A Metabolomics Study of Feces Revealed That a Disturbance of Selenium-Centered Metabolic Bioprocess Was Involved in Kashin-Beck Disease, an Osteoarthropathy Endemic to China.

Background: Kashin-Beck disease (KBD) is a distinct osteoarthropathy in China with an unclear pathogenesis. This study aims to explore whether perturbations in the intestine metabolome could be linked to KBD individuals. Methods: An investigation was conducted in KBD endemic villages and fecal samples were collected. After applying inclusion and exclusion criteria, a total of 75 subjects were enrolled for this study, including 46 KBD (including 19 Grade I KBD and 27 Grade II KBD) and 29 controls. Untargeted metabolomics analysis was performed on the platform of UHPLC-MS. PLS-DA and OPLS-DA were conducted to compare the groups and identify the differential metabolites (DMs). Pathway analysis was conducted on MPaLA platform to explore the functional implication of the DMs. Results: Metabolomics analysis showed that compared with the control group, KBD individuals have a total of 584 differential metabolites with dysregulated levels such as adrenic acid (log2FC = -1.87, VIP = 4.84, p = 7.63 × 10-7), hydrogen phosphate (log2FC = -2.57, VIP = 1.27, p = 1.02 × 10-3), taurochenodeoxycholic acid (VIP = 1.16, log2FC = -3.24, p = 0.03), prostaglandin E3 (VIP = 1.17, log2FC = 2.67, p = 5.61 × 10-4), etc. Pathway analysis revealed several significantly perturbed pathways associated with KBD such as selenium micronutrient network (Q value = 3.11 × 10-3, Wikipathways), metabolism of lipids (Q value = 8.43 × 10-4, Reactome), free fatty acid receptors (Q value = 3.99 × 10-3, Reactome), and recycling of bile acids and salts (Q value = 2.98 × 10-3, Reactome). Subgroup comparisons found a total of 267 differential metabolites were shared by KBD vs. control, KBD II vs. control, and KBD I vs. control, while little difference was found between KBD II and KBD I (only one differential metabolite detected). Conclusions: KBD individuals showed distinct metabolic features characterized by perturbations in lipid metabolism and selenium-related bioprocesses. Our findings suggest that the loss of nutrients metabolism balance in intestine was involved in KBD pathogenesis. Linking the nutrients metabolism (especially selenium and lipid) to KBD cartilage damage should be a future direction of KBD study.

Untargeted Metabolomics Approach Correlated Enniatin B Mycotoxin Presence in Cereals with Kashin-Beck Disease Endemic Regions of China.

Kashin-Beck disease (KBD) is a multifactorial endemic disease that only occurs in specific Asian areas. Mycotoxin contamination, especially from the Fusarium spp., has been considered as one of the environmental risk factors that could provoke chondrocyte and cartilage damage. This study aimed to investigate whether new mycotoxins could be identified in KBD-endemic regions as a potential KBD risk factor. This was investigated on 292 barley samples collected in Tibet during 2009-2016 and 19 wheat samples collected in Inner Mongolia in 2006, as control, from KBD-endemic and non-endemic areas. The LC-HRMS(/MS) data, obtained by a general mycotoxin extraction technic, were interpreted by both untargeted metabolomics and molecular networks, allowing us to identify a discriminating compound, enniatin B, a mycotoxin produced by some Fusarium spp. The presence of Fusarium spp. DNA was detected in KBD-endemic area barley samples. Further studies are required to investigate the role of this mycotoxin in KBD development in vivo.

Health-related quality of life in patients with Kashin-Beck disease is lower than in those with osteoarthritis: a cross-sectional study.

