Online popularity of JUUL and Puff Bars in the USA: 2019-2020.

BACKGROUND: The US Food and Drug Administration (FDA) announced a flavour ban on cartridge-based e-cigarettes in January 2020. It is unclear whether e-cigarette users will switch to disposable vaping products with a variety of kids-appealing flavours available. METHODS: We performed piece-wise regression and autoregressive integrated moving average (ARIMA) algorithms to compare the relative search volume (RSV) of JUUL and Puff Bar (a disposable vaping product) using the 1-year Google Trends data from 24 February 2019 to 20 February 2020, separated by three events that may have spurred changes in RSV for each product. RESULTS: The RSV for JUUL was relatively stable before Trump Administration announced plans to ban flavoured e-cigarettes. After that, the RSV for JUUL dropped sharply (rate of change=-8.8 per week) from 11 September 2019 to 17 October 2019 when JUUL Labs announced to halt online sales of some flavoured products, and the RSV resumed the decreasing trend after FDA announced enforcement policy of cartridge-based e-cigarettes on 2 January 2020. In comparison, the RSV for Puff Bar started to increase after 11 September 2019 with a low rate of change (0.6) until 17 October 2019. After that, the increase in RSV for Puff Bar accelerated. The RSV of puff bars surpassed that of JUUL during the week of 2 February 2020. CONCLUSION: The popularity of Puff Bar on Google Search suggests that users may replace cartridge-based vaping products with disposable e-cigarettes in the circumvention of the partial flavour ban. Continuous surveillance and further assessment are needed to prevent potential loopholes in tobacco regulation.

Retail violations of sales to minors on e-cigarettes and cigars.

OBJECTIVES: The finalized 'Deeming Rule' extended the Food and Drug Administration (FDA) authority to regulate e-cigarettes, cigars, and other newly deemed tobacco products. We seek to assess the neighborhood characteristics associated with retail violations of sales to minors (RVSM) by tobacco product. STUDY DESIGN: We collected national inspection data on tobacco retailers during August 8, 2016, and May 31, 2018, from the FDA compliance check database. METHODS: A web scraping tool was applied to text mine the FDA decision letters and extract information on the tobacco product involved in RVSM. Separate logistic regression models with random effects were performed to examine the association between zip code-level neighborhood characteristics and RVSM by tobacco product. RESULTS: Of 268,317 minor-involved compliance inspections, 35,403 (13.2%) were identified as RVSM. Among 23,352 warning letters included in the final analysis, e-cigarettes, cigars, cigarettes, and smokeless tobacco accounted for 20.0% (n = 4673), 40.4% (9439), 35.6% (8303), and 4.0% (937) of RVSM, respectively. Flavored tobacco products were abundant among underage sales. For e-cigarettes, RVSM were more likely to occur in zip codes with a larger proportion of youth population aged 10-17 years (adjusted odds ratio [AOR] = 1.17 [1.02-1.34]). A larger proportion of African Americans was associated with a higher risk of RVSM for cigars (AOR = 1.09 [1.07-1.11]) but a lower risk of RVSM for e-cigarettes (AOR = 0.90 [0.87-0.93]). CONCLUSIONS: Retail violations of underage sales for cigars and e-cigarettes are prevalent and neighborhood characteristics associated with violations differ by tobacco product. Continued inspections with tailored strategies to reduce RVSM of all tobacco products are needed.

Temporal Trends of Sources of Cigarettes Among US High School Students: 2001-2015.

