Chronic exposure to Zearalenone leads to endometrial hyperplasia in CD-1 mice by altering the inflammatory markers.

Background: Zearalenone (ZEA), a natural food contaminant, is reported to act as a mycoestrogen due to its estrogen-mimicking properties. According to studies, ZEA has a greater potential for estrogenic activity compared to any other naturally occurring non-steroidal estrogen. ZEA has been found in the endometrium of individuals with reproductive problems and the serum of children facing early puberty. These studies suggested a possible link between ZEA exposure and endometrial toxicity; nonetheless, no thorough research has been done. This study assessed the endometrium's response to chronic ZEA exposure. Methods: Four groups of CD-1 female mice were exposed to control, estradiol (E2), and two different doses of ZEA for 90 days. At the end of treatment, blood and uterus were collected, and samples were used for inflammatory cytokines level, immunochemical, histopathological, and biophysical analysis. Results: Our data indicated that the uterus showed a change in body/organ weight ratio, while other organs did not have any notable changes. Immunochemical and histological studies showed hyperplasia and a higher number of glands in the endometrium after ZEA and E2 exposure. Similarly, proliferation markers such as proliferative cell nuclear antigen (PCNA), Ki-67, and inflammatory cytokines such as interleukin 6 (IL-6), interleukin 8 (IL-8), and interferon-gamma (IFN-?) levels were found to be higher in the E2 and ZEA-exposed groups. Conclusion: Our finding conclude that ZEA targets the uterus and cause inflammation due to increased levels of inflammatory cytokines and proliferation mediators, as well as systemic toxicity denoted by a strong binding affinity with serum proteins.

Development of an immunoassay for the detection of mycotoxins using xMAP technology and its evaluation in black tea samples.

Mycotoxins, a natural food contaminant, are secondary metabolites of fungi. Aflatoxin B1 (AFB1) and ochratoxin A (OTA) are two major mycotoxins found in various food commodities. These mycotoxins are hepatotoxic, nephrotoxic, cytotoxic, mutagenic and carcinogenic, thus they are a public health concern and their monitoring in food commodities is necessary. There are several conventional techniques available for mycotoxin detection, such as HPLC, LCMS, and ELISA. However, extensive nature and huge cost allowances make it challenging to deploy these techniques for monitoring of mycotoxins in the large sample size. Therefore, a robust, responsive and high-throughput technique is required. Here, we aimed to develop a multiplexed Luminex suspension assay based on multi analyte profiling (xMAP) technology for the simultaneous detection of AFB1 and OTA in the black tea, which is found to be contaminated with these mycotoxins during the cultivation or processing steps. Limit of detection for AFB1 and OTA, was 0.06 ng/ml and 0.49 ng/ml, respectively without any cross-reactivity with other mycotoxins and this assay is suitable for simultaneous detection of AFB1 and OTA in the same sample. Collectively, based on the results, we suggest that the developed Luminex suspension assay is sensitive, accurate, rapid and suitable for high-throughput screening of multiple mycotoxins. Supplementary Information: The online version contains supplementary material available at 10.1007/s13197-023-05848-3.

Increased Serum Levels of Matrix-metalloproteinase-9, Cyclo-oxygenase-2 and Prostaglandin E-2 in Patients with Chronic Obstructive Pulmonary Disease (COPD).

