulation of COX-2 mRNA and protein levels was dose and time dependent and IL-1 beta altered PGE(2) metabolism, via regulation of both synthetic and degradative enzymes. IL-1 beta increased nuclear factor (NF)-kappaB activation and nuclear translocation. Inhibition of the p50 and p65 subunits of NF-kappaB decreased IL-1 beta-induced COX-2 transcription. IL-1 beta also altered mRNA expression of four cell-surface prostaglandin receptors.

CONCLUSIONS

Inflammation and fibrosis are important in the vocal fold pathophysiologic response to injury. Our data suggest that COX-2 and PGE(2) are inducible in human vocal fold fibroblasts, and this response appears to be NF-kappaB-dependent. We purport this fundamental investigation will lead to increased insight regarding injury and repair in the vocal folds, with the ultimate goal of developing novel clinical care paradigms.

Experimentally induced phonation increases matrix metalloproteinase-1 gene expression in normal rabbit vocal fold

OBJECTIVES

An in vivo rabbit model was used to study the effect of 3 hours of experimentally induced phonation on messenger RNA expression of the normal vocal fold.

STUDY DESIGN

Prospective; animal model.

SUBJECTS AND METHODS

Ten rabbits received experimental phonation for 3 hours, followed by 1 hour of recovery. A separate group of 5 rabbits served as no-phonation controls. We measured messenger RNA expression of matrix metalloproteinase-1, MMP-9, and interleukin-1beta using real-time reverse-transcribed polymerase chain reaction. Gene expression ratios from phonation and control animals were assessed with the Mann-Whitney U test.

RESULTS

Phonation (77 +/- 3 dB; 429 +/- 141 Hz) resulted in increased matrix metalloproteinase-1 gene expression from rabbits receiving experimental phonation compared with controls, and a nonsignificant increase in matrix metalloproteinase-9 and interleukin-1beta gene expression.

CONCLUSION

Matrix metalloproteinases play a role in maintaining tissue homeostasis. Investigation of cellular responses to experimental phonation may provide insight into how matrix metalloproteinases and other extracellular matrices contribute to maintenance of the vocal fold and development of pathology.