INTRODUCTION: Restricting the supply of cigarettes to youth plays an important role in reducing youth smoking. METHODS: The study included data from 8 years of the national Youth Risk Behavior Survey (YRBS) from 2001 to 2015 with 99572 high school students less than 18 years old. Data were weighted to provide national estimates of the temporal trends of cigarette sources. Each cigarette source was analyzed by a separate multivariable logistic regression model and the linear trend odds ratio (aOR) was adjusted by age, sex, race/ethnicity, and smoking frequency. RESULTS: The current smoking prevalence among US high school students less than 18 years of age declined from 26.9% in 2001 to 9.9% in 2015. Among current smokers, we found an overall downward trend of buying cigarettes in a store (aOR = 0.98, confidence interval [CI] = [0.96-1.00]) and an overall upward trend of getting them "some other way" (aOR = 1.03, CI = [1.01-1.05]). The prevalence of purchasing cigarettes in a store significantly declined among smokers aged 16-17, male smokers, white smokers, and daily smokers, but not among other categories. The prevalence of getting cigarettes "some other way" significantly increased across all groups except Hispanic smokers and medium-level or daily smokers. CONCLUSIONS: The proportion of high school students reporting that they bought cigarettes from a store has been declining over the years, while the proportion of high schoolers reporting that they got cigarettes "some other way" has been increasing. The temporal trends also varied by age, sex, race/ethnicity, and smoking frequency. IMPLICATIONS: Patterns of high school student access to cigarettes have changed from 2001 to 2015, with access from "some other way" becoming more prevalent. The differences in cigarette acquisition by age, sex, race/ethnicity, and smoking frequency highlight the importance of implementing tailored policies and interventions to reduce youth access to cigarettes and prevent youth from smoking.

Sleep Deprivation and Chronic Health Conditions Among Sexual Minority Adults.

OBJECTIVES: To examine associations between sleep duration and health outcomes among distinct groups of sexual minority adults. METHODS: Using data from the 2014 Behavioral Risk Factor Surveillance System, we compared sleep duration (very short: ≤ 5 hr; short: 6 hr; normal: 7-8 hr; and long: ≥ 9 hr per day) between cisgender straight adults and distinct groups of sexual minorities. We further examined associations between sleep duration and 10 chronic health conditions among sexual minorities. RESULTS: Of 146,893 respondents, 142,507 (96.2%) were cisgender straight, and 4,386 (3.8%) were lesbian, gay, bisexual, transgender (LGBT). Overall, 17.3% of LGBT respondents reported very short sleep per day, compared with 12.2% for cisgender straight respondents (p < 0.0001). Among LGBT populations, the prevalence of very short sleep varied significantly among distinct groups, ranging from 13.2% among transgender female to male adults to 35.5% among transgender gender nonconforming adults. Very short sleep was further associated with increased odds of having stroke (aOR = 4.1, 95% CI [2.2-7.6]), heart attack (aOR = 3.0, CI [1.6-5.8]), coronary heart disease (aOR = 3.1, 95% CI [1.5-6.2]), asthma (aOR = 1.7, 95% CI [1.1-2.4]), chronic obstructive pulmonary disease (aOR = 2.5, CI [1.5-4.0]), arthritis (aOR = 2.1, CI [1.4-3.0]), and cancer (aOR = 1.8, 95% CI [1.0-3.2]) among sexual minorities. Disparities in the prevalence of stroke, heart attack, coronary health disease, COPD, diabetes, obesity, arthritis, and cancer were found among LGBT populations. CONCLUSIONS: Sexual minorities have a higher prevalence of sleep deprivation as compared with their straight counterparts. Sleep deprivation varies by sexual identity and gender. Very short sleep duration is associated with some chronic health conditions among LGBT populations. Promotion of sleep health education and routine medical assessment of sleep disorders are critically needed for sexual minority adults.

Flavored Tobacco Use Among U.S. Adults by Age Group: 2013-2014.

