Synergistic antitumor efficacy of gemcitabine and cisplatin to induce ferroptosis in pancreatic ductal adenocarcinoma via Sp1-SAT1-polyamine metabolism pathway.

PURPOSE: The combination of cisplatin and gemcitabine-based chemotherapy has been recommended as a preferred regimen for pancreatic ductal adenocarcinoma (PDAC) patients with germline-based mutations. However, the underlying mechanism remains poorly elucidated. Therefore, our study aimed to explore the mechanistic basis of the cell-killing activity of gemcitabine plus cisplatin and identify potential therapeutic targets. METHODS: First, we explored the synergistic cytotoxic effects of gemcitabine and cisplatin on PDAC through in vitro and in vivo experiments. Then, we investigated ferroptosis-related biomarkers, to assess the impact of the combination therapy on ferroptosis. Using bioinformatics methods, we identified SAT1 as a potential key mediator of ferroptosis induced by gemcitabine and cisplatin. We tested the polyamine levels in PDAC cells by LC-MS after overexpressed or knocked down SAT1, and explored the role of polyamines in ferroptosis using exogenous supplementation. Finally, we explored the regulatory effect of Sp1 on SAT1 through ChIP-qPCR and dual-luciferase reporter assay. RESULTS: Gemcitabine plus cisplatin enhanced cell death and induced ferroptosis in PDAC. This combination upregulated SAT1 transcription by inhibiting Sp1. SAT1 activation promoted the catabolism of spermine and spermidine, leading to iron accumulation and lipid peroxide generation, ultimately resulting in ferroptosis. CONCLUSIONS: In summary, our findings suggested the gemcitabine and cisplatin combination therapy induced ferroptosis in a GSH-independent manner in PDAC. The combined treatment inhibited Sp1 and upregulated SAT1 transcription, leading to the breakdown of spermine and spermidine. Therefore, targeting SAT1-induced polyamine metabolism may represent a promising therapeutic strategy for PDAC.

SPOCK1 and POSTN are valuable prognostic biomarkers and correlate with tumor immune infiltrates in colorectal cancer.

BACKGROUND: Immune cells and stromal cells in the tumor microenvironment play a vital role in the progression of colorectal cancer (CRC). The study aimed to screen valuable prognostic biomarkers in CRC based on stromal and immune scores. METHOD: The ESTIMATE algorithm was used to calculate the immune and stromal scores of CRC samples in TCGA. Then samples were divided into high and low score groups based on the median value of the scores. Differentially expressed genes (DEGs) associated with immune and stromal scores were screened. WGCNA and univariate COX regression analysis were performed to further identify key prognostic genes. Analysis of scRNA-seq for CRC was used for verifying the main source of the key genes. The prognostic value of they was validated based on The Gene Expression Profiling Interactive Analysis and GSE17536 dataset. TIMER and CIBERSORT algorithms were applied to analyze the correlations among key genes and tumor-infiltrating immune cells. Several pairs of colon cancer tissue were used to be proven. RESULT: 1314 upregulated and 4 downregulated genes were identified, which were significantly enriched in immune-related biological processes and pathways. Among these DEGs, SPOCK1 and POSTN were identified as key prognostic genes and mainly expressed in cancer-associated fibroblasts for CRC. High expression of SPCOK1 and POSTN was associated with advanced clinical stage, T stage, N stage, and poor prognosis of CRC. The results from CIBERSORT and TIMER revealed that SPOCK1 and POSTN were associated with tumor-infiltrating immune cells, especially macrophages and neutrophils. Meanwhile, in several pairs of human colorectal tissue samples, SPOK1 and POSTN were found to be significantly overexpressed in colorectal tissue compared with para-cancer tissue, and macrophage surface markers CD68 (co-expressed by M1 and M2 macrophages) and CD206 (M2-specific macrophage expression) were also overexpressed in cancer tissue. Besides, SPOCK1 and POSTN expression were positively correlated with the expression of immune checkpoints. CONCLUSION: Collectively, our results indicate that SPOCK1 and POSTN associated with CAF may be novel prognostic biomarkers in CRC and correlate with immune infiltrates.

