Developmental estrogen exposure in mice disrupts uterine epithelial cell differentiation and causes adenocarcinoma via Wnt/ß-catenin and PI3K/AKT signaling.

Tissue development entails genetically programmed differentiation of immature cell types to mature, fully differentiated cells. Exposure during development to non-mutagenic environmental factors can contribute to cancer risk, but the underlying mechanisms are not understood. We used a mouse model of endometrial adenocarcinoma that results from brief developmental exposure to an estrogenic chemical, diethylstilbestrol (DES), to determine causative factors. Single-cell RNA sequencing (scRNAseq) and spatial transcriptomics of adult control uteri revealed novel markers of uterine epithelial stem cells (EpSCs), identified distinct luminal and glandular progenitor cell (PC) populations, and defined glandular and luminal epithelium (LE) cell differentiation trajectories. Neonatal DES exposure disrupted uterine epithelial cell differentiation, resulting in a failure to generate an EpSC population or distinguishable glandular and luminal progenitors or mature cells. Instead, the DES-exposed epithelial cells were characterized by a single proliferating PC population and widespread activation of Wnt/ß-catenin signaling. The underlying endometrial stromal cells had dramatic increases in inflammatory signaling pathways and oxidative stress. Together, these changes activated phosphoinositide 3-kinase/AKT serine-threonine kinase signaling and malignant transformation of cells that were marked by phospho-AKT and the cancer-associated protein olfactomedin 4. Here, we defined a mechanistic pathway from developmental exposure to an endocrine disrupting chemical to the development of adult-onset cancer. These findings provide an explanation for how human cancers, which are often associated with abnormal activation of PI3K/AKT signaling, could result from exposure to environmental insults during development.

WNK1 is required during male pachynema to sustain fertility.

WNK1 is an important regulator in many physiological functions, yet its role in male reproduction is unexplored. In the male germline, WNK1 is upregulated in preleptotene spermatocytes indicating possible function(s) in spermatogenic meiosis. Indeed, deletion of Wnk1 in mid-pachytene spermatocytes using the Wnt7a-Cre mouse led to male sterility which resembled non-obstructive azoospermia in humans, where germ cells failed to complete spermatogenesis and produced no sperm. Mechanistically, we found elevated MTOR expression and signaling in the Wnk1-depleted spermatocytes. As MTOR is a central mediator of translation, we speculated that translation may be accelerated in these spermatocytes. Supporting this, we found the acrosome protein, ACRBP to be prematurely expressed in the spermatocytes with Wnk1 deletion. Our study uncovered an MTOR-regulating factor in the male germline with potential implications in translation, and future studies will aim to understand how WNK1 regulates MTOR activity and impact translation on a broader spectrum.

Chromatin architectural factor CTCF is essential for progesterone-dependent uterine maturation.

Receptors for estrogen and progesterone frequently interact, via Cohesin/CTCF loop extrusion, at enhancers distal from regulated genes. Loss-of-function CTCF mutation in >20% of human endometrial tumors indicates its importance in uterine homeostasis. To better understand how CTCF-mediated enhancer-gene interactions impact endometrial development and function, the Ctcf gene was selectively deleted in female reproductive tissues of mice. Prepubertal Ctcfd/d uterine tissue exhibited a marked reduction in the number of uterine glands compared to those without Ctcf deletion (Ctcff/f mice). Post-pubertal Ctcfd/d uteri were hypoplastic with significant reduction in both the amount of the endometrial stroma and number of glands. Transcriptional profiling revealed increased expression of stem cell molecules Lif, EOMES, and Lgr5, and enhanced inflammation pathways following Ctcf deletion. Analysis of the response of the uterus to steroid hormone stimulation showed that CTCF deletion affects a subset of progesterone-responsive genes. This finding indicates (1) Progesterone-mediated signaling remains functional following Ctcf deletion and (2) certain progesterone-regulated genes are sensitive to Ctcf deletion, suggesting they depend on gene-enhancer interactions that require CTCF. The progesterone-responsive genes altered by CTCF ablation included Ihh, Fst, and Errfi1. CTCF-dependent progesterone-responsive uterine genes enhance critical processes including anti-tumorigenesis, which is relevant to the known effectiveness of progesterone in inhibiting progression of early-stage endometrial tumors. Overall, our findings reveal that uterine Ctcf plays a key role in progesterone-dependent expression of uterine genes underlying optimal post-pubertal uterine development.