OBJECTIVE: This study sought to assess patterns of flavored tobacco product (FTP) use and their associations with (1) susceptibility to smoke cigarettes among young adults aged 18-29 who have never smoked; (2) quit attempts in the past 12 months among current cigarette users by age group (18-29, 30-49, and 50+). METHODS: We used the 2013-2014 National Adult Tobacco Survey (n = 75,233) to estimate the prevalence of single-, dual-, and poly-use of FTP (menthol cigarettes, e-cigarettes, cigars, regular pipes/hookahs, and smokeless). Logistic regression models were performed to examine the associations between FTP use and smoking behaviors. RESULTS: Among current tobacco users, young adults aged 18-29 (72.7%) had a higher prevalence of FTP use than other age groups (30-49: 51.7% and 50+: 37.9%). For FTP use within each age group, dual- and poly-FTP use was most popular among young adults aged 18-29 and menthol cigarette use was most popular among older adults aged 50+. Compared with not using any tobacco products, FTP use was associated with higher odds of susceptibility to cigarette smoking among young adult never smokers (single FTP use: aOR =5.5, CI: 4.2-7.3; dual/poly FTP use: aOR =10.7, CI: 6.2-18.4). FTP use was not associated with quit attempts among current cigarettes users aged under 50, while dual/poly-FTP use was associated with higher odds of quit attempts among current cigarette users aged 50 + (aOR =1.7, CI: 1.2-2.4). CONCLUSIONS: This study shows the heterogeneity of FTP use among adults by age group and demonstrates its associations with susceptibility to cigarette smoking among young adult never smokers.

The effects of tobacco control policies on retailer sales to minors in the USA, 2015.

BACKGROUND: Under the 2009 Family Smoking Prevention and Tobacco Control Act, the Food and Drug Administration (FDA) has been routinely inspecting tobacco retailers' compliance with under-age sales laws. We seek to identify factors associated with Retail Violation Rate for sale to minors (RVRm). METHODS: We collected the tobacco retailer inspection data for 2015 from the FDA compliance check database. RVRm was calculated at the census tract level and overlaid with tobacco regulations and youth smoking prevalence at the state level. Multi-level spatial analysis was performed to examine the impacts of tobacco jurisdiction variations, youth smoking rates and neighbourhood social characteristics on RVRm. RESULTS: A total of 136 816 compliance checks involving minors conducted by the FDA in 2015 were analysed. A higher RVRm was associated with higher youth smoking prevalence (aRR=1.04, p<0.0001). Tobacco regulations show significant relationships with RVRm. For every one dollar increase in cigarette tax per pack, the likelihood of retail violations was reduced by 2% (aRR=0.98, p=0.03). For every 10% increase in tobacco prevention spending towards Centers for Disease Control recommended funding targets, the likelihood of retail violations was reduced by 1% (aRR=0.99, p=0.01). RVRm increased in states that enacted stronger smoke-free air policies (aRR=1.08, p<0.0001). CONCLUSION: We observed associations of tobacco regulations and neighbourhood social characteristics with tobacco retailers' compliance with under-age sales laws. This study provides evidence to support stronger tobacco regulations and control policies in reducing youth access to tobacco products.

Direct Marketing Promotion and Electronic Cigarette Use Among US Adults, National Adult Tobacco Survey, 2013-2014.

INTRODUCTION: The use of electronic cigarettes (e-cigarettes) among US adults has increased since 2007. The objective of this study was to investigate the prevalence of direct marketing promotion of e-cigarettes and its association with e-cigarette use among US adults. METHODS: We used using data from the 2013-2014 National Adult Tobacco Survey (NATS) to estimate prevalence of e-cigarette promotions received by mail or email. Multinomial logistic regression was used to examine the associations between e-cigarette promotions and the prevalence and frequency of e-cigarette use among US adults. RESULTS: In the 2013-2014 survey period, 7.1% of adults (about 16.0 million) reported receiving mail or email e-cigarette promotions in the previous 6 months; 3.2% received mail promotions, and 5.1% received email promotions. A higher prevalence of promotions was found among men versus women, adults aged under 65 years versus those older, current e-cigarette users, current smokers, and people with no smoking restriction rules in their homes or vehicles. In the multivariable analysis, receiving mail or email e-cigarette promotions was associated with higher odds of being current e-cigarette users (adjusted odds ratio [aOR] = 2.0; P < .001) than being noncurrent e-cigarette users. Receiving promotions was also associated with higher odds of using e-cigarettes some days (aOR = 1.6; P = .006) or every day (aOR = 1.7; P = .008) than using e-cigarettes rarely. CONCLUSION: Receipt of e-cigarette direct marketing promotions was prevalent among US adults. Receiving e-cigarette promotions was associated with increased odds of both prevalence and frequency of e-cigarette use. Future longitudinal studies are needed to measure causal effects of e-cigarette promotions on e-cigarette use among adults.