Chronic obstructive pulmonary disease (COPD), a heterogeneous lung disorder that is characterized by airflow obstruction and the third leading cause of death, globally. COPD is influenced by environmental and genetic factors. Here, we measured the serum level of matrix metalloproteinase-9 (MMP-9), cyclooxygenase-2 (COX-2) and prostaglandin E-2 (PGE-2) and reveal the correlation between their levels in COPD subjects. In this study, we included a total of 79 COPD and 79 healthy controls. We assessed demographic profile, risk factors, respiratory symptoms, clinical history, COPD Assessment Test (CAT) score and spirometry. Further, we determined the serum levels of MMP-9, COX-2 and PGE-2 by enzyme-linked immunosorbent assay (ELISA). The correlation between their serum levels was also determined. Among the studied population age, gender, body mass index and socioeconomic status were comparable. Serum levels of MMP-9, COX-2 and PGE-2 were significantly increased in the COPD group than in healthy controls (P < 0.0001). Moreover, MMP-9, COX-2 and PGE-2 levels were increased with the GOLD grades and CAT score (> 10). Serum levels of MMP-9, COX-2 and PGE-2 was enhanced in patients with larger clinical history (> 20 years) than those with lower clinical history (< 10 years). Serum levels of MMP-9 and COX-2; MMP-9 and PGE-2; COX-2 and PGE-2 showed a positive correlation (P < 0.0001) with the COPD group. Our data demonstrate that serum levels of MMP-9, COX-2 and PGE-2 were correlated with the GOLD grade, CAT score and clinical history of the COPD group, pointing that they can be used as a indicators to understand the disease progression. Supplementary Information: The online version contains supplementary material available at 10.1007/s12291-021-00973-2.

Ochratoxin A treated rat derived urinary exosomes enhanced cell growth and extracellular matrix production in normal kidney cells through modulation of TGF-ß1/smad2/3 signaling pathway.

AIMS: Kidney is the main target organ for ochratoxin A (OTA) toxicity; however, the mechanism(s) involved in OTA-induced nephrotoxicity is not fully understood. Recently, exosomes, nano-sized vesicles have been found to play an important role in promotion and progression of disease as well as environmental toxicant-induced patho-physiology of toxicity. Hence, we aimed to investigate the role of exosomes in OTA-mediated nephrotoxicity. MAIN METHODS: Male Wistar rats were divided in to two groups. Rats of one group were treated with OTA (210 µg/kg b. wt) and another with vehicle control through oral gavage (5 days/week) for 270 days. At the end of experiment, exosomes concentrations from rat's urine were measured. To examine the OTA-induced nephrotoxicity, histopathology was performed using H & E, Masson's trichome and PAS staining. For mechanistic study, normal rat kidney (NRK52E) cells were exposed with either vehicles treated rat's urinary exosomes (NEx) or OTA treated rat's urinary exosomes (OEx) and effects on cell proliferation, cell growth, extracellular matrix production and TGF-ß1/smad2/3 pathway was analyzed. KEY FINDINGS: OTA treatment to Wistar rats caused histopathological changes such as tubular degeneration, glomeruli shrinkage and hypercellularity in kidney tissue. Interestingly, OTA treated rat's urine has more exosomes secretion. Moreover, treatment of NRK52E cells with OEx caused increased cell proliferation, cell growth, enhanced the expression of extracellular matrix proteins and activation of TGF-ß1/smad2/3 pathway. SIGNIFICANCE: Our investigations exogenous exposure of OTA derived urinary exosomes caused TGF-ß1/smad2/3 pathway-mediated activation of pro-fibrotic changes in kidney will helpful for deeper understanding the OTA-induced nephrotoxicity.

Transcriptomic and proteomic insights into patulin mycotoxin-induced cancer-like phenotypes in normal intestinal epithelial cells.

Patulin (PAT) is a natural contaminant of fruits (primarily apples) and their products. Significantly, high levels of contamination have been found in fruit juices all over the world. Several in vitro studies have demonstrated PAT's ability to alter intestinal structure and function. However, in real life, the probability of low dose long-term exposure to PAT to humans is significantly higher through contaminated food items. Thus, in the present study, we have exposed normal intestinal cells to non-toxic levels of PAT for 16 weeks and observed that PAT had the ability to cause cancer-like properties in normal intestinal epithelial cells after chronic exposure. Here, our results showed that chronic exposure to low doses of PAT caused enhanced proliferation, migration and invasion ability, and the capability to grow in soft agar (anchorage independence). Moreover, an in vivo study showed the appearance of colonic aberrant crypt foci (ACFs) in PAT-exposed Wistar rats, which are well, establish markers for early colon cancer. Furthermore, as these neoplastic changes are consequences of alterations at the molecular level, here, we combined next-generation RNA sequencing with liquid chromatography mass spectrometry-based proteomic analysis to investigate the possible underlying mechanisms involved in PAT-induced neoplastic changes.

