Mesothelioma carcinogenesis of chrysotile and forsterite compared and validated by intraperitoneal injection in rat.

Asbestos, especially chrysotile, continues to be exposed to humans globally. Hence, it should be disposed properly to prevent asbestos-related diseases, including mesothelioma and lung cancer. This study aimed to verify whether forsterite, a heating product of chrysotile, can cause carcinogenicity, particularly mesothelioma. Forsterite (FO-1000) and enstatite (EN-1500) produced by heating chrysotile at 1000°C and 1500°C, respectively, were subjected. We injected 10 mg of chrysotile, FO-1000, or EN-1500 in rats intraperitoneally and observed the development of peritoneal mesothelioma until 24 months. The incidence of peritoneal mesothelioma in the chrysotile group was 91.2%, whereas in the FO-1000 and EN-1500 groups, peritoneal mesothelioma did not develop. Urinary 8-hydroxy-2'-deoxyguanosine and serum N-ERC/mesothelin concentrations significantly increased in the chrysotile group that developed peritoneal mesothelioma, while they only temporarily changed in the FO-1000 or EN-1500 groups during early treatment. Furthermore, there was a significant homozygous deletion of the CDKN2A/p16 gene in the chrysotile group compared to the control group, in contrast to no significant difference in the FO-1000 and EN-1500 groups. Therefore, this study provides clear evidence that forsterite is a nonmesothelioma carcinogen and suggests that forsterite and enstatite are sufficient substances for chrysotile detoxification.

Clinical course of neurogenic bladder dysfunction in human T-cell leukemia virus type-1-associated myelopathy/tropical spastic paraparesis: a nationwide registry study in Japan.

BACKGROUND: Most patients with human T-cell leukemia virus type 1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) develop neurogenic bladder dysfunction. However, longitudinal changes and treatment effects remain poorly understood. This study aimed to characterize the clinical course of urinary dysfunction in this population. METHODS: This prospective observational study included 547 patients enrolled in HAM-net, a nationwide registry for HAM/TSP in Japan. Urinary dysfunction severity was evaluated using the HAM/TSP-bladder dysfunction symptom score (HAM-BDSS) and the HAM/TSP-bladder dysfunction severity grade (HAM-BDSG). These specific measures were recently developed for assessing urinary dysfunction in HAM/TSP. We analyzed longitudinal changes over a 6-year follow-up period, associations between urinary and gait dysfunction, and treatment efficacy of urinary catheterization and mirabegron (a ß3-adrenergic agonist for overactive bladder symptoms). RESULTS: The mean (standard deviation [SD]) age and disease duration at enrollment were 61.9 (10.7) years and 16.6 (11.6) years, respectively, and 74.6% of patients were women. Only 8.0% were free from urinary symptoms (HAM-BDSG 0), 65.4% had urinary symptoms or were on medication (HAM-BDSG I), and 23.2% and 3.3% used intermittent and indwelling catheters (HAM-BDSG II and III), respectively. HAM-BDSG and BDSS were worse in patients with greater gait dysfunction (p < 0.001 for both). During the 6-year follow-up, 66.7% of patients with HAM-BDSG 0 developed new urinary symptoms. Of those with HAM-BDSG I at enrollment, 10.8% started using urinary catheters. Importantly, HAM-BDSS significantly improved after initiating catheterization (mean [SD] change, - 8.93 [10.78], p < 0.001). The number of patients receiving mirabegron increased in the fourth year. Multivariable linear regression analysis significantly associated mirabegron with improvement in HAM-BDSS (- 5.82, 95% confidence interval - 9.13 to - 2.51, p = 0.001). CONCLUSIONS: Urinary dysfunction affected 92% of patients and progressed over the 6-year follow-up. Urinary symptoms were more severe in patients with poorer gait function. Urinary catheterization and mirabegron were effective in relieving symptoms. Effective utilization of real-world data is key to establishing evidence for rare diseases, such as HAM/TSP.

Creation and validation of a bladder dysfunction symptom score for HTLV-1-associated myelopathy/tropical spastic paraparesis.