Vape Shop Density and Socio-Demographic Disparities: A US Census Tract Analysis.

INTRODUCTION: Vape shops are an emerging business specializing in the sales and promotion of e-cigarette, e-juice, and other vaping products. This study sought to evaluate the associations between vape shop density and socio-demographic characteristics at the US census tract level. METHODS: Vape shop data (n = 9943) were collected from three online directories: Yelp.com, Yellowpages.com, and Guidetovaping.com. Addresses of vape shops were geocoded and the density per 10 000 people was estimated at each US census tract. Zero inflated negative binomial regression model was performed to examine the socio-demographic factors associated with vape shop density. RESULTS: Overall, there was a higher vape shop density in urban versus nonurban census tracts. In urban areas, higher vape shop density was associated with larger proportions of Hispanics and Asians, adults aged 18-44 years old and higher poverty, while the decrease in vape shop density was associated with larger proportions of population under 18 years old, higher education, larger household size, and a higher percentage of owner occupied housing units. In nonurban areas, higher vape shop density was associated larger proportions of African Americans and Hispanics, smaller household size and a lower percentage of owner occupied housing units. CONCLUSION: At the national level, there are inequalities of vape shop density by some socio-demographic characteristics and heterogeneity between urban and nonurban areas. IMPLICATIONS: Vape shops are more likely to be concentrated in areas where people with a higher risk for vaping and smoking reside. Our findings could inform initiatives aimed at a stronger licensing requirement for vape shops and federal and state-level regulations of this industry to prevent vape shop from targeting minority and other socially disadvantaged groups.

Geographic density and proximity of vape shops to colleges in the USA.

BACKGROUND: Vape shops have been spreading rapidly in the USA since 2008, catering to the fast-growing market for electronic cigarettes. Little is known about the geographic density and proximity of vape shops near colleges. METHODS: Names and addresses of vape shops were collected from 3 online directories: Yelp.com, Yellowpages.com and Guidetovaping.com. We identified the prevalence of US-based vape shops and their density and proximity to colleges using a geographic information system. General linear model and negative binomial regression were performed to examine the factors associated with proximity and density of vape shops near colleges. RESULTS: We identified 9945 vape shops in the USA as of December 2015, a nearly threefold increase from 2013. Among the 2755 colleges included in this study, 66.5% had at least 1 vape shop within a 3-mile radius. The median proximity of the nearest vape shop to each college/university was 1.8 miles. Proximity increased by student population, private as compared to public institutions, and location (city vs rural). Within a 1-mile radius, colleges with smoke-free campus policies had a lower density of vape shops (RR=0.6, p=0.002) than those without smoke-free campus policies. Private institutions had a higher density of vape shops (RR=7.8, p<0.0001) than did public institutions. Colleges with campus housing had a lower density of vape shops (RR=0.4, p<0.0001) than those without campus housing, and colleges located in cities had a much higher density of vape shops than those located in rural areas (RR=6.6, p<0.0001). Smoke-free and e-cigarette-free campus policies had significant interactions with college type (private vs public) and campus housing in reducing vape shop density. CONCLUSIONS: Vape shops are more likely to be located near private institutions and colleges in cities as opposed to rural areas. Smoke-free and e-cigarette-free campus policies have had significant effects in reducing the density of vape shops but have not reduced the proximity of vape shops to colleges. Regulations on the sale and advertisement of e-cigarettes to youth and young adults are critically needed.

Mining social media data for opinion polarities about electronic cigarettes.