TGF-ß/Smad signaling pathway plays a crucial role in patulin-induced pro-fibrotic changes in rat kidney via modulation of slug and snail expression.

Patulin (PAT) is a mycotoxin that contaminates a variety of food and foodstuffs. Earlier in vitro and in vivo findings have indicated that kidney is one of the target organs for PAT-induced toxicity. However, no study has evaluated the chronic effects of PAT exposure at environmentally relevant doses or elucidated the detailed mechanism(s) involved. Here, using in vitro and in vivo experimental approaches, we delineated the mechanism/s involved in pro-fibrotic changes in the kidney after low-dose chronic exposure to PAT. We found that non-toxic concentrations (50 nM and 100 nM) of PAT to normal rat kidney cells (NRK52E) caused a higher generation of reactive oxygen species (ROS) (mainly hydroxyl (•OH), peroxynitrite (ONOO-), and hypochlorite radical (ClO-). PAT exposure caused the activation of mitogen-activated protein kinases (MAPKs) and its downstream c-Jun/Fos signaling pathways. Moreover, our chromatin immunoprecipitation (ChIP) analysis suggested that c-Jun/Fos binds to the promoter region of Transforming growth factor beta (TGF-ß1) and possibly induces its expression. Results showed that PAT-induced TGF-ß1 further activates the TGF-ß1/smad signaling pathways. Higher activation of slug and snail transcription factors further modulates the regulation of pro-fibrotic molecules. Similarly, in vivo results showed that PAT exposure to rats through gavage at 25 and 100 µg/kg b. wt had higher levels of kidney injury/toxicity markers namely vascular endothelial growth factor (VEGF), kidney Injury Molecule-1 (Kim-1), tissue inhibitor of metalloproteinase-1 (Timp-1), and clusterin (CLU). Additionally, histopathological analysis indicated significant alterations in renal tubules and glomeruli along with collagen deposition in PAT-treated rat kidneys. Overall, our data provide evidence of the involvement of ROS mediated MAPKs and TGF-ß1/smad pathways in PAT-induced pro-fibrotic changes in the kidney via modulation of slug and snail expression.

Safety studies of Nexrutine, bark extract of Phellodendron amurense through repeated oral exposure to rats for 28 days.

Nexrutine (NX), a marketable herbal extract from a traditional Chinese herbal plant, Phellodendron amurense, is majorly used for the resolution of inflammation, gastroenteritis, and some tissue-specific cancer. Strategies for the identification of the safety of anticancer solutions of plant origin are an important area of study. The present investigation assesses the single and repeated dose (28 days) toxicity of NX following OECD guidelines 425 and 407, respectively. Briefly, to identify acute toxic properties of NX, a dose of 2000 mg/kg b. wt was administered once orally. Simultaneously, repeated dose toxicity was evaluated through daily administration of the three different doses (250, 500, 750 mg/kg b. wt) of NX for 28days. The single administration of NX showed no signs of toxicity and morbidity, suggesting LD50 of NX more than 2000 mg/kg b. wt. Furthermore, repeated dose exposure of NX for 28 days did not show any sign of toxicity. Hematology, serum biochemistry, and histopathological analysis also did not show any significant abnormalities. However, a marginal decrease in triglyceride, cholesterol, and glucose levels along with mild tubular degeneration in the kidney was also noticed in the high dose NX treatment group. Overall, the findings of the study suggest that NX is safe for use up to 500 mg/kg b.wt.

Study of the metabolic alterations in patulin-induced neoplastic transformation in normal intestinal cells.

