MUC1 Expression in the Oral Mucosal Epithelial cells of the Elderly

Abstract

노년층 구강 점막 상피에서 MUC1 발현

MUC1은 호흡기, 생식기, 위장관 표면 상피세포 모두에서 발현되는 mucin으로, 분비된 후 세포 표면에 부착되어 상피 세포 표면 방어에 중요한 역할을 수행하는 것으로 알려져 있다. 구강점막 방어기능 감소는 특히 노년층에서 다양한 구강점막 질환의 발생 및 악화 요인으로 작용할 수 있다. 본 연구의 목적은 노년층과 청년층의 구강점막 상피에서 MUC1의 발현 정도를 비교하는 것이다. 이와 함께 MUC1의 발현과 타액 cytokine 농도와의 관련성도 분석하였다. 이를 위해 노년층 30명, 청년층 30명(남녀 각각 15명)을 연구대상으로 하여, 치아, 치주 및 구강점막 상태를 포함한 전반적인 구강검진을 시행하고 타액분비율 측정과 함께 타액 검체를 채취하였다. 자극시 채취된 전타액 검체의 침전물은 real-time PCR을 활용하여 MUC1의 발현을 평가하는데 사용하였고, 상층액은 antibody-immobilized fluorescently labeled microsphere beads를 가진 high sensitivity multiplex assay 법을 활용하여 타액 검체의 IL-1β, IL-6 및 TNF-α 농도를 측정하는데 이용하였으며 그 결과는 다음과 같다.

1. 비자극시 전타액 분비율은 노년층에서 청년층에 비해 유의하게 감소하였고 (P < 0.01), 치은 지수는 유의하게 증가하였다 (P < 0.01).

2. MUC1 transcripts의 양은 노년층에서 청년층에 비해 유의하게 감소하였다 (남자, P < 0.05; 여자, P < 0.01).

3. 타액 IL-6 농도는 노년층 남자에서 청년층 남자에 비해 유의하게 증가하였다 (P < 0.05).

4. 노년층에서는 MUC1 발현과 치은 지수(rs = 0.505, P < 0.01), MUC1 발현과 잔존치아 수(rs = 0.463, P < 0.01) 사이에 유의한 양의 상관관계를 보였다.

이상의 결과를 종합해 볼 때, 노년층에서 MUC1의 감소가 구강점막 방어기능 감소로 이어져, 구강점막 질환의 발생에 중요한 역할을 할 수 있을 것으로 생각된다.

MUC1 Expression in the Oral Mucosal Epithelial Cells of the Elderly

MUC1 is ubiquitously expressed in the epithelial cells lining the respiratory, reproductive, and gastrointestinal tracts. This mucin remains on the cell surface after secretion and is primarily involved in the protection of epithelial surfaces. Decreases in oral mucosal defense can be a predisposing factor for the development of oral mucosal diseases in the elderly. The aim of this study was to compare MUC1 expression level in oral mucosal epithelial cells of the elderly with that of young adults and the relationships between MUC1 expression and salivary cytokine levels were also investigated. Thirty elderly and thirty young adults (15 men and 15 women in each group) were included in the study. Oral examination, including tooth, periodontal, and oral mucosal status, was performed and whole saliva samples were collected along with flow rate measurements. Precipitates of stimulated whole saliva were used for the evaluation of MUC1 expression using real-time PCR. Clarified supernatants were used for the measurement of pro-inflammatory cytokines, IL-1β, IL-6, and TNF-α using the high sensitivity multiplex assay based on antibody-immobilized fluorescently labeled microsphere beads.

The obtained results were as follows:

1. The flow rate of unstimulated whole saliva was significantly decreased (P < 0.01) and the gingival index (GI) was significantly increased (P < 0.01) in the elderly subjects compared with those of young subjects.

2. There was a significant decrease in the amounts of MUC1 transcripts in the elderly subjects compared with those of young subjects (men, P < 0.05; women, P < 0.01).

3. There was a significant increase (P < 0.05) in the level of IL-6 in men in the elderly subjects compared with those of young subjects.

4. The expression level of MUC1 showed significantly positive correlations with GI (rs = 0.505, P < 0.01) and number of teeth (rs = 0.463, P < 0.01) in the elderly subjects.

Collectively, our results suggest that oral mucosal defense provided by MUC1 was decreased in the elderly. This decrease may play a role in the development of oral mucosal diseases in the aged population.