MAIT cells ameliorate liver fibrosis by enhancing the cytotoxicity of NK cells in cholestatic murine models.

BACKGROUND AND AIMS: Mucosal-associated invariant T (MAIT) cells are innate-like lymphocytes that display a critical role in various liver diseases. However, the role of MAIT cells in cholestatic liver fibrogenesis remains obscure. Our study aims to assess the contribution of MAIT cells and underlying mechanisms during this process. METHODS: Cholestatic murine models using MAIT cell-deficient (MR1- /- ) and wild-type (WT) mice were established by feeding a 0.1% 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC)-enriched diet or bile duct ligation (BDL). Liver samples were collected to determine the severity of fibrosis. Lymphocytes of the liver were isolated for analysing the phenotype and function of MAIT cells. Cell co-culture experiments were performed to investigate the cross-talk between MAIT and NK cells. RESULTS: Liver MAIT cells were more activated with increased cytokines in cholestatic mice models than in control mice, although their frequency was decreased. MAIT cell deficiency led to severe liver inflammation and fibrosis with more activated HSCs in cholestatic mice. In addition, MR1- /- mice had an increased frequency of NK cells with higher expression of stimulatory receptors relative to WT mice. Paradoxically, activated MAIT cells significantly promoted the anti-fibrotic ability of NK cells by enhancing their cytotoxicity against HSCs in co-culture experiments. Importantly, this effect depended on direct cell-cell contact and TNF-α produced by MAIT cells. CONCLUSION: Our findings indicate that MAIT cells ameliorate cholestatic liver fibrosis by enhancing the cytotoxicity of NK cells against HSCs. An in-depth understanding of the MAIT cell-mediated regulatory effect will provide more valuable immunotherapy strategies to treat liver fibrosis.

Blockade of GCH1/BH4 Axis Activates Ferritinophagy to Mitigate the Resistance of Colorectal Cancer to Erastin-Induced Ferroptosis.

Ferroptosis, a type of cell death triggered by excessive accumulation of iron-dependent lipid peroxidation, possesses an excellent potential in cancer treatment. However, many colorectal cancer (CRC) cell lines are resistant to ferroptosis induced by erastin and RSL3, the classical ferroptotic inducers. Moreover, the underlying mechanism of resistance remains poorly elucidated. This study sought to discover the major factor contributing to ferroptosis resistance in CRC. The study findings will help design strategies for triggering ferroptosis for application in individualized tumor therapy. Here, we show that tetrahydrobiopterin (BH4) determines the sensitivity of CRC cells to ferroptosis induced by erastin. GTP cyclohydrolase-1 (GCH1) is the first rate-limiting enzyme of BH4. Genetic or pharmacological inhibition of GCH1 decreased BH4 and assisted erastin in cell death induction, lipid peroxidation enhancement, and ferrous iron accumulation. BH4 supplementation completely inhibited ferroptotic features resulting from GCH1 knockdown. Unexpectedly, GCH1 knockdown failed to enhance RSL3-induced cell death in CRC. Mechanistically, GCH1 knockdown drastically activated ferritinophagy during erastin treatment rather than RSL3 treatment. Administration of an autophagy inhibitor reversed erastin resistance in GCH1-knockdown cells. GCH1 inhibitor and erastin co-treatment in vivo synergistically inhibited tumor growth in CRC. Overall, our results identified GCH1/BH4 metabolism as a burgeoning ferroptosis defense mechanism in CRC. Inhibiting GCH1/BH4 metabolism promoted erastin-induced ferroptosis by activating ferritinophagy, suggesting that combining GCH1 inhibitors with erastin in the treatment of CRC is a novel therapeutic strategy.

Identification of SCN7A as the key gene associated with tumor mutation burden in gastric cancer.