BACKGROUND: Kashin-Beck disease (KBD) is an endemic deformable bone and joint disease, which affects the quality of life (QOL) of patients. We conducted a cross-sectional study of the QOL of KBD patients by a new KBD quality of life (KBDQOL) questionnaire. METHODS: A total of 252 KBD patients and 248 OA patients came from Northwest China, and 260 healthy people living in the same area as KBD and osteoarthritis (OA) patients served as the controls. KBDQOL questionnaire was used to evaluate the QOL of all objects. RESULTS: The average scores for physical functions, activity limitations, support of society, mental health and general health were significantly lower in KBD patients than that in OA patients and healthy people except for economics. Monofactor analysis showed that age, height, weight status, education level and grade of KBD had a significant effect on KBDQOL score. Multivariate analysis showed that grade of KBD was the influencing factor of physical function score; gender, age, height, grade of KBD and duration of symptoms were the influencing factors of activity restriction score; age and grade of KBD were factors affecting the general health score. CONCLUSION: The QOL of KBD patients was significantly lower than that of OA patients and healthy people. The KBDQOL questionnaire may be a promising tool for assessing the QOL of KBD patients.

The alteration of urinary metabolomics profiles in Kashin-Beck disease in a three consecutive year study.

Kashin-Beck disease (KBD) is a serious, endemic chronic osteochondral disease characterized by symmetrical enlargement of the phalanges, brachydactyly, joint deformity, and even dwarfism. To investigate the urinary metabolomic profiles of KBD patients, we performed an untargeted metabolomics approach using liquid chromatography coupled with mass spectrometry (LC-MS). Adult urinary specimens were collected from 39 patients with KBD and 19 healthy subjects; the children's urinary specimens were collected from 5 patients with KBD, 25 suspected KBD cases and 123 healthy subjects in the KBD endemic area during a three consecutive year study. We identified 10 upregulated and 28 downregulated secondary level metabolites highly associated with aetiology and pathogenesis of KBD between adult KBD and adult controls. A total of 163, 967 and 795 metabolites were significantly different in the urine among children with KBD, suspected children with KBD cases and healthy child controls, respectively, for each year in three consecutive years. HT-2 toxin, Se-adenosylselenomethionine (AdoSeMet), the toxin T2 tetrol, and many kinds of amino acids were identified as differential metabolites in this study. Amino sugar and nucleotide sugar metabolism, fructose and mannose metabolism, arachidonic acid metabolism, D-glutamine and D-glutamate metabolism, ubiquinone and other terpenoid-quinone biosynthesis, and D-glutamine and D-glutamate metabolism were perturbed pathways in adult and child KBD patients. Our study provides new insight into the underlying mechanisms of KBD, and suggests that we should pay more attention to these differences in small-molecule metabolites and metabolic pathways in the environmental aetiology and pathogenesis of KBD.

The Prevalence of Kashin-Beck Disease in China: a Systematic Review and Meta-analysis.

Kashin-Beck disease (KBD) is a serious degenerative chronic joint disease. However, there are few quantitative syntheses of KBD prevalence studies. In this study, an initial systematic review and meta-analysis were performed to study the prevalence of KBD in China. Five databases (PubMed, Web of Science, Chinese National Knowledge Infrastructure (CNKI), WanFang Data, and the China Science-Technology Journal Database (VIP)) were searched by performing an overall search method to identify studies of KBD prevalence in China that were published from the inception of the database to May 30, 2022. The risk of bias was assessed with the standardized risk of bias tool. Heterogeneity was assessed with the I2 statistic. A random-effect meta-analysis was performed to study the prevalence of KBD through an analysis of published studies. A total of 34 studies involving 24,820 patients with KBD were included in this meta-analysis. These studies were geographically divided into 3 endemic areas. The pooled overall prevalence rate for KBD was 0.06% (95% CI, 0.04-0.08%). The pooled prevalence estimates were 0.05% (95% CI, 0.01-0.12%) for northeast endemic areas, 0.06% (95% CI, 0.03-0.09%) for northwest endemic areas, and 0.04% (95% CI, 0-0.14%) for southwest endemic areas. There was a negative correlation between KBD prevalence and the publication year. No potential risk of publication bias was found by Begg's test and Egger's test. The publication year and quality score were significantly associated with the detected heterogeneity. Our study indicates that the occurrence and development of KBD have been effectively controlled in recent decades. More effective strategies are needed to prevent and treat KBD.

