Conserved long noncoding RNA TILAM promotes liver fibrosis through interaction with PML in HSCs.

BACKGROUND AND AIMS: Fibrosis is the common end point for all forms of chronic liver injury, and the progression of fibrosis leads to the development of end-stage liver disease. Activation of HSCs and their transdifferentiation into myofibroblasts results in the accumulation of extracellular matrix proteins that form the fibrotic scar. Long noncoding RNAs regulate the activity of HSCs and provide targets for fibrotic therapies. APPROACH AND RESULTS: We identified long noncoding RNA TILAM located near COL1A1 , expressed in HSCs, and induced with liver fibrosis in humans and mice. Loss-of-function studies in human HSCs and human liver organoids revealed that TILAM regulates the expression of COL1A1 and other extracellular matrix genes. To determine the role of TILAM in vivo, we annotated the mouse ortholog ( Tilam ), generated Tilam- deficient green fluorescent protein-reporter mice, and challenged these mice in 2 different models of liver fibrosis. Single-cell data and analysis of single-data and analysis of Tilam-deficient reporter mice revealed that Tilam is induced in murine HSCs with the development of fibrosis in vivo. Tilam -deficient reporter mice revealed that Tilam is induced in murine HSCs with the development of fibrosis in vivo. Furthermore, loss of Tilam expression attenuated the development of fibrosis in the setting of in vivo liver injury. Finally, we found that TILAM interacts with promyelocytic leukemia nuclear body scaffold protein to regulate a feedback loop by which TGF-ß2 reinforces TILAM expression and nuclear localization of promyelocytic leukemia nuclear body scaffold protein to promote the fibrotic activity of HSCs. CONCLUSIONS: TILAM is activated in HSCs with liver injury and interacts with promyelocytic leukemia nuclear body scaffold protein to drive the development of fibrosis. Depletion of TILAM may serve as a therapeutic approach to combat the development of end-stage liver disease.

Integrins in biliary injury and fibrosis.

PURPOSE OF REVIEW: Current treatment options for cholangiopathies are severely limited and there is thus a critical need to identify and develop therapies. This review discusses the role of integrins in biliary injury and fibrosis and their potential as therapeutic targets. RECENT FINDINGS: There are a diverse set of roles that integrins play in biliary injury and fibrosis. Some integrins activate TGF-ß signaling or are involved in sensing of the extracellular matrix, making them attractive targets for biliary fibrosis. In recent work, autoantibodies to α v ß 6 were identified in patients with PSC, supporting the relevance of this integrin in the disease. In addition, a role for α 2 ß 1 in cyst formation was identified in a mouse model of polycystic liver disease. Leukocyte integrins (e.g. α E ß 7 and α 4 ß 7 ) contribute to lymphocyte trafficking, making them potential targets for biliary inflammation; however, this has not yet translated to the clinic. SUMMARY: While all members of the same family of proteins, integrins have diverse roles in the pathogenesis of biliary disease. Targeting one or multiple of these integrins may slow or halt the progression of biliary injury and fibrosis by simultaneously impacting different pathologic cells and processes.

Telehepatology Satisfaction Is Associated with Ethnicity: The Real-World Experience of a Vulnerable Population with Fatty Liver Disease.

BACKGROUND: Since the coronavirus disease 2019 (COVID-19) pandemic began, telemedicine use has transformed healthcare delivery. Yet there is concern that telemedicine may widen care disparities for vulnerable populations, and patient experience data are limited. AIMS: We aimed to assess patient satisfaction with hepatology-related telemedicine (telehepatology) for delivery of fatty liver disease (FLD) care in a safety-net healthcare system. METHODS: Adult patients with FLD were surveyed regarding satisfaction with telehepatology. Clinical, demographic, resources, and social determinants of health (SDoH) data were collected to identify factors associated with satisfaction through multivariable modeling. RESULTS: From June 2020 to March 2022, 220 participants were enrolled: the median age was 52 years, 37% were men, and 68% were Hispanic. One hundred nineteen (54%) had prior telehepatology experience. Overall, satisfaction was high; 70% reported being somewhat or very satisfied. On univariate analysis, Hispanic ethnicity (versus non-Hispanic, OR 0.34, 95% CI 0.1-0.9, p = 0.03) and limited access to personal cellphone/internet (OR 0.16, 95% CI 0.04-0.6, p = 0.01) were associated with lower satisfaction. On multivariable logistic regression modeling adjusted for pandemic duration, age, sex, severity of liver disease, and coexisting liver disease, Hispanic ethnicity and lack of personal cellphone/internet remained independently associated with lower telehepatology satisfaction (OR 0.24, 95% CI 0.07-0.9, p = 0.03 and OR 0.2, 95% CI 0.04-0.9, p = 0.04, respectively). The association remained statistically significant after inclusion of various SDoH in the multivariable model. CONCLUSIONS: Satisfaction with telehepatology among FLD patients in a safety-net clinical setting was high overall. However, Hispanic ethnicity and lack of personal cellphone/internet were independently associated with lower telehepatology satisfaction. A better understanding of patients' experience with telehepatology is needed to identify reasons for dissatisfaction, and in-person visits should remain an option for patients to ensure equitable care.

