Influence of Helicobacter hepaticus infection on the chronic toxicity and carcinogenicity of triethanolamine in B6C3F1 mice

Relationship between exposure to metalworking fluids and nonalcoholic fatty liver disease

OBJECTIVE

The relationship between metalworking fluids (MWFs) and nonalcoholic fatty liver disease (NAFLD) has not been previously explored. We aim to investigate the relationship between occupational exposure to MWFs and the prevalence of NAFLD and to determine the cumulative exposure threshold per day.

METHODS

In 2020, 2079 employees were selected randomly from one computer numerical control machining factory in Wuxi for a questionnaire survey, and occupational health examinations were conducted at the affiliated branch of Wuxi Eighth People's Hospital. MWF samples were collected within the factory using the National Institute for Occupational Safety and Health (NIOSH) 5524 method. NAFLD was defined as having a hepatic steatosis index (HSI) ≥ 36 without significant alcohol consumption. The relationship between NAFLD and MWFs was analyzed using logistic regression, and the daily exposure threshold was calculated using R software.

RESULTS

MWF exposure was found to be a risk factor for NAFLD in exposed workers compared to the non-exposed group. The OR for NAFLD in workers exposed to MWFs compared to controls was 1.42 (95% CI: 1.04-1.95). An increased risk of NAFLD was shown to be associated with an increasing dose. The daily exposure dose threshold to MWFs was found to be 6.54 mg/m3 (OR = 2.09, 95% CI: 1.24-3.52).

CONCLUSION

An association between occupational exposure to MWFs and NAFLD was found. As the concentration of exposure rose, the prevalence of NAFLD was also escalated.

Helicobacter hepaticus infection induces chronic hepatitis and fibrosis in male BALB/c mice via the activation of NF-κB, Stat3, and MAPK signaling pathways

BACKGROUND

It has been documented that Helicobacter hepaticus (H hepaticus) infection is linked to chronic hepatitis and liver cancer. However, our understanding of the molecular mechanisms underlying progression of the H hepaticus-induced hepatic inflammation to cellular hepatocarcinoma is still limited.

MATERIALS AND METHODS

In our study, male BALB/c mice were infected by H hepaticus for 8, 12, 16, 20, and 24 weeks. Histopathology, H hepaticus colonization dynamics, select signaling pathways, and expression of key inflammatory cytokines in the liver were examined.

RESULTS

We found that H hepaticus was detectible in feces of mice at 7 days postinfection (DPI) by PCR, but it was not detected in the livers by PCR until 8 weeks postinfection (WPI). In addition, abundance of colonic and hepatic H hepaticus was progressively increased over the infection duration. H hepaticus-induced hepatic inflammation and fibrosis were aggravated over the infection duration, and necrosis or cirrhosis developed in the infected liver at 24 WPI H hepaticus infection increased levels of alanine aminotransferase and aspartate aminotransferase. Moreover, mRNA levels of Il-6 and Tnf-α were significantly elevated in the livers of H hepaticus-infected mice compared to uninfected control from 8 WPI to 24 WPI. Furthermore, Stat3, nuclear factor-κB (p65), and MAPK (Erk1/2 and p38) were activated by H hepaticus infection.

CONCLUSIONS

These data demonstrated that male BALB/c mice can be used as a new mouse model of H hepaticus-induced liver diseases and that the H hepaticus-induced liver injury is triggered by NF-κB, Jak-Stat, and MAPK signaling pathways.

Helicobacter hepaticus infection-induced IL-33 promotes hepatic inflammation and fibrosis through ST2 signaling pathways in BALB/c mice

It has been documented that Helicobacter hepaticus (H. hepaticus) infection is linked to hepatic inflammation and fibrosis. Interleukin 33 (IL-33) is a cytokine involved in inflammatory and fibrotic diseases, but its relevance to H. hepaticus infection-induced liver inflammation and fibrosis is unknown. In this study, we found that the expression of IL-33 in mice liver was significantly induced by H. hepaticus infection at 24 weeks post infection (WPI). Immunohistochemistry analysis revealed that IL-33 was transferred from the nucleus to the cytoplasm due to infection. The quantitation of inflammatory cytokine and histopathology evaluation showed that IL-33 knockdown attenuated the H. hepaticus-induced hepatic inflammation and fibrosis. More importantly, H. hepaticus promoted the expression of the IL-33 receptor ST2 on cell surfaces, and the expression of ST2 then activated the expression nuclear factor-κB (p65), α-SMA, and Erk1/2. These observations provide novel insights into the pathogenic mechanism of hepatic inflammation and fibrosis during H. hepaticus infection.

Good Research Practice: Lessons from Animal Care and Use

Animal care and use play a pivotal role in the research process. Ethical concerns on the use of animals in research have promoted the creation of a legal framework in many geographical areas that researchers must comply with, and professional organizations continuously develop recommendations on specific areas of laboratory animal science. Scientific evidence demonstrates that many aspects of animal care and use which are beyond the legal requirements have direct impact on research results. Therefore, the review and oversight of animal care and use programs are essential to identify, define, control, and improve all of these aspects to promote the reproducibility, validity, and translatability of animal-based research outcomes. In this chapter, we summarize the ethical principles driving legislation and recommendations on animal care and use, as well as some of these laws and international recommendations. Examples of the impact of specific animal care and use aspects on research, as well as systems of internal and external oversight of animal care and use programs, are described.