BACKGROUND: There is an ongoing debate about harm and benefit of e-cigarettes, usage of which has rapidly increased in recent years. By separating non-commercial (organic) tweets from commercial tweets, we seek to evaluate the general public's attitudes towards e-cigarettes. METHODS: We collected tweets containing the words 'e-cig', 'e-cigarette', 'e-liquid', 'vape', 'vaping', 'vapor' and 'vaporizer' from 23 July to 14 October 2015 (n=757 167). A multilabel Naïve Bayes model was constructed to classify tweets into 5 polarities (against, support, neutral, commercial, irrelevant). We further analysed the prevalence of e-cigarette tweets, geographic variations in these tweets and the impact of socioeconomic factors on the public attitudes towards e-cigarettes. RESULTS: Opinions from organic tweets about e-cigarettes were mixed (against 17.7%, support 10.8% and neutral 19.4%). The organic-against tweets delivered strong educational information about the risks of e-cigarette use and advocated for the general public, especially youth, to stop vaping. However, the organic-against tweets were outnumbered by commercial tweets and organic-support tweets by a ratio of over 1 to 3. Higher prevalence of organic tweets was associated with states with higher education rates (r=0.60, p<0.0001), higher percentage of black and African-American population (r=0.34, p=0.01), and higher median household income (r=0.33, p=0.02). The support rates for e-cigarettes were associated with states with fewer persons under 18 years old (r=-0.33, p=0.02) and a higher percentage of female population (r=0.3, p=0.02). CONCLUSIONS: The organic-against tweets raised public awareness of potential health risks and could aid in preventing non-smokers, adolescents and young adults from using e-cigarettes. Opinion polarities about e-cigarettes from social networks could be highly influential to the general public, especially youth. Further educational campaigns should include measuring their effectiveness.

The Prevalence of Exposure to Workplace Secondhand Smoke in the United States: 2010 to 2015.

OBJECTIVE: To compare changes in exposure to workplace secondhand smoke (SHS) by industry of employment and occupation from 2010 to 2015. METHODS: Data were collected from 2010 and 2015 National Health Interview Survey. Weighted estimates of the prevalence of exposure to workplace SHS among currently working nonsmokers in 2010 (n = 12 627) and 2015 (n = 16 399) were compared. RESULTS: The prevalence of exposure to workplace SHS among currently working nonsmokers was 10.0% in 2015 and 9.5% in 2010. Exposure to workplace SHS is disproportionally high among male workers, young workers, non-Hispanic blacks, Hispanics, workers with low education and low income, and workers residing in the Southern United States. Tobacco control policies have effectively reduced exposure to workplace SHS in a few white-collar and service job categories but blue-collar workers remain to have a high prevalence of exposure to workplace SHS. From 2010 to 2015, "transportation and warehousing industries" had the largest increase in SHS exposure (13.3%-21.5%, p value = .004) and "arts, entertainment, and recreation industries" had the largest decline in prevalence of exposure to SHS (20.1%-11.5%, p value = .01). In the multivariate analysis, workers with service (aOR = 1.4, p < .0001) and blue-collar occupations (aOR = 2.5, p < .0001) had a significantly higher prevalence of exposure to workplace SHS than those with white-collar occupations. CONCLUSIONS: Disparities of SHS exposure by industry, occupation, and social demographic class continue to exist. Blue-collar workers, especially those working in "transportation and construction industries," along with young workers and workers in high risk social classes are priority groups for future workplace SHS prevention. IMPLICATIONS: An estimated 12.6 million working nonsmokers were regularly exposed to SHS at work in 2015. We compared the changes in prevalence of exposure to workplace SHS from 2010 to 2015 by social demographic class, industry of employment and occupation. Our findings could help inform the policymakers and health practitioners to establish stronger smoke-free air laws and conduct education campaigns to reduce the exposure to workplace SHS, especially among certain industries and occupations with a disproportionally high prevalence of exposure to workplace SHS.

Geographic variations in electronic cigarette advertisements on Twitter in the United States.

OBJECTIVES: Studies have identified a proliferation of e-cigarette advertisements on Twitter. We investigate whether the prevalence of e-cigarette related advertising is associated with state tobacco regulations after taking socio-economic characteristics into account. METHODS: We collected e-cigarette related tweets from July 23 to October 14, 2015 (n = 757,167) on Twitter. State regulations and smoking prevalence were provided by the Campaign for Tobacco-Free Kids program. The socio-economic data were provided by the American Community Survey. RESULTS: The number of commercial tweets was 319,041/day with a high potential reach (830,495,700/day). The prevalence of commercial tweets varied significantly by US state. The higher prevalence of e-cigarette advertising was associated with states with better tobacco control impact (r = 0.54, p < 0.0001) and lower youth smoking prevalence (r = -0.39, p = 0.005). In the multivariate analysis, state tobacco control impact is significantly associated with the prevalence of commercial tweets (ß = 0.03 ± 0.01, p = 0.02). CONCLUSIONS: Policies at both the federal and state levels are needed to regulate the content of commercial tweets and mitigate the negative effect of social media advertisements.