Examining the feasibility of a "top-down" approach to enhancing the keratinocyte-implant adhesion.

The adhesion of human epidermal keratinocytes to the implant surface is one of the most critical steps during the patient's recovery from implantation of transcutaneous prosthesis. To improve the success rate of transcutaneous prosthetic implants, we explored a new "top-down" approach to promoting this dynamic adhering process through modulation of upstream cell signaling pathways. To examine the feasibility of this novel approach, we first established an in vitro platform that is capable of providing a non-invasive, real-time, quantitative characterization of the keratinocyte-implant interaction. This platform is based on the dissipation monitoring function of the quartz crystal microbalance with dissipation monitoring (QCM-D) in conjunction with the open-module setup of the QCM-D. We then employed this platform to assess the effects of various pathways-specific modulators on the adhering process of keratinocytes. We demonstrated that this "top-down" approach is as effective in enhancing the adhesion of keratinocytes as the conventional "bottom-up" approach that relies on modifying the substrate surface with the adhesion protein such as fibronectin. We envision that this new "top-down" approach combined with the QCM-D-based in vitro platform will help facilitate the future development of new therapies for enhancing osseointegration and promoting wound healing.

On the Measurement of Energy Dissipation of Adhered Cells with the Quartz Microbalance with Dissipation Monitoring.

We previously reported the finding of a linear correlation between the change of energy dissipation (Δ D) of adhered cells measured with the quartz crystal microbalance with dissipation monitoring (QCM-D) and the level of focal adhesions of the cells. To account for this correlation, we have developed a theoretical framework for assessing the Δ D-response of adhered cells. We rationalized that the mechanical energy of an oscillating QCM-D sensor coupled with a cell monolayer is dissipated through three main processes: the interfacial friction through the dynamic restructuring (formation and rupture) of cell-extracellular matrix (ECM) bonds, the interfacial viscous damping by the liquid trapped between the QCM-D sensor and the basal membrane of the cell layer, and the intracellular viscous damping through the viscous slip between the cytoplasm and stress fibers as well as among stress fibers themselves. Our modeling study shows that the interfacial viscous damping by the trapped liquid is the primary process for energy dissipation during the early stage of the cell adhesion, whereas the dynamic restructuring of cell-ECM bonds becomes more prevalent during the later stage of the cell adhesion. Our modeling study also establishes a positive linear correlation between the Δ D-response and the level of cell adhesion quantified with the number of cell-ECM bonds, which corroborates our previous experimental finding. This correlation with a wide well-defined linear dynamic range provides a much needed theoretical validation of the dissipation monitoring function of the QCM-D as a powerful quantitative analytical tool for cell study.

AMPK stimulation inhibits YAP/TAZ signaling to ameliorate hepatic fibrosis.

Hepatic fibrosis is driven by the activation of hepatic stellate cells (HSCs). The Hippo pathway and its effectors, YAP and TAZ, are key regulators of HSC activation and fibrosis. However, there is a lack of mechanistic understanding of YAP/TAZ regulation in HSCs. Here we show that AMPK activation leads to YAP/TAZ inhibition and HSC inactivation in vitro, while the expression of a kinase-inactive mutant reversed these effects compared to wild type AMPKɑ1. Notably, the depletion of LATS1/2, an upstream kinase of YAP/TAZ signaling, rescues YAP/TAZ activation, suggesting that AMPK may be mediating YAP/TAZ inhibition via LATS1/2. In the carbon tetrachloride mouse model of fibrosis, pharmacologic activation of AMPK in HSCs inhibits YAP/TAZ signaling and reduces fibrosis. The findings implicate AMPK as a critical regulator of YAP/TAZ signaling and HSC inactivation and highlight AMPK activation as a therapeutic target for the treatment of hepatic fibrosis.