Dietary and drinking water intake of essential trace elements in a typical Kashin-Beck disease endemic area of Tibet, China.

BACKGROUND: Essential trace elements (ETEs), such as copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo), selenium (Se), zinc (Zn), are very important elements for human health. METHODS: In this study, 89 drinking water samples and 85 highland barleys were collected from 48 villages in 11 townships, and the average daily dose (ADD) of ETEs were calculated, in addition, health effects of ETEs to rural residents in Luolong County, a typical Kashin-Beck disease (KBD) endemic area in Tibet, were assessed. RESULTS: The mean concentrations of Cu, Fe, Mn, Mo, Se, Zn in drinking water were 0.278 ± 0.264 µg·kg-1, 0.766 ± 0.312 µg·kg-1, 0.411 ± 0.526 µg·kg-1, 0.119 ± 0.223 µg·kg-1, 0.155 ± 0.180 µg·kg-1, and 0.804 ± 1.112 µg·kg-1, respectively; and mean concentrations of Cu, Fe, Mn, Mo, Se and Zn in highland barley were 3.550 ± 0.680 mg·kg-1, 81.17 ± 38.14 mg·kg-1, 14.03 ± 1.42 mg·kg-1, 0.350 ± 0.200 mg·kg-1, 0.0028 ± 0.0056 mg·kg-1, and 23.58 ± 3.10 mg·kg-1, respectively. The ADD of Cu in the study area was appropriate; the ADD of Fe and Mn in each township were higher than the maximum oral reference dose recommended by the National Health Commission of China, indicating that Fe and Mn had non-carcinogenic health risks; the ADD of Mo and Zn in 36.36% and 54.55% of the townships exceeded the maximum oral reference dose; and 72.73% of the townships had insufficient ADD of Se. The ADD of Mo, Cu and Se in different townships was significantly correlated with the prevalence of KBD. CONCLUSIONS: Therefore, in order to prevent and control the prevalence of KBD and ensure the health of local residents, it is necessary to reduce the intake of high concentrations of Fe, Mn and Zn in diet, as well as increase the intake of Mo, Cu, especially Se.

Investigation of selenium nutritional status and dietary pattern among children in Kashin-Beck disease endemic areas in Shaanxi Province, China using duplicate portion sampling method.

BACKGROUND AND OBJECTIVES: Selenium deficiency is a primary risk factor of Kashin-Beck disease (KBD). This study aimed to investigate whether children in endemic areas could maintain sufficient selenium intake after termination of selenium supplement administration, and evaluate their comprehensive nutritional status and dietary structure. METHODS: Duplicate portion sampling combined with a questionnaire was adopted to collect data on categories and quantity of all food ingested in three consecutive days. Occipital hair was also collected to detect selenium content by hydride generation atomic fluorescence spectrometry (HGAFS). CDGSS3.0 software and factor analysis were integrated to assess the children's comprehensive nutritional status and dietary structure. RESULTS: This study included 240 sex-matched (1:1) children aged 7-12 years from KBD endemic (n = 120) and non-endemic (n = 120) areas. Overall, 720 solid food, 720 liquid, and 240 hair samples were collected for selenium determination. The mean selenium level in hair of children in endemic areas (0.38 ± 0.16 mg/kg) was significantly lower than that in children in non-endemic areas (0.56 ± 0.28 mg/kg, Z = -5.249, p < 0.001). The dietary selenium intake of children in endemic areas was 40.0% lower than that in children in non-endemic areas (Z = -9.374, p < 0.001). Children in endemic areas consumed significantly less diverse dietary items leading to significantly less intake of multiple nutrients compared to children in non-endemic areas. CONCLUSIONS: The dietary selenium intake of most children in endemic areas was less than the recommended amount. The dietary structure of children was undiversified, which limited the intake of multiple nutrients. Therefore, comprehensive nutrition rather than sole selenium intake should be the primary concern in the future.

