Coming of age: reconstruction of heterosexual HIV-1 transmission in human ex vivo organ culture systems

dl-Mandelic acid exhibits high sperm-immobilizing activity and low vaginal irritation: A potential non-surfactant spermicide for contraception

dl-Mandelic acid (MA), an alpha-hydroxycarboxylic acid, has been widely used as an intermediate of pharmaceutical and fine chemicals. Here, we evaluated the sperm-immobilizing activity of MA and its safety profiles. Spermatozoon motility was assessed by computer-aided sperm analysis, the integrity of the plasma membrane and. mitochondrial potential was assessed using fluorescein isothiocyanate-pisum sativum agglutinin and JC-1, respectively. The local tolerance of the MA-containing gel formulation was evaluated using a rabbit vaginal irritation test. We found that MA inhibited sperm motility and movement patterns in a concentration-dependent manner. Within 20 s, MA-induced spermatozoa immobilization occurred with a minimum effective concentration and a median effective concentration of 0.86 and 0.54 mg/mL, respectively. Plasma membrane disruptions of MA-treated spermatozoa were relatively mild, but mitochondrial depolarization occurred. Histopathological examination showed that MA exposure did not exert obvious effects on the integrity of spermatozoa membrane structures and only caused slight irritation to the rabbit vaginal epithelium. The vaginal irritation scores of the vehicle control and the nonoxynol -9 gel control groups were 1.38 ± 0.65 and 7.88 ± 1.67, respectively (p < 0.01), whereas those of the MA gel groups at 10, 20, and 40 mg/mL were 1.69 ± 1.04, 2.98 ± 0.77, and 4.35 ± 1.04 with p values of >0.05, >0.05, and <0.05 (vs. vehicle control), respectively, which were within the clinically acceptable range (<8). Therefore, our results confirmed that MA exhibited significant sperm-immobilizing effects and caused mild plasma membrane injury, suggesting that it has potential for development as a future non-surfactant spermicide.

Visualization of X4- and R5-Tropic HIV-1 Viruses Expressing Fluorescent Proteins in Human Endometrial Cells: Application to Tropism Study

Worldwide most HIV infections occur through heterosexual transmission, involving complex interactions of cell-free and cell-associated particles with cells of the female genital tract mucosa. The ability of HIV-1 to “infect” epithelial cells remains poorly understood. To address this question, replicative-competent chimeric constructs expressing fluorescent proteins and harboring the envelope of X4- or R5-tropic HIV-1 strains were used to “infect” endometrial HEC1-A cells. The virus-cell interactions were visualized using confocal microscopy (CM) at various times post infection. Combined with quantification of viral RNA and total HIV DNA in infected cells, the CM pictures suggest that epithelial cells do not support a complete viral replication cycle: X4-tropic viruses are imported into the nucleus in a non-productive way, whereas R5-tropic viruses transit through the cytoplasm without replication and are preferentially transmitted to susceptible activated peripheral blood mononuclear cells. Within the limit of experiments conducted in vitro on a continued cell line, these results indicate that the epithelial mucosa may participate to the selection of HIV-1 strains at the mucosal level.

Seminal fluid factors regulate activin A and follistatin synthesis in female cervical epithelial cells

Seminal fluid induces pro-inflammatory cytokines and elicits an inflammation-like response in the cervix. Here, Affymetrix microarray and qPCR was utilised to identify activin A (INHBA) and its inhibitor follistatin (FST) amongst the cytokines induced by seminal plasma in Ect1 ectocervical epithelial cells, and a similar response was confirmed in primary ectocervical epithelial cells. TGFB is abundant in seminal plasma and all three TGFB isoforms induced INHBA in Ect1 and primary cells, and neutralisation of TGFB in seminal plasma suppressed the INHBA response. Bacterial lipopolysaccharide in seminal plasma also elicited INHBA, but potently suppressed FST production. There was moderate reciprocal inhibition between FST and INHBA, and cross-attenuating effects were seen. These data identify TGFB and potentially LPS as factors mediating seminal plasma-induced INHBA synthesis in cervical cells. INHBA and FST induced by seminal fluid in cervical tissues may thus contribute to regulation of the post-coital response in women.