Electronic cigarette and marijuana use among youth in the United States.

BACKGROUND: There are growing concerns over the high rate of electronic cigarette (e-cigarette) use and decreases in perceived harm of marijuana use among youth. We seek to identify risk factors associated with e-cigarette and marijuana use among U.S. middle and high school students. METHODS: Estimates of e-cigarette use only, marijuana use only, dual use of both substances as well as frequency of substance use were calculated for 8th, 10th and 12th grades with the typical age of 13, 15, 17 years old respectively by using the 2014 Monitoring the Future survey (n=16,184). RESULTS: Overall, 7.9% of students only used e-cigarettes, 9.3% of students only used marijuana, and 6.6% of students used both e-cigarettes and marijuana in the last 30days. E-cigarette use only was most prevalent among 8th and 10th graders while marijuana use only was most prevalent among 12th graders. The dual use of e-cigarettes and marijuana rapidly increased from 8th graders (2.6%) to 10th graders (7.3%) and maintained a high level for 12th graders (8.5%). Students' sociodemographic factors, school performance and work intensity were associated with e-cigarette and marijuana use in the multivariate analysis. Being a dual user of e-cigarettes and marijuana was associated with increased risk of a medium level or a high level of e-cigarette use and a medium level of marijuana use CONCLUSIONS: This study raised the possibility that youth start to use e-cigarettes at an earlier age and then progress to other substances. Education campaigns with tailored messages to prevent youth from vaping and drug use are critically needed.

Flavored Electronic Cigarette Use and Smoking Among Youth.

BACKGROUND AND OBJECTIVE: Flavored electronic cigarettes (e-cigarettes) are not prohibited in the United States, and e-cigarette flavors proliferate on the market. This study sought to examine flavored e-cigarette use and its association with smoking among youth. METHODS: Estimates of flavored e-cigarette use from the 2014 National Youth Tobacco Survey were investigated. A logistic regression model was used to assess whether flavored e-cigarette use was associated with (1) intention to initiate cigarette use among never-smoking youth (n = 16 471), (2) intention to quit tobacco use among current-smoking youth (n = 1338), and (3) perception of tobacco's danger among all respondents (n = 21 491). RESULTS: A total of 2017 respondents reported using e-cigarettes in the last 30 days, of whom 1228 (60.9%) reported using flavored e-cigarettes. Among never-smoking youth, 55.6% (288) of current e-cigarette users reported using flavored e-cigarettes. Among current smokers, 68.4% (495) of current e-cigarette users reported using flavored e-cigarettes. Compared with not using e-cigarettes in the past 30 days, using flavored e-cigarettes was associated with higher odds of intention to initiate cigarette use among never-smoking youth (adjusted odds ratio [aOR] = 5.7; P < .0001), lower odds of intention to quit tobacco use among current-smoking youth (aOR = 0.6; P = .006), and a lower prevalence of perception of tobacco's danger among all respondents (aOR = 0.5; P < .0001). CONCLUSIONS: Flavored e-cigarette use is associated with increased risks of smoking among youth. Comprehensive tobacco control and prevention strategies that address flavored e-cigarette products are critically needed to reduce tobacco use among youth.

Exposure to Advertisements and Susceptibility to Electronic Cigarette Use Among Youth.