Hydrochemical characteristics of surface waters and their relationships to the Kashin-Beck Disease in Longzi County, Tibet.

Although previous studies have been reported between the Kashin-Beck Disease (KBD) epidemic and the hydrochemical characteristics of surface waters, the etiology of the disease remains unclear. In the present study, we comprehensively investigated the relationship between the KBD and the hydrochemical characteristics of surface waters in Longzi County. Results show that, the pH (mean = 7.27 ± 0.30), total hardness (TH, mean = 57.08 ± 45.74 mg L-1), total dissolved solids (TDS, mean = 67.56 ± 44.00 mg L-1) and oxidation-reduction potential (ORP, mean = 84.11 ± 23.55 mV) of surface waters in KBD endemic areas are lower than those in the non-KBD endemic areas (means of pH = 7.49 ± 0.30; TH = 262.06 ± 123.29 mg L-1; TDS = 253.25 ± 100.39 mg L-1; ORP = 215.90 ± 55.99 mV). These results suggest that long-term consumption of low TDS, essential trace elements (e.g., nickel, cobalt, iron, selenium, zinc, molybdenum, and iodine) deficient, and potential toxic elements (e.g., arsenic) enriched waters by humans likely causes the KBD. Environmental factors such as the geology and geomorphology may produce biogeochemical imbalance, geomorphic, vegetation types and local climatic conditions may have significant impact on food fungi toxin poisoning and water organic compound poisoning, and these also impact the KBD occurrence.

Growth surveillance indices and Kashin-Beck Disease in children.

Selenium, manganese, and calcium are necessary elements for maintaining normal growth and skeleton formation. Kashin-Beck disease mostly occurs in children, resulting in deformities, dwarfism, and disabilities. Selenium deficiency was considered a risk factor in China, while manganese was reportedly involved in it in Russia. Single-element regulation cannot be used in diagnosis because of unclear boundaries in patients compared to healthy individuals. In this study, new indices of elements were designed to predict the status of disease. MS (Mn/Se), CS (Ca'/Se), and MC (Mn/Ca') values were designed, and prediction formulas were generated by comparing healthy children with those with Kashin-Beck disease via multiple linear regression analysis and discriminant analysis. In the disease group, 42.86% of patients had positive MS, CS, and MC values, and 57.14% of patients had positive MS and CS values. In the treatment group, the patients presented improved indices. In the prediction group, subjects with negative clinical criteria features were predicted by new indices, and 26.67% of them presented with positive MS, CS, and MC values, whereas 40.00% had positive MS and CS values. The 3D model of MS, CS, and MC refers to the setup of elements. The MS, CS, and MC indices are helpful in disease prediction, diagnosis, prognosis, and surveillance. The distribution model of the indices could serve in the growth surveillance of children.

Abnormal Level of Manganese, Iron, Iodine, and Selenium in the Hair of Children Living in Kashin-Beck Disease Endemic Areas.

