After the occurrence of acute rejection following solid organ transplantation, high-dose glucocorticoid (steroid) pulse therapy is commonly used. However, high-dose steroid pulse therapy is ineffective for some patients, leading to steroid resistant acute rejection, which may easily result in graft loss and severely affect patient prognosis. It is currently believed that both cell-mediated rejection and antibody-mediated rejection are involved in the occurrence and development of steroid resistant acute rejection. The diagnosis and treatment of steroid resistant acute rejection after kidney transplantation have become relatively mature, while the focus on steroid resistant acute rejection after liver transplantation has been relatively low in the past in China, and a unified standardized treatment plan has not yet been formed. Therefore, this article reviews the pathogenesis, diagnosis, and treatment of steroid resistant acute rejection after liver transplantation, in order to provide a reference for the diagnosis and treatment of steroid resistant acute rejection after liver transplantation.

ObjectiveThis paper aims to verify the therapeutic effect of Cranial Painkiller pills' extract powder prepared by the new process on the rat's trigeminal neuralgia model caused by infraorbital injection of Talci Pulvis， evaluate its potential clinical application value， and compare the therapeutic effect with that of Cranial Painkiller granules， so as to provide data support for the application of the Cranial Painkiller pills' extract powder and precise treatment. MethodsThe rat's trigeminal neuralgia model was constructed by infraorbital injection of Talci Pulvis， and the rats were randomly divided into the normal group， model group， carbamazepine group （60 mg·kg^-1）， Cranial Painkiller granules group （2.70 g·kg^-1）， and low， medium， and high dosage groups of Cranial Painkiller pills' extract powder （1.35， 2.70， 5.40 g·kg^-1） according to the basal mechanical pain thresholds， and there were 10 rats in each group. The drug was administered by gavage to each group 2 h after modeling， and distilled water was given by gavage to the normal and model groups under the same conditions once a day for 10 d. Von Frey brushes were used to measure mechanical pain thresholds in rats. Hematoxylin-eosin （HE） staining was used to detect pathological changes in the trigeminal ganglion， and enzyme-linked immunosorbent assay （ELISA） was used to detect the inflammatory factors interleukin-1 （IL-1）， interleukin-6 （IL-6）， interleukin-8 （IL-8）， and tumor necrosis factor-α （TNF-α） levels in rat serum， as well as neuropeptide substance P （SP） and β-endorphin （β-EP） levels in rat brain tissue. Western blot technique was used to detect the levels of NLRP3， ASC， Caspase-1， and OTULIN proteins in rat brain tissue. ResultsCompared with the normal group， the pain threshold of rats in the model group showed a continuous significant decrease （P<0.01）. The pathological damage of brain tissue was significant （P<0.01）， and the inflammatory levels of IL-1， IL-6， IL-8， and TNF-α in serum were significantly elevated （P<0.01）. The level of the SP in the brain tissue was significantly elevated （P<0.01）， and the level of β-EP was significantly reduced （P<0.01）， while the level of OTULIN was significantly reduced， and NLRP3， ASC， and Caspase-1 protein levels were significantly elevated （P<0.01）. After administration of the drug， compared with the model group， the pain threshold of each dose group of the Cranial Painkiller pills' extract powder and the Cranial Painkiller granules group significantly increased （P<0.01）. The inflammatory levels of IL-1， IL-6， IL-8， and TNF-α and SP levels significantly decreased （P<0.01）， and the β-EP levels were significantly elevated （P<0.01）， while the levels of OTULIN protein were significantly elevated （P<0.05， P<0.01）， and the levels of NLRP3， ASC proteins were decreased （P<0.01）in high dose Cranial Painkiller pills' extract powder. Meanwhile， compared with those in the model group， the trigeminal ganglion lesions of rats in the Cranial Painkiller pills' extract powder and Cranial Painkiller granules groups showed different degrees of improvement （P<0.05， P<0.01）. ConclusionThe Cranial Painkiller pills' extract powder has significant therapeutic effects on the rat model of trigeminal neuralgia induced by infraorbital injection of Talci Pulvis， and its mechanism is related to the improvement of OTULIN-regulated neuroinflammation.