Scientific and Regulatory Policy Committee Points to Consider: Primary Digital Histopathology Evaluation and Peer Review for Good Laboratory Practice (GLP) Nonclinical Toxicology Studies.

The Society of Toxicologic Pathology's Scientific and Regulatory Policy Committee formed a working group to consider the present and future use of digital pathology in toxicologic pathology in general and specifically its use in primary evaluation and peer review in Good Laboratory Practice (GLP) environments. Digital histopathology systems can save costs by reducing travel, enhancing organizational flexibility, decreasing slide handling, improving collaboration, increasing access to historical images, and improving quality and efficiency through integration with laboratory information management systems. However, the resources to implement and operate a digital pathology system can be significant. Given the magnitude and risks involved in the decision to adopt digital histopathology, this working group used pertinent previously published survey results and its members' expertise to create a Points-to-Consider article to assist organizations with building and implementing digital pathology workflows. With the aim of providing a comprehensive perspective, the current publication summarizes aspects of digital whole-slide imaging relevant to nonclinical histopathology evaluations, and then presents points to consider applicable to both primary digital histopathology evaluation and digital peer review in GLP toxicology studies. The Supplemental Appendices provide additional tabulated resources.

Scientific and Regulatory Policy Committee Brief Communication: 2019 Survey on Use of Digital Histopathology Systems in Nonclinical Toxicology Studies.

Histopathologic evaluation and peer review using digital whole-slide images (WSIs) is a relatively new medium for assessing nonclinical toxicology studies in Good Laboratory Practice (GLP) environments. To better understand the present and future use of digital pathology in nonclinical toxicology studies, the Society of Toxicologic Pathology (STP) formed a working group to survey STP members with the goal of creating recommendations for implementation. The survey was administered in December 2019, immediately before the COVID-19 pandemic, and the results suggested that the use of digital histopathology for routine GLP histopathology assessment was not widespread. Subsequently, in follow-up correspondence during the pandemic, many responding institutions either began investigating or adopting digital WSI systems to reduce employee exposure to COVID-19. Therefore, the working group presents the survey results as a pre-pandemic baseline data set. Recommendations for use of WSI systems in GLP environments will be the subject of a separate publication.

Whole-body inhalation exposure to 2-ethyltoluene for two weeks produced nasal lesions in rats and mice.

OBJECTIVE: Ethyltoluenes are isolated during crude oil refinement for use in gasoline and commercial products and are ubiquitous in the environment. However, minimal toxicity data are available. Previously, we identified 2-ethyltoluene (2-ET) as the most potent isomer via nose-only inhalation exposure in rodents. Here, we expanded the hazard characterization of 2-ET in two rodent models using whole-body inhalation exposure and evaluated the role of prenatal exposure. METHODS: Time-mated Hsd:Sprague Dawley® SD® rats were exposed to 0, 150, 300, 600, 900, or 1200 ppm 2-ET via inhalation starting on gestation day 6 until parturition. Rat offspring (n = 8/exposure/sex) were exposed to the same concentrations as the respective dams for 2 weeks after weaning. Adult male and female B6C3F1/N mice (n = 5/exposure/sex) were exposed to the same concentrations for 2 weeks. RESULTS AND DISCUSSION: Exposure to ≥600 ppm 2-ET produced acute toxicity in rats and mice characterized by large decreases in survival, body weight, adverse clinical observations, and diffuse nasal olfactory epithelium degeneration (rats) or necrosis (mice). Due to the early removal of groups ≥600 ppm, most endpoint evaluations focused on lower exposure groups. In 150 and 300 ppm exposure groups, reproductive performance and littering were not significantly changed and body weights in exposed rats and mice were 9-18% lower than controls. Atrophy of the olfactory epithelium and nerves was observed in all animals exposed to 150 and 300 ppm. These lesions were more severe in mice than in rats. CONCLUSION: Nasal lesions were observed in all animals after whole-body exposure up to 600 ppm 2-ET for 2 weeks. Future studies should focus on 2-ET metabolism and distribution to better understand species differences and refine hazard characterization of this understudied environmental contaminant.

Phthalate Toxicity in Rats and Its Relation to Testicular Dysgenesis Syndrome in Humans.