PURPOSE: Despite the rapid increase in e-cigarette use among youth, little is known about the social and behavioral factors that have contributed to this rise. We investigated whether young e-cigarette users are susceptible to e-cigarette advertisements. METHODS: Estimates of e-cigarette use and exposure to e-cigarette advertisements from the 2014 National Young Tobacco Survey were investigated. Factors associated with the prevalence and levels of e-cigarette use were analyzed using multinomial logistic regression. RESULTS: Of all respondents (n = 21,491), 19.8% had tried e-cigarettes and 9.4% were current e-cigarette users. Exposure to e-cigarette ads was prevalent among youth, with 38.6%/29.6%/53.2%/35.4% having medium to high exposure to e-cigarette ads from the Internet/newspapers/stores/TV, respectively. Current use of e-cigarettes among youth was associated with frequent exposure (high vs. low) to e-cigarette advertising from the Internet (odd ratio [OR] = 3.1, p < .0001), newspapers/magazines (OR = 2.5, p < .0001), stores (OR = 2.8, p < .0001), and TV/movies (OR = 2.1, p < .0001). In the multivariate analysis that joint analyzed four advertisement channels and covariates, greater exposure to e-cigarette ads on the Internet (adjusted OR = 1.9, p < .0001) and in retail stores (adjusted OR = 1.9, p < .0001) remained to be significantly associated with increased odds of using e-cigarettes. Vaping by other household members significantly increased the risk of adolescent e-cigarette use (OR = 8.7, p < .0001). CONCLUSIONS: Exposure to e-cigarette ads significantly increased susceptibility to e-cigarette use among adolescents. E-cigarette advertising regulations and educational campaigns are critically needed.

Hair follicle dermal sheath derived cells improve islet allograft survival without systemic immunosuppression.

Immunosuppressive drugs successfully prevent rejection of islet allografts in the treatment of type I diabetes. However, the drugs also suppress systemic immunity increasing the risk of opportunistic infection and cancer development in allograft recipients. In this study, we investigated a new treatment for autoimmune diabetes using naturally immune privileged, hair follicle derived, autologous cells to provide localized immune protection of islet allotransplants. Islets from Balb/c mouse donors were cotransplanted with syngeneic hair follicle dermal sheath cup cells (DSCC, group 1) or fibroblasts (FB, group 2) under the kidney capsule of immune-competent, streptozotocin induced, diabetic C57BL/6 recipients. Group 1 allografts survived significantly longer than group 2 (32.2 ± 12.2 versus 14.1 ± 3.3 days, P < 0.001) without administration of any systemic immunosuppressive agents. DSCC reduced T cell activation in the renal lymph node, prevented graft infiltrates, modulated inflammatory chemokine and cytokine profiles, and preserved better beta cell function in the islet allografts, but no systemic immunosuppression was observed. In summary, DSCC prolong islet allograft survival without systemic immunosuppression by local modulation of alloimmune responses, enhancing of beta cell survival, and promoting of graft revascularization. This novel finding demonstrates the capacity of easily accessible hair follicle cells to be used as local immunosuppression agents in islet transplantation.

B7-H4.Ig inhibits the development of type 1 diabetes by regulating Th17 cells in NOD mice.

Type 1 diabetes (T1D) is an autoimmune disease characterized by immunological destruction of insulin-producing pancreatic ß-cells and subsequent hyperglycemia. The non-obese diabetic (NOD) mouse strain spontaneously develops a disease similar to human T1D and is commonly used as an animal model for studying this disease. We have previously shown that the administration of B7-H4-immunoglobulin fusion protein (B7-H4.Ig), a newly identified T-cell co-inhibitory signaling molecule, blocks the onset of diabetes in NOD mice. However, the mechanism(s) by which B7-H4 protects NOD mice from T1D is not fully understood. IL-17 is a pro-inflammatory cytokine, produced by Th17 cells, that activates T cells and other immune cells to produce a variety of cytokines and chemokines. Increasing evidence has shown that therapeutic agents targeting the IL-17 molecule or directly inhibiting IL-17-producing cells regulate autoimmune diabetes in NOD mice, suggesting that IL-17 is involved in the pathogenesis of this disease. In this study, we investigate whether B7-H4.Ig treatment inhibits the generation of Th17 cells which subsequently decreases IL-17 production and prevents the onset of T1D in NOD mice. Pre-diabetic female NOD mice were injected intraperitoneally with control mouse IgG or B7-H4.Ig starting at 4 weeks of age for 12 weeks. Our data showed that the frequency of Th17 cells in B7-H4.Ig-treated mice was significantly decreased. In addition, our data showed that B7-H4.Ig-treated mice had decreased levels of pro-inflammatory cytokines and Th17-associated cytokines, and an increased level of the potent Th17 inhibitor IFN-γ. To further investigate the effect of B7-H4.Ig on differentiation of Th17 cells, we co-cultured splenocytes with Th17-polarizing cytokines in the absence or presence of B7-H4.Ig. Our results indicated that splenocytes, under the Th17 driving conditions in the presence of B7-H4.Ig, had significantly decreased the numbers of Th17 cells compared to cells co-cultured in the absence of B7-H4.Ig. Together, this study suggests that blocking the generation of Th17 cells with the administration of B7-H4.Ig effectively inhibits the development of T1D in NOD mice.