ObjectiveThis paper aims to verify the therapeutic effect of Cranial Painkiller pills' extract powder prepared by the new process on the rat's trigeminal neuralgia model caused by infraorbital injection of Talci Pulvis， evaluate its potential clinical application value， and compare the therapeutic effect with that of Cranial Painkiller granules， so as to provide data support for the application of the Cranial Painkiller pills' extract powder and precise treatment. MethodsThe rat's trigeminal neuralgia model was constructed by infraorbital injection of Talci Pulvis， and the rats were randomly divided into the normal group， model group， carbamazepine group （60 mg·kg^-1）， Cranial Painkiller granules group （2.70 g·kg^-1）， and low， medium， and high dosage groups of Cranial Painkiller pills' extract powder （1.35， 2.70， 5.40 g·kg^-1） according to the basal mechanical pain thresholds， and there were 10 rats in each group. The drug was administered by gavage to each group 2 h after modeling， and distilled water was given by gavage to the normal and model groups under the same conditions once a day for 10 d. Von Frey brushes were used to measure mechanical pain thresholds in rats. Hematoxylin-eosin （HE） staining was used to detect pathological changes in the trigeminal ganglion， and enzyme-linked immunosorbent assay （ELISA） was used to detect the inflammatory factors interleukin-1 （IL-1）， interleukin-6 （IL-6）， interleukin-8 （IL-8）， and tumor necrosis factor-α （TNF-α） levels in rat serum， as well as neuropeptide substance P （SP） and β-endorphin （β-EP） levels in rat brain tissue. Western blot technique was used to detect the levels of NLRP3， ASC， Caspase-1， and OTULIN proteins in rat brain tissue. ResultsCompared with the normal group， the pain threshold of rats in the model group showed a continuous significant decrease （P<0.01）. The pathological damage of brain tissue was significant （P<0.01）， and the inflammatory levels of IL-1， IL-6， IL-8， and TNF-α in serum were significantly elevated （P<0.01）. The level of the SP in the brain tissue was significantly elevated （P<0.01）， and the level of β-EP was significantly reduced （P<0.01）， while the level of OTULIN was significantly reduced， and NLRP3， ASC， and Caspase-1 protein levels were significantly elevated （P<0.01）. After administration of the drug， compared with the model group， the pain threshold of each dose group of the Cranial Painkiller pills' extract powder and the Cranial Painkiller granules group significantly increased （P<0.01）. The inflammatory levels of IL-1， IL-6， IL-8， and TNF-α and SP levels significantly decreased （P<0.01）， and the β-EP levels were significantly elevated （P<0.01）， while the levels of OTULIN protein were significantly elevated （P<0.05， P<0.01）， and the levels of NLRP3， ASC proteins were decreased （P<0.01）in high dose Cranial Painkiller pills' extract powder. Meanwhile， compared with those in the model group， the trigeminal ganglion lesions of rats in the Cranial Painkiller pills' extract powder and Cranial Painkiller granules groups showed different degrees of improvement （P<0.05， P<0.01）. ConclusionThe Cranial Painkiller pills' extract powder has significant therapeutic effects on the rat model of trigeminal neuralgia induced by infraorbital injection of Talci Pulvis， and its mechanism is related to the improvement of OTULIN-regulated neuroinflammation.