Several surveillance studies have reported significantly high level of patulin (PAT), mycotoxin in fruit juices suggesting the possible exposure to human. In vitro studies have showed that PAT can alter the permeability, ion transport and modulates tight junction of intestine. In real scenario, human can be exposed with low levels of PAT for longer duration through different fruits and their products. Hence, keeping this possibility in view, we conducted a study where normal intestinal cells were exposed with non-toxic levels of PAT for longer duration and found that PAT exposure causes cancer-like properties in normal intestinal cells. It is a well-known fact that cancer cells rewired their metabolism for cell growth and survival and metabolites closely depict the phenotypic properties of cells. Here, metabolomic study was performed in the PAT transformed and passage matched non-transformed cells using 1H HRMAS NMR. We have identified 12 significantly up-regulated metabolites, which, interestingly, were majorly amino acids, suggesting that PAT-induced pre-cancerous cells are involved in acquirement of nutrients for high protein turn-over. Furthermore, pathway analysis of metabolomics data indicated that aminoacyl tRNA biosynthesis, D-glutamate metabolism, glyoxylate and dicarboxylate metabolism and nitrogen metabolism were majorly hampered in PAT-induced pre-cancerous properties in normal intestinal cells.

Occurrence of Alternariol and Alternariolmonomethyl ether in edible oils: Their thermal stability and intake assessment in state of Uttar Pradesh, India.

Alternariol (AOH) and Alternariol monomethyl ether (AME) mycotoxins are found to be present naturally in various food commodities, such as barley, oats, pepper, rye, sorghum, sunflower seeds, tomatoes, and wheat. A few epidemiological studies have correlated the consumption of Alternaria-contaminated cereal grains with higher occurrence of esophageal cancer in Chinese populations. In addition, several studies have reported the toxicological properties of Alternaria mycotoxins. However, surveillance data on AOH and AME occurrence are still limited. Therefore, the goal of this study was to determine the presence of AOH and AME in various commonly consumed, edible oils using HPLC-FLD method. Thirty four percent of samples were found positive for AOH and 35% for AME. Moreover, AOH retained 80% stability, while AME retained 84% stability, after deep frying for 25 min, which is an important factor with respect to Indian cooking style. To the best of our knowledge, this is the first report on the presence of Alternaria mycotoxins in edible oils and their probable dietary intake in Indian population. This surveillance study may help in formulating guidelines for Alternaria mycotoxin levels in India, which are not yet implemented by Food Safety and Standards Authority of India. PRACTICAL APPLICATIONS: At present, no safety guidelines exist for Alternaria mycotoxins in any part of the world. This study will help the regulatory bodies to set permissible levels of Alternaria mycotoxins to safeguard the health of consumers. This study shows that Alternaria mycotoxins are heat stable even after deep frying for 25 min. The data will also help to issue guidelines against exposure of these mycotoxins, keeping in the mind the heat stability factor.

Safety evaluation of Ochratoxin A and Citrinin after 28 days repeated dose oral exposure to Wistar rats.

Mycotoxins, ochratoxin A (OTA), and citrinin (CTN) are toxic metabolites of filamentous fungi. The most common fungal species that produce OTA and CTN belong to genera Aspergillus, Penicillium, Fusarium, and Monascus, and these fungal species are found to be contaminant a wide range of grains, food, and food product. The aim of our study was to evaluate the sub-acute repeated dose oral toxicity of OTA and CTN in experimental rodents by following OECD test guidelines for testing chemicals no. 407 with minor modifications. Twenty-five rats of each sex were divided equally into five groups; vehicle control, OTA 25 µg/kg b. wt., OTA 100 µg/kg b. wt., CTN 25 µg/kg b.wt. and CTN 100 µg/kg b. wt. The results of this study showed no abnormal clinical signs during 28 days of the experimental period. We did not found any significant changes in body weight gain, food consumption pattern, organ weight, hematology except few parameters, and biochemical values in any of the treatment and control groups. However, histopathological observations revealed severe nephrotoxicity and mild follicular depletion in the spleen of 100 µg/kg b. wt. treated groups of both OTA and CTN mycotoxins. The findings of our study are of its first kind that reports the systemic toxicity of OTA and CTN oral exposure to laboratory rodents.

Accelerated and scarless wound repair by a multicomponent hydrogel through simultaneous activation of multiple pathways.