This work describes the relevance of toxicology studies of environmental chemicals, with a focus on phthalates, for a hypothesis that certain human male reproductive disorders and diseases have a common etiology of disturbance of normal development in utero. The "Testicular Dysgenesis Syndrome" hypothesis in humans has parallels in male reproductive tract abnormalities and microscopic lesions reported for phthalate toxicity in rats. Additionally, this work describes the histological findings of abnormal testicular development (testicular dysgenesis) in rats as compared to those in humans, as well as potential findings in rats at different ages, from the embryo to the adult.

Phase II, Double-Blind, Vehicle-Controlled Study to Determine the Cantharidin Dose Regimen, Efficacy, Safety, and Tolerability of VP-102 in Subjects with External Genital Warts.

BACKGROUND: External genital warts are caused by various subtypes of the human papilloma virus and spread through direct skin-to-skin contact. Approximately 1% of the US population have external genital warts. Although cantharidin has been used to treat external genital warts for decades, there are no US Food and Drug Administration-approved cantharidin products and no reliable or controlled sources of cantharidin available. VP-102 is a drug-device combination product containing cantharidin (0.7% w/v) in a single-use shelf-stable applicator. OBJECTIVE: The objective of this randomized, double-blind, vehicle-controlled, phase II clinical trial was to determine the optimal regimen for the treatment, safety, and efficacy of VP-102 in external genital warts. METHODS: The study was conducted in two parts. Part A was dose finding and Part B was performed following the completion of Part A for a safety and efficacy evaluation. Following completion of Part A, 6-h and 24-h VP-102 regimens under occlusion were selected to be evaluated in Part B. RESULTS: Pooled results from Part B and Part A of the 6-h and 24-h VP-102 treatment regimens showed that 36.7% and 33.3% of participants achieved complete clearance of all treatable external genital warts at the end of treatment vs 4.2% (p < 0.0048) and 0% (p < 0.0075) with the vehicle. Adverse events experienced by the VP-102-treated participants were consistent with the pharmacodynamic action of cantharidin as a vesicant and were primarily mild to moderate in severity. The most common adverse events included application-site vesicles, pain, and erythema. No participants discontinued the study because of adverse events and no serious adverse events were deemed treatment related. CONCLUSIONS: The adverse event profile and efficacy of VP-102 under occlusion demonstrated in this study support the conclusion that a 6-h or up to 24-h exposure regimen represents an acceptable risk:benefit profile and justifies the conduct of a larger vehicle-controlled phase III study in external genital warts. CLINICAL TRIAL REGISTRATION: NCT03981822, actual study start date: 25 June, 2019; actual primary completion date: 21 May, 2020; actual study completion date: 8 July, 2020.

COVE-1: A Phase 2, Open-Label Study to Evaluate Efficacy and Safety and the Optimal Regimen of VP-102, a Proprietary Drug-Device Product Containing Topical Cantharidin (0.7% w/v) Under Occlusion for the Treatment of Common Warts.

INTRODUCTION: Verrucae vulgaris, or common warts, is a common skin condition for which there is no US Food and Drug Administration-approved treatment. Compounded cantharidin has been used to treat warts for years but lacks a controlled formulation, consistent application schedule and methods, and robust safety and efficacy studies. VP-102 is a proprietary drug-device combination product containing a topical formulation of 0.7% (w/v) cantharidin in a single-use delivery device. This objective of the phase 2 study was to evaluate the efficacy, safety, tolerability, and optimal regimen of VP-102 in the treatment of common warts. METHODS: In this open-label trial, participants aged ≥ 2 years with one to six common warts were administered VP-102 topically to treatable common warts once every 14 days (Cohort 1) or once every 21 days in conjunction with paring (Cohort 2), for up to four treatments. Participants were evaluated through to day 84 (Cohort 1) or day 147 (Cohort 2). The primary endpoint was the percentage of participants with complete clearance of all treatable common warts (baseline and new) at day 84. Secondary endpoints included percentage of participants achieving complete clearance of all treatable common warts at other visits. Safety assessments included treatment-emergent adverse events (TEAEs), including local skin reactions (LSRs). RESULTS: A total of 21 and 35 participants were enrolled in Cohort 1 and Cohort 2, respectively. Complete clearance at day 84 was seen in 19.0% of participants in Cohort 1 and 51.4% of those in Cohort 2. The most common TEAEs were expected LSRs and included application site vesicles, pain, pruritus, erythema, and scab. Most LSRs were mild or moderate in severity. CONCLUSION: VP-102 showed efficacy in complete clearance of common warts from baseline to day 84, as well as at follow-up visits. Due to the higher percentage of patients exhibiting complete clearance in Cohort 2, the treatment regimen of Cohort 2 will be pursued in future studies. TEAEs were expected due to the pharmacodynamic action of cantharidin, a vesicant. Clinical Trials ID: NCT03487549.