Objective To investigate the predictive value of preoperative combined detection of neutrophil-to-lymphocyte ratio (NLR) and prothrombin time-international normalized ratio to albumin ratio (PTAR) for early abdominal infection after liver transplantation. Methods Clinical data of 287 recipients who underwent liver transplantation at the Liver Transplant Center of Beijing Friendship Hospital, Affiliated to Capital Medical University, from January 2020 to April 2024 were retrospectively analyzed. The patients were divided into infection group (n=60) and non-infection group (n=227) based on whether abdominal infection occurred within 30 days after surgery. The distribution characteristics of pathogens and infection time in infected patients were analyzed. Spearman correlation analysis was used to assess the correlation between NLR, PTAR, Child-Pugh score and preoperative model for end-stage liver disease (MELD) score. Univariate and multivariate logistic regression analyses were performed to identify risk factors for abdominal infection. Receiver operating characteristic (ROC) curves were plotted for NLR, PTAR, and the combined prediction model to evaluate their predictive efficacy for abdominal infection after liver transplantation. Based on the cutoff value of the combined model, recipients were divided into low-risk and high-risk groups, and Kaplan-Meier analysis was used to compare the cumulative incidence of abdominal infection within 30 days after surgery between the two groups. Results Among the 287 recipients who underwent liver transplantation, 60 developed bacterial or fungal abdominal infections postoperatively. A total of 86 strains were isolated from infected patients, with Gram-negative bacteria accounting for 58%, Gram-positive bacteria for 36%, and fungi for 5%. Preoperative NLR and PTAR were positively correlated with Child-Pugh and MELD scores (all 1 > r > 0, P < 0.05). Logistic regression analysis showed that preoperative NLR, preoperative PTAR, postoperative ICU stay duration and postoperative biliary leakage were risk factors for abdominal infection within 30 days after surgery. The area under the curve (AUC) for NLR, PTAR, Child-Pugh score and MELD score were 0.771, 0.735, 0.650 and 0.741, respectively. The AUC for the combined NLR and PTAR prediction model was 0.824 (95% confidence interval: 0.763-0.885, P < 0.001), with a cutoff value of 0.168. Kaplan-Meier analysis showed that the cumulative incidence of abdominal infection within 30 days after surgery was lower in the low-risk group than in the high-risk group, with statistically significant difference (P < 0.001). Conclusions Preoperative NLR and PTAR are independent risk factors for abdominal infection within 30 days after liver transplantation. The combined prediction model of NLR and PTAR may effectively identify high-risk recipients for early abdominal infection after liver transplantation, providing basis for early intervention.

BACKGROUND: G protein-coupled receptor kinase 2 (GRK2) could participate in the regulation of diverse cells via interacting with non-G-protein-coupled receptors. In the present work, we explored how paroxetine, a GRK2 inhibitor, modulates the differentiation and activation of immune cells in rheumatoid arthritis (RA). METHODS: The blood samples of healthy individuals and RA patients were collected between July 2021 and March 2022 from the First Affiliated Hospital of Anhui Medical University. C57BL/6 mice were used to induce the collagen-induced arthritis (CIA) model. Flow cytometry analysis was used to characterize the differentiation and function of dendritic cells (DCs)/T cells. Co-immunoprecipitation was used to explore the specific molecular mechanism. RESULTS: In patients with RA, high expression of GRK2 in peripheral blood lymphocytes, accompanied by the increases of phosphatidylinositol 3 kinase (PI3K), protein kinase B (AKT), and mammalian target of rapamycin (mTOR). In animal model, a decrease in regulatory T cells (T regs ), an increase in the cluster of differentiation 8 positive (CD8 + ) T cells, and maturation of DCs were observed. Paroxetine, when used in vitro and in CIA mice, restrained the maturation of DCs and the differentiation of CD8 + T cells, and induced the proportion of T regs . Paroxetine inhibited the secretion of pro-inflammatory cytokines, the expression of C-C motif chemokine receptor 7 in DCs and T cells. Simultaneously, paroxetine upregulated the expression of programmed death ligand 1, and anti-inflammatory cytokines. Additionally, paroxetine inhibited the PI3K-AKT-mTOR metabolic pathway in both DCs and T cells. This was associated with a reduction in mitochondrial membrane potential and changes in the utilization of glucose and lipids, particularly in DCs. Paroxetine reversed PI3K-AKT pathway activation induced by 740 Y-P (a PI3K agonist) through inhibiting the interaction between GRK2 and PI3K in DCs and T cells. CONCLUSION Paroxetine exerts an immunosuppressive effect by targeting GRK2, which subsequently inhibits the metabolism-related PI3K-AKT-mTOR pathway of DCs and T cells in RA.