BACKGROUND: Urinary dysfunction is one of the main features of human T-cell leukemia virus type 1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). However, a comprehensive assessment of the severity is difficult because a standardized assessment measure is unavailable. Therefore, this study aimed to develop a novel symptom score for the assessment of urinary dysfunction in HAM/TSP. We interviewed 449 patients with HAM/TSP using four internationally validated questionnaires for assessment of urinary symptoms (27 question items in total): the International Prostate Symptom Score; the International Consultation on Incontinence Questionnaire-Short Form; the Overactive Bladder Symptom Score; and the Nocturia Quality-of-Life questionnaire. We developed a symptom score based on the data of 322 patients who did not use urinary catheters by selecting question items from questionnaires focused on descriptive statistics, correlation analysis, and exploratory factor analysis. The score distribution, reliability, and validity of the developed score were evaluated. RESULTS: First, 16 questions related to quality of life, situations, or subjective assessment were omitted from the 27 questions. Exploratory factor analysis revealed that the remaining 11 questions pertained to three factors: frequent urination, urinary incontinence, and voiding symptoms. Three questions, which had similar questions with larger factor loading, were deleted. Finally, we selected eight question items for inclusion in the novel score. The score distribution exhibited no ceiling or floor effect. The Cronbach's alpha (0.737) demonstrated reliable internal consistency. The new score comprised two subscales with acceptable factorial validity (inter-factor correlation coefficient, 0.322): storage symptoms (frequent urination plus urinary incontinence) and voiding symptoms. The correlation between each item and the subscales suggested acceptable construct validity. CONCLUSIONS: We developed a novel score, the HAM/TSP-Bladder Dysfunction Symptom Score, and demonstrated its reliability and validity. The applicability of this score to patients using catheters should be examined in future research.

Mortality and risk of progression to adult T cell leukemia/lymphoma in HTLV-1-associated myelopathy/tropical spastic paraparesis.

Human T cell leukemia virus 1 (HTLV-1) causes the functionally debilitating disease HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) as well as adult T cell leukemia lymphoma (ATLL). Although there were concerns that the mortality of HAM/TSP could be affected by the development of ATLL, prospective evidence was lacking in this area. In this 5-y prospective cohort study, we determined the mortality, prevalence, and incidence of ATLL in 527 HAM/TSP patients. The standard mortality ratio of HAM/TSP patients was 2.25, and ATLL was one of the major causes of death (5/33 deaths). ATLL prevalence and incidence in these patients were 3.0% and 3.81 per 1,000 person-y, respectively. To identify patients at a high risk of developing ATLL, flow cytometry, Southern blotting, and targeted sequencing data were analyzed in a separate cohort of 218 HAM/TSP patients. In 17% of the HAM/TSP patients, we identified an increase in T cells positive for cell adhesion molecule 1 (CADM1), a marker for ATLL and HTLV-1-infected cells. Genomic analysis revealed that somatic mutations of HTLV-1-infected cells were seen in 90% of these cases and 11% of them had dominant clone and developed ATLL in the longitudinal observation. In this study, we were able to demonstrate the increased mortality in patients with HAM/TSP and a significant effect of ATLL on their prognosis. Having dominant clonal expansion of HTLV-1-infected cells with ATLL-associated somatic mutations may be important characteristics of patients with HAM/TSP who are at an increased risk of developing ATLL.

Real-world clinical course of HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) in Japan.

BACKGROUND: As human T-cell leukemia virus type 1 (HTLV-1)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is a rare chronic neurological disease, large scale studies to collect continuous clinical data have been difficult to conduct. Therefore, the incidence of comorbidities and drug utilization data remain unknown. When conducting trials to develop new drugs in rare disease such as HAM/TSP, historical control data obtained from registry studies would be useful, as cohorts in rare disease tend to be small. Long-term follow-up of patients with a chronic disease can also be challenging. In this study, we addressed the following two goals using registry data on patients (n = 486) enrolled in the Japanese HAM/TSP patient registry "HAM-net" from 2012 to 2016: 1) to clarify the epidemiological information of HAM/TSP such as the incidence of comorbidities and drug utilization and 2) to provide the real-world data on changes in lower limb motor dysfunction. RESULTS: In HAM-net-registered patients, common comorbidities were fractures, herpes zoster, and uveitis, with incidences of 55.5, 10.4, and 6.5, respectively, per 1000 person-years. Every year, oral steroid treatment was administered in 48.2-50.7% of the HAM-net-registered patients and interferon-α treatment was used in 2.6-3.5% of patients. The median dose of oral prednisolone was low at 5.0 mg/day. The incidence of fractures and herpes zoster tended to be higher in the steroid-treated group than in the untreated group (fractures: 61.0 vs. 48.3, herpes zoster: 12.7 vs. 8.8, per 1000 person-years). The analysis of chronological change in Osame motor disability score (OMDS) indicated that the mean change in OMDS was + 0.20 [95% confidence intervals (CI): 0.14-0.25] per year in the one-year observation group (n = 346) and + 0.57 (95% CI: 0.42-0.73) over four years in the four-year observation group (n = 148). Significant deterioration of OMDS was noted in all subgroups with varying steroid use status. CONCLUSIONS: This study revealed the incidence of comorbidities and drug utilization data in patients with HAM/TSP using registry data. Furthermore, this study provided real-world data on chronological changes in lower limb motor dysfunction in patients with HAM/TSP, indicating the utility of these data as historical controls.

