Vocal Fold Fibroblasts in Reinke's Edema Show Alterations Involved in Extracellular Matrix Production, Cytokine Response and Cell Cycle Control

Describing the Cellular Impact of IQOS™ Smoke Extract and Vibration on Human Vocal Fold Fibroblasts

OBJECTIVES

The isolated or combined effects of vibration and smoke extract (SE) from the IQOS™ "heat-not-burn" technology on human vocal fold fibroblasts (hVFF) were evaluated in an in vitro setting in order to elucidate their influence on vocal fold (patho-) physiology.

STUDY DESIGN

Experimental pilot study using intervention with IQOS™-SE in vitro.

METHODS

Immortalized hVFF were exposed to IQOS™-SE or control medium under static or vibrational conditions. A phonomimetic bioreactor was used to deliver vibrational patterns to hVFF over a period of 5days. Cytotoxicity was quantified by lactate dehydrogenase assay. Effects on extracellular matrix production, inflammation, fibrogenesis, and angiogenesis were assessed by reverse transcription-quantitative polymerase chain reaction, western blot, enzyme-linked immunosorbent assay, and Magnetic Luminex assays.

RESULTS

We observed significant changes induced either by IQOS™-SE exposure alone (matrix metalloproteinase 1, fibronectin, cyclooxygenase (COX)1, interleukin-8 gene expression), or by the combination of IQOS™-SE and vibration (hyaluronidase 2, COX2, interleukin-8 protein levels, vascular endothelial growth factor D).

CONCLUSION

Short-term in vitro exposure of hVFF to IQOS™-SE did not result in cytotoxicity and reduced the gene expression of measured inflammation mediators, but had no effect on their protein expression. However, the clinical effects of long-term IQOS™ use are still not known and further research is needed in order to assess, if IQOS™ is in fact less harmful than conventional cigarettes.

Exploring the anti-inflammatory potential of topical hyaluronic acid for vocal fold injury in a rat model

PURPOSE

Vocal fold injuries are associated with fibrosis and dysphonia, which is a major obstacle to surgical treatment. The aim of this study is to evaluate the effect of topical hyaluronic acid with or without diclofenac on the inflammatory phase of vocal fold wound healing.

METHODS

Forty-one male Sprague-Dawley rats were randomly assigned to four groups: an uninjured control group, an injured control group without any treatment, and two intervention groups in which hyaluronic acid with or without diclofenac was applied to the injured vocal fold. Gene expression of inflammatory markers and ECM-related molecules were examined.

RESULTS

Vocal fold injury resulted in a significant upregulation of inflammatory parameters [Ptgs2, Il1b and Il10] and Has1. Tgfb1, Has3 and Eln gene expression were significantly downregulated by the topical application of hyaluronic acid. The combination of hyaluronic acid and diclofenac did not result in any significant changes.

CONCLUSIONS

Vocal fold wound healing was significantly improved by a single post-operative topical application of hyaluronic acid. The addition of diclofenac may provide no additional benefit.

Comparing Effects of Short- and Long-Term Exposure of Cigarette Smoke Extract on Human Vocal Fold Fibroblasts

OBJECTIVES

To explore the effects of short- and long-term cigarette smoke extract (CSE) stimulation on the expression of extracellular matrix (ECM) components and inflammatory cytokines in an in vitro model for studying Reinke's edema using human vocal fold fibroblasts (hVFF).

STUDY DESIGN

Experimental pilot study using intervention with CSE in vitro.

METHODS

Immortalized hVFF were pretreated with 5% CSE or control medium over a period of 2 or 8 weeks, followed by a final 3-day incubation time. We evaluated cell proliferation and examined gene and protein expression of control- and CSE-treated cells using quantitative polymerase chain reaction, Western Blot and enzyme linked immunosorbent assay.

RESULTS

Cell numbers of CSE-treated hVFF strongly decreased after 8 weeks and limited the overall duration of the experiment. We observed significant upregulations in gene expression and protein levels of inflammatory markers (cyclooxygenase COX1, COX2) and ECM components (decorin, matrix metalloproteinase 1, transglutaminase 2, gremlin 2) induced by CSE after 2 and 8 weeks. Interleukin 1 receptor 1, prostaglandin I2 synthase, collagen- and hyaluronan-related gene expression showed minor upregulations. The majority of the observed genes were similarly regulated at both time points. However, the CSE-induced mRNA level of COX1 was ablated after 8 weeks.

CONCLUSION

Long-term treatment did not yield results significantly different from the short-term protocol. Therefore, we propose that prolonged CSE exposure is not superior to short-term settings, which save both time and materials.

Effects of Electronic (E)-cigarette Vapor and Cigarette Smoke in Cultured Vocal Fold Fibroblasts

OBJECTIVE

The public use of electronic-cigarettes (e-cigs) is rapidly growing. When heated, e-cigs produce a vapor that is inhaled. The vocal folds are among the first tissues exposed to this insult. However, the impact of e-cigs on vocal fold health is almost entirely unknown. Our objective was to evaluate the effects of e-cig vapor on cultured human vocal fold fibroblasts (hVFFs), the primary cell type of the lamina propria. We compared the cellular effects of e-cig vapor without and with nicotine and conventional cigarette smoke.

STUDY DESIGN

In vitro.

METHODS

E-cig vapor extract (EVE) and cigarette smoke extract (CSE) were created by bubbling vapor and smoke, respectively, into the cell culture medium. hVFFs were exposed to EVE without or with nicotine or CSE for 24 hours. Untreated cells were used as a control group. Cells were harvested, and cytotoxicity, extracellular matrix and inflammatory gene expression, and DNA damage were assessed.

RESULTS

Undiluted EVE without and with nicotine reduced the viability of hVFFs to a cytotoxic level. CSE reduced hVFFs viability to a greater extent than EVE and induced DNA damage as measured by DNA double-strand breaks. No changes in gene expression were observed following EVE or CSE exposure.

CONCLUSION

EVE induces cytotoxicity in hVFFs. However, cellular responses were greater following exposure to CSE, suggesting cigarette smoke may induce more harm, at least in the short term. Findings from this investigation improve our understanding of responses of hVFFs to e-cigs and form the basis for an in vitro methodology to study the vocal fold responses to these products.

LEVEL OF EVIDENCE

NA Laryngoscope, 133:139-146, 2023.

Mindin (SPON2) Is Essential for Cutaneous Fibrogenesis in a Mouse Model of Systemic Sclerosis

Systemic sclerosis is a fibrotic disease that initiates in the skin and progresses to internal organs, leading to a poor prognosis. Unraveling the etiology of a chronic, multifactorial disease such as systemic sclerosis has been aided by various animal models that recapitulate certain aspects of the human pathology. We found that the transcription factor SNAI1 is overexpressed in the epidermis of patients with systemic sclerosis, and a transgenic mouse recapitulating this expression pattern is sufficient to induce many clinical features of the human disease. Using this mouse model as a discovery platform, we have uncovered a critical role for the matricellular protein Mindin (SPON2) in fibrogenesis. Mindin is produced by SNAI1 transgenic skin keratinocytes and aids fibrogenesis by inducing early inflammatory cytokine production and collagen secretion in resident dermal fibroblasts. Given the dispensability of Mindin in normal tissue physiology, targeting this protein holds promise as an effective therapy for fibrosis.