G-Protein-Coupled Receptor Kinase 2/metabolism* ; Arthritis, Rheumatoid/immunology* ; Animals ; Dendritic Cells/metabolism* ; Paroxetine/therapeutic use* ; Proto-Oncogene Proteins c-akt/metabolism* ; Mice ; Humans ; Mice, Inbred C57BL ; Signal Transduction/drug effects* ; Male ; Phosphatidylinositol 3-Kinases/metabolism* ; Lymphocyte Activation/drug effects* ; Female ; T-Lymphocytes/metabolism* ; Middle Aged

BACKGROUND: Neoadjuvant therapeutic strategies play a pivotal role in the comprehensive treatment of non-small cell lung cancer (NSCLC). However, lung squamous cell carcinoma (SCC) generally exhibits a more favorable response to neoadjuvant therapy compared with lung adenocarcinoma (ADC). The aim of this study is to elucidate how baseline cancer-associated fibroblasts (CAFs) and tumor-associated endothelial cells (TAECs) influence the differential therapeutic outcomes of neoadjuvant treatment in SCC versus ADC. METHODS: We retrospectively collected pretreatment biopsy samples from 104 patients with stage II-III NSCLC who underwent neoadjuvant chemotherapy (NAC) or neoadjuvant chemoimmunotherapy (NAIC) at Shandong Cancer Hospital between January 1, 2018 and December 31, 2023. Tissue microarrays were constructed using an automated arrayer, and multiplex immunofluorescence staining (α-SMA/CD31/CK/DAPI) was performed to identify CAFs (α-SMA+/CK-) and TAECs (CD31+/CK-). Quantitative analyses included CAFs and TAECs densities, the nearest neighbor distance (NND) between CAFs and TAECs, and their spatial proximity (30 μm). Differences in major pathological response (MPR) between groups, defined as residual viable tumor cells ≤10% in resected specimens after neoadjuvant therapy, were assessed using the χ² test. The Mann-Whitney U test was applied to analyze intergroup differences in quantitative indicators, and receiver operating characteristic (ROC) curve analysis was conducted to evaluate the predictive performance of immune-related markers for MPR in the NAIC cohort. RESULTS: Among the 104 NSCLC patients who received neoadjuvant therapy, 35 underwent NAIC and 69 received NAC. Overall, patients with SCC were more likely to achieve MPR compared with those with ADC (50.0% vs 22.4%, P=0.006). This trend persisted in the NAIC subgroup (72.7% vs 30.8%, P=0.038), whereas no significant difference in MPR rates was observed between SCC and ADC in the NAC subgroup. At baseline, prior to NAIC or NAC, programmed cell death ligand 1 (PD-L1)/programmed cell death 1 (PD-1) expression, CAFs and TAECs densities, CAFs-TAECs NND, and CAFs-TAECs proximity (30 μm) showed no significant differences between SCC and ADC. In patients with SCC receiving NAIC, baseline PD-L1/PD-1 expression, CAFs density, and TAECs density showed not significant differences between MPR and NMPR groups. However, the CAFs-TAECs distance was significantly greater in the MPR group (NND: 31.2 vs 24.7 μm, P=0.038), and the number of TAECs within 30 μm of CAFs was significantly lower (proximity: 1.1 vs 3.6, P=0.038). Univariate Cox regression analysis indicated that low TAECs density was associated with MPR following NAIC (OR=36.00, 95%CI: 2.68-1486.88, P=0.019). Furthermore, ROC analysis demonstrated that baseline CAFs-TAECs NND and proximity (30 μm) exhibited strong predictive performance for MPR in SCC patients treated with NAIC, with an area under the curve (AUC) of 0.893, sensitivity of 0.857, and specificity of 1.000. CONCLUSIONS CAFs are more spatially distant from TAECs and more prone to MPR after NAIC in SCC, which may be related to the reduced interaction of CAFs with TAECs and reduced tumor-associated angiogenesis.