Nation-wide epidemiological study of Japanese patients with rare viral myelopathy using novel registration system (HAM-net).

BACKGROUND: At least one million people are infected with human T-lymphotropic virus type 1 (HTLV-1) in Japan, a small percentage of whom develop HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) or adult T-cell leukemia/lymphoma (ATLL). Patients with HAM/TSP suffer from progressively worsening myelopathic symptoms, such as motor disability and bladder dysfunction, and may become wheelchair-bound or even bedridden. METHODS: To learn more about this rare, debilitating disease, we established the national registration system "HAM-net" in March 2012. We continuously obtain detailed data from enrolled patients using the registration forms and an annual telephone interview. In this retrospective study, we describe the demographics and clinical histories of 383 registered patients from all over Japan. RESULTS: Patients were diagnosed at a median of 53 years old, long after disease onset at 45. Most (55.3 %) were originally from the southernmost regions, Kyushu and Okinawa. The main initial symptoms were difficulty walking (81.9 %), urinary dysfunction (38.5 %), and lower limb sensory disturbances (13.9 %). Many patients reported frequent leg numbness and leg pain, and the vast majority required medical intervention for urinary symptoms and constipation. A median of 8 years elapsed from the onset of motor symptoms to Osame Motor Disability Score (OMDS) 5 (requiring unilateral support), 12.5 years to OMDS 6 (requiring bilateral support), and 18 years to OMDS 9 (unable to walk). Health Assessment Questionnaire - Disability Index (HAQ-DI) tasks related to mobility, as opposed to hand motions, were very difficult for HAM/TSP patients and well-correlated with OMDS. Scores on the MOS 36-Item Short-Form Health Survey (SF-36) indicated that physical functioning was severely impaired in HAM/TSP patients. Patients with a history of blood transfusion (19.1 %) were older and suffered from more severe disability as indicated by their high HAQ-DI scores. Patients with a family history of HAM/TSP (8.4 %) were younger and had relatively mild symptoms given their long disease durations; many (15.6 %) also had a relative with ATLL. CONCLUSIONS: The HAM-net national registration system has been an effective tool for gathering personal and clinical data from HAM/TSP patients scattered throughout Japan. We expect to conduct many retrospective and prospective epidemiological studies using HAM-net in the future.

Combined effects of asbestos and cigarette smoke on the development of lung adenocarcinoma: different carcinogens may cause different genomic changes.

The carcinogens in cigarette smoke are distinct from asbestos. However, an understanding of their differential effects on lung adenocarcinoma development remains elusive. We investigated loss of heterozygosity (LOH) and the p53 mutation in 132 lung adenocarcinomas, for which asbestos body burden (AB; in numbers per gram of dry lung) was measured using adjacent normal lung. All cases were classified into 9 groups based on a matrix of cumulative smoking (CS in pack­years; CS=0, 00 groups, LOH frequency increased as AB and/or CS was elevated and was significantly higher in the ≥1,000 AB, ≥25 CS group (p=0.032). p53 mutation frequency was the lowest in the AB=0, CS=0 group, increased as AB and/or CS rose, and was significantly higher in the ≥1,000 AB, ≥25 CS group (p=0.039). p53 mutations characteristic of smoking were frequently observed in the CS>0 groups contrary to non-specific mutations in the CS=0, AB>0 groups. Combined effects of asbestos and smoking were suggested by LOH and p53 analyses. Sole exposure to asbestos did not increase LOH frequency but increased non­specific p53 mutations. These findings indicate that the major carcinogenic mechanism of asbestos may be tumor promotion, acting in an additive or synergistic manner, contributing to the genotoxic effect of smoking. Since this study was based on a general cancer center's experience, the limited sample size did not permit the consideration that the result was conclusive. Further investigation with a large sample size is needed to establish the mechanism of asbestos-induced lung carcinogenesis.