Biological geochemistry is a main suggested cause of Kashin-Beck disease (KBD), due to the absence or excess of elements in the environment. Initially, Se deficiency is regarded as the most key role in the etiology of KBD, and selenium supplementation effectively helps to prevent and control KBD. However, several elements are reported to be relevant to KBD or selenium in succession, which indicated selenium deficiency is not the original etiology of KBD. The study comprehensively analyzed the characteristics of the bio-element profile of KBD and further re-examined the unique role of selenium in etiology. The study measured 14 elements, including sodium, potassium, calcium, phosphorus, magnesium, copper, iron, zinc, selenium, iodine, manganese, lead, arsenic, and mercury, which were detected from hair samples collected from 150 boys. Research participants were separated based on whether they had received any preventative treatment (with and without selenium supplementation). From endemic areas, 30 KBD and 30 healthy children without any preventative treatment were selected alongside 30 KBD and 30 healthy children with selenium supplementation. The participants from endemic areas were then compared to 30 healthy children living in non-endemic areas. Compared to the non-endemic group, the levels of iron and manganese were all significantly higher in the endemic groups and were further elevated in KBD participants (p < 0.05). In contrast, selenium and iodine levels in endemic areas were much lower than those of the control group (p < 0.05). The proportions of selenium excess (p < 0.05) and iodine deficiency (p < 0.05) in endemic groups were significantly lower than participants from non-endemic areas. Meanwhile, excess levels of iron (p < 0.05) and manganese (p < 0.05) were higher in the endemic groups. Moreover, the proportions of Zn/Fe and Se/Mn were found to be significantly lower in endemic area participants than those in the control group (p < 0.05). Three pairs of elements had a correlation coefficient value of more than 0.6: 0.7423 for manganese and calcium, 0.6446 for potassium and sodium, and 0.6272 for manganese and iron. The ratios of Se/Mn and Zn/Fe were associated with a correlation coefficient value of 0.8055. Magnesium, sodium, copper, and iodine levels were meticulously examined using binary regression analysis. This was also used to determine the ratios of Ca/Mg, Ca/P, Zn/Fe, Se/Mn, and Se/I. Thus, the study largely revealed the vital role of manganese, iron, and iodine (in conjunction with selenium) in KBD etiology and pathogenesis. High manganese and iron levels with low selenium and iodine levels were identified as characteristic features of the bio-element profile of KBD. The different element ratios reflect the interaction between several elements. The most significant of these were the proportions of Se/Mn and Zn/Fe, which may be significant in the occurrence and development of KBD.

Polymorphism of MMP-3 gene and imbalance expression of MMP-3 / TIMP-1 in articular cartilage are associated with an endemic osteochondropathy, Kashin- Beck disease.

BACKGROUND: The etiology of Kashin-Beck disease (KBD), an endemic osteochondropathy, is largely unknown. Matrix metalloproteinase-3 (MMP-3) plays a central role in the initiation and progression of cartilage destruction, however, no study has reported on the relationship between KBD and MMP-3. The objective of this study was to explore the polymorphism of MMP-3 gene and expression of MMP-3 / TIMP-1(Tissue inhibitors of matrixmetalloproteinases-1) in the pathogenesis of KBD. METHODS: Single nucleotide polymorphism (SNP) genotyping was conducted in 274 KBD cases and 248 healthy controls for eight SNPs in MMP-3 using the Sequenom MassARRAY system. Additionally, the expression of MMP-3、TIMP-1 in different layers of the articular cartilage was analyzed by immunohistochemistry for 22 KBD patients, 15 osteoarthritis (OA) patients and 21 controls. RESULTS: The results showed that six SNPs (rs520540、rs591058、rs679620、rs602128、rs639752 and rs678815) in MMP-3 were associated with the increased risk of KBD, however, after Bonferroni correction, only the SNP rs679620 in the recessive model remained significant difference (OR = 2.31, 95%CI = 1.29-4.14, P = 0.0039), homozygous for "T" allele have a risk for KBD than "C" allele carriers. Moreover, the percentages of cells expressing MMP-3 in articular cartilage were significantly higher in the KBD and OA groups than in the controls (t = 5.37 and 4.19, P<0.01). While the KBD and OA groups had lower levels of TIMP-1 positive staining compared with the controls (t = 5.23and 5.06, P<0.01). And there was no significant different between KBD and OA for the levels of MMP-3 and TIMP-1 positive staining (t = 0.05and 0.28, P>0.05). CONCLUSIONS: MMP-3 is associated with the susceptibility of KBD, and the imbalance expression of MMPs / TIMPs leading to cartilage degradation may play an important role in cartilage degradation and osteoarthritis formation in OA and KBD.

Differences of selenium and other trace elements abundances between the Kaschin-Beck disease area and nearby non-Kaschin-Beck disease area, Shaanxi Province, China.

