Targeted transgenesis identifies Gαs as the bottleneck in ß2-adrenergic receptor cell signaling and physiological function in airway smooth muscle.

G protein-coupled receptors are the most pervasive signaling superfamily in the body and act as receptors to endogenous agonists and drugs. For ß-agonist-mediated bronchodilation, the receptor-G protein-effector network consists of the ß2-adrenergic receptor (ß2AR), Gs, and adenylyl cyclase, expressed on airway smooth muscle (ASM). Using ASM-targeted transgenesis, we previously explored which of these three early signaling elements represents a limiting factor, or bottleneck, in transmission of the signal from agonist binding to ASM relaxation. Here we overexpressed Gαs in transgenic mice and found that agonist-promoted relaxation of airways was enhanced in direct proportion to the level of Gαs expression. Contraction of ASM from acetylcholine was not affected in Gαs transgenic mice, nor was relaxation by bitter taste receptors. Furthermore, agonist-promoted (but not basal) cAMP production in ASM cells from Gαs-transgenic mice was enhanced compared with ASM from nontransgenic littermates. Agonist-promoted inhibition of platelet-derived growth factor-stimulated ASM proliferation was also enhanced in Gαs mouse ASM. The enhanced maximal ß-agonist response was of similar magnitude for relaxation, cAMP production, and growth inhibition. Taken together, it appears that a limiting factor in ß-agonist responsiveness in ASM is the expression level of Gαs. Gene therapy or pharmacological means of increasing Gαs (or its coupling efficiency to ß2AR) thus represent an interface for development of novel therapeutic agents for improvement of ß-agonist therapy.

Genital human papillomavirus (HPV) concordance in heterosexual couples.

BACKGROUND: Few studies have assessed genital human papillomavirus (HPV) concordance and factors associated with concordance among asymptomatic heterosexual couples. METHODS: Genotyping for HPV was conducted with male and female sex partners aged 18-70 years from Tampa, Florida. Eligibility included no history of HPV-associated disease. Type-specific positive concordance (partners with ≥ 1 genotype in common) and negative concordance (neither partner had HPV) were assessed for 88 couples. Factors associated with concordance were assessed with Fisher exact tests and tests for trend. RESULTS: Couples reported engaging in sexual intercourse for a median of 1.7 years (range, 0.1-49 years), and 75% reported being in the same monogamous relationship for the past 6 months. Almost 1 in 4 couples had type-specific positive concordance, and 35% had negative concordance for all types tested, for a total concordance of 59%. Concordance was not associated with monogamy. Type-specific positive concordance was associated with an increasing difference in partners' lifetime number of sex partners and inversely associated with an increasing difference in age. Negative concordance was inversely associated with both the couple's sum of lifetime number of sex partners and the difference in the partners' lifetime number of sex partners. CONCLUSIONS: Genital HPV concordance was common. Viral infectiousness and number of sex partners may help explain concordance among heterosexual partners.

Six-month incidence, persistence, and factors associated with persistence of anal human papillomavirus in men: the HPV in men study.

BACKGROUND: Although there are limited numbers of incidence and persistence estimates for anal human papillomavirus (HPV) in women and in men who have sex with men (MSM), there are no such reports for men who have sex with women (MSW). METHODS: Genotyping was performed on anal samples from men, aged 18-70, from São Paulo, Brazil; Cuernavaca, Mexico; and Tampa, Florida, who provided specimens at enrollment and the 6-month visit of a 4-year prospective study. Eligibility included no history of genital warts or human immunodeficiency virus. A total of 954 MSW and 156 MSM provided evaluable specimens at both visits. Persistence was defined as type-specific infection at each visit. RESULTS: Incident anal infection was common among both MSM and MSW but generally higher for MSM for HPV groups and specific genotypes. A total of 5.1% of MSM and 0.0% of MSW had a persistent HPV-16 infection at the 6-month visit. Cigarette smoking among MSM and age among MSW were associated with persistent infection with any HPV genotype. CONCLUSIONS: Although anal HPV infection is commonly acquired by both MSW and MSM, incident events and persistence occurred more often among MSM. Cigarette smoking is a modifiable risk factor that may contribute to HPV persistence among MSM.

The prevalence of genital HPV and factors associated with oncogenic HPV among men having sex with men and men having sex with women and men: the HIM study.