Effectiveness of serum megakaryocyte potentiating factor in evaluating the effects of chrysotile and its heated products on respiratory organs.

Chrysotile (CH), the most common form of asbestos, is rendered less toxic by heating it at 1000°C and converting it to forsterite (FO-1000). However, further safety tests are needed to evaluate human health risk of these materials. It has been reported that serum concentrations of megakaryocyte potentiating factor N-ERC/mesothelin become elevated in patients with mesotheliomas caused by asbestos exposure. In this study, a single 2mg dose of CH or FO-1000 was intratracheally administered to rats. Within 180days after the administrations, serum N-ERC/mesothelin concentrations, levels of 8-hydroxy-2'-deoxyguanosine (8-OHdG) in lung tissues and pathological changes in respiratory organs were determined. In the CH group, a significant increase in serum N-ERC/mesothelin concentrations was observed immediately after intratracheal administration, and the elevation lasted for 30days. In lung tissues, positive staining for 8-OHdG in bronchioles, alveolar epithelium, inflammatory cells, and granulomas was evidence of a marked DNA oxidative damage. Furthermore, measurements of 8-OHdG in lung tissues based on the HPLC-ECD method suggested that serum N-ERC/mesothelin concentrations tended to increase when there are significant DNA damages in lung tissues. In contrast, in the FO-1000 group, a marked rise in serum N-ERC/mesothelin concentrations occurred only in the early phase (1-7days) after intratracheal administration. Similarly, FO-1000 induced elevation of 8-OHdG in lung tissues was transient and modest compared with those of the CH-treated animals. In both the CH and FO-1000 groups, we observed significant correlations between serum N-ERC/mesothelin concentrations and lung 8-OHdG concentrations (r=0.559, p=0.001 for the CH group; r=0.516, p=0.01 for the FO-1000 group). In summary, we demonstrated the possibility of using serum N-ERC/mesothelin concentrations as a useful biomarker for early phase exposure to either CH or FO-1000.

Pulmonary toxicity induced by intratracheal instillation of coarse and fine particles of cerium dioxide in male rats.

In order to examine the short-, medium- and long-term effects of cerium dioxide particles of different sizes on the lung, 10-wk-old male Wistar rats were administered a physiological saline solution with a suspension of coarse or fine particles of cerium dioxide at 34 mg/kg body weight by a single intratracheal instillation. Lungs were examined with cellular and biochemical analyses of the bronchoalveolar lavage (BAL) fluid and histopathology on different days after the instillation. Geometric mean and geometric standard deviation of the diameter were 3.90 microm +/- 1.93 for the coarse (Ce-C) particles, and 0.20 microm +/- 1.20 for the fine (Ce-F) particles. There were no lesions in the lung in the Ce-C-instilled group at any time point after the instillation. The instillation of Ce-F particles primarily induced inflammation, granulomas, mobilization and impairment of alveolar macrophages (AMs), and pulmonary alveolar proteinosis, together with very slight degrees of Type II epithelial cell hyperplasia and of collagen deposition. The pulmonary toxicity of Ce-F-instilled rats was found to be markedly enhanced in sharp contrast to that of Ce-C-instilled rats on the basis of equal mass concentration, suggesting clear dependence of the pulmonary toxicity on numbers and sizes of particles. Causative factors for the pulmonary alveolar proteinosis are discussed with reference to the impaired AMs.

Forsterite exposure causes less oxidative DNA damage and lung injury than chrysotile exposure in rats.