Pooled Results of Two Randomized Phase III Trials Evaluating VP-102, a Drug-Device Combination Product Containing Cantharidin 0.7% (w/v) for the Treatment of Molluscum Contagiosum.

BACKGROUND: Compounded cantharidin has been used for decades to treat molluscum contagiosum but lacks rigorous clinical evidence to support its safety and efficacy. VP-102 is a shelf-stable drug-device combination product that contains topical cantharidin (0.7% weight/volume [w/v]) and is being evaluated for the treatment of molluscum. OBJECTIVES: Our objective was to present pooled safety and efficacy analyses of VP-102 in the treatment of molluscum compared with vehicle. METHODS: Participants aged ≥ 2 years were randomized 3:2 to topical administration of VP-102 or vehicle in two randomized, double-blind, vehicle-controlled phase III trials. Study drug was applied to all baseline and new lesions once every 21 days until clear or for a maximum of four applications. Assessors blinded to treatment counted all lesions at each study visit. All adverse events (AEs) were documented. Data were pooled for analyses. RESULTS: In total, 310 participants received VP-102 and 218 received vehicle. Mean age was 7.5 years (range 2-60) for VP-102 and 6.8 (2-54) for vehicle. Complete clearance of all molluscum lesions at day 84 occurred in 50% of VP-102 participants and 15.6% of vehicle recipients (p < 0.0001). Mean molluscum lesion counts decreased 76% for VP-102 and 0.3% for vehicle at day 84 (p < 0.0001). The most common AEs in the VP-102 group were application site blistering, pruritus, pain, and erythema, which were generally mild or moderate in severity. CONCLUSIONS: Pooled analyses showed a significantly higher percentage of participants with complete molluscum lesion clearance and larger reductions in lesion counts with VP-102 than with vehicle. AEs were anticipated because of the pharmacodynamic properties of cantharidin. TRIAL REGISTRATION: ClinicalTrials.gov identifiers: NCT03377790 (first posted 19 December 2017) and NCT03377803 (first posted 19 December 2017). Video abstract: Pooled Results of Two Randomized Phase III Trials Evaluating VP 102, a Drug Device Combination Product Containing Cantharidin 0.7% (w/v) for the Treatment of Molluscum Contagiosum (MP4 131293 KB).

A Phase 2 Open-Label Study to Evaluate VP-102 for the Treatment of Molluscum Contagiosum.

BACKGROUND: This Phase 2, open-label study evaluated the safety, efficacy, systemic exposure, and impact on quality of life (QoL) with treatment using VP-102, a drug-device combination containing cantharidin (0.7% w/v) in subjects with molluscum contagiosum (MC). STUDY DESIGN: Pediatric subjects with MC (2–15 years of age) were eligible to enroll in this 12-week study. MC lesions were treated topically with VP-102 every 21 days until clearance (maximum of 4 treatments). Adverse events (AEs) and QoL outcomes (using the Children's Quality of Life Index, CDLQI) were documented at each visit. Rate of complete clearance and the percent reduction in lesions were measured at each visit on days 21, 42, 63, and 84 (end of study [EOS] visit). A group of 17 subjects with at least 21 MC lesions was evaluated for systemic cantharidin exposure via plasma samples obtained before the first application of VP-102, and at 2 hours, 6 hours, and 24 hours post-application. RESULTS: A total of 33 subjects enrolled in the study (n=17 systemic exposure group, n=16 standard group). There were an equal number of male and female subjects. Subject mean (SD, range) age was 6.7 (3.3, 2–15) years, with a mean lesion count of 30 (26.1, 3–113). Complete lesion clearance was achieved in 48.5% of subjects, with a 90.4% reduction in lesions from baseline to the EOS visit. Mean CDLQI score decreased from 2.6 at baseline to 0.38 at the EOS visit. AEs were mild to moderate in severity and expected due to the pharmacodynamic action of cantharidin. There were no serious treatment-related adverse events and no study discontinuations due to treatment. In the systemic exposure group plasma cantharidin levels were below the lower limit of quantitation (LLOQ, 2.5 ng/mL) in 65 of 66 samples. CONCLUSIONS: VP-102 treatment resulted in a reduction in lesion counts and improved QoL. Treated subjects had a 48.5% rate of complete clearance of molluscum lesions. Negligible systemic cantharidin exposure was observed in the systemic exposure group. This data demonstrates safety and efficacy of treatment with VP-102 in MC; a widespread viral infection that does not have any current FDA-approved treatments. Significant Finding: Treatment of subjects with MC using VP-102 resulted in negligible systemic cantharidin exposure, as well as a reduction in lesion counts, improved QoL, and a demonstrated efficacy in clearance of new and baseline MC lesions. Meaning: Results of this Phase 2 study demonstrate efficacy and safety outcomes in using VP-102 in MC subjects, and large randomized clinical trials are warranted to compare topical VP-102 with a vehicle control in order to fully evaluate the use of the medication. ClinicalTrials.gov identifier: NCT03186378 J Drugs Dermatol. 2021;20(1):70-75. doi:10.36849/JDD.5626.

