The Impact of Di-Isononyl Phthalate Exposure on Specialized Epithelial Cells in the Colon

Insights into the molecular mechanisms underlying Phthalates-induced nephrotoxicity

Phthalates are the most common environmental toxicants that are added to plastics to improve their elasticity and extensibility. Different products containing PAEs, such as Di-(2-ethylhexyl) phthalate (DEHP), Dibutyl phthalate (DBP), etc., include baby toys, personal care products, packaging materials and pharmaceutical products. During processing, transportation and preparation, these chemicals can leach out into food and drinks. Despite their commercial advantages, phthalates have shown multi-organ toxicity, including nephrotoxicity. Phthalates exposure can lead to morphological as well as functional alterations in renal tissues. Intoxication to these phthalates can increase the risk of nephrotoxicity through various signaling pathways, including ferroptosis, oxidative stress, inflammatory, mitochondrial and DNA damage-associated pathways. This review aims to outline recent in-vivo and epidemiological studies to deepen the knowledge on underlying molecular mechanisms of nephrotoxicity caused by different phthalates. Moreover, various pharmacological interventions have also been discussed in this review, which serve as the scientific basis for the prevention and treatment of the Phthalates-induced kidney damage.

Prenatal exposure to an environmentally relevant phthalate mixture alters serum cytokine levels and inflammatory markers in the F1 mouse ovary

Phthalates are used as plasticizers and solvents in consumer products. Virtually 100% of the US population has measurable exposure levels to phthalates, however, the mechanisms by which prenatal exposure to phthalate mixtures affects reproductive health in the offspring remain unclear. Thus, this study tested the hypothesis that prenatal exposure to an environmentally relevant phthalate mixture promotes inflammation in F1 ovarian tissue. Pregnant CD-1 dams were dosed orally with vehicle control (corn oil) or phthalate mixture (20 μg/kg/d, 200 μg/kg/d, 200 mg/kg/d, 500 mg/kg/d). Pregnant dams delivered pups naturally and ovaries and sera from the F1 females were collected at postnatal day (PND) 21, PND 60, 3 mo, and 6 mo. Sera were used to measure levels of C-reactive protein (CRP). Ovaries and sera were used for cytokine array analysis. RNA was isolated from F1 ovaries and used to quantify expression of selected cytokine genes. Prenatal exposure to the mixture significantly increased the levels of CRP at 200 µg/kg/d on PND 21 compared with controls. The mixture altered 6 immune factors in sera at PND 21 and 33 immune factors in the ovary and sera at 6 mo compared with controls. The mixture increased ovarian expression of cytokines at PND 21 and decreased ovarian expression of cytokines at 6 mo compared with controls. These data suggest that prenatal exposure to a phthalate mixture interferes with the immune response in F1 female mice long after initial exposure.

Exploring the relationship between urinary phthalate metabolites and Crohn's disease via oxidative stress, and the potential moderating role of gut microbiota: A conditional mediation model

OBJECTIVE

Interactions between phthalic acid esters (PAEs) exposure and Crohn's disease (CD) were unknown. This study aims to examine the association between exposure to PAEs and CD activity and to explore the roles of oxidative stress and microbiota.

METHODS

A cross-sectional study with 127 CD patients was conducted. The disease activity was evaluated based on symptoms (Harvey-Bradshaw index, HBI), endoscopy findings (Simple Endoscopic Score for CD, SES-CD), and computed tomography enterography (CTE-scores). Ten urinary PAEs metabolites (mPAEs), two urinary oxidative stress biomarkers, including 8-hydroxydeoxyguanosine (8-OHdG) and 8-iso-prostaglandin-F2α (8-iso-PGF2α), as well as 16S rRNA sequencing of stool samples were determined. Multiple linear regression models and Hayes's PROCESS macro for SPSS were used to evaluate the interplays between urinary PAEs metabolites, CD activities, oxidative stress, and microbiota diversity.

RESULTS

There were positive associations between most mPAEs and HBI. Oxidative stress mediated 20.69-89.29% of the indirect associations between low molecular weight (LMW) mPAEs and HBI, while the majority of the high molecular weight (HMW) mPAEs were directly associated with HBI. In addition, microbiota diversity moderated the indirect associations of LMW mPAEs on HBI.

