To accurately evaluate the protective effects of titanium dioxide-based emulsion from infrared-A rays (IRA) irradiation in daily life, we assessed the harmful effects of natural level of IRA irradiation on human skin cells. Using a well-defined solar IRA simulator, short-term (less than seven days) IRA irradiation on fibroblasts at 34°C elicited an increase in the matrix metalloproteinase-1 (MMP1) mRNA level and decrease in the collagen type-1 α-1 (COL1A1) mRNA level. While short-term IRA exposure showed negligible effects on cell proliferation at 34°C, long-term (24 days) IRA irradiation significantly decreased the proliferation of fibroblasts at the same temperature. However, in the presence of heat stress at 43°C, short-term IRA exposure also elicited severe damage including reduction in cell proliferation and procollagen type 1 C-terminal peptide (PIP) level. In addition, formulated titanium dioxide-based emulsion (IRA protective cream; IRC) with an infrared-A protection factor value of ten could successfully protect cells from damage by short-term and long-term IRA exposures. In this study, we demonstrated that IRC reduces mild and severe damages elicited by natural level of IRA irradiation mimicking system after short-term and long-term exposures.

为了准确评估基于二氧化钛的乳液在日常生活中对红外线 (IRA) 辐射的保护作用，我们评估了自然水平的 IRA 辐射对人体皮肤细胞的有害影响。使用定义明确的太阳 IRA 模拟器，在 34°C 下对成纤维细胞进行短期（少于 7 天）IRA 照射引起基质金属蛋白酶-1 (MMP1) mRNA 水平的增加和 1 型胶原α- 1 (COL1A1) mRNA 水平。虽然短期 IRA 暴露在 34°C 下对细胞增殖的影响可以忽略不计，但长期（24 天）IRA 照射显着降低了相同温度下成纤维细胞的增殖。然而，在 43°C 的热应力存在下，短期 IRA 暴露也会引起严重损害，包括细胞增殖和 1 型原胶原 C 端肽 (PIP) 水平降低。此外，配制的二氧化钛基乳液（IRA 保护霜；IRC）的红外线-A 保护因子值为 10，可成功保护细胞免受短期和长期 IRA 暴露的损害。在这项研究中，我们证明了 IRC 减少了短期和长期暴露后由自然水平的 IRA 辐射模拟系统引起的轻度和重度损伤。