Constitutive expression of progesterone receptor isoforms promotes the development of hormone-dependent ovarian neoplasms.

Differences in the relative abundances of the progesterone receptor (PGR) isoforms PGRA and PGRB are often observed in women with reproductive tract cancers. To assess the importance of the PGR isoform ratio in the maintenance of the reproductive tract, we generated mice that overexpress PGRA or PGRB in all PGR-positive tissues. Whereas few PGRA-overexpressing mice developed reproductive tract tumors, all PGRB-overexpressing mice developed ovarian neoplasms that were derived from ovarian luteal cells. Transcriptomic analyses of the ovarian tumors from PGRB-overexpressing mice revealed enhanced AKT signaling and a gene expression signature similar to those of human ovarian and endometrial cancers. Treating PGRB-overexpressing mice with the PGR antagonist RU486 stalled tumor growth and decreased the expression of cell cycle-associated genes, indicating that tumor growth and cell proliferation were hormone dependent in addition to being isoform dependent. Analysis of the PGRB cistrome identified binding events at genes encoding proteins that are critical regulators of mitotic phase entry. This work suggests a mechanism whereby an increase in the abundance of PGRB relative to that of PGRA drives neoplasia in vivo by stimulating cell cycling.

Safety and Efficacy of VP-102, a Proprietary, Drug-Device Combination Product Containing Cantharidin, 0.7% (w/v), in Children and Adults With Molluscum Contagiosum: Two Phase 3 Randomized Clinical Trials.

Importance: Molluscum contagiosum (MC) is a common viral skin infection that primarily affects children. Cantharidin, a topical vesicant, has a long history of use for MC in compounded formulations, but the safety and efficacy of doses, regimens, and application methods have not been demonstrated in large-scale trials. Objective: To determine the safety and efficacy of VP-102, a drug-device combination containing cantharidin, 0.7% (w/v), compared with vehicle in individuals with MC. Design, Setting, and Participants: Two phase 3, randomized, double-blind, vehicle-controlled trials of identical design (Cantharidin Application in Molluscum Patients [CAMP-1 and CAMP-2]) were conducted in 31 centers across the US. A total of 528 individuals aged 2 years or older with MC participated. CAMP-1 was conducted from March 21 to November 26, 2018, and CAMP-2 was conducted from February 14 to September 26, 2018. Interventions: Participants were randomized (3:2) to topical application of VP-102 or vehicle to all treatable lesions every 21 days until complete lesion clearance or up to 4 treatments. Main Outcomes and Measures: The primary efficacy outcome was the proportion of VP-102-treated participants achieving complete clearance of all MC lesions (baseline and new) compared with those who received the vehicle at the end-of-study visit on day 84. Intent-to-treat analysis was conducted for the efficacy population. Secondary efficacy outcomes included the proportion of participants achieving complete clearance of lesions at days 21, 42, and 63. Safety outcomes included assessment of adverse events, including expected local skin reactions. Results: Of the 528 participants enrolled, 527 received treatment (CAMP-1, n = 265; CAMP-2, n = 262). A total of 267 of 527 participants (50.7%) were male; mean (SD) ages for CAMP-1 and CAMP-2 were 7.5 (5.3) years and 7.4 (8.0) years for the VP-102 groups and 6.3 (4.7) years and 7.3 (6.7) years for the vehicle groups. Treatment with VP-102 demonstrated superior efficacy to vehicle in the percentage of participants with complete clearance of MC lesions at the end of the study visit for CAMP-1 (VP-102: 46.3% vs vehicle: 17.9%; P < .001) and CAMP-2 (VP-102: 54.0% vs vehicle: 13.4%; P < .001). Adverse events were observed in 99% (CAMP-1) and 95% (CAMP-2) of VP-102-treated participants and 73% (CAMP-1) and 66% (CAMP-2) of vehicle-treated participants. The most common adverse events included application site vesicles, pain, pruritus, erythema, and scab. Most adverse events were mild or moderate in severity. Conclusions and Relevance: In the 2 phase 3 trials reported herein, VP-102 was statistically significantly superior to vehicle in achieving complete clearance of MC lesions at the end of the study visit in both trials, with adverse events that were generally mild to moderate and confined to application sites. These findings show that VP-102 is potentially an effective and safe treatment for MC, a common skin condition with no US Food and Drug Administration-approved treatments. Trial Registrations: ClinicalTrials.gov Identifiers: NCT03377790 and NCT03377803.