BACKGROUND: Comparative studies of genital human papillomavirus (HPV) among men having sex with men (MSM), men having sex with women and men (MSWM), and men having sex with women (MSW) have not been conducted so far; however, such comparisons may be important for planning prevention strategies like vaccination. METHODS: Men, aged 18 to 70 years, were enrolled in a study of genital HPV in São Paulo, Brazil; Cuernavaca, Mexico; and Tampa, FL. Men were classified as MSM (n = 170), MSWM (n = 214), and MSW (n = 3326) based on self-reported sexual behavior. Genotyping for HPV was conducted on cells from the penis and scrotum. Prevalence data were adjusted by country. Factors potentially associated with genital HPV were assessed using multivariable Poisson regression. RESULTS: Genital HPV prevalence was typically higher among MSWM than among MSM or MSW for groups of HPV genotypes including nononcogenic types (51%, 36%, and 42%, respectively), and multiple types (37%, 24%, and 29%, respectively). Age and alcohol consumption in the past month were associated with oncogenic HPV among both MSM and MSWM; however, there were no statistically significant associations between sexual behaviors and genital HPV among MSM or MSWM. CONCLUSIONS: Prevalence of genital HPV may be higher among MSWM than among MSW or MSM. Number of female sex partners was associated with genital HPV among MSW, but number of male anal sex partners was not associated with genital HPV among MSM and MSWM.

Prevalence of and risk factors for anal human papillomavirus infection in men who have sex with women: a cross-national study.

BACKGROUND: Although the primary cause of anal cancer is human papillomavirus (HPV) infection in the anal canal, little attention has been paid to the epidemiology of anal HPV infection in men who have sex with women (MSW). METHODS: Exfoliated cells from the anal canal of 902 MSW in Brazil (São Paulo), Mexico (Cuernavaca), and the United States (Tampa) were tested for HPV DNA. RESULTS: The prevalence of HPV infection in the anal canal (12.0%) was similar among MSW in each city (P=.77), whereas 7.0% had infection with oncogenic types. Men in Tampa had a 4-fold higher prevalence of infection with HPV type 16 (HPV-16) than that among men in São Paulo or Cuernavaca (P<.001). Duration of relationship with a primary sex partner and ever having oral or anal sex with a man was associated with infection with any HPV type and with any oncogenic type, whereas lifetime number of female sex partners was associated with infection with any HPV type. CONCLUSIONS: Anal canal HPV infection is commonly found among MSW, and the prevalence of infection with HPV-16 may differ substantially by geography. Men who have a larger lifetime number of female sex partners, who are in a sexual relationship of <1 year in duration, and who have a history of oral or anal sex with men were most likely to have an anal HPV infection.

Pleiotropic Effects of Bitter Taste Receptors on [Ca2+]i Mobilization, Hyperpolarization, and Relaxation of Human Airway Smooth Muscle Cells.

Asthma is characterized by airway inflammation and airflow obstruction from human airway smooth muscle (HASM) constriction due to increased local bronchoconstrictive substances. We have recently found bitter taste receptors (TAS2Rs) on HASM, which increase [Ca2+]i and relax the muscle. We report here that some, but not all, TAS2R agonists decrease [Ca2+]i and relax HASM contracted by G-protein coupled receptors (GPCRs) that stimulate [Ca2+]i. This suggests both a second pathway by which TAS2Rs relax, and, a heterogeneity of the response phenotype. We utilized eight TAS2R agonists and five procontractile GPCR agonists in cultured HASM cells. We find that heterogeneity in the inhibitory response hinges on which procontractile GPCR is activated. For example, chloroquine inhibits [Ca2+]i increases from histamine, but failed to inhibit [Ca2+]i increases from endothelin-1. Conversely, aristolochic acid inhibited [Ca2+]i increases from endothelin-1 but not histamine. Other dichotomous responses were found when [Ca2+]i was stimulated by bradykinin, angiotensin, and acetylcholine. There was no association between [Ca2+]i inhibition and TAS2R subtype, nor whether [Ca2+]i was increased by Gq- or Gi-coupled GPCRs. Selected studies revealed a correlation between [Ca2+]i inhibition and HASM cell-membrane hyperpolarization. To demonstrate physiologic correlates, ferromagnetic beads were attached to HASM cells and cell stiffness measured by magnetic twisting cytometry. Consistent with the [Ca2+]i inhibition results, chloroquine abolished the cell stiffening response (contraction) evoked by histamine but not by endothelin-1, while aristolochic acid inhibited cell stiffening from endothelin-1, but not from histamine. In studies using intact human bronchi, these same differential responses were found. Those TAS2R agonists that decreased [Ca2+]i, promoted hyperpolarization, and decreased HASM stiffness, caused relaxation of human airways. Thus TAS2Rs relax HASM in two ways: a low-efficiency de novo [Ca2+]i stimulation, and, a high-efficiency inhibition of GPCR-stimulated [Ca2+]i. Furthermore, there is an interaction between TAS2Rs and some GPCRs that facilitates this [Ca2+]i inhibition limb.