Evaluating insulin secretagogues in a humanized mouse model with functional human islets.

OBJECTIVE: To develop a rapid, easy and clinically relevant in vivo model to evaluate novel insulin secretagogues on human islets, we investigated the effect of insulin secretagogues on functional human islets in a humanized mouse model. MATERIALS/METHODS: Human islets were transplanted under the kidney capsule of streptozotocin (STZ)-induced diabetic mice with immunodeficiency. Human islet graft function was monitored by measuring non-fasting blood glucose levels. After diabetes was reversed, human islet transplanted mice were characterized physiologically by oral glucose tolerance and pharmacologically with clinically proven insulin secretagogues, glucagon-like peptide-1 (GLP-1), exenatide, glyburide, nateglinide and sitagliptin. Additionally, G protein-coupled receptor 40 (GPR40) agonists were evaluated in this model. RESULTS: Long-term human islet graft survival could be achieved in immunodeficient mice. Oral glucose challenge in human islet transplanted mice resulted in an immediate incremental increase of plasma human C-peptide, while the plasma mouse C-peptide was undetectable. Treatments with GLP-1, exenatide, glyburide, nateglinide and sitagliptin effectively increased plasma human C-peptide levels and improved postprandial glucose concentrations. GPR40 agonists also stimulated human C-peptide secretion and significantly improved postprandial glucose in the human islet transplanted mice. CONCLUSIONS: Our studies indicate that a humanized mouse model with human islet grafts could mimic the in vivo characteristics of human islets and could be a powerful tool for the evaluation of novel insulin secretagogues or other therapeutic agents that directly and/or indirectly target human ß cells.

Blockade of both B7-H4 and CTLA-4 co-signaling pathways enhances mouse islet allograft survival.

Costimulation blockade is an effective way to prevent allograft rejection. In this study, we tested the efficacy of two negative co-signaling molecules in protecting islet allograft function. We used local expression of B7-H4 by adenoviral transduction of islets (Ad-B7-H4) and systemic administration of CTLA-4.Ig to investigate the outcomes of allograft survival. Five groups of streptozotocin-induced diabetic C57BL/6 mice received 400 islets each from BALB/c donors. The groups consisted of control (G1); CTLA-4.Ig (G2); Ad-LacZ (G3); Ad-B7-H4 (G4); and Ad-B7-H4 and CTLA-4.Ig combined (G5). G1 and G3 developed graft failure on average of two weeks. G2, G4 and G5 survived for 43.8 ± 34.8, 54.7 ± 31.2 and 77.8 ± 21.5 d, respectively. Activated T and B cells in the lymph nodes were significantly controlled by CTLA-4.Ig treatment. Significantly reduced infiltrates were also detected in the allografts of G2 compared with G1. By contrast, B7-H4 significantly inhibited Th1-associated IFN-gamma secretion in the early stage and increased Foxp3 (+) T cells in the long-term surviving allografts. Our study suggests that CTLA-4 and B7-H4 inhibit alloimmune responses through distinct mechanisms, and that combination therapy which activates two negative co-signaling pathways can further enhance islet allograft survival.