OBJECTIVE: Previous studies have shown that tumor mutation burden (TMB) in cancer is associated with prognosis. The purpose of this study is to identify TMB related genes in gastric cancer (GC) and to explore their prognostic value. METHODS: In our research, weighted gene coexpression network analysis (WGCNA) algorithm was used to cluster the most relevant TMB modules in the Cancer Genome Atlas (TCGA) database. Limma package was used to screen the differentially expressed genes, and the intersection was identified as hub genes. We used gene expression profiling interactive analysis (GEPIA) and survival algorithm to analyze the clinical characteristics and prognosis of hub genes in tumor and normal tissue samples of TCGA and Gene Expression Omnibus cohort respectively. We also used CIBERSORT algorithm to calculate the proportion of 22 tumor immune cells in the high and low expression subgroups of hub genes. In addition, we used gene set enrichment analysis (GSEA) to predict the biological function of hub genes. P < 0.05 was considered statistically significant. RESULTS: In the TCGA cohort, TMB was significantly correlated with the clinical features of GC (P < 0.05). Through WGCNA and differential gene analysis, we identified SCN7A as the hub gene (P < 0.05, |log2fc|> 1, and mm > 0.8). We found that the expression of SCN7A in tumor tissues was lower than that in normal tissues, and its expression level was also related to overall survival rate and tumor stage. GSEA analysis showed that SCN7A low expression group was enriched with "DNA replication", "base extension repair" and "proteasome" gene sets in GC. In addition, we found that there were significant differences in the infiltration degree of 7 kinds of immune cells between the two groups. CONCLUSION: TMB can indicate the prognosis of gastric cancer. SCN7A is a hub gene associated with TMB, and its low expression is associated with better prognosis.

The Role of Ferroptosis Signature in Overall Survival and Chemotherapy of Pancreatic Adenocarcinoma.

Studies have shown that ferroptosis, an iron-dependent regulated cell death, is related to prognosis and chemotherapy, but the role of ferroptosis in pancreatic adenocarcinoma (PAAD) is still unclear. We aimed at constructing a ferroptosis-related gene (FRGs) model to predict the PAAD patients' overall survival (OS) and at exploring their values in chemotherapy. We downloaded the mRNA-sequencing data and corresponding clinical data of patients with PAAD from The Cancer Genome Atlas. Lasso-penalized Cox regression analysis was utilized to construct a prognostic risk model, including spermidine/spermine N1-acetyltransferase 1 (SAT1), SAT2, TFRC, SLC39A8, MAP1LC3A, ALOX15, and PROM2. Receiver operating characteristic curves were used to evaluate the prognostic model. International Cancer Genome Consortium cohorts were used to validate this model. Then, we used Genomics of Drug Sensitivity in Cancer and Gene Expression Omnibus databases to analyze the correlation between FRGs and drug sensitivity. Notably, SAT1 showed significant influence in cisplatin and gemcitabine resistance. Finally, in vitro experiments demonstrated that the combination of gemcitabine and cisplatin could induce ferroptosis in AsPC1 cells, probably through elevated SAT1 expression. Taken together, Our 7-gene signature has significant values in predicting the PAAD patients' OS, and it may help inform the clinical treatment of PAAD.

Identification and validation of an immune prognostic signature in colorectal cancer.

BACKGROUND: Colorectal cancer (CRC) is one of the most common malignant neoplasms worldwide. Although the significant efficacy of immunotherapy has been shown, only limited CRC patients benefit from it. Therefore, we aimed to establish a prognostic signature based on immune-related genes (IRGs) to predict overall survival (OS) and the potential response to immunotherapy in CRC patients. METHODS: Gene expression profiles and clinical information of CRC patients were collected from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases. The prognostic signature composed of IRGs was established using univariate Cox regression and the least absolute shrinkage and selection operator (LASSO) regression analysis. CIBERSORT was used to estimate the immune cell infiltration. RESULTS: A total of 24 survival-related IRGs were identified from 247 differentially expressed IRGs. Then, 16 IRGs were selected to establish the prognostic signature that stratified the patients into the high-risk and low-risk groups with statistically different survival outcomes. The AUCs of the time-dependent ROC curves indicated that the signature had a strong predictive accuracy in internal and external validation sets. Multivariate cox regression analysis suggested that the signature could also act as an independent prognostic factor for OS. The low-risk group had a higher proportion of immune cell infiltration than the high-risk group, such as CD4 memory resting T cells, activated dendritic cells, and resting dendritic cells. In addition, patients in the high-risk group exhibited higher tumor mutation burden and BRAF mutation. CONCLUSION: We developed an immune-related prognostic signature to predict the OS and immune status in CRC patients. We believed that our signature is conducive to better stratification and more precise immunotherapy for CRC patients.