Scarless healing of injury remains a clinical challenge because of its complicated and overlapping phases of inflammation, clearing, and regeneration. Curcumin has been already established as a potential wound healing agent for normal and diabetic-impaired wounds. Herein, the question has been addressed whether a well-known antioxidant cerium oxide nanoparticle (CNP) can potentiate the activity of curcumin to promote a cellular program for scarless healing. In this study, we have developed a biocompatible poly (acrylamide) hydrogel (PAGE)-based dressing material comprising of CNP and curcumin (ACC) and tested its wound healing activity in an animal model of acute wound. Characterization of the CNP- and curcumin-entrapped hydrogel dressing (ACC) demonstrated high loading efficiency and sustained release of curcumin. In a full-thickness acute wound healing model of rat, a single application of ACC dressing demonstrated higher wound healing efficacy (78%) and negligible scarring compared to dressings containing only curcumin or CNP in 7 days. Enhanced cell proliferation, higher collagen content, advanced wound maturity, re-epithelialization, and granulation tissue formation were observed using the combination of curcumin and CNP (ACC). Study of cellular mechanisms identified MCP-1 and TGF-ß as the key drivers of differential and accelerated healing observed in the ACC group. These, coupled with the upregulation of growth-related signaling pathways (HER2/ErbB2, TGF-ß-Smad2/3, MAPK/ERK, AKT, and VEGF), promoted almost scarless healing in animals treated with ACC. The optimized combination of curcumin and CNP used in our study shows distinct advantage and can be a better agent for complete wound healing.

Alternariol induced proliferation in primary mouse keratinocytes and inflammation in mouse skin is regulated via PGE2/EP2/cAMP/p-CREB signaling pathway.

Alternariol (AOH) is a mycotoxin that contaminates various food stuffs as well as animal feed and may cause toxicity after consumption. However, a dermal toxic potential of AOH has not been explored so far. In the present study, skin toxicity after topical exposure of AOH and the involved mechanism/s are revealed. Single topical application of different AOH doses (12.5, 25, 50 µg/animal) caused increased bi-fold thickness as well as hyperplasia and higher production of prostaglandin E2 (PGE2) along with cAMP in the skin demonstrating its inflammatory potential. Western blot analysis showed that exposure of AOH lead to phosphorylation of CREB and increased the expression of COX-2, cyclin D1 as well as prostanoid EP2 receptor. Further studies on primary mouse keratinocytes (PMK) revealed that very low concentrations of AOH (50-500 nM) resulted in significant PMK proliferation. Additionally, using specific antagonist or agonist of prostanoid receptors, we delineated that EP2 receptor play a key role in AOH-induced PMKs proliferation. Collectively, our findings show that AOH can lead to dermal toxicity in mice by activating the EP2/cAMP/p-CREB signaling cascade.

COX-2/EP2-EP4/ß-catenin signaling regulates patulin-induced intestinal cell proliferation and inflammation.

Patulin (PAT), a mycotoxin, is a natural contaminant that is produced by certain species of Penicillium, Aspergillus and Byssochlamys. The major contamination of PAT is in apple and apple based products. PAT is known to cause glutathione depletion, oxidative DNA damage and cell proliferation. Recently, in vitro studies have indicated that PAT can also increase the intestinal epithelial permeability, modulate tight junctions and decrease transepithelial electrical resistance. Nonetheless, no previous study has evaluated the mechanisms responsible for PAT-induced intestinal toxicity or its relevance to the in vivo situation. Here, Wistar rats were orally treated with 100 µg/kg body weight (b.wt.) of PAT, either alone or along with 100 mg/kg b. wt. of celecoxib for 3 days. We found that PAT exposure led to significantly higher levels of PGE2 in serum and intestinal tissue and high expression of COX-2 and Ki-67 compared to controls. Interestingly, our results showed that celecoxib treatment could decrease the PAT-induced PGE2 and reduce the PAT-induced intestinal damage. To study the mechanistic aspect, normal rat intestinal epithelial cells (IEC-6) were treated with non-toxic concentrations (100 nM, 250 nM and 500 nM) of PAT for 6 h. It was observed that PAT exposure caused enhanced proliferation, higher expression of COX-2, and EP2 and EP4 receptors, along with increased PGE2 secretion. Additionally, PAT exposure caused enhanced Akt expression, which in turn inhibits GSK-3ß and stabilizes ß-catenin. Overall, our study suggests that the COX-2/EP2-EP4/ß-catenin signaling cascades are involved in the regulation of PAT-induced intestinal cell proliferation and inflammation.

