1.Factors affecting and identification of key environmental determinants of the Oncomelania hupensis snail density in the Yangtze River Delta based on machine learning models
Yinlong LI ; Qin LI ; Suying GUO ; Shizhen LI ; Lijuan ZHANG ; Chunli CAO ; Jing XU
Chinese Journal of Schistosomiasis Control 2026;38(1):14-19
Objective To identify factors affecting and key environmental factors of the Oncomelania hupensis snail density in the Yangtze River Delta region using machine learning methods. Methods Administrative village-level O. hupensis snail survey data in the Yangtze River Delta (including Shanghai Municipality, Jiangsu Province, Zhejiang Province and Anhui Province) from 2011 to 2021 were retrieved from the Information Management System for Parasitic Disease Control of Chinese Center for Disease Control and Prevention. Environmental factor data were captured from the Google Earth Engine platform, including elevation, slope, terrain, normalized difference vegetation index (NDVI), vegetation type, soil type, total petroleum hydrocarbon (TPH), ammonium nitrogen, inorganic nitrogen, dissolved oxygen, pH of water, chemical oxygen demand (COD) and inorganic phosphorus, and climatic factor data in the study region were retrieved from the Copernicus Climate Data Store, including annual precipitation, aridity index and annual mean temperature (AMT). O. hupensis snail survey data in the Yangtze River Delta region from 2011 to 2021 were randomly divided into a training set (70%) and a test set (30%), and five machine learning models were selected for machine learning model construction and comparative analysis of the O. hupensis snail density using the software R 4.3.0, including random forest (RF), eXtreme gradient boosting (XGBoost), support vector machine (SVM), gradient boosting machine (GBM) and neural network (NN). The XGBoost model was employed to construct a predictive model for the O. hupensis snail density, and the impact of each environmental factor on O. hupensis snail distribution was quantified. The SHapley Additive exPlanations (SHAPs) values were calculated to estimate the average contribution of each variable to the model prediction, and the core environmental factors affecting the O. hupensis snail population density were screened. Results Among the five machine learning models, the XGBoost model exhibited the optimal comprehensive performance, with the coefficient of determination (R2) of 0.855, mean squared error (MSE) of 0.188, root mean squared error (RMSE) of 0.434 and mean absolute error (MAE) of 0.155, respectively. Analysis of factors affecting the O. hupensis snail density with the XGBoost model showed that among the 16 environmental factors, the top four high-impact factors ranked by SHAPs values included annual precipitation, elevation, aridity index and NDVI, with cumulative SHAPs contributions of 75%, which was higher than that of other environmental factors. If NDVI was higher than 0.6, the O. hupensis snail density increased with NDVI and peaked if NDVI was 0.8 (1.60 snails/0.1 m2). The O. hupensis snail density increased with elevation if the elevation ranged from 14 to 40 m, and slowly rose if the annual precipitation ranged from 900 to 1 300 mm, and then increased rapidly to the peak (1.52 snails/0.1 m2) if the annual precipitation ranged from 1 300 to 1 500 mm. In addition, the O. hupensis snail density increased rapidly to the maximum (1.60 snails/0.1 m2) if the aridity index ranged from 0.8 to 1.1, and decreased gradually if the aridity index exceeded 1.1. Conclusions The XGBoost model shows excellent performance in prediction of the O. hupensis snail density and identification of key environmental factors in the Yangtze River Delta region. Annual precipitation, elevation, aridity index and NDVI are key environmental factors affecting the distribution and density of O. hupensis snails in the Yangtze River Delta region.