Eosinophilic gastritis in adult complicated by gastric ulcer perforation.

Eosinophilic gastritis is a rare type of eosinophilic gastrointestinal diseases. Patients with eosinophilic gastritis usually present with symptoms such as nausea, emesis, abdominal pain, and weight loss. In severe cases, patients can suffer rare complications such as gastric outlet obstruction and spontaneous perforation. Here, we present the case of a young adult male who presented with acute onset abdominal pain for 1 day. The patient was found to have significant mural thickening of gastric antrum with pneumoperitoneum on abdominal CT scan, consistent with a perforated gastric ulcer. The patient underwent exploratory laparotomy and required modified graham patch repair. The diagnosis of eosinophilic gastritis was made based on the pathology review of intraoperative endoscopic biopsy specimens.

Problematic alcohol use and its impact on liver disease quality of life in a multicenter study of patients with cirrhosis.

BACKGROUND: Management of cirrhosis is challenging and has been complicated by the COVID-19 pandemic due to decreased access to care, increased psychological distress, and alcohol misuse. Recently, The National Institute on Alcohol Abuse and Alcoholism has broadened the definition of recovery from alcohol use disorder to include quality of life (QoL) as an indicator of recovery. This study examined the associations of alcohol-associated cirrhosis etiology and problematic drinking with liver disease QoL (LDQoL). METHODS: Patients with cirrhosis (N=329) were recruited from 3 sites (63% from 2 Veterans Affairs Health Care Systems and 37% from 1 safety net hospital) serving populations that are economically or socially marginalized. Cirrhosis etiology was ascertained by chart review of medical records. Problematic drinking was defined by ≥8 on the Alcohol Use Disorders Identification Test. Multivariable general linear modeling adjusting for age, sex, race/ethnicity, site, pandemic-related stress, and history of anxiety/depressive disorder were conducted. Sensitivity analyses further adjusted for indicators of liver disease severity. RESULTS: Participants were on average 64.6 years old, 17% female, 58% non-White, 44% with alcohol-associated cirrhosis, and 17% with problematic drinking. Problematic drinking was significantly associated with worse LDQoL scores in the overall scale and in the memory/concentration and health distress subscales. These associations remained significant after adjusting for indicators of liver disease severity, including Model for End-Stage Liver Disease-Sodium score and decompensated cirrhosis status. CONCLUSIONS: Among patients with cirrhosis, problematic drinking was associated with worse LDQoL, especially in the domains of memory/concentration and health distress. Assessment and awareness of cognitive deficits and negative emotionality within the context of cirrhosis and problematic drinking may help clinicians provide better integrated care for this population.

Effects of the expression level of epidermal growth factor receptor on the ligand-induced restructuring of focal adhesions: a QCM-D study.

Epidermal growth factor receptor (EGFR) plays a major role in cell migration and invasion and is considered to be the primary source of activation of various malignant tumors. To gain insight into how elevated levels of EGFR influence cellular function, particularly cell motility, we used a quartz crystal microbalance with dissipation monitoring (QCM-D) to examine restructuring of focal adhesions in MCF-10A cells induced by epidermal growth factor. Engineered cells that overexpress epidermal growth factor receptor (EGFR) exhibited a very different kinetic profile from wildtype MCF-10A cells that have a lower level of EGFR with a higher rate for the initial disassembly of focal adhesion and a much lower rate for the later reassembly of focal adhesions. It is conceivable that these effects exhibited by EGFR-overexpressing cells may promote the initiation and maintenance of a more favorable adhesion state for cell migration. This study has demonstrated the capability of the dissipation monitoring function of the QCM-D to quantitatively assess kinetic aspects of cellular processes with a high temporal resolution and sensitivity.

Characterization of mechanical behavior of an epithelial monolayer in response to epidermal growth factor stimulation.