Improving the coverage and accuracy of syphilis testing: The development of a novel rapid, point-of-care test for confirmatory testing of active syphilis infection and its early evaluation in China and South Africa.

BACKGROUND: Current point-of-care tests (POCT) for syphilis, based on the detection of Treponema pallidum (TP) total antibodies, have limited capacity in distinguishing between active and past/treated syphilis. We report the development and early evaluation of a new prototype POCT based on the detection of TP-IgA antibodies, a novel biomarker for active syphilis. METHODS: The TP-IgA POCT (index test) was developed in response to the World Health Organisation (WHO) target product profile (TPP) for a POCT for confirmatory syphilis testing. Two sub-studies were conducted consecutively using 458 pre-characterised stored plasma samples in China (sub-study one, addressing the criteria for the WHO TPP), and 503 venous blood samples collected from pregnant/postpartum women in South Africa (sub-study two, addressing potential clinical utility). Performance of the index test was assessed against standard laboratory-based serology using a combination of treponemal (TPHA) and non-treponemal (rapid plasma reagin [RPR]) tests. FINDINGS: In sub-study one, the index test demonstrated 96·1% (95%CI=91·7%-98·5%) sensitivity and 84·7% (95%CI=80·15-88·6%) specificity for identification of active syphilis (TPHA positive, RPR positive). It correctly identified 71% (107/150) samples of past-treated syphilis (TPHA positive, RPR negative). In sub-study two, the index test achieved 100% (95%CI=59%-100%) sensitivity for active syphilis and correctly identified all nine women with past syphilis. INTERPRETATION: The TP-IgA POCT has met the WHO TPP for a POCT for diagnosis of active syphilis and demonstrated its potential utility in a clinical setting. Future studies are warranted to evaluate field performance of the final manufactured test. FUNDING: Saving Lives at Birth: Grand Challenge for Development, Thrasher Research Fund, and the Victorian Government Operational Infrastructure Scheme.

MicroRNA-375-3p enhances chemosensitivity to 5-fluorouracil by targeting thymidylate synthase in colorectal cancer.

Resistance to chemotherapy is a major challenge for the treatment of patients with colorectal cancer (CRC). Previous studies have found that microRNAs (miRNAs) play key roles in drug resistance; however, the role of miRNA-373-3p (miR-375-3p) in CRC remains unclear. The current study aimed to explore the potential function of miR-375-3p in 5-fluorouracil (5-FU) resistance. MicroRNA-375-3p was found to be widely downregulated in human CRC cell lines and tissues and to promote the sensitivity of CRC cells to 5-FU by inducing colon cancer cell apoptosis and cycle arrest and by inhibiting cell growth, migration, and invasion in vitro. Thymidylate synthase (TYMS) was found to be a direct target of miR-375-3p, and TYMS knockdown exerted similar effects as miR-375-3p overexpression on the CRC cellular response to 5-FU. Lipid-coated calcium carbonate nanoparticles (NPs) were designed to cotransport 5-FU and miR-375-3p into cells efficiently and rapidly and to release the drugs in a weakly acidic tumor microenvironment. The therapeutic effect of combined miR-375 + 5-FU/NPs was significantly higher than that of the individual treatments in mouse s.c. xenografts derived from HCT116 cells. Our results suggest that restoring miR-375-3p levels could be a future novel therapeutic strategy to enhance chemosensitivity to 5-FU.

Seropositivity and risk factors for herpes simplex virus type 2 infection among female sex workers in Guangxi, China.