2.Progress of research on the potential impacts of extreme climates on the distribution of Oncomelania hupensis
Yu PENG ; Jingbo XUE ; Yinlong LI ; Lijuan ZHANG
Chinese Journal of Schistosomiasis Control 2026;38(1):96-99
The frequent extreme climatic events post multifaceted impacts on the distribution of Oncomelania hupensis, the intermediate host of Schistosoma japonicum in the context of global climate change. This article systematically reviews the effects of four types of extreme climatic events, including floods, droughts, heat waves, and cold waves, on the survival, reproduction, and distribution of Oncomelania hupensis. Floods may expand suitable snail habitats, and increase both emerging and re-emerging snail habitats; however, the impact of floods on O. hupensis density is characterized by a lag effect of a decline followed by a rise. Droughts may cause fragmentation of suitable O. hupensis snail habitats, reduced O. hupensis snail egg production rates, and increased O. hupensis snail mortality, and heat waves may cause an increase in O. hupensis snail mortality, a reduction in numbers of O. hupensis snail populations and shrinking of O. hupensis snail distribution, while cold waves may cause a reduction in O. hupensis snail density and a rise in O. hupensis snail mortality. Extreme climate events pose both shortand long-term effects on the distribution of O. hupensis. Intensified surveillance of O. hupensis snails is required in high-risk environments.
3.Progress of schistosomiasis control in the People’s Republic of China in 2024
Junyi HE ; Lijuan ZHANG ; Fan YANG ; Hui DANG ; Yinlong LI ; Suying GUO ; Shizhen LI ; Chunli CAO ; Jing XU ; Shizhu LI
Chinese Journal of Schistosomiasis Control 2025;37(3):223-231
To understand the progress of, summarize the lessons learned from and analyze the challenges in the national schistosomiasis elimination program of China in 2024, this article presented the endemic situation of schistosomiasis and national schistosomiasis surveillance results in the People’s Republic of China in 2024. By the end of 2024, Shanghai Municipality, Zhejiang Province, Fujian Province, Guangdong Province and Guangxi Zhuang Autonomous Region continued to consolidate schistosomiasis elimination achievements, and 7 provinces of Jiangsu, Sichuan, Yunnan, Hubei, Hunan, Anhui and Jiangxi maintained the criteria of schistosomiasis transmission interruption. A total of 450 counties (cites, districts) were found to be endemic for schistosomiasis in China in 2024, including 26 061 endemic villages covering 73 630 500 residents at risk of infections. Among the 450 counties (cities, districts) endemic for schistosomiasis, 388 (86.22%) achieved the criteria of schistosomiasis elimination and 62 (13.78%) achieved the criteria of transmission interruption. In 2024, a total of 4 102 624 individuals received immunological tests for schistosomiasis in China, with 44 823 sero-positives identified (1.09% seroprevalence), and a total of 169 722 individuals received parasitological examinations, with 1 egg-positives detected. A total of 27 321 cases with advanced schistosomiasis were documented in China by the end of 2024. In 2024, a total of 575 686 bovines were raised in schistosomiasis-endemic villages of China, and 113 842 bovines received immunological tests, with 235 sero-positives detected (0.21% seroprevalence), while no egg-positives were identified among the 167 475 bovines receiving parasitological examinations. In 2024, snail survey was performed covering an area of 680 498.27 hm2 in China, and 190 778.66 hm2 snail habitats were identified, including 59.09 hm2 emerging snail habitats and 704.23 hm2 reemerging snail habitats. In 2024, a total of 19 665 schistosomiasis patients receiving chemotherapy with praziquantel in China, and expanded chemotherapy was given to humans at 571 722 person-times and to bovines at 306 740 herd-times. In addition, snail control with chemical treatment covered 117 111.37 hm2 snail habitats across China in 2024, and the actual area of chemical treatment was 66 562.95 hm2, while environmental improvements were performed in snail habitats covering an area of 1 374.26 hm2. The national schistosomiasis surveillance results showed that the mean prevalence rates of Schistosoma japonicum infections were both 0 among humans and bovines in China in 2024, and no S. japonicum infection was detected in snails. These data demonstrated that the prevalence of schistosomiasis remained at a low level in China in 2024; however, the areas of snail habitats remained high and the number of fenced cattle showed a slight increase. To address these risks, it is imperative to maintain the integrated strategy with an emphasis on management of the source of S. japonicum infection and intensified snail control in high-risk areas, and to reinforce schistosomiasis surveillance and forecast and snail control in high-risk areas.