Cell signaling often causes changes in cellular mechanical properties. Knowledge of such changes can ultimately lead to insight into the complex network of cell signaling. In the current study, we employed a combination of atomic force microscopy (AFM) and quartz crystal microbalance with dissipation monitoring (QCM-D) to characterize the mechanical behavior of A431 cells in response to epidermal growth factor receptor (EGFR) signaling. From AFM, which probes the upper portion of an individual cell in a monolayer of cells, we observed increases in energy dissipation, Young's modulus, and hysteresivity. Increases in hysteresivity imply a shift toward a more fluid-like mechanical ordering state in the bodies of the cells. From QCM-D, which probes the basal area of the monolayer of cells collectively, we observed decreases in energy dissipation factor. This result suggests a shift toward a more solid-like state in the basal areas of the cells. The comparative analysis of these results indicates a regionally specific mechanical behavior of the cell in response to EGFR signaling and suggests a correlation between the time-dependent mechanical responses and the dynamic process of EGFR signaling. This study also demonstrates that a combination of AFM and QCM-D is able to provide a more complete and refined mechanical profile of the cells during cell signaling.

Highly active antiretroviral therapy and adverse birth outcomes among HIV-infected women in Botswana.

BACKGROUND: It is unknown whether adverse birth outcomes are associated with maternal highly active antiretroviral therapy (HAART) in pregnancy, particularly in resource-limited settings. METHODS: We abstracted obstetrical records at 6 sites in Botswana for 24 months. Outcomes included stillbirths (SBs), preterm delivery (PTD), small for gestational age (SGA), and neonatal death (NND). Among human immunodeficiency virus (HIV)-infected women, comparisons were limited to HAART exposure status at conception, and those with similar opportunities for outcomes. Comparisons were adjusted for CD4(+) lymphocyte cell count. RESULTS: Of 33,148 women, 32,113 (97%) were tested for HIV, of whom 9504 (30%) were HIV infected. Maternal HIV was significantly associated with SB, PTD, SGA, and NND. Compared with all other HIV-infected women, those continuing HAART from before pregnancy had higher odds of PTD (adjusted odds ratio [AOR], 1.2; 95% confidence interval [CI], 1.1, 1.4), SGA (AOR, 1.8; 95% CI, 1.6, 2.1) and SB (AOR, 1.5; 95% CI, 1.2, 1.8). Among women initiating antiretroviral therapy in pregnancy, HAART use (vs zidovudine) was associated with higher odds of PTD (AOR, 1.4; 95% CI, 1.2, 1.8), SGA (AOR, 1.5; 95% CI, 1.2, 1.9), and SB (AOR, 2.5; 95% CI, 1.6, 3.9). Low CD4(+) was independently associated with SB and SGA, and maternal hypertension during pregnancy with PTD, SGA, and SB. CONCLUSIONS: HAART receipt during pregnancy was associated with increased PTD, SGA, and SB.

Cellular stress in the pathogenesis of nonalcoholic steatohepatitis and liver fibrosis.

The burden of chronic liver disease is rising substantially worldwide. Fibrosis, characterized by excessive deposition of extracellular matrix proteins, is the common pathway leading to cirrhosis, and limited treatment options are available. There is increasing evidence suggesting the role of cellular stress responses contributing to fibrogenesis. This Review provides an overview of studies that analyse the role of cellular stress in different cell types involved in fibrogenesis, including hepatocytes, hepatic stellate cells, liver sinusoidal endothelial cells and macrophages.

Conserved long noncoding RNA TILAM promotes liver fibrosis through interaction with PML in hepatic stellate cells.

Background & Aims: Fibrosis is the common endpoint for all forms of chronic liver injury, and progression of fibrosis leads to the development of end-stage liver disease. Activation of hepatic stellate cells (HSCs) and their transdifferentiation to myofibroblasts results in the accumulation of extracellular matrix (ECM) proteins that form the fibrotic scar. Long noncoding (lnc) RNAs regulate the activity of HSCs and may provide targets for fibrotic therapies. Methods: We identified lncRNA TILAM as expressed near COL1A1 in human HSCs and performed loss-of-function studies in human HSCs and liver organoids. Transcriptomic analyses of HSCs isolated from mice defined the murine ortholog of TILAM . We then generated Tilam -deficient GFP reporter mice and quantified fibrotic responses to carbon tetrachloride (CCl 4 ) and choline-deficient L-amino acid defined high fat diet (CDA-HFD). Co-precipitation studies, mass spectrometry, and gene expression analyses identified protein partners of TILAM . Results: TILAM is conserved between human and mouse HSCs and regulates expression of ECM proteins, including collagen. Tilam is selectively induced in HSCs during the development of fibrosis in vivo . In both male and female mice, loss of Tilam results in reduced fibrosis in the setting of CCl 4 and CDA-HFD injury models. TILAM interacts with promyelocytic leukemia protein (PML) to stabilize PML protein levels and promote the fibrotic activity of HSCs. Conclusion: TILAM is activated in HSCs and interacts with PML to drive the development of liver fibrosis. Depletion of TILAM may serve as a therapeutic approach to combat the development of end stage liver disease.

