Skin aging is a specific manifestation of the physiological aging process that occurs in virtually all organisms. In this study, we used data independent acquisition mass spectrometry to perform a comparative analysis of protein expression in volar forearm skin samples from of 20 healthy young and elderly Chinese individuals. Our quantitative proteomic analysis identified a total of 95 differentially expressed proteins (DEPs) in aged skin compared to young skin. Enrichment analyses of these DEPs (57 upregulated and 38 downregulated proteins) based on the GO, KEGG, and KOG databases revealed functional clusters associated with immunity and inflammation, oxidative stress, biosynthesis and metabolism, proteases, cell proliferation, cell differentiation, and apoptosis. We also found that GAPDH, which was downregulated in aged skin samples, was the top hub gene in a protein-protein interaction network analysis. Some of the DEPs identified herein had been previously correlated with aging of the skin and other organs, while others may represent novel age-related entities. Our non-invasive proteomics analysis of human epidermal proteins may guide future research on skin aging to help develop treatments for age-related skin conditions and rejuvenation.

Summary: Chemokine receptors are important in the entry of leucocytes into the inflammatory sites of systemic lupus erythematosus (SLE). CCR7⁺ and CCR7^– memory T cells exert different functions in homing, cytokine production and cytotoxicity. To determine whether differential expression and functions of the CCR7 occur in SLE patients, we examined CCR3, CCR4, CCR5, CCR7 and CCR9 on CD4⁺ and CD8⁺ T cells from normal and SLE subjects. Flow cytometry, real‐time quantitative reverse transcription polymerase chain reactions and Northern blotting were used to detect the expression of chemokine receptors and cytokines; a chemotaxis assay was used to detect their functions. CD4⁺ T‐cell stimulation with syngeneic CCR7⁺ CD8⁺ CD45RO⁺ T cells and dendritic cells (including transwell chambers) was used to induce cytokine expression. We demonstrated that CCR7 was selectively, frequently and functionally expressed on CD8⁺ (94·8%) but not on CD4⁺ (16·1%) T cells from patients with active SLE, whereas this phenomenon was not seen in normal subjects and in those whose SLE was inactive. CCR7⁺ CD8⁺ CD45RO⁺ memory T cells from patients with active SLE, themselves T helper type 2 (Th2) biased, were inducers of Th2 bias in CD4⁺ T cells in a cell–cell contact manner in vitro, meanwhile, the cells from both normal subjects and those whose SLE was inactive drove CD4⁺ T cells into a regulatory T‐cell‐derived cytokine pattern. Our findings might provide new clues to understanding the functions of CCR7⁺ CD8⁺ CD45RO⁺‘central’ memory T cells in autoimmue diseases (such as SLE). We suggest that in the case of active SLE, CCR7⁺ central memory T cells were able to enter peripheral blood and inflammatory sites from secondary lymphoid organs, were continuously expressing CCR7, and interacted with dendritic cells and functioned as CCR7^–‘effector’ memory T cells, which were described in normal humans.

The mechanism of hair loss caused by aging is related to mitochondrial dysfunction. Pep-1-mediated mitochondrial transplantation is a potential therapeutic application for mitochondrial disorders, but its efficacy against hair aging remains unknown. This study compared platelet-rich plasma (PRP) therapy with mitochondrial transplantation for hair restoration and examined the related regulation in naturally aging mice. After dorsal hair removal, 100-week-old mice received weekly unilateral injections of 200 μg of allogeneic mitochondria-labeled 5-bromo-2'-deoxyuridine with (P-Mito) or without Pep-1 conjugation (Mito) or human PRP with a stamp-type electric injector for 1 month. The contralateral sides were used as corresponding sham controls. Compared with the control and corresponding sham groups, all treatments stimulated hair regrowth, and the effectiveness of P-Mito was equal to that of PRP. However, histology revealed that only P-Mito maintained hair length until day 28 and yielded more anagen follicles with abundant dermal collagen equivalent to that of the PRP group. Mitochondrial transplantation increased the thickness of subcutaneous fat compared with the control and PRP groups, and only P-Mito consistently increased mitochondria in the subcutaneous muscle and mitochondrial DNA copies in the skin layer. Therefore, P-Mito had a higher penetrating capacity than Mito did. Moreover, P-Mito treatment was as effective as PRP treatment in comprehensively reducing the expression of aging-associated gene markers, such as IGF1R and MRPS5, and increasing antiaging Klotho gene expression. This study validated the efficacy of mitochondrial therapy in the restoration of aging-related hair loss and demonstrated the distinct effects of PRP treatment.