Humans ; Lung Neoplasms/therapy* ; Neoadjuvant Therapy ; Male ; Female ; Middle Aged ; Retrospective Studies ; Endothelial Cells/drug effects* ; Aged ; Cancer-Associated Fibroblasts/drug effects* ; Immunotherapy ; Carcinoma, Squamous Cell/drug therapy* ; Carcinoma, Non-Small-Cell Lung/drug therapy* ; Adult

Objective:To determine the optimal irradiation energy and frequency for the establishment of melasma mouse model using simple ultraviolet irradiation, and to provide guidance on animal strains and irradiation protocols for the successful establishment of melasma model.Methods:Animal models of melasma were established using BALB/c female mice and C57BL/6JNifdc female mice. BALB/c female mice were divided into 4 groups using a simple randomization method: A, B, C and G, with 5 mice in each group. C57BL/6JNifdc female mice were divided into 4 groups: D, E, F and H, with 5 mice in each group. All mice were irradiated with 8.428 mW/cm 2 of ultraviolet light. The irradiation time was 15 s (single irradiation energy of 0.13 J/cm 2) in groups A and D, 15 min (single irradiation energy of 7.59 J/cm 2) in groups B and E, and 30 min (single irradiation energy of 15.17 J/cm 2) in groups C and F. Each cycle consisted of 5 consecutive days of irradiation followed by 2 days of cessation, totaling 4 cycles of irradiation. Groups G and H were not irradiated. At the end of irradiation, all mice were kept under normal conditions. One week later, 3 mice from each group were selected for HE, Masson-Fontana, Masson, and immunohistochemical staining. Quantitative analysis was performed to measure the thickness of the acanthocyte layer, melanin granules, collagen percentage, and interleukin-1 (IL-1) levels. The remaining mice were kept for an additional week, depilated and photographed to observe the changes in coloration. Data were analyzed using SPSS 27.0 software, measurement data that did not conform to normal distribution were represented by M( Q1, Q3) and comparisons between groups were made using the Kruskal-Wallis rank sum test. Results:During the entire irradiation process, no visible discoloration was observed in the BALB/c female mice in all groups. In contrast, varying sizes of discoloration appeared in the C57BL/6JNifdc female mice in groups D, E, and F after irradiation in the second week. However, by the third week, the discoloration in group D gradually disappeared, while the discoloration in group E was more obvious than before. At the same time, group F exhibited significant discoloration, with some mice exhibited signs of skin peeling, burning and breakage on their backs. After the 4th week of irradiation, no new discoloration was formed in group D. The discoloration was more obvious in group E, and most mice in group F showed skin burn breakage. Two weeks after the completion of irradiation, there was no obvious discoloration on the dorsal skin of BALB/c female mice in all groups. In C57BL/6JNifdc female mice, group D showed no obvious discoloration, group E exhibited lighter discoloration compared to the 4th week post-irradiation, and group F had crusted skin at the burn sites with lighter discoloration than before. However, the discoloration in groups E and F was still obviously visible to the naked eye. HE staining showed that the difference in the thickness of the echinocyte layer was not statistically significant in groups A, B, C, and G ( H=1.08, P=0.782); whereas the difference was statistically significant in groups D, E, F and H ( H=12.85, P=0.005). The thickness of the echinocyte layer decreased gradually with the extension of the irradiation time. Additionally, there was a disruption in the arrangement of epidermal spindles in group F, and this situation was not observed in groups D and E. Masson-Fontana staining revealed no significant pigmentation in any of the BALB/c female mice. The difference in melanin granule counts between groups A, B, C, and G was not statistically significant ( H=7.77, P=0.051). In contrast, C57BL/6JNifdc female mice exhibited more noticeable pigmentation in the epidermis and dermis in groups E and F. The difference in melanin particle counts among groups D, E, F and H was statistically significant ( H=17.61, P<0.001), with melanin deposition increasing gradually with the duration of irradiation. Masson staining showed that the difference in collagen percentage between groups A, B, C, and G was not statistically significant ( H=7.26, P=0.064). However, significant disorganization of fibers and a loose structure were observed in groups E and F. The difference in collagen percentage between groups D, E, F, and H was statistically significant ( H=8.65, P=0.034). Immunohistochemical results showed that the difference in IL-1 expression levels between groups A, B, C, and G was statistically significant ( H=17.86, P<0.001); also between groups D, E, F, and H was statistically significant ( H=14.19, P=0.003), suggesting that ultraviolet irradiation stimulated an inflammatory response in the skin of mice. Conclusion:BALB/c female mice are not suitable for melasma models under the frequency and duration of irradiation in this experiment. C57BL/6JNifdc female mice are irradiated with a single irradiation energy dose of 7.59 J/cm 2 five days a week for 4 weeks, which can establish stable animal models of melasma with a specific level of pigmentation that persisted for at least 2 weeks.