Extended therapy with pegylated interferon and weight-based ribavirin for HCV-HIV coinfected patients.

BACKGROUND: It is unknown whether extended treatment with pegylated interferon (PEG) and weight-based ribavirin (WBR) results in higher rates of sustained viro-logic response (SVR) among HCV-HIV coinfected patients compared with standard duration therapy. OBJECTIVE: The study aimed to measure rates of SVR among coinfected patients who received extended therapy with PEG plus WBR. METHODS: HCVHIV coinfected subjects were treated with PEG and WBR, and those who achieved early virologic response (EVR; ≥ 2 log decrease in HCV RNA from baseline or HCV RNA<600 IU/mL) at week 12 were eligible to continue treatment for 72 weeks. SVR (HCV RNA<60 IU/mL) was measured 24 weeks after treatment discontinuation. Predictors of SVR were assessed in simple and multivariate logistic regression. RESULTS: A total of 329 subjects enrolled at 36 sites. Of 184 subjects who achieved EVR, 169 entered Step 3: 89% male, 52% White, 29% Black, and 71% HCV treatment naïve. The overall SVR rate was 27% (95% CI, 22%-32%) among all subjects, and 33% (95% CI, 27%-40%) among the 223 who were HCV treatment naïve. In exploratory analyses, among 120 treatment-naïve subjects who entered Step 3, the SVR rate was 62% (95% CI, 52%-70%). In this subgroup, predictors of SVR were HCV genotype 2 or 3 (P = .03), HCV RNA <800,000 IU/mL at study entry (P = .05), and achievement of complete EVR (HCV RNA<600 IU/mL at week 12;P < .0001). CONCLUSION: Among all subjects, we observed a comparable overall SVR rate to prior studies of subjects treated for 48 weeks. Extended treatment with PEG and WBR may be beneficial to subsets of coinfected patients, specifically those who are treatment naïve and achieve complete EVR.

Controlled fabrication of functional liver spheroids with microfluidic flow cytometric printing.

Multicellular liver spheroids are 3D culture models useful in the development of therapies for liver fibrosis. While these models can recapitulate fibrotic disease, current methods for generating them via random aggregation are uncontrolled, yielding spheroids of variable size, function, and utility. Here, we report fabrication of precision liver spheroids with microfluidic flow cytometric printing. Our approach fabricates spheroids cell-by-cell, yielding structures with exact numbers of different cell types. Because spheroid function depends on composition, our precision spheroids have superior functional uniformity, allowing more accurate and statistically significant screens compared to randomly generated spheroids. The approach produces thousands of spheroids per hour, and thus affords a scalable platform by which to manufacture single-cell precision spheroids for disease modeling and high throughput drug testing.

Targeting acid ceramidase ameliorates fibrosis in mouse models of non-alcoholic steatohepatitis.

Non-alcoholic fatty liver disease (NAFLD) is a common cause of liver disease worldwide, and is characterized by the accumulation of fat in the liver. Non-alcoholic steatohepatitis (NASH), an advanced form of NAFLD, is a leading cause of liver transplantation. Fibrosis is the histologic feature most associated with liver-related morbidity and mortality in patients with NASH, and treatment options remain limited. In previous studies, we discovered that acid ceramidase (aCDase) is a potent antifibrotic target using human hepatic stellate cells (HSCs) and models of hepatic fibrogenesis. Using two dietary mouse models, we demonstrate that depletion of aCDase in HSC reduces fibrosis without worsening metabolic features of NASH, including steatosis, inflammation, and insulin resistance. Consistently, pharmacologic inhibition of aCDase ameliorates fibrosis but does not alter metabolic parameters. The findings suggest that targeting aCDase is a viable therapeutic option to reduce fibrosis in patients with NASH.

Nanchangmycin regulates FYN, PTK2, and MAPK1/3 to control the fibrotic activity of human hepatic stellate cells.