Relationship between Helicobacter hepaticus infection and hepatocellular carcinoma

Hepatocellular carcinoma (HCC) has a high incidence worldwide, with a low diagnostic rate in the early period and therefore a high death rate. Causes for some cases of liver cancer are not completely clear. The finding that the rate of liver cancer in male A/Jr mice is significantly higher makes researchers realize that Helicobacter hepaticus may cause HCC in human beings. To get a new perspective for exploring causes of liver cancer, this paper introduces the biological nature of and detecting methods for Helicobacter hepaticus, as well as the relationship between Helicobacter hepaticus infection and HCC. Helicobacter hepaticus infection may play an important role in some HCC cases.

Proliferative and nonproliferative lesions of the rat and mouse hepatobiliary system

The INHAND Project (International Harmonization of Nomenclature and Diagnostic Criteria for Lesions in Rats and Mice) is a joint initiative of the Societies of Toxicologic Pathology from Europe (ESTP), Great Britain (BSTP), Japan (JSTP) and North America (STP) to develop an internationally-accepted nomenclature for proliferative and non-proliferative lesions in laboratory animals. The purpose of this publication is to provide a standardized nomenclature and differential diagnosis for classifying microscopic lesions observed in the hepatobiliary system of laboratory rats and mice, with color microphotographs illustrating examples of some lesions. The standardized nomenclature presented in this document is also available for society members electronically on the internet (http://goreni.org). Sources of material included histopathology databases from government, academia, and industrial laboratories throughout the world. Content includes spontaneous and aging lesions as well as lesions induced by exposure to test materials. A widely accepted and utilized international harmonization of nomenclature for lesions of the hepatobiliary system in laboratory animals will decrease confusion among regulatory and scientific research organizations in different countries and provide a common language to increase and enrich international exchanges of information among toxicologists and pathologists.

Investigating the potential for toxicity from long-term use of the herbal products, goldenseal and milk thistle

Two-year toxicity studies were conducted on the widely used herbal products, goldenseal and milk thistle, in male and female F344/N rats and B6C3F1 mice. With goldenseal root powder, the primary finding was an increase in liver tumors in rats and mice, and with milk thistle extract, a decrease in spontaneous background tumors including mammary gland tumors in female rats and liver tumors in male mice. Increased tumorigenicity in rodents exposed to goldenseal root powder may be due in part to the topoisomerase inhibition properties of berberine, a major alkaloid constituent in goldenseal, or its metabolite, berberrubine. In the clinic, use of topoisomerase-inhibiting agents has been associated with secondary tumor formation and inhibition in DNA repair processes. In contrast, the radical-scavenging and antioxidant properties of silibinin and other flavonolignans in milk thistle extract may have contributed to the decrease in background tumors in rodents in the present studies. The fate of the active constituents of goldenseal and milk thistle is similar in humans and rodents; therefore, the modes of action may translate across species. Further studies are needed to extrapolate the findings to humans.

Distance burning: how gut microbes promote extraintestinal cancers

Gut microbes play a major role in carcinogenesis of the gastrointestinal tract. We and others have shown in mouse models that colonic bacteria also influence the development of extraintestinal cancers including hepatocellular and mammary carcinomas. Microbes such as Helicobacter hepaticus invoke a proinflammatory microenvironment in the lower bowel that may extend to distant organs, often in the absence of histologically evident inflammation. Innate immunity plays a crucial role in the promotion of liver cancer and other systemic diseases by gut microbes. Additional mechanisms include type 1 adaptive immunity, altered metabolism, and oxidative stress. Emerging links between host genetics, gut microbes, inflammatory bowel disease and colorectal cancer also may prove useful for the correlation of specific bacterial populations with extraintestinal neoplasms. Interruption of deleterious host-microbe networks through judicious use of antibiotics and targeted molecular therapies may help reduce the incidence of liver, breast, and other human cancers.

Indication of cocarcinogenic potential of chronic UMTS-modulated radiofrequency exposure in an ethylnitrosourea mouse model

PURPOSE

To evaluate putative effects on tumour susceptibility in mice exposed to a UMTS (universal mobile telecommunications system) test signal for up to 24 months, commencing with embryo-fetal exposure.

MATERIAL AND METHODS

Animals were exposed to UMTS fields with intensities of 0, 4.8, and 48 W/m(2), the low-dose group (4.8 W/m(2)) was subjected to additional prenatal ethylnitrosourea treatment (40 mg ENU/kg body weight).

RESULTS

The high-level UMTS exposure (48 W/m(2)), the sham exposure, and the cage control groups showed comparable tumour incidences in the protocol organs. In contrast, the ENU-treated group UMTS-exposed at 4.8 W/m(2) displayed an enhanced lung tumour rate and an increased incidence of lung carcinomas as compared to the controls treated with ENU only. Furthermore, tumour multiplicity of the lung carcinomas was increased and the number of metastasising lung tumours was doubled in the ENU/UMTS group as compared to the ENU control group.

CONCLUSION

This pilot study indicates a cocarcinogenic effect of lifelong UMTS exposure (4.8 W/m(2)) in female B6C3F1 descendants subjected to pretreatment with ethylnitrosourea.

Hepatocellular carcinoma: prevalence and molecular pathogenesis of Helicobacter spp

Helicobacter pylori infection is one of the most common chronic bacterial infections in humans. The association of other Helicobacter spp. with extragastric diseases in animals is well established, and a role of these bacteria in human liver disease is becoming clearer. Several case-control studies have reported possible associations of Helicobacter spp. with various liver diseases, including hepatocellular carcinoma, which is the fifth most common type of carcinoma among men worldwide, and the eighth most common among women. Thus, it is important to understand molecular mechanisms that may lead to hepatotoxicity or hepatocellular dysfunction in which Helicobacter spp. may play a role in inducing malignant transformation of liver cells.