4.Imaging poly(ADP-ribose) polymerase-1 (PARP1) in vivo with 18F-labeled brain penetrant positron emission tomography (PET) ligand.
Xin ZHOU ; Jiahui CHEN ; Jimmy S PATEL ; Wenqing RAN ; Yinlong LI ; Richard S VAN ; Mostafa M H IBRAHIM ; Chunyu ZHAO ; Yabiao GAO ; Jian RONG ; Ahmad F CHAUDHARY ; Guocong LI ; Junqi HU ; April T DAVENPORT ; James B DAUNAIS ; Yihan SHAO ; Chongzhao RAN ; Thomas L COLLIER ; Achi HAIDER ; David M SCHUSTER ; Allan I LEVEY ; Lu WANG ; Gabriel CORFAS ; Steven H LIANG
Acta Pharmaceutica Sinica B 2025;15(10):5036-5049
Poly(ADP-ribose) polymerase 1 (PARP1) is a multifunctional protein involved in diverse cellular functions, notably DNA damage repair. Pharmacological inhibition of PARP1 has therapeutic benefits for various pathologies. Despite the increased use of PARP inhibitors, challenges persist in achieving PARP1 selectivity and effective blood-brain barrier (BBB) penetration. The development of a PARP1-specific positron emission tomography (PET) radioligand is crucial for understanding disease biology and performing target occupancy studies, which may aid in the development of PARP1-specific inhibitors. In this study, we leverage the recently identified PARP1 inhibitor, AZD9574, to introduce the design and development of its 18F-isotopologue ([18F]AZD9574). Our comprehensive approach, encompassing pharmacological, cellular, autoradiographic, and in vivo PET imaging evaluations in non-human primates, demonstrates the capacity of [18F]AZD9574 to specifically bind to PARP1 and to successfully penetrate the BBB. These findings position [18F]AZD9574 as a viable molecular imaging tool, poised to facilitate the exploration of pathophysiological changes in PARP1 tissue abundance across various diseases.
5.Risk factors for new-onset atrial fibrillation after off-pump coronary artery bypass grafting: A systematic review and meta-analysis
Nan MU ; Qiuyu HE ; Minggui CHEN ; Yinlong QIU ; Yuqing LI ; Mingxin WANG ; Xiaoxuan ZHANG
Chinese Journal of Clinical Thoracic and Cardiovascular Surgery 2024;31(08):1206-1214
Objective To systematically evaluate the risk factors for new-onset atrial fibrillation after off-pump coronary artery bypass grafting (OPCABG). Methods PubMed, EMbase, The Cochrane Library, CNKI, Wanfang, VIP, SinoMed were searched to collect published literature on risk factors for new-onset atrial fibrillation after OPCABG from inception to September 2022. Two authors independently screened, extracted data and evaluated the quality. The Newcastle-Ottawa Scale (NOS) was used to evaluate the quality of the included studies, and Stata 12.0 and RevMan 5.4 softwares were used for meta-analysis. Results A total of 18 researches were included, including 6 354 patients of OPCABG. The NOS scores of the included studies were 6-8 points. Meta-analysis showed that age [MD=2.56, 95%CI (1.61, 3.52), P<0.001], hypertension [OR=1.77, 95%CI (1.18, 2.66), P<0.001], EuroSCORE Ⅱ score [MD=0.70, 95%CI (0.34, 1.06), P<0.001], frequent atrial premature beats or atrial tachycardia [OR=3.77, 95%CI (2.13, 6.68), P<0.001], left atrium diameter (LAD) [MD=1.64, 95%CI (0.26, 3.03), P=0.010], left ventricular ejection fraction (LVEF) [MD=−1.84, 95%CI (−2.85, −0.83), P<0.001], right coronary stenosis [OR=2.49, 95%CI (1.29, 4.81), P=0.006], three-vessel coronary artery lesions [OR=0.73, 95%CI (0.54, 0.97), P=0.030], not using β blockers [OR=0.81, 95%CI (0.69, 0.96), P=0.010], operation time [MD=10.13, 95%CI (8.15, 12.10), P<0.001], duration of mechanical ventilation [OR=2.85, 95%CI (1.79, 3.91), P<0.001] were risk factors for new-onset atrial fibrillation after OPCABG. Conclusion Advanced age, hypertension, high EuroSCOREⅡ score, frequent atrial premature beats or atrial tachycardia, increased LAD, decreased LVEF, right coronary stenosis, three-vessel coronary artery lesions, not using β blockers, prolonged operation time and mechanical ventilation are risk factors for new-onset atrial fibrillation after OPCABG. Due to factors such as the methodology, content and quality of the included literature, the conclusion of this study need to be supported by more high-quality studies.