Chronic liver injury causes fibrosis, characterized by the formation of scar tissue resulting from excessive accumulation of extracellular matrix (ECM) proteins. Hepatic stellate cell (HSC) myofibroblasts are the primary cell type responsible for liver fibrosis, yet there are currently no therapies directed at inhibiting the activity of HSC myofibroblasts. To search for potential anti-fibrotic compounds, we performed a high-throughput compound screen in primary human HSC myofibroblasts and identified 19 small molecules that induce HSC inactivation, including the polyether ionophore nanchangmycin (NCMC). NCMC induces lipid re-accumulation while reducing collagen expression, deposition of collagen in the extracellular matrix, cell proliferation, and migration. We find that NCMC increases cytosolic Ca2+ and reduces the phosphorylated protein levels of FYN, PTK2 (FAK), MAPK1/3 (ERK2/1), HSPB1 (HSP27), and STAT5B. Further, depletion of each of these kinases suppress COL1A1 expression. These studies reveal a signaling network triggered by NCMC to inactivate HSC myofibroblasts and reduce expression of proteins that compose the fibrotic scar. Identification of the antifibrotic effects of NCMC and the elucidation of pathways by which NCMC inhibits fibrosis provide new tools and therapeutic targets that could potentially be utilized to combat the development and progression of liver fibrosis.

Real-time and label-free detection of cellular response to signaling mediated by distinct subclasses of epidermal growth factor receptors.

Epidermal growth factor receptors (EGFRs) have often shown two distinct binding affinities for epidermal growth factor. It is the high-affinity EGFR that is predominantly responsible for mediating the cell signaling that plays an indispensable role in cell growth, proliferation, motility, and differentiation. We applied the quartz crystal microbalance with dissipation monitoring (QCM-D) to track short-term cellular responses to EGFR signaling in human carcinoma A431 cells. Cellular responses to high- and low-affinity EGFR signaling were detected individually as well as simultaneously based on changes in mass and viscoelasticity of cells. These responses are associated with EGF-induced biological processes including the cytoskeleton remodeling and calcium influx. QCM-D provides a label-free sensor technology that can be exploited to investigate the role of high-affinity EGFR in cancer development and cancer prognosis.

Birth weight for gestational age norms for a large cohort of infants born to HIV-negative women in Botswana compared with norms for U.S.-born black infants.

BACKGROUND: Standard values for birth weight by gestational age are not available for sub-Saharan Africa, but are needed to evaluate incidence and risk factors for intrauterine growth retardation in settings where HIV, antiretrovirals, and other in utero exposures may impact birth outcomes. METHODS: Birth weight data were collected from six hospitals in Botswana. Infants born to HIV-negative women between 26-44 weeks gestation were analyzed to construct birth weight for gestational age charts. These data were compared with published norms for black infants in the United States. RESULTS: During a 29 month period from 2007-2010, birth records were reviewed in real-time from 6 hospitals and clinics in Botswana. Of these, 11,753 live infants born to HIV-negative women were included in the analysis. The median gestational age at birth was 39 weeks (1st quartile 38, 3rd quartile 40 weeks), and the median birth weight was 3100 grams (1st quartile 2800, 3rd quartile 3400 grams). We constructed estimated percentile curves for birth weight by gestational age which demonstrate increasing slope during the third trimester and leveling off beyond 40 weeks. Compared with black infants in the United States, Botswana-born infants had lower median birth weight for gestational age from weeks 37 through 42 (p < .02). CONCLUSIONS: We present birth weight for gestational age norms for Botswana, which are lower at term than norms for black infants in the United States. These findings suggest the importance of regional birth weight norms to identify and define risk factors for higher risk births. These data serve as a reference for Botswana, may apply to southern Africa, and may help to identify infants at risk for perinatal complications and inform comparisons among infants exposed to HIV and antiretrovirals in utero.

Stress testing reveals gaps in clinic readiness of image-based diagnostic artificial intelligence models.

Artificial intelligence models match or exceed dermatologists in melanoma image classification. Less is known about their robustness against real-world variations, and clinicians may incorrectly assume that a model with an acceptable area under the receiver operating characteristic curve or related performance metric is ready for clinical use. Here, we systematically assessed the performance of dermatologist-level convolutional neural networks (CNNs) on real-world non-curated images by applying computational "stress tests". Our goal was to create a proxy environment in which to comprehensively test the generalizability of off-the-shelf CNNs developed without training or evaluation protocols specific to individual clinics. We found inconsistent predictions on images captured repeatedly in the same setting or subjected to simple transformations (e.g., rotation). Such transformations resulted in false positive or negative predictions for 6.5-22% of skin lesions across test datasets. Our findings indicate that models meeting conventionally reported metrics need further validation with computational stress tests to assess clinic readiness.