CONCLUSIONS

PAEs exposure was related to CD activity, and the association could be mediated by oxidative stress and reversed or alleviated by rich gut microbiota.

Subchronic exposure to environmentally relevant concentrations of di-(2-ethylhexyl) phthalate differentially affects the colon and ileum in adult female mice

Di(2-ethylhexyl) phthalate (DEHP) is a large-molecular-weight phthalate added to plastics to impart versatile properties. DEHP can be found in medical equipment and devices, food containers, building materials, and children's toys. Although DEHP exposure occurs most commonly by ingesting contaminated foods in the majority of the population, its effects on the gastrointestinal tract have not been well studied. Therefore, we analyzed the effects of subchronic exposure to DEHP on the ileum and colon morphology, gene expression, and immune microenvironment. Adult C57BL/6 female mice were orally dosed with corn oil (control, n = 7) or DEHP (0.02, 0.2, or 30 mg/kg, n = 7/treatment dose) for 30-34 days. Mice were euthanized during diestrus, and colon and ileum tissues were collected for RT-qPCR and immunohistochemistry. Subchronic DEHP exposure in the ileum altered the expression of several immune-mediating factors (Muc1, Lyz1, Cldn1) and cell viability factors (Bcl2 and Aifm1). Similarly, DEHP exposure in the colon impacted the gene expression of factors involved in mediating immune responses (Muc3a, Zo2, Ocln, Il6, and Il17a); and also altered the expression of cell viability factors (Ki67, Bcl2, Cdk4, and Aifm1) as well as a specialized epithelial cell marker (Vil1). Immunohistochemical analysis of the ileum showed DEHP increased expression of VIL1, CLDN1, and TNF and decreased number of T-cells in the villi. Histological analysis of the colon showed DEHP altered morphology and reduced cell proliferation. Moreover, in the colon, DEHP increased the expression of MUC2, MUC1, VIL1, CLDN1, and TNF. DEHP also increased the number of T-cells and Type 2 immune cells in the colon. These data suggest that subchronic DEHP exposure differentially affects the ileum and colon and alters colonic morphology and the intestinal immune microenvironment. These results have important implications for understanding the effects of DEHP on the gastrointestinal system.

Isolation of DiNP-Degrading Microbes from the Mouse Colon and the Influence DiNP Exposure Has on the Microbiota, Intestinal Integrity, and Immune Status of the Colon

Di-isononyl phthalate (DiNP) is a plasticizer used to impart flexibility or stability in a variety of products including polyvinyl chloride, cable coatings, artificial leather, and footwear. Previous studies have examined the impact of DiNP on gut integrity and the colonic immune microenvironment, but this study further expands the research by examining whether DiNP exposure alters the colonic microbiota and various immune markers. Previous studies have also revealed that environmental microbes degrade various phthalates, but no studies have examined whether anaerobic gut bacteria can degrade DiNP. Thus, this study tested the hypothesis that DiNP exposure alters the gut microbiota and immune-related factors, and that anaerobic bacteria in the gut can utilize DiNP as the sole carbon source. To test this hypothesis, adult female mice were orally dosed with corn oil or various doses of DiNP for 10–14 consecutive days. After the treatment period, mice were euthanized during diestrus. Colonic contents were collected for full-length 16S rRNA gene sequencing to identify the bacteria in the colon contents. Sanger sequencing of the 16S rRNA gene was used to identify bacteria that were able to grow in Bacteroides minimal media with DiNP as the sole carbon source. Colon tissues were collected for immunohistochemistry of immune(-related) factors. An environmentally relevant dose of DiNP (200 µg/kg) significantly increased a Lachnoclostridium taxon and decreased Blautia compared to the control. Collectively, minimal changes in the colonic microbiota were observed as indicated by non-significant beta-diversities between DiNP treatments and control. Furthermore, three strains of anaerobic bacteria derived from the colon were identified to use DiNP as the sole carbon source. Interestingly, DiNP exposure did not alter protein levels of interleukin-6, tumor necrosis factor alpha, claudin-1, and mucin-1 compared to the control. Collectively, these findings show that DiNP exposure alters the gut microbiota and that the gut contains DiNP-degrading microbes.