Chrysotile (CH) is a pathogenic waste building material that can potentially be rendered innocuous via conversion to forsterite (FO) by heating at high temperatures. We compared the ability of FO and CH to cause oxidative DNA damage and lung injury. A single 1-mg intratracheal dose of CH or FO was administered to rats. Significant changes were observed 3 to 7 days after CH injection in alveolar macrophages, neutrophils, eosinophils, lymphocytes, total protein, and lactate dehydrogenase. High concentrations of 8-hydroxy-29-deoxyguanosine (8-OHdG) were also observed in the macrophages, other infiltrating inflammatory cells, granulomas, and in bronchiolar and alveolar epithelial cells. The overexpression of 8-OHdG was limited to airway epithelial and inflammatory cells surrounding the fibrotic foci 540 days after injection, indicating that the inflammatory effects of CH were persistent yet decreased with time. Compared to the CH group, acute lung inflammation observed in the FO group was less apparent and exhibited no progressive fibrosing lesions. The expression of 8-OHdG was transient and weak in the bronchiolar epithelial cells as well as in the inflammatory cells, consistent with low concentrations of 8-OHdG observed in the lungs. These findings confirm that FO causes significantly less inflammation and oxidative DNA damage in the lungs than CH.

Mesothelioma in a worker who spun chrysotile asbestos at home during childhood.

BACKGROUND: Malignant mesothelioma has a long latency period and more commonly found in those exposed to amphibole than chrysotile asbestos. METHOD: A 35 years old asbestos worker in an asbestos textile plant in Chongqing, China, developed mesothelioma after only 4 years of employment. He was born and bred in a company residence of an asbestos plant and manually spun asbestos thread during school age. In the plant, not amphibole but only chrysotile has been used. RESULTS: Diagnosis of malignant mesothelioma was confirmed by comprehensive approaches including gross appearance, histology, histochemistry, and immunocytochemistry. In the lung and tumor tissues, huge number of tremolite with exceptional chrysotile was observed despite the reverse proportion in the work environment. DISCUSSION: Residential exposure and home spinning of asbestos seemed contributed to the early development of mesothelioma in this subject. Although only chrysotile was used and contamination of tremolite was low in the work environment, chrysotile seemed to be cleared leaving tremolite remain in the tissue. CONCLUSION: Chrysotile with little contamination of tremolite can lead to early development of malignant mesothelioma when heavily exposed from childhood at a company residence with household exposure. There can be several mechanisms for tremolite to remain in the lung tissue, far exceeding chrysotile in number.

Alport syndrome-like basement membrane changes in Frasier syndrome: an electron microscopy study.

Frasier syndrome (FS) is a rare disease characterized by male pseudohermaphroditism and slowly progressing nephropathy. FS originates from heterozygous mutation in the intron 9 splicing donor site of Wilms' tumor suppressor gene (WT1). Focal segmental glomerular sclerosis is common in FS, but there have not been so many detailed pathologic investigations. The authors examined the kidneys of 3 patients with FS. The results showed that nephropathy started as mesangial proliferative glomerulonephritis, and later a concomitant focal segmental lesion developed. In all cases, electron microscopy results showed widespread thinning, splitting, and lamellation of the glomerular basement membrane, which mimicked hereditary nephritis. Throughout adulthood, WT1 protein expresses on glomerular podocytes. Recent reports described that podocytes expressing WT1 play an important role in maintaining the glomerular basement membrane. Hereditary nephritis-like glomerular basement membrane findings in FS suggest that one of the important functions of podocytes is to form and maintain the glomerular basement membrane.

Responsiveness of chemotherapy based on the histological type and Wilms' tumor suppressor gene mutation in bilateral Wilms' tumor.

To clarify a characteristic of bilateral Wilms' tumor (WT), we examined the clinical and histological features, chemotherapy response and mutations in Wilms' tumor suppressor gene (WT1) in five patients. Deoxyribonucleic acid was extracted from peripheral lymphocytes and tumor samples, and direct DNA sequencing was performed to detect WT1 mutations. Paraffin sections were stained with H&E for histological review and immunostained with anti-WT1, anti-Ki-67, anti-S-100 protein and antimyogenin antibodies. In contrast to the single case of epithelial-type WT, the other four cases were fetal rhabdomyomatous nephroblastoma (FRN) or contained a premature skeletal muscle component and appeared to be resistant to chemotherapy because there was no reduction in tumor volume. However, after chemotherapy, most of the tumor components changed into mature striated muscle cells, most of which immunostained almost completely negative for Ki-67. All four cases had the same point mutation of WT1. From our results, the histological findings correlated with WT1 mutations in bilateral WT. The tumor volume of FRN did not decrease in response to chemotherapy. It is possible to predict the chemotherapy response by examining bilateral WT for WT1 mutations and the histological characteristics of tumors.