In order to solve the problem of strong subjectivity and difficulty in quantification,clinical objectification mainly adopts the techniques of image processing,computer vision and machine learning.The acquisition and processing of prior knowledge is a key link in the objectification of inspection,as well as an important elaboration of the quantification of subjective judgment and macro performance in objectification research.However,there is still a lack of in-depth summary and parametric processing of prior knowledge.Based on the analysis of the current research status of objectification of inspection,this paper uses data mining technology to summarize the experience of TCM inspection.Moreover,the observation information can be transformed into quantifiable digital features through natural language processing and representation learning.Meanwhile,the application of deep learning can realize automatic diagnosis and analysis of observation images to improve accuracy and efficiency,and promote the process of TCM modernization.

Objective:To investigate the comorbidity status of hypertension, diabetes, and dyslipidemia (the"three diseases") among residents aged≥40 in Liaoning Province, and to explore the correlation between the comorbidity and cardiovascular disease mortality.Methods:This investigation was a prospective cohort study. From February 2017 to March 2019, a multi-stage stratified cluster random sampling method was used to carry out a baseline survey of 18 758 permanent residents aged≥40 years in Liaoning Province. Demographic information and history of hypertension, diabetes, and dyslipidemia were collected and followed up every year. Death was mainly identified by linkage to the Population Death Information Registration Management System. Cox proportional hazard regression model was used to analyze the association between the comorbidity of the "three diseases" and cardiovascular disease mortality risk.Results:A total of 18 758 residents aged≥40 in Liaoning Province were included, with an age of (60.3±9.9) years and 7 325 males (39.1%). The comorbidity rate of hypertension, diabetes, and dyslipidemia was 6.7% (1 256/18 758), and the standardized prevalence rate was 5.4%. The comorbidity rate increased with age (P<0.001), which was higher in women than in men, and more significant in urban areas than in rural areas (all P<0.001). The comorbidity of "three diseases" accounted for 39.3% (1 256/3 198), 18.7% (1 256/6 710), and 11.8% (1 256/10 653) in patients with diabetes, dyslipidemia, and hypertension, respectively. With a follow-up of (4.3±0.6) years, 463 people died of cardiovascular disease. The mortality rate of cardiovascular disease in the comorbidity of hypertension, diabetes, and dyslipidemia was 8.74/1 000 person-years. After adjusting potential confounders, Cox proportional hazard regression model analysis showed that compared with normal individuals, the hazard ratio of cardiovascular disease mortality in patients with the "three diseases" was 2.55 (95% CI: 1.63-3.99). Conclusion:The prevalence of comorbidity of hypertension, diabetes, and dyslipidemia among residents aged≥40 in Liaoning Province was relatively high, and the risk of cardiovascular disease mortality in patients with the "three diseases" was increased.

