POS0102 GLOBAL CHARACTERIZATION OF SALIVARY GLANDS IMMUNE MICROENVIRONMENT IN PRIMARY SJÖGREN’S SYNDROME BY SINGLE-CELL SEQUENCING

Background

Primary Sjögren’s syndrome (pSS) is a heterogeneous, chronic, complex systemic autoimmune disease. The hallmark symptom of the disease is exocrinopathy, chiefly salivary and lachrymal glands, which often results in dryness of the mouth and eyes. As of today, although a lot of genetic and epigenetic studies have reveal the complexity of pSS to a certain extent, but the knowledge of existing pSS disease heterogeneity is still limited and the immune mechanisms of salivary glands (SG) injury have been challenging to clarify.

Objectives

Single-cell RNA sequencing (scRNA-seq) is a powerful tool capable of defining cell types and states on the basis of their individual transcriptome in a given sample from health and disease. To characterize the salivary glands immune microenvironment of patients with pSS, we performed droplet-based single cell mRNA sequencing (scRNA-seq) (10X Genomics) to provide a deeper insight into the cellular and molecular characteristics of salivary glands from pSS patients.

Methods

11 patients and 5 non-pSS controls were recruited from the The First Affiliated Hospital of USTC. The non-pSS were subjects who had experienced subjective symptoms of dryness, but no not meet any of the classification criteria of pSS. The clinical characteristics and laboratory findings of enrolled patients were also collected. After resection, salivary glands tissue samples were obtained after labial gland biopsy, rapidly digested to a single-cell suspension and subjected to scRNA-seq using the 10X platform. After rigorous quality control (QC) definition, low-quality cells were filtered. Following gene expression normalization for read depth and mitochondrial read count, we applied principle component analysis on genes variably expressed across all 72,853 cell.

Results

A total of 72,853 cells were obtained from all salivary glands samples. Our results revealed 12 major unique cell populations of salivary glands cell, including T cells, B cells, plasma cells, epithelial cells, myoepithelial cells, endothelial cells, myofibroblast, pericytes, melanocytes, fibroblast, myeloid cells and a cluster of unknown cells. As expected, lymphocytes (T and B cell populations) were significant increase in the salivary glands of patients with pSS. For further subsets analysis, we identify 41 subsets, including novel subpopulations in cell types hitherto considered to be homogeneous, as well as transcription factors underlying their heterogeneity. Strikingly, we found that differentially expressed genes (DEGs) that myoepithelial cells uniquely downregulated in pSS patients were involved in regeneration, stem cell population maintenance, cell division, and epithelial cell proliferation. This indicated an impaired stem cell property and regeneration capacity of myoepithelial cells in the SG of pSS patients which may result in the reduction of normal epithelial cells differentiation and proliferation. Our results identified three distinct endothelial subtypes according to the differentially expressed cell markers. ACKR1+ endothelial cells were expanded in the SG of pSS patients which may enhance Leukocyte transendothelial migration. A clear interferon response was observed in most celltypes. We also found a significantly expand PD-1hiCXCR5–CD4+T peripheral helper (Tph), GZMK+CD8+ T cells and a patient-specific fibroblasts in pSS patients. Cellular interaction analysis of SG revealed a strong interaction between epithelial cells and immune cells from pSS patients through CD74-MIF, MIF-TNFRSF14 and HLA-C-FAM3C receptor/ ligand pairs. Chemokine receptors CXCR4 were broadly expressed in SG immune cells implying a potentially central role in cell trafficking.

Conclusion

This resource provides deeper insights into pSS salivary glands immune microenvironment that will be helpful in understanding of the disease heterogeneity and advancing pSS therapy.

Disclosure of Interests

None declared

Smartphone wallpapers for dermoscopy training in medical students and residents

BACKGROUND

Several dermoscopy training programs have found the accuracy of dermoscopy examination depends on adequate training of practitioners. Smartphones are readily available and time-efficient tools for dermoscopy training.

AIM

To evaluate the learning efficacy of utilizing dermoscopy smartphone wallpapers to train medical students, PGY (postgraduate year)-1 trainees, and junior dermatological residents without prior dermoscopy training.