In order to find out the environmental geochemical characteristics of KBD affected area, KBD and non-KBD villages in KBD Counties, Weibei KBD area, Shaanxi Province, China were studied. Contents of Se and other elements in soil, wheat, maize and drinking water were analyzed. The results show that soil of Weibei KBD area is deficient in trace elements comparing with BSC and non-KBD area. Wheat of Weibei KBD area is deficient both in major elements and trace elements comparing with REC. Wheat of KBD village is especially deficient in Cr, Co, Se, Mo and Mg. Contents of Sr, Li and Mo in wheat of KBD village are significantly lower than nearby non-KBD village, but the average Se content is slightly higher. The deficiency of trace elements, especially Se, Sr, Li and Mo in staple food and trace elements in soil, is the main characteristic for the environment of KBD area.

Alterations in the gut microbiota and metabolite profiles of patients with Kashin-Beck disease, an endemic osteoarthritis in China.

Kashin-Beck disease (KBD) is a severe osteochondral disorder that may be driven by the interaction between genetic and environmental factors. We aimed to improve our understanding of the gut microbiota structure in KBD patients of different grades and the relationship between the gut microbiota and serum metabolites. Fecal and serum samples collected from KBD patients and normal controls (NCs) were used to characterize the gut microbiota using 16S rDNA gene and metabolomic sequencing via liquid chromatography-mass spectrometry (LC/MS). To identify whether gut microbial changes at the species level are associated with the genes or functions of the gut bacteria in the KBD patients, metagenomic sequencing of fecal samples from grade I KBD, grade II KBD and NC subjects was performed. The KBD group was characterized by elevated levels of Fusobacteria and Bacteroidetes. A total of 56 genera were identified to be significantly differentially abundant between the two groups. The genera Alloprevotella, Robinsoniella, Megamonas, and Escherichia_Shigella were more abundant in the KBD group. Consistent with the 16S rDNA analysis at the genus level, most of the differentially abundant species in KBD subjects belonged to the genus Prevotella according to metagenomic sequencing. Serum metabolomic analysis identified some differentially abundant metabolites among the grade I and II KBD and NC groups that were involved in lipid metabolism metabolic networks, such as that for unsaturated fatty acids and glycerophospholipids. Furthermore, we found that these differences in metabolite levels were associated with altered abundances of specific species. Our study provides a comprehensive landscape of the gut microbiota and metabolites in KBD patients and provides substantial evidence of a novel interplay between the gut microbiome and metabolome in KBD pathogenesis.

Identifying discriminative features for diagnosis of Kashin-Beck disease among adolescents.

INTRODUCTION: Diagnosing Kashin-Beck disease (KBD) involves damages to multiple joints and carries variable clinical symptoms, posing great challenge to the diagnosis of KBD for clinical practitioners. However, it is still unclear which clinical features of KBD are more informative for the diagnosis of Kashin-Beck disease among adolescent. METHODS: We first manually extracted 26 possible features including clinical manifestations, and pathological changes of X-ray images from 400 KBD and 400 non-KBD adolescents. With such features, we performed four classification methods, i.e., random forest algorithms (RFA), artificial neural networks (ANNs), support vector machines (SVMs) and linear regression (LR) with four feature selection methods, i.e., RFA, minimum redundancy maximum relevance (mRMR), support vector machine recursive feature elimination (SVM-RFE) and Relief. The performance of diagnosis of KBD with respect to different classification models were evaluated by sensitivity, specificity, accuracy, and the area under the receiver operating characteristic (ROC) curve (AUC). RESULTS: Our results demonstrated that the 10 out of 26 discriminative features were displayed more powerful performance, regardless of the chosen of classification models and feature selection methods. These ten discriminative features were distal end of phalanges alterations, metaphysis alterations and carpals alterations and clinical manifestations of ankle joint movement limitation, enlarged finger joints, flexion of the distal part of fingers, elbow joint movement limitation, squatting limitation, deformed finger joints, wrist joint movement limitation. CONCLUSIONS: The selected ten discriminative features could provide a fast, effective diagnostic standard for KBD adolescents.