6.Screening and functional analysis of differentially expressed long non-coding RNA in the liver of mice infected with Schistosoma japonicum during the chronic pathogenic stage
Yinlong LI ; Qin LI ; Weina LIN ; Ting FENG ; Zhiqiang QIN ; Chunli CAO ; Shizhu LI ; Jing XU
Chinese Journal of Schistosomiasis Control 2024;36(2):137-147
Objective To screen differentially expressed long non-coding RNAs (lncRNAs) in the liver of mice infected with Schistosoma japonicum during the chronic pathogenic stage and identify their functions, so as to provide insights into unravelling the role of lncRNAs in S. japonicum infection-induced liver disorders. Methods Twenty 6-week-old C57BL/6 mice were randomly divided into two groups, of 10 animals each group. Each mouse in the experimental group was infected with (15 ± 2) S. japonicum cercariae via the abdomen for modeling chronic S. japonicum infection in mice, and distilled water served as controls. All mice were sacrificed 70 days post-infection, and mouse liver specimens were sampled for RNA extraction and library construction. All libraries were sequenced on the Illumina NovaSeq 6000 sequencing platform. Data cleaning was performed using the fastp software, and reference genome alignment and gene expression (FPKM) calculation were performed using the HISAT2 software. Potential lncRNA sequences were predicted using the software CNIC, CPC, Pfam, and PLEK, and potential lncRNAs were screened. Differentially expressed lncRNAs were screened with the DESeq2 software and subjected to Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses to identify biological processes and metabolic pathways involved in target genes of differentially expressed lncRNAs. Results A total of 333 potential lncRNAs were screened, and 67 were identified as differentially expressed lncRNAs, including 49 up-regulated and 18 down-regulated lncRNAs. A total of 53 target genes were predicted for differentially expressed lncRNAs. GO enrichment analysis showed that these target genes were mainly enriched in biological process and molecular function, among which Sema7a, Arrb1, and Ccl21b genes may be hub target genes for positive regulation of extracellular regulated protein kinase 1 (ERK1) and ERK2 cascades and may participate in the regulation of collagen expression. KEGG enrichment analysis showed that the target genes of differentially expressed lncRNAs were mainly enriched in cytokine-cytokine receptor interaction, viral protein interactions with cytokines and cytokine receptors, chemokine signaling pathway, and nuclear factor kappa-B (NF-κB) signaling pathway. Conclusions This study identifies differentially expressed lncRNAs and functional enrichment of their target genes in the liver of mice during the chronic pathogenic stage of S. japonicum infection. Up-regulated lncRNAs may affect biological processes of ERK1/2 cascades and chemokine signaling pathways via target genes Sema7a, Arrb1, and Ccl21b, thereby affecting collagen expression and inflammatory signal pathways, ultimately affecting the development of liver disorders.