OBJECTIVES: To determine seropositivity of herpes simplex virus type 2 (HSV-2) infection and associated risk factors among female sex workers (FSWs) in Guangxi, China. METHODS: A convenience sample of FSWs was recruited from different types of sex work venues in two cities (Wuzhou and Hezhou) in Guangxi. Blood specimens were collected for ELISA-based detection of HSV-2 antibodies to examine the seropositivity of HSV-2 infection. Socio-demographic and behavioral data were collected through a structured questionnaire interview. Association of HSV-2 seropositivity with socio-demographic and behavioral characteristics and HIV status was analyzed. RESULTS: The overall prevalence of HSV-2 seropositivity among 2453 FSWs was 54.9% (95% confidence interval [CI], 52.9-56.9%). The HSV-2 seropositivity was independently associated with older age, low education level, non-Han minority, migration status, working in lower-tier venues and positive HIV status. CONCLUSIONS: The study indicates a high prevalence of HSV-2 infection among FSWs, particularly in those working in low-tier venues in study areas, suggesting the needs to further emphasize the inclusion of HSV-2 in surveillance and intervention programs in this population.

Outreach syphilis testing services by different health providers to female sex workers in southern China.

Health providers have played important roles on delivering prevention and care services to control syphilis in China. The current study was aimed to evaluate the performance of different health providers in providing outreach syphilis testing services to female sex workers (FSWs). The current study carried out during April to August 2009 in Liuzhou was aimed to investigate the services delivered by two different types of clinics in China. A total of 1,808 FSWs recruited from sex work venues were included in the study. Prevalence of positive syphilis test (6.4%) among FSWs accessed by the local center for disease control outreach teams (CDC teams) was significantly lower than that (9.3%) among FSWs accessed by the local reproductive health hospital outreach teams (RHH teams). As compared with CDC teams, RHH teams had more FSWs to be successfully referred to the designated STD clinics for further syphilis confirmation and intervention (85.7% vs. 26.7%, P<0.001). These findings indicate that RHH teams may be more efficient than CDC teams to provide outreach-based services to FSWs. Participation of the reproductive health providers or other medical facilities in outreach services to FSWs should be considered in developing intervention programs in China.

A dual point-of-care test shows good performance in simultaneously detecting nontreponemal and treponemal antibodies in patients with syphilis: a multisite evaluation study in China.

BACKGROUND: Rapid point-of-care (POC) syphilis tests based on simultaneous detection of treponemal and nontreponemal antibodies (dual POC tests) offer the opportunity to increase coverage of syphilis screening and treatment. This study aimed to conduct a multisite performance evaluation of a dual POC syphilis test in China. METHODS: Participants were recruited from patients at sexually transmitted infection clinics and high-risk groups in outreach settings in 6 sites in China. Three kinds of specimens (whole blood [WB], fingerprick blood [FB], and blood plasma [BP]) were used for evaluating sensitivity and specificity of the Dual Path Platform (DPP) Syphilis Screen and Confirm test using its treponemal and nontreponemal lines to compare Treponema pallidum particle agglutination (TPPA) assay and toluidine red unheated serum test (TRUST) as reference standards. RESULTS: A total of 3134 specimens (WB 1323, FB 488, and BP 1323) from 1323 individuals were collected. The sensitivities as compared with TPPA were 96.7% for WB, 96.4% for FB, and 94.6% for BP, and the specificities were 99.3%, 99.1%, and 99.6%, respectively. The sensitivities as compared with TRUST were 87.2% for WB, 85.8% for FB, and 88.4% for BP, and the specificities were 94.4%, 96.1%, and 95.0%, respectively. For specimens with a TRUST titer of 1:4 or higher, the sensitivities were 100.0% for WB, 97.8% for FB, and 99.6% for BP. CONCLUSIONS: DPP test shows good sensitivity and specificity in detecting treponemal and nontreponemal antibodies in 3 kinds of specimens. It is hoped that this assay can be considered as an alternative in the diagnosis of syphilis, particularly in resource-limited areas.