Prevalence of pediatric Kashin-Beck disease in Tibet.

INTRODUCTION: To estimate the prevalence of Kashin-Beck disease (KBD) among children in 2017 in Changdu of Tibet. METHODS: We adopted a four-step recruitment to include children aged 7-12 years from seven identified historically endemic counties in Changdu. Posterior-anterior radiographs of right hand and wrist were taken and were graded at four sites (metaphysis, epiphysis, and bony end of phalanges and metacarpal and carpal bones). Two trained researchers independently read the films. Inter-rater reliability was assessed using weighted Kappa and percentage agreement. We fitted logistic regression model to examine the association of age, sex, and altitude of residential village with prevalence of KBD. We examined association between site involvement and severity of KBD using chi-square test. RESULTS: We recruited 13,573 children (mean age = 9.3 years, 48.40% girls) with a response rate of 95.81%. The overall prevalence of radiographic KBD was 0.26%. Luolong County had the highest prevalence (0.69%), followed by Bianba (0.26%), Basu (0.24%), Mangkang (0.14%), Zuogong (0.14%), Dingqing (0.07%), and Chaya (0.00%). A higher risk of radiographic KBD was associated with older age (P for trend <0.001) and girls (OR=1.86, 95% CI: 0.94, 3.70), but not the altitude of residential village (P for trend=0.957). Metaphysis was involved in all cases of KBD while lesions in epiphysis and bony end of phalanges and metacarpals were only observed in severe cases. CONCLUSIONS: The prevalence of radiographic KBD among children aged 7-12 years was low in Changdu compared with previous census data, suggesting the effectiveness of preventative measures. Key Points • In this study, 13,573 Tibetan children were taken X-ray films of their hands and wrists. • The prevalence of radiographic KBD among children aged 7-12 years was low in Changdu of Tibet. • The preventative measures against KBD launched by Chinese government were effective in decreasing new onsets of KBD among Tibetan children.

Differences in quinone redox system of humic substances between endemic and disease-free areas in Kashin-Beck disease-affected Changdu Region, Tibet, China.

Kashin-Beck disease (KBD) is an endemic disease in China with the highest incidence rate in Tibet region. Promoted generation of oxygen free radicals by semiquinone structure of humic substance (HS) in drinking water was considered to be one of its pathogeneses. Therefore, detailed analysis of HS was performed in water and sediment samples collected from three endemic and three disease-free areas in Changdu Region, Tibet, China. After purification of the HS in the samples, the fractions of HS were characterized using electron paramagnetic resonance, 13C nuclear magnetic resonance, fluorescence spectroscopy with parallel factor analysis and Fourier transform infrared spectroscopy (FTIR). The organic carbon content of HS did not show a significant difference between endemic and disease-free areas or correlation with KBD-associated morbidity. Except FTIR, all techniques succeeded in characterization of the quinone redox system, indicating their validity and consistency. The quinone redox system in aquatic HS exhibited significantly higher level of the following indexes in endemic areas than disease-free areas: semiquinone radical content of fulvic acid (FA) (p < 0.05), aromaticity of FA (p < 0.05), fluorescence intensity (per gram carbon) of reduced quinone-like component of FA (p < 0.05) and humic acid (HA) (p < 0.1). Semiquinone radical content (r = 0.781, p < 0.1), aromaticity of FA (r = 0.891, p < 0.05), intensity of oxidized quinone-like component (r = 0.875, p < 0.05) and reduced quinone-like component of FA (r = 0.793 p < 0.1) showed medium to strong correlation with KBD-associated morbidity. Generally, the content of reduced quinone and aquatic FA showed stronger differences between endemic and disease-free areas than oxidized quinone and aquatic HA, respectively. The quinone redox system in sediment HS did not show any significant relationship with KBD. The present study is a successful attempt to combine the three indexes, semiquinone radical content, aromaticity and fluorescence intensity, in characterizing quinone redox system in HS, facilitating more comprehensive understanding of the characteristics of HS in KBD-affected regions.