7.Progress of schistosomiasis control in People’s Republic of China in 2023
Lijuan ZHANG ; Junyi HE ; Fan YANG ; Hui DANG ; Yinlong LI ; Suying GUO ; Shizhen LI ; Chunli CAO ; Jing XU ; Shizhu LI
Chinese Journal of Schistosomiasis Control 2024;36(3):221-227
To understand the progress of national schistosomiasis elimination program of China in 2023 and summarize the lessons and experiences, data on the endemic status of schistosomiasis and national schistosomiasis surveillance results in the People’s Republic of China were collected and analyzed at a national level. By the end of 2023, Shanghai Municipality, Zhejiang Province, Fujian Province, Guangdong Province and Guangxi Zhuang Autonomous Region continued to consolidate the achievements of schistosomiasis elimination, and Sichuan and Jiangsu provinces maintained the criteria of transmission interruption, while Yunnan and Hubei provinces were identified to achieve the criteria of transmission interruption in 2020, and Anhui, Jiangxi and Hunan provinces achieved the criteria of transmission interruption in 2023. A total of 451 counties (cites, districts) were found to be endemic for schistosomiasis in China in 2023, including 26 250 endemic villages covering 73 034 500 residents at risk of infections. Among the 451 endemic counties (cities, districts), 78.49% (354/451) achieved the criteria of schistosomiasis elimination and 21.51% (97/451) achieved the criteria of transmission interruption, respectively. In 2023, a total of 4 216 643 individuals received immunological tests, with 47 794 sero-positives identified, and a total of 184 216 individuals received parasitological examinations, with 4 egg-positives detected. A total of 27 768 cases with advanced schistosomiasis were documented in China by the end of 2023. In 2023, 539 548 bovines were raised in schistosomiasis-endemic areas of China, and 125 440 bovines received immunological tests, with 124 sero-positives detected, while no egg-positives were identified among the 133 508 bovines receiving parasitological examinations. In 2023, snail survey was performed at an area of 641 339.53 hm2 and 184 819.77 hm2 snail habitats were identified, including 51.53 hm2 emerging snail habitats and 642.25 hm2 reemerging snail habitats. In 2023, there were 20 198 schistosomiasis patients receiving praziquantel chemotherapy, and 598 183 person-time individuals and 283 954 herdtime bovines were given expanded chemotherapy. In 2023, snail control with chemical treatment was performed in 116 347.95 hm2 snail habitats, and the actual area of chemical treatment was 65 690.89 hm2, while environmental improvements were performed in snail habitats covering an area of 1 334.62 hm2. The national schistosomiasis surveillance results showed that the mean prevalence of Schistosoma japonicum infections were both zero among humans and bovines in 2023, and no S. japonicum infection was detected in snails. These data demonstrated that transmission interruption of schistosomiasis had been achieved across all endemic provinces in China in 2023, and the endemic status of schistosomiasis tended to be stable, while advanced cases were predominant among all schistosomiasis cases. However, the areas of snail habitats remained high and cattle re-raising was very common in some regions. Intensified schistosomiasis surveillance and forecast and snail control in high-risk areas are needed.
8.Progress of schistosomiasis control in People’s Republic of China in 2022
Lijuan ZHANG ; Junyi HE ; Fan YANG ; Hui DANG ; Yinlong LI ; Suying GUO ; Shizhen LI ; Chunli CAO ; Jing XU ; Shizhu LI ; Xiaonong ZHOU
Chinese Journal of Schistosomiasis Control 2023;35(3):217-224
This report presented the endemic status of schistosomiasis and analyzed the data collected from the national schistosomiasis prevention and control system and national schistosomiasis surveillance program in the People’s Republic of China in 2022. Among the 12 provinces (municipality and autonomous region) endemic for schistosomiasis, Shanghai Municipality, Zhejiang Province, Fujian Province, Guangdong Province and Guangxi Zhuang Autonomous Region continued to maintain the achievements of schistosomiasis elimination, and Sichuan and Jiangsu provinces maintained the criteria of transmission interruption, while Yunnan, Hubei, Anhui, Jiangxi and Hunan provinces maintained the