Objective:To determine the optimal irradiation energy and frequency for the establishment of melasma mouse model using simple ultraviolet irradiation, and to provide guidance on animal strains and irradiation protocols for the successful establishment of melasma model.Methods:Animal models of melasma were established using BALB/c female mice and C57BL/6JNifdc female mice. BALB/c female mice were divided into 4 groups using a simple randomization method: A, B, C and G, with 5 mice in each group. C57BL/6JNifdc female mice were divided into 4 groups: D, E, F and H, with 5 mice in each group. All mice were irradiated with 8.428 mW/cm 2 of ultraviolet light. The irradiation time was 15 s (single irradiation energy of 0.13 J/cm 2) in groups A and D, 15 min (single irradiation energy of 7.59 J/cm 2) in groups B and E, and 30 min (single irradiation energy of 15.17 J/cm 2) in groups C and F. Each cycle consisted of 5 consecutive days of irradiation followed by 2 days of cessation, totaling 4 cycles of irradiation. Groups G and H were not irradiated. At the end of irradiation, all mice were kept under normal conditions. One week later, 3 mice from each group were selected for HE, Masson-Fontana, Masson, and immunohistochemical staining. Quantitative analysis was performed to measure the thickness of the acanthocyte layer, melanin granules, collagen percentage, and interleukin-1 (IL-1) levels. The remaining mice were kept for an additional week, depilated and photographed to observe the changes in coloration. Data were analyzed using SPSS 27.0 software, measurement data that did not conform to normal distribution were represented by M( Q1, Q3) and comparisons between groups were made using the Kruskal-Wallis rank sum test. Results:During the entire irradiation process, no visible discoloration was observed in the BALB/c female mice in all groups. In contrast, varying sizes of discoloration appeared in the C57BL/6JNifdc female mice in groups D, E, and F after irradiation in the second week. However, by the third week, the discoloration in group D gradually disappeared, while the discoloration in group E was more obvious than before. At the same time, group F exhibited significant discoloration, with some mice exhibited signs of skin peeling, burning and breakage on their backs. After the 4th week of irradiation, no new discoloration was formed in group D. The discoloration was more obvious in group E, and most mice in group F showed skin burn breakage. Two weeks after the completion of irradiation, there was no obvious discoloration on the dorsal skin of BALB/c female mice in all groups. In C57BL/6JNifdc female mice, group D showed no obvious discoloration, group E exhibited lighter discoloration compared to the 4th week post-irradiation, and group F had crusted skin at the burn sites with lighter discoloration than before. However, the discoloration in groups E and F was still obviously visible to the naked eye. HE staining showed that the difference in the thickness of the echinocyte layer was not statistically significant in groups A, B, C, and G ( H=1.08, P=0.782); whereas the difference was statistically significant in groups D, E, F and H ( H=12.85, P=0.005). The thickness of the echinocyte layer decreased gradually with the extension of the irradiation time. Additionally, there was a disruption in the arrangement of epidermal spindles in group F, and this situation was not observed in groups D and E. Masson-Fontana staining revealed no significant pigmentation in any of the BALB/c female mice. The difference in melanin granule counts between groups A, B, C, and G was not statistically significant ( H=7.77, P=0.051). In contrast, C57BL/6JNifdc female mice exhibited more noticeable pigmentation in the epidermis and dermis in groups E and F. The difference in melanin particle counts among groups D, E, F and H was statistically significant ( H=17.61, P<0.001), with melanin deposition increasing gradually with the duration of irradiation. Masson staining showed that the difference in collagen percentage between groups A, B, C, and G was not statistically significant ( H=7.26, P=0.064). However, significant disorganization of fibers and a loose structure were observed in groups E and F. The difference in collagen percentage between groups D, E, F, and H was statistically significant ( H=8.65, P=0.034). Immunohistochemical results showed that the difference in IL-1 expression levels between groups A, B, C, and G was statistically significant ( H=17.86, P<0.001); also between groups D, E, F, and H was statistically significant ( H=14.19, P=0.003), suggesting that ultraviolet irradiation stimulated an inflammatory response in the skin of mice. Conclusion:BALB/c female mice are not suitable for melasma models under the frequency and duration of irradiation in this experiment. C57BL/6JNifdc female mice are irradiated with a single irradiation energy dose of 7.59 J/cm 2 five days a week for 4 weeks, which can establish stable animal models of melasma with a specific level of pigmentation that persisted for at least 2 weeks.