Prevalence and risk factors of HSV-2 infection and HSV-2/HIV coinfection in men who have sex with men in China: a multisite cross-sectional study.

OBJECTIVES: To determine the prevalence and risk factors of herpes simplex virus type 2 (HSV-2) infection and its coinfection with human immunodeficiency virus (HIV) in men who have sex with men (MSM) in China. METHODS: A convenience sample of 1462 MSM were recruited from different settings (an STD clinic, a health center, and MSM venues) in 3 cities in China. Blood specimens were collected for testing for antibodies to HSV-2 and HIV to determinate the seroprevalence of HSV-2 infection and HSV-2/HIV coinfection. Information on sociodemographic and behavioral characteristics was collected to determine the risk factors associated with the infections. RESULTS: The prevalence of HSV-2 infection in 1462 MSM was 16.0% (95% confidence interval [CI], 14.2%-18.0%), the prevalence of HIV infection in this population was 9.5% (95% CI, 8.1%-11.1%), and the rate of coinfection of HSV-2 and HIV was 3.2% (95% CI, 2.4%-4.3%). Multivariate logistic regression analysis showed that risk factors for HSV-2 infection included age older than 30 years, education level lower than senior high school, involvement in commercial sex work, and HIV-positive status. Education level lower than junior high school and history of sexual abuse were associated with HSV-2/HIV coinfection. CONCLUSIONS: The high prevalence of HSV-2 infection and HSV-2/HIV coinfection among MSM in China suggests that an increased focus on HSV control is warranted within China's prevention and intervention programs targeted toward MSM.

Prevalence of syphilis infection in different tiers of female sex workers in China: implications for surveillance and interventions.

BACKGROUND: Syphilis has made a dramatic resurgence in China during the past two decades and become the third most prevalent notifiable infectious disease in China. Female sex workers (FSWs) have become one of key populations for the epidemic. In order to investigate syphilis infection among different tiers of FSWs, a cross-sectional study was conducted in 8 sites in China. METHODS: Serum specimens (n = 7,118) were collected to test for syphilis and questionnaire interviews were conducted to obtain socio-demographic and behavioral information among FSWs recruited from different types of venues. FSWs were categorized into three tiers (high-, middle- and low-tier FSWs) based on the venues where they solicited clients. Serum specimens were screened with enzyme-linked immunosorbent assay (ELISA) for treponemal antibody followed by confirmation with non-treponemal toluidine red unheated serum test (TRUST) for positive ELISA specimens to determine syphilis infection. A logistic regression model was used to determine factors associated with syphilis infection. RESULTS: Overall syphilis prevalence was 5.0% (95%CI, 4.5-5.5%). Low-tier FSWs had the highest prevalence (9.7%; 95%CI, 8.3-11.1%), followed by middle-tier (4.3%; 95%CI, 3.6-5.0%, P < 0.001) and high-tier FSWs (2.2%; 95%CI, 1.6-2.9%, P < 0.001). Factors independently associated with syphilis infection included older age, lower education level, geographic location, lower tier of typology, and injection drug use. CONCLUSIONS: This multi-site survey showed a high prevalence of syphilis infection among FSWs and substantial disparities in syphilis prevalence by the tier of FSWs. The difference in syphilis prevalence is substantial between different tiers of FSWs, with the highest rate among low-tier FSWs. Thus, current surveillance and intervention activities, which have low coverage in low-tier FSWs in China, should be further examined.

Epidemiology of sexually transmitted infections, HIV, and related high-risk behaviors among female sex workers in Guangxi Autonomous Region, China.