In utero exposure to arsenite contributes to metabolic and reproductive dysfunction in male offspring of CD-1 mice.

In utero exposure to arsenite (iAs) is known to increase disease risks later in life. We investigated the effect of in utero exposure to iAs in the drinking water on metabolic and reproductive parameters in male mouse offspring at postnatal and adult stages. Pregnant CD-1 mice were exposed to iAs (as sodium arsenite) in the drinking water at 0 (control), 10 ppb (EPA standard for drinking water), and 42.5 ppm (tumor-inducing dose in mice) from embryonic day (E) 10-18. At birth, pups were fostered to unexposed females. Male offspring exposed to 10 ppb in utero exhibited increase in body weight at birth when compared to controls. Male offspring exposed to 42.5 ppm in utero showed a tendency for increased body weight and a smaller anogenital distance. The body weight in iAs-exposed pups continued to increase significantly compared to control at 3 weeks and 11 weeks of age. At 5 months of age, iAs-exposed males exhibited greater body fat content and glucose intolerance. Male offspring exposed to 10 ppb in utero had higher circulating levels of leptin compared to control. In addition, males exposed to 42.5 ppm in utero exhibited decreased total number of pups born compared to controls and lower average number of litters sired over a six-month period. These results indicate that in utero exposure to iAs at either human relevant concentration or tumor-inducing concentration is a potential cause of developmental origin of metabolic and reproductive dysfunction in adult male mice.

Multigenerational reproductive assessment of 4-methylimidazole administered in the diet to Hsd:Sprague Dawley SD rats.

The general population, including children and adolescents, is exposed to 4-methylimidazole (4-MI) in the diet. 4-MI is a by-product of caramel color manufacturing. It has been previously classified as a possible human carcinogen and displays potential reproductive toxicity. A follow up assessment of reproductive toxicity was conducted in rats utilizing the reproductive assessment by continuous breeding paradigm, in which multiple generations were exposed to 4-MI in diet at 750, 2500, and 5000 ppm. 4-MI exposure was associated with delays in preputial separation and vaginal opening, impairment in reproductive performance, and concomitant histopathological findings in the prostate, testis, and epididymis at 2500 and 5000 ppm. The Lowest Observed Adverse Effect Level for reproductive (based on prostate atrophy) and developmental toxicity (based on delays in preputial separation and vaginal opening) was 750 ppm, equivalent to approximately 50-60 mg/kg bw/day.

Noncanonical autophagy in dermal dendritic cells mediates immunosuppressive effects of UV exposure.

