A Preliminary Study On The Clinical And Pathological Features And Pathogenesis Of Granulomatous Rosacea

Background:Rosacea is a chronic inflammatory skin disease,which is mainly manifested as flushing,persistent erythema,papules and pustules,rhinophyma and so on.According to the National Rosacea Society Expert Committee,rosacea is classified into four clinical subtypes:erythematotelangiectatic rosacea,papulopustular rosacea,phymatous rosacea,ocular rosacea,and one variant,granulomatous rosacea(GR).As the only variant,GR differs from non-granulomatous rosacea(NGR)in clinical manifestations,histological changes and treatment response due to its granulomatous histological structure.However,systematic studies have not been conducted yet.Moreover,the unique inflammatory infiltration mode and the mechanism of granuloma formation are rarely explored.Objective:To explore the differences between GR and NGR in clinical characteristics,histological characteristics and gene expression,and to provide a basis for the diagnosis,treatment target and accurate prognosis of rosacea,as well as new ideas for the pathogenesis and further exploration of the disease.Method:1.Analysis of clinical features:A retrospective study was conducted on patients who visited Xiangya Hospital of Central South University from January 2017 to December 2021 and met the inclusion criteria and were pathologically diagnosed as rosacea.A total of 30 GR cases and 60 NGR cases were included,and a comparative analysis was conducted on the general information,clinical manifestations and treatment response of patients in the two groups.2.Histological analysis:(1)the pathological characteristics of skin lesions in 30 GR and 60 NGR patients were analyzed by HE staining.(2)The characteristics of inflammatory cell infiltration in skin tissue of 20GR and 25 NGR patients were investigated by multiple immunohistochemical staining.3.RNA-seq and gene expression difference analysis:(1)fresh skin lesions from 3 GR and 3 NGR patients were collected and sequenced,and differential genes were screened by bioinformatics method,and candidate genes were further explored from cytological components,molecular biological functions,biological processes and related pathways.(2)Immunohistochemical staining was used to verify the expression of candidate genes in skin lesions from 20 GR patients and 25 NGR patients.Result:1.Clinical features:(1)General information:there were no significant differences between GR and NGR group in gender,age,height,weight,BMI,marital status,education level,occupation and family history(P>0.05).(2)The prevalence of GR was higher than that of NGR in forehead,eyes and mouth,and there were statistical differences between groups(P=0.001,P<0.001,P=0.001).There were no significant differences in the prevalence of eyebrow,cheek,nose and chin between the two groups(P>0.05).(3)Clinical features:GR was more severe than NGR with papules and pustules,and the severity of flushing and burning was lighter,with statistical differences between groups(P=0.032,P=0.034,P=0.036).There were no significant differences in erythema permanence,hypertrophy,telangiectasia,plaque,edema,tingling and pruritus between the two groups(P>0.05).(4)Treatment response:the treatment effect of isotretinic acid in GR group was better than tetracycline,and the clinical remission rates were 75%and 52.9%,respectively,but there was no statistical difference(P=0.152).There was no significant difference in NGR group(P>0.05).Compared with NGR,GR group required longer treatment time to achieve clinical remission,4.00±1.51 months and 2.13±0.885 months,the difference was statistically significant(P=0.010).2.Histopathological features:(1)The epidermis was more common in GR group than NGR group(P=0.020,P=0.022).There were no significant differences in hair follicle plug,mites and epidermal thickness between the two groups(P>0.05).(2)Dermis:GR group had more tissue cells,multinucleated giant cells and foam cells than NGR group(P<0.001,P<0.001,P<0.001);The number of neutrophils was higher and the infiltration of inflammatory cells was deeper(P=0.036,P=0.003).In GR group,the infiltration of inflammatory cells was mainly around hair follicles,and in NGR group,the infiltration of inflammatory cells was mainly around blood vessels.GR group had stronger hair follicle damage and collagen hyperplasia(P=0.003,P=0.026).There were no significant differences in mucus deposition,solar elastic degeneration and vascular dilation between groups(P>0.05).(3)Immunohistochemistry:the expression levels of CD4~+cells,CD8~+cells and CD68~+cells in GR group were higher than those in NGR group(P=0.047,P<0.001,P<0.001);There was no significant difference in the expression levels of CD19~+cells and CD11b~+cells between groups(P>0.05).3.Differential gene analysis:(1)Bioinformatics analysis:A total of420 differential genes were screened out,of which 358 genes were up-regulated in GR and 62 genes were down-regulated in GR;Enrichment analysis of differentially expressed genes,especially MMP9,CTSS and CTSZ,showed differences in the expression of genes related to neutrophil activation,T lymphocyte-mediated immune response,processing and presentation of peptide antigens and other pathways.(2)Immunohistochemistry:the expression levels of MMP9,CTSS and CTSZ in GR lesions were higher than those in NGR(P<0.001),which was consistent with the sequencing results.Conclusion:GR was different from NGR in clinical manifestations,histopathological features and treatment response,and the mechanism may be related to the inflammatory infiltration pattern and related gene expression differences between GR and NGR.This study provides new evidence for the classification of rosacea,and provides new ideas for further exploration of the pathogenesis and precise treatment of rosacea.