criteria of transmission control by the end of 2022. A total of 452 counties (cites, districts) were found to be endemic for schistosomiasis in China in 2022, with 27 434 endemic villages covering 73 424 400 people at risk of infections. Among the 452 endemic counties (cities, districts), 75.89% (343/452), 23.45% (106/452) and 0.66% (3/452) achieved the criteria of elimination, transmission interruption and transmission control of schistosomiasis, respectively. In 2022, 4 317 356 individuals received serological tests for schistosomiasis, and 62 228 were sero-positive. A total of 208 646 individuals received stool examinations for schistosomiasis, with one positive and another two cases positive for urine microscopy, and these three 3 cases were imported schistosomiasis patients from Africa. There were 28 565 cases with advanced schistosomiasis documented in China by the end of 2022. Oncomelania hupensis snail survey was performed in 18 891 endemic villages in China in 2022 and O. hupensis snails were found in 6 917 villages (36.62% of all surveyed villages), with 8 villages identified with emerging snail habitats. Snail survey was performed at an area of 655 703.01 hm2 and 183 888.60 hm2 snail habitats were found, including 110.58 hm2 emerging snail habitats and 844.35 hm2 re-emerging snail habitats. There were 477 200 bovines raised in the schistosomiasis endemic areas of China in 2022, and 113 946 bovines received serological examinations for schistosomiasis, with 204 sero-positives detected. Among the 131 715 bovines received stool examinations, no positives were identified. In 2022, there were 19 726 schistosomiasis patients receiving praziquantel chemotherapy, and expanded chemotherapy was performed in 714 465 person-time for humans and 234 737 herd-time for bovines in China. In 2022, snail control with chemical treatment was performed at an area of 119 134.07 hm2, and the actual area of chemical treatment was 65 825.27 hm2, while environmental improvements were performed at an area of 1 163.96 hm2. Data from the national schistosomiasis surveillance program of China showed that the mean prevalence of Schistosoma japonicum infections was both zero in humans and bovines in 2022, and no S. japonicum infection was detected in O. hupensis snails. These data demonstrated that the endemic status of schistosomiasis continued to decline in China in 2022, with 3 confirmed schistosomiasis patients that had a foreign nationality and all imported from Africa, and the areas of snail habitats remained high. Further improvements in the construction of the schistosomaisis surveillance and forecast system, and reinforcement of O. hupensis survey and control are required to prevent the re-emerging schistosomiasis.
9.Value of cervical vagus cross-sectional area in diagnosis of Parkinson's disease
Siyuan CHEN ; Yinlong LIU ; Qi GU ; Limin ZHU ; Shaopu WU ; Dongsheng LI ; Jianjun MA ; Xue LI
Journal of Xinxiang Medical College 2023;40(12):1131-1135
Objective To investigate the diagnostic value of cervical vagus nerve cross-sectional area(CAS)for Parkinson's disease(PD).Methods Thirty patients with PD admitted to the People's Hospital of Zhengzhou University from October 2019 to October 2022 were selected as PD group,25 patients with multiple system atrophy(MSA)admitted to the People's Hospital of Zhengzhou University during the same period were selected as the MSA group,and 30 healthy individuals who underwent physical examination in the People's Hospital of Zhengzhou University during the same period were selected as healthy control group.Cervical vagus CAS of subjects in the three groups were measured by high-resolution ultrasound,and the difference of CAS of cervical vagus nerve was compared among the three groups.The degree of impairment of autonomic nervous function of subjects in the three groups was evaluated by PD autonomic symptom scale(SCOPA-AUT).The diagnostic value of cervical vagus nerve CAS for PD was analyzed by receiver operating characteristic(ROC)curve.Results The CAS of the right cervical vagus nerve of subjects was significantly larger than that of the left in the healthy control group and PD group(P<0.05);there was no significant difference in CAS of bilateral cervical vagus nerve of subjects in the MSA group(P>0.05).The CAS and average CAS of bilateral cervical vagus nerve of subjects