BACKGROUND: Control of the inflammatory response is critical to maintaining homeostasis, and failure to do so contributes to the burden of chronic inflammation associated with several disease states. The mechanisms that underlie immunosuppression, however, remain largely unknown. Although defects in autophagy machinery have been associated with inflammatory pathologic conditions, we now appreciate that autophagic components participate in noncanonical pathways distinct from classical autophagy. We have previously demonstrated that LC3-associated phagocytosis (LAP), a noncanonical autophagic process dependent on Rubicon (rubicon autophagy regulator [RUBCN]), contributes to immunosuppression. OBJECTIVE: We used Rubcn-/- mice to examine the role of the LAP pathway in mediating the UV-induced immunotolerant program in a model of contact hypersensitivity (CHS). METHODS: Flow cytometry and transcriptional analysis were used to measure immune cell infiltration and activation in the skin of Rubcn+/+ and Rubcn-/- mice during the CHS response. RESULTS: Here, we demonstrate that LAP is required for UV-induced immunosuppression and that UV exposure induces a broadly anti-inflammatory transcriptional program dependent on Rubicon. Rubcn-/- mice are resistant to UV-induced immunosuppression and instead display exaggerated inflammation in a model of CHS. Specifically, RUBCN deficiency in CD301b+ dermal dendritic cells results in their increased antigen presentation capacity and subsequent hyperactivation of the CD8+ T-cell response. CONCLUSIONS: LAP functions to limit the immune response and is critical in maintaining the balance between homeostasis and inflammation.

Proceedings of the 2019 National Toxicology Program Satellite Symposium.

The 2019 annual National Toxicology Program Satellite Symposium, entitled "Pathology Potpourri," was held in Raleigh, North Carolina, at the Society of Toxicologic Pathology's 38th annual meeting. The goal of this symposium was to present and discuss challenging diagnostic pathology and/or nomenclature issues. This article presents summaries of the speakers' talks along with select images that were used by the audience for voting and discussion. Various lesions and topics covered during the symposium included aging mouse lesions from various strains, as well as the following lesions from various rat strains: rete testis sperm granuloma/fibrosis, ovarian cystadenocarcinoma, retro-orbital schwannoma, periductal cholangiofibrosis of the liver and pancreas, pars distalis hypertrophy, chronic progressive nephropathy, and renal tubule regeneration. Other cases included polyovular follicles in young beagle dogs and a fungal blood smear contaminant. One series of cases challenged the audience to consider how immunohistochemistry may improve the diagnosis of some tumors. Interesting retinal lesions from a rhesus macaque emphasized the difficulty in determining the etiology of any particular retinal lesion due to the retina's similar response to vascular injury. Finally, a series of lesions from the International Harmonization of Nomenclature and Diagnostic Criteria Non-Rodent Fish Working Group were presented.

National Toxicology Program Position Statement on Informed ("Nonblinded") Analysis in Toxicologic Pathology Evaluation.

The National Toxicology Program (NTP) uses histopathological evaluation of animal tissues as a key element in its toxicity and carcinogenicity studies. The initial histopathological evaluations are subjected to a rigorous peer review process involving several steps. The NTP peer review process is conducted by multiple, highly trained, and experienced toxicological pathologists employing standardized terminology. In addition, ancillary data, such as body and organ weights and clinical pathology findings, are used to corroborate the diagnoses. The NTP does employ masked analysis to confirm subtle lesions or severity scores, as needed, and during its Pathology Working Groups. The use of masked analysis can have a negative effect on histopathological evaluation because it is important for the pathologist to compare treated groups to the concurrent controls, which would not be possible in a blinded evaluation. Therefore, the NTP supports an informed approach to histopathological evaluation in its toxicity and carcinogenicity studies.

ERBB2 Regulates MED24 during Cancer Progression in Mice with Pten and Smad4 Deletion in the Pulmonary Epithelium.

ERBB2 is an oncogenic driver with frequent gene mutations and amplification in human lung tumors and is an attractive target for lung cancer therapy. However, target therapies can be improved by understanding the in vivo mechanisms regulated by ERBB2 during lung tumor development. Here, we generated genetic mouse models to show that Erbb2 loss inhibited lung tumor development induced by deletion of Pten and Smad4. Transcriptome analysis showed that Erbb2 loss suppressed the significant changes of most of the induced genes by ablation of Pten and Smad4. Overlapping with ERBB2-associated human lung cancer genes further identified those ERBB2 downstream players potentially conserved in human and mouse lung tumors. Furthermore, MED24 was identified as a crucial oncogenic target of ERBB2 in lung tumor development. Taken together, ERBB2 is required for the dysregulation of cancer-related genes, such as MED24, during lung tumor development.