Spatial distribution and determinants of health loss from Kashin-Beck disease in Bin County, Shaanxi Province, China.

BACKGROUND: Kashin-Beck disease (KBD) is one of the major endemic diseases in China, which severely impacts the physical health and life quality of people. A better understanding of the spatial distribution of the health loss from KBD and its influencing factors will help to identify areas and populations at high risk so as to plan for targeted interventions. METHODS: The data of patients with KBD at village-level were collected to estimate and analyze the spatial pattern of health loss from KBD in Bin County, Shaanxi Province. The years lived with disability (YLDs) index was applied as a measure of health loss from KBD. Spatial autocorrelation methodologies, including Global Moran's I and Local Moran's I, were used to describe and map spatial clusters of the health loss. In addition, basic individual information and environmental samples were collected to explore natural and social determinants of the health loss from KBD. RESULTS: The estimation of YLDs showed that patients with KBD of grade II and patients over 50 years old contributed most to the health loss of KBD in Bin County. No significant difference was observed between two genders. The spatial patterns of YLDs and YLD rate of KBD were clustered significantly at both global and local scales. Villages in the southwestern and eastern regions revealed higher health loss, while those in the northern regions exhibited lower health loss. This clustering was found to be significantly related to organically bound Se in soil and poverty rate of KBD patients. CONCLUSIONS: Our results suggest that future treatment and prevention of KBD should focus on endemic areas with high organically bound Se in soil and poor economic conditions. The findings can also provide important information for further exploration of the etiology of KBD.

Assessing the Health Loss from Kashin-Beck Disease and Its Relationship with Environmental Selenium in Qamdo District of Tibet, China.

Kashin-Beck Disease (KBD) is one of major endemic diseases in China. In this study, we estimated the health loss from KBD in Qamdo district of Tibet using the years lived with disability (YLD) metric and investigated the influence of environmental selenium (Se) on it by multiple regression model. The results showed that YLD rates produced a different ranking of health loss of KBD from that produced by prevalence rates between Basu and Luolong County, with higher health loss from KBD (43.61 YLD/1000) but lower prevalence (17.86%) in Basu County. YLD rates in two counites were both highest for the 45-64 years age group. Compared with the prevalence rate, the YLD rate had a closer relation to environmental Se and was significantly negatively correlated with Se in both soil and highland barley. The multiple linear regression further revealed that Se contents in cultivated soil and highland barley were main influencing factors for the health loss of KBD, which could explain 90.5% of the variation in YLD rates. The information obtained highlights the significance of the YLD metric in exploring the environmental etiology of KBD and provides important information on which to base decisions on future prevention and control of endemic diseases.

Effects of methylation of deiodinase 3 gene on gene expression and severity of Kashin-Beck disease.

Kashin-Beck disease (KBD) is a complex endemic osteoarthropathy, which mainly occurs in the northeast to southwest China. Iodothyronine deiodinases 3 (DIO3) is one of the selenoproteins, which is closely related to bone metabolism and unclear to KBD. This study aims to investigate the role and associated mechanisms of methylation and expression of DIO3 with disease severity in patients with KBD. We performed a bioinformatics analysis first to identify the biological mechanisms involved in selenoproteins. The methylation status of the DIO3 gene and DIO3 gene expression, as well as DIO3-related regulatory genes in patients with KBD, were analyzed. We found that 15 CpG sites of six selenoproteins were hypomethylated with 5-azacytidine treatment. DIO3 hypermethylation was associated with an increased risk of KBD and may lead to downregulation of DIO3 gene expression as well as be an indicator of the severity of KBD, which may provide a new insight for gene-environment correlations and interactions in etiology and pathogenesis of KBD.