in the PD group and MSA group were significantly lower than those in the healthy control group(P<0.01).The CAS of the right vagus nerve of subjects in the MSA group was significantly lower than that in the PD group(P<0.05);there was no significant difference in CAS and the average CAS of the left vagus nerve between the MSA group and the PD group(P>0.05).The total score of SCOPA-AUT and gastrointestinal(GI),cardiovascular(CV),urinary(UR)and sexual(SX)scores of subjects in the PD group and MSA group were significantly higher than those in the healthy control group(P<0.01).The total score of SCOPA-AUT and UR,SX scores of subjects in the MSA group were significantly higher than those in the PD group(P<0.05).There was no significant difference in temperature(TH)and pupil(PU)of subjects among the three groups(P>0.05).Pearson correlation analysis showed that the CAS of cervical vagus nerve of PD patients was not correlated with the total score of SCOPA-AUT and the UR,TH,PU,SX scores(r=-0.143,0.281,0.297,0.265,0.312;P>0.05).The CAS of cervical vagus nerve of PD patients was negatively correlated with GI and CV scores(r=-0.683,-0.373;P<0.05).ROC curve analysis showed that the area under the curve of cervical vagus nerve for diagnosing PD was 0.870(95%confidence interval:0.773-0.966,P<0.05);the critical value was 3.064 mm2,the sensitivity was 96%,and the specificity was 67%.The area under the curve of CAS of cervical vagus nerve in differential diagnosis of PD,MSA was 0.680(95%confidence interval:0.537-0.823,P<0.05).The sensitivity and specificity for the diagnosis of MSA were 68%and 70%when the CAS of the cervical vagus nerve<2.709 mm2.Conclusion The CAS of cervical vagal nerve has high clinical diagnostic value for PD,and it provides a new way to improve the diagnosis rate of PD.
10.Structure-activity relationship of pyrazol-4-yl-pyridine derivatives and identification of a radiofluorinated probe for imaging the muscarinic acetylcholine receptor M4.
Ahmed HAIDER ; Xiaoyun DENG ; Olivia MASTROMIHALIS ; Stefanie K PFISTER ; Troels E JEPPESEN ; Zhiwei XIAO ; Vi PHAM ; Shaofa SUN ; Jian RONG ; Chunyu ZHAO ; Jiahui CHEN ; Yinlong LI ; Theresa R CONNORS ; April T DAVENPORT ; James B DAUNAIS ; Vahid HOSSEINI ; Wenqing RAN ; Arthur CHRISTOPOULOS ; Lu WANG ; Celine VALANT ; Steven H LIANG
Acta Pharmaceutica Sinica B 2023;13(1):213-226
There is an accumulating body of evidence implicating the muscarinic acetylcholine receptor 4 (M4) in schizophrenia and dementia with Lewy bodies, however, a clinically validated M4 positron emission tomography (PET) radioligand is currently lacking. As such, the aim of this study was to develop a suitable M4 PET ligand that allows the non-invasive visualization of M4 in the brain. Structure-activity relationship studies of pyrazol-4-yl-pyridine derivates led to the discovery of target compound 12 - a subtype-selective positive allosteric modulator (PAM). The radiofluorinated analogue, [18F] 12, was synthesized in 28 ± 10% radiochemical yield, >37 GBq/μmol and an excellent radiochemical purity >99%. Initial in vitro autoradiograms on rodent brain sections were performed in the absence of carbachol and showed moderate specificity as well as a low selectivity of [18F] 12 for the M4-rich striatum. However, in the presence of carbachol, a significant increase in tracer binding was observed in the rat striatum, which was reduced by >60% under blocking conditions, thus indicating that orthosteric ligand interaction is required for efficient binding of [18F] 12 to the allosteric site. Remarkably, however, the presence of carbachol was not required for high specific binding in the non-human primate (NHP) and human striatum, and did not further improve the specificity and selectivity of [18F] 12 in higher species. These results pointed towards significant species-differences and paved the way for a preliminary PET study in NHP, where peak brain uptake of [18F] 12 was found in the putamen and temporal cortex. In conclusion, we report on the identification and preclinical development of the first radiofluorinated M4 PET radioligand with promising attributes. The availability of a clinically validated M4 PET radioligand harbors potential to facilitate drug development and provide a useful diagnostic tool for non-invasive imaging.

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