METHODS

We designed smartphone wallpapers with dermoscopy pictures and features of several common melanocytic and nonmelanocytic conditions. Pretests and posttests were performed before and after a 10-day-long smartphone wallpaper training program to evaluate their diagnostic accuracy using dermoscopy images.

RESULTS

Significant progressions were noted between the pretest and posttest scores both in the nonmelanocytic (P < 0.001) and the melanocytic (P = 0.003) sections. Medical students and PGY-1 trainees demonstrated more significant improvement in nonmelanocytic lesions, compared to dermatology residents. Residents of dermatology showed more progression in the melanocytic section than nonresidents.

LIMITATIONS

There were limited participants. The frequency and time allotted by each participant in perusing the wallpapers were variable. Further study of the application on clinical practice is still needed.

CONCLUSION

Smartphone wallpapers training improves dermoscopic interpretation significantly in medical students, PGY-1 trainees, and dermatological residents. The background knowledge of dermatology has an effect on the degree of improvement in the training course.

Photoinduced Reduction of Nitrobenzenes to Primary Aromatic Amines

Primary aromatic amines were synthesized from the corresponding nitrobenzenes via photoinduced reduction. The reaction was found to be effective when nitrobenzenes with electron-withdrawing substituents were irradiated with a broad band of UV light centered at 306 nm. When reactions are completed, products could be isolated by acid–base extraction or by column chromatography. This presenting photoreaction procedure for the synthesis of primary aromatic amines from the corresponding nitrobenzenes proceeds without the need of a sensitizer in isopropanol or THF. Without the usage of catalysts, or stoichiometric reducing reagent containing heavy metals, this photoinduced reduction of nitrobenzenes fulfils the concept of green chemistry.

Lentigines, laser, and melanoma: a case series and discussion

Solar lentigines are considered one of the earliest signs of photoaging and are an extremely common cosmetic complaint. Successful removal of these lesions can be achieved with laser and non-laser light sources, and is one of the most frequently performed cosmetic procedures in laser centers. Distinguishing a benign lentigo from other pigmented lesions can sometimes be challenging, even for a trained dermatologist. We report a series of three patients who presented to our laser center within 2 months of one another for cosmetic removal of pigmented lesions that were found to be melanoma. One patient was referred by another dermatologist, one by a physician family member, and the other presented on his own. These cases highlight the need for careful evaluation of pigmented lesions prior to laser treatment, regardless of the source of the referral. In this article, we will review the diagnostic and treatment differences between lentigines and their malignant counterparts, and examine the role of laser in both.

Peroxisome proliferator-activated receptor (PPAR)-beta/delta stimulates differentiation and lipid accumulation in keratinocytes

Peroxisome proliferator-activated receptor (PPAR) are nuclear hormone receptors that are activated by endogenous lipid metabolites. Previous studies have demonstrated that PPAR-alpha activation stimulates keratinocyte differentiation in vitro and in vivo, is anti-inflammatory, and improves barrier homeostasis. Recent studies have shown that PPAR-beta/delta activation induces keratinocyte differentiation in vitro. This study demonstrated that topical treatment of mice with a selective PPAR-beta/delta agonist (GW1514) in vivo had pro-differentiating effects, was anti-inflammatory, improved barrier homeostasis, and stimulated differentiation in a disease model of epidermal hyperproliferation [corrected]. In contrast to PPAR-alpha activation, PPAR-beta/deltain vivo did not display anti-proliferative or pro-apoptotic effects. The pro-differentiating effects persisted in mice lacking PPAR-alpha, but were decreased in mice deficient in retinoid X receptor-alpha, the major heterodimerization partner of PPAR. Furthermore, in vitro PPAR-beta/delta activation, aside from stimulating differentiation-related genes, additionally induced adipose differentiation-related protein (ADRP) and fasting induced adipose factor (FIAF) mRNA in cultures keratinocytes, which was paralleled by increased oil red O staining indicative of lipid accumulation, the bulk of which were triglycerides (TG). Comparison of differentially expressed genes between PPAR-beta/delta and PPAR-alpha activation revealed distinct profiles. Together, these studies indicate that PPAR-beta/delta activation stimulates keratinocyte differentiation, is anti-inflammatory, improves barrier homeostasis, and stimulates TG accumulation in keratinocytes.