Topical application of Nexrutine inhibits ultraviolet B-induced cutaneous inflammatory responses in SKH-1 hairless mouse.

BACKGROUND: Ultraviolet B (UVB) radiation is the major contributor to skin inflammation which leads to the development of skin cancer. Hence, in this study, we studied the effect of Nexrutine (NX) on UVB-induced cutaneous inflammation and its mediators. METHODS: Ultraviolet absorption spectra of NX were measured by spectrophotometer. To conduct the photoprotective studies, SKH-1 hairless mice were topically treated with NX, 30 minutes before to the UVB (180 mJ/cm2 ) exposure. Twenty hours of post-UVB irradiation, mouse skin was used for edema measurements, H & E staining, myeloperoxidase (MPO) activity, and estimation of plasma cytokines. In addition, expression levels of inflammatory cytokines, cyclooxygenase-2 (COX-2), and inducible nitric oxide synthase (iNOS) were also determined by Western blot analysis. RESULTS: Nexrutine displayed absorbance over the UVB spectrum. NX significantly decreased the UVB-induced epidermal edema, skin thickness, leukocyte infiltration, number of the sunburn, and TUNEL-positive cells. NX treatment also decreased the number of mast cells, MPO activity, expression of pro-inflammatory cytokines, and inflammation mediator protein in mouse skin. CONCLUSION: These results provide evidences that NX inhibits the UVB-induced cutaneous inflammatory responses in SKH-1 mouse skin.

Protective Activity of Silk Sericin against UV Radiation-Induced Skin Damage by Downregulating Oxidative Stress.

Topical delivery of potential antioxidants protects the skin against ultraviolet (UV) radiation-induced oxidative damage through maintaining redox balance. Sericin, one of the major components of silk, possesses antioxidant property along with skin-protective activity against UVB radiation-induced damage. However, the protective activity of silk sericin (SS) extracted from different sources has not been explored against UVA and UVB radiation-induced oxidative damage. In the present study, we have systematically investigated the protective activity of sericin against UVA and UVB radiation-induced skin damage. MTT and neutral red assays showed that Philosamia ricini sericin (PRS) and Antheraea assamensis sericin (AAS) (10 µg/mL) treatment prior to UVA (12 J/cm2) and UVB (120 mJ/cm2) irradiations enhanced the viability of human keratinocytes. Examination of cell cycle arrest and apoptotic/necrotic cell death using flow cytometry showed that sericin treatment before UVA and UVB irradiation protected the cells from apoptotic cell death by arresting the cell cycle at G1 phase. Sericin pretreatment downregulated the interleukin (IL)-6 and IL-8, upregulated p53 and decrease the dysregulation of Bcl-2/Bax gene expression. AAS treatment prior to UVB irradiation significantly reduced skin inflammation, DNA fragmentation, and lipid peroxidation in the female SKH-1 hairless mouse skin. Altogether, our results substantiate the use of AAS in effectively ameliorating UVA and UVB radiation-induced skin damage, which holds prospects as a potent antioxidant supplement in the preparation of skin care products.

Toxicological effects of patulin mycotoxin on the mammalian system: an overview.

The mycotoxin PAT (4-hydroxy-4H-furo[3,2c]pyran-2[6H]-one) is a secondary metabolic product of molds such as Penicillium, Aspergillus, and Byssochlamys species. PAT is a common contaminant of fruit and vegetable based products, most notably apples. Despite PAT's original discovery as an antibiotic, it has come under heavy scrutiny for its potential to impart negative health effects. Studies investigating these health effects have proved its toxic potential. PAT occurrence in the food commodities poses a serious threat and necessitates novel and cost-effective mitigation methods to remove it from food products. It also creates a demand to improve handling and food processing techniques. With this being the case, several studies have been devoted to understanding the key biological and chemical attributes of PAT. While past research has elucidated a great deal, PAT contamination continues to be a challenge for the food industry. Here, we review its influence within the mammalian system, including its regulation, incidences of experimental evidence of PAT toxicity, its interaction with intracellular components, and the effects of PAT induced systemic toxicity on vital organs. Finally, key areas where future PAT research should focus to best control the PAT contamination problem within the food industry have been addressed.