This study assessed the epidemiology of sexually transmitted infections (STIs), HIV, and associated risk factors among female sex workers (FSWs) in Guangxi autonomous region, China. A cross-sectional study of 488 FSWs was conducted using a structured questionnaire to collect sociodemographic and behavioral information. Biological specimens from subjects were sampled to detect various STIs and HIV infection. Among FSWs, the prevalence rates of syphilis, Neisseria gonorrhoeae, Chlamydia trachomatis, genital herpes, condyloma acuminate, and HIV were 7.2%, 1.8%, 18.2%, 0.4%, 2.3%, and 0.8%, respectively. The prevalence rates of single, double, and triple infections were 22.3%, 3.9%, and 0.20%, respectively. Multivariate analysis indicated that STIs and HIV infection was independently related to low education level (OR = 7.244; 95% CI = 3.031-17.213; P < 0.001), low knowledge of STIs/HIV (OR = 0.191; 95% CI = 0.108-0.337; P < 0.001), low-grade working place (OR = 1.64; 95%CI = 1.016-2.648; P = 0.046), and no condom use during the last sexual intercourse (OR = 0.199; 95% CI = 0.113-0.350; P < 0.001). The prevalence of STIs is high among FSWs in Guangxi, is accompanied by a 0.8% HIV-positive rate, and may be largely related to high-risk sexual behaviors. Future interventions should be focused on the reduction of risk factors, including promotion of condom use and improvement of knowledge of STIs and HIV among FSWs.

Rapid syphilis testing uptake for female sex workers at sex venues in Southern China: implications for expanding syphilis screening.

BACKGROUND: Accessibility of syphilis testing services is critical in syphilis control programs for female sex workers (FSWs), but few FSWs attend public STI clinics or other testing sites. Introduction of free rapid syphilis testing (RST) into outreach programs for FSWs will help improve test uptake. METHODS: Commercial sex venues were identified in two cities in South China. In cooperation with health advocacy organizations, health outreach teams from local public health or medical facilities approached all types of sex venues in study areas to offer free RST. Acceptability and uptake of RST among FSWs were evaluated. RESULTS: A total of 2812 FSWs were offered RST and 2670 (95.0%) accepted syphilis testing. 182 (6.8%) FSWs had a positive RST result among whom 136 (74.7%) were willing to attend an STD clinic for confirmatory testing and treatment. More than half (89, 66.4%) of those with syphilis were not willing to notify their sex partners. Multivariate logistic analysis showed that syphilis test uptake was associated with residing in Jiangmen (AOR, 1.78; 95% CI, 1.15-2.77), older age (AOR, 2.11, 95% CI, 1.17-3.79 for age of 31 years or above), and not working at a service venue (AOR, 1.60; 95% CI, 1.10-2.34). CONCLUSIONS: RST at sex venues is well accepted by FSWs when it is integrated into ongoing outreach services. Such programs provide excellent opportunities for expanding syphilis screening efforts among specific subgroups of FSW who are difficult to reach through clinic-based programs.

Molecular typing of Treponema pallidum causing early syphilis in China: a cross-sectional study.

BACKGROUND: There have been limited data on molecular epidemiology of syphilis in China. This study aimed to analyze strain type distribution of Treponema pallidum causing early syphilis across geographic areas in China using an enhanced method. METHODS: Genital samples were collected from patients in East, South, and North China. Positive DNA of T. pallidum was analyzed by arp, tpr, and tp0548 genes. RESULTS: Sufficient DNA for full molecular typing existed in 197 of 324 samples, and 27 strain types were identified. A range of 3 to 20 repeats (except 4, 11, and 19 repeats) and 25 repeats were found for the 60-bp tandem repeats of the arp gene. This was the first time the 9 and 25 repeats were detected. For the RFLP analysis of the tpr genes, patterns a, d, h, j, and l were identified. This was the first time the h, j, and l patterns were observed in China. For the sequence analysis of the tp0548 gene, sequences c, e, and f were identified. Strain type distribution was significantly different across geographic areas (χ² = 20.6, P = 0.006). Overall, 14d/f was most predominant (39% of fully typed samples, 95% CI = 32%-46%); 13d/f, 15d/f, and 16d/f were next most common (each 13% of fully typed samples, 95% CI = 9%-18%). CONCLUSIONS: There is substantial genetic diversity of T. pallidum in China. The broad and ununiform distribution of strain types may reflect differences in regional sexual network patterns. Predominance of few strain types may indicate a linked transmission.

Performance of serological tests for syphilis in sexually transmitted diseases clinics in Guangxi Autonomous Region, China: implications for syphilis surveillance and control.

BACKGROUND: China is experiencing a growing syphilis epidemic. Individuals are currently screened and cases are confirmed using traditional serological testing methods. METHODS: A total of 11 558 serum specimens from patients at 14 sexually transmitted diseases (STD) clinics at provincial, prefecture and county levels in Guangxi Autonomous Region were tested at local clinics using the toluidine red unheated serum test (TRUST) and the SD Bioline Syphilis 3.0 Treponema Pallidum (SD-TP) test and then transported to the National STD Reference Laboratory for TRUST and confirmatory Treponema pallidum particle assay (TPPA) testing. RESULTS: In local clinics, 13.2% of specimens were TRUST positive and 12.8% were TRUST and SD-TP positive. At the Reference Laboratory, 15.4% of specimens were TRUST positive and 11.8% were TRUST and TPPA positive. Local clinics showed a significantly higher prevalence of active syphilis compared with results from the Reference Laboratory (12.8 v. 11.8%, chi(2) = 4.59, P = 0.03). The local TRUST tests had consistent results with Reference Laboratory tests qualitatively among 96.2% of the specimens and quantitatively among 95.5% of the specimens. The algorithm of TRUST screening and then SD-TP confirmation among positive TRUST specimens at local STD clinics had 96.6% sensitivity and 99.3% specificity in diagnosing active syphilis compared with the 'gold standard' based on TRUST and TPPA positivity at the Reference Laboratory (positive predictive value 95.1% and negative predictive value 99.5%). CONCLUSION: The TRUST screening and SD-TP confirmation in combination can be used at local STD clinics for the efficient diagnosis of serologically active syphilis. However, continuing capacity building and quality assurance remain critical in ensuring the quality of syphilis diagnosis at local clinics.

Risk of syphilis in STI clinic patients: a cross-sectional study of 11,500 cases in Guangxi, China.

OBJECTIVE: To measure prevalence of syphilis among the STI clinic population in Guangxi, China, and to assess the socioeconomic and behavioural characteristics associated with the infection. METHODS: We undertook a cross-sectional survey and syphilis and HIV serologic testing among 11 473 patients attending 14 community and hospital-based dermatovenereal clinics across eight cities in Guangxi between December 2004 and February 2006. RESULTS: 1297 (11.9%) patients demonstrated positive toludine red unheated serum test and Treponema pallidum particle agglutination results with serologic testing. A total of 58% (752) of seropositive subjects presented with a genital ulcer, palmar/plantar rash or inguinal lymphadenopathy. Female sex (OR = 2.23, 95% confidence intervals (CI) = 1.69 to 3.00, p<0.001), less education (middle school, OR = 1.70, 95% CI = 1.11 to 2.62, p = 0.023; primary school or less, OR = 1.98, 95% CI = 1.13 to 3.46, p = 0.017) and high annual income (OR = 1.91, 95% CI = 1.18 to 3.10, p = 0.009 for >30 000 RMB yuan) were associated with serologically positive status. Syphilis infection was significantly more prevalent in city 2 (19.5%, OR = 3.07, 95% CI = 1.83 to 5.16, p<0.001), city 4 (16.6%, OR = 1.90, 95% CI = 1.10 to 3.28, p = 0.011) and city 8 (13.8%, OR = 1.83, 95% CI = 1.13 to 2.97, p = 0.006). A total of 40.1% (532) of infected subjects engaged in commercial sex and increased rates of the infection was associated with multiple sexual partners (OR = 1.54, 95% CI = 1.16 to 2.06, p = 0.003). A total of 1.2% (133) of participants carried laboratory markers for HIV and 1.8% (23) of patients with syphilis were positive for HIV. CONCLUSIONS: Syphilis infection has reached alarming rates in China's STI clinic population, suggesting a generalised spread of the disease through commercial sex and bridging populations. Syphilis control is deserving of China's highest priority. Universal screening for syphilis and HIV testing in STI clinics should be considered as measures for control.