UVB irradiation-enhanced zinc oxide nanoparticles-induced DNA damage and cell death in mouse skin.

UV-induced reactive oxygen species (ROS) have been implicated in photocarcinogenesis and skin aging. This is because UV-induced ROS can induce DNA damage that, if unrepaired, can lead to carcinogenesis. Sunscreens contain UV attenuators, such as organic chemical and/or physical UV filters, which can prevent all forms of damage from UV irradiation. In recent years, the effective broad-spectrum UV attenuation properties of ZnO-nanoparticles (ZnO-NPs) have made them attractive as active components in sunscreens and other personal care products. As the use of ZnO-NPs in sunscreens is on the rise, so is public concern about their safety, particularly with exposure to sunlight. Therefore, in the present study, using various experimental approaches, we investigated the possible toxic effects resulting from exposure to UVB and ZnO-NPs in primary mouse keratinocytes (PMKs) as well as in the skin of SKH-1 hairless mice. The findings of the present study demonstrated that co-exposure to UVB and ZnO-NPs: (1) translocated the ZnO-NPs into the nucleus of PMKs; (2) caused enhanced generation of ROS; (3) induced more severe DNA damage as evident by alkaline comet assay and immunocytochemistry for γ-H2AX and 8-hydroxy-2'-deoxyguanosine (8-OHdG); and (4) subsequently caused much more pronounced cell death in PMKs. Further, to elucidate the physiological relevance of these in vitro findings, SKH-1 hairless mice were topically treated with ZnO-NPs and after 30min irradiated with UVB (50mJ/cm(2)). Interestingly, we found that co-exposure of ZnO-NPs and UVB caused increased oxidative DNA damage and cell death, indicated by immunostaining for 8-OHdG and TUNEL assay in sections of exposed mouse skin. Thus, collectively, our findings suggest that UVB exposure increases ZnO-NPs-mediated oxidative stress and oxidative damage, thereby enhancing ZnO-NPs-induced cell death.

UVB exposure enhanced benzanthrone-induced inflammatory responses in SKH-1 mouse skin by activating the expression of COX-2 and iNOS through MAP kinases/NF-κB/AP-1 signalling pathways.

This study was conducted to explore the role of UVB on benzanthrone (BA)-induced skin inflammation and its mechanism/s. SKH-1 hairless mice were topically exposed with BA (25 and 50 mg/kg b.wt) either alone or along with UVB (50 mJ/cm(2)) for 24 h and estimation of ROS, histopathological analysis, myeloperoxidase (MPO) activity, mast cell staining, immunohistochemistry for COX-2 and iNOS as well as western blotting for MAPKs, p-NF-κB, c-jun, c-fos COX-2 and iNOS were carried out. Enhanced ROS generation, increased epidermal thickness, mast cell number, MPO activity, enhanced expression of COX-2 and iNOS, MAPKs, c-jun, c-fos, NF-κB were found in BA either alone or when followed by UVB treatment, compared to the control groups. Expression of COX-2, iNOS and phosphorylation of ERK1/2 were found to be more enhanced in BA and UVB- exposed group compared to BA and UVB only group, while phosphorylation of JNK1/2, p38, NF-κB and expression of c-jun and c-fos were comparable with BA and UVB only groups. In summary, we suggest that UVB exposure enhanced BA-induced SKH-1 skin inflammation possibly via oxidative stress-mediated activation of MAPKs-NF-κB/AP-1 signalling, which subsequently increased the expression of COX-2 and iNOS and led to inflammation in SKH-1 mouse skin.