Adding new dimensions: towards an integrative understanding of HIV-1 spread

In vitro studies in primary or immortalized cells continue to be used to elucidate the essential principles that govern the interactions between HIV-1 and isolated target cells. However, until recently, substantial technical barriers prevented this information from being efficiently translated to the more complex scenario of HIV-1 spread in the host in vivo, which has limited our understanding of the impact of host physiological parameters on the spread of HIV-1. In this Review, we discuss the recent development of imaging approaches to visualize HIV-1 spread and the adaptation of these approaches to organotypic ex vivo models and animal models. We focus on new concepts, including the mechanisms and in vivo relevance of cell-cell transmission for HIV-1 spread and the function of the HIV-1 pathogenesis factor Nef, which have emerged from the application of these integrative approaches in complex cell systems.

Live simian immunodeficiency virus vaccine correlate of protection: immune complex-inhibitory Fc receptor interactions that reduce target cell availability

Principles to guide design of an effective vaccine against HIV are greatly needed, particularly to protect women in the pandemic's epicenter in Africa. We have been seeking these principles by identifying correlates of the robust protection associated with SIVmac239Δnef vaccination in the SIV-rhesus macaque animal model of HIV-1 transmission to women. We identified one correlate of SIVmac239Δnef protection against vaginal challenge as a resident mucosal system for SIV-gp41 trimer Ab production and neonatal FcR-mediated concentration of these Abs on the path of virus entry to inhibit establishment of infected founder populations at the portal of entry. In this study, we identify blocking CD4(+) T cell recruitment to thereby inhibit local expansion of infected founder populations as a second correlate of protection. Virus-specific immune complex interactions with the inhibitory FcγRIIb receptor in the epithelium lining the cervix initiate expression of genes that block recruitment of target cells to fuel local expansion. Immune complex-FcγRIIb receptor interactions at mucosal frontlines to dampen the innate immune response to vaginal challenge could be a potentially general mechanism for the mucosal immune system to sense and modulate the response to a previously encountered pathogen. Designing vaccines to provide protection without eliciting these transmission-promoting innate responses could contribute to developing an effective HIV-1 vaccine.

Innate and adaptive anti-HIV immune responses in the female reproductive tract

The mucosal surface of the female reproductive tract (FRT) is the primary site of transmission for a plethora of sexually transmitted infections, including human immunodeficiency virus (HIV), that represent a significant burden upon womens' health worldwide. However, fundamental aspects of innate and adaptive immune protection against HIV infection in the FRT are poorly understood. The FRT immune system is regulated by the cyclical changes of the sex hormones estradiol and progesterone across the menstrual cycle, which as we have hypothesized, leads to the creation of a window of vulnerability during the secretory stage of the menstrual cycle, when the risk of HIV transmission is increased. The goal of this review is to summarize the multiple levels of protection against HIV infection in the FRT, the contribution of different cell types including epithelial cells, macrophages, T cells, and dendritic cells to this, and their regulation by estradiol and progesterone. Understanding the unique immune environment in the FRT will allow for the potential development of novel therapeutic interventions such as vaccines and microbicides that may reduce or prevent HIV transmission in women.

Microbicides: still a long road to success

The development of efficient microbicides, the topically applied compounds that protect uninfected individuals from acquiring HIV-1, is a promising strategy to contain HIV-1 epidemics. Such microbicides should of course possess anti-HIV-1 activity, but they should also act against other genital pathogens, which facilitate HIV-1 transmission. The new trend in microbicide strategy is to use drugs currently used in HIV-1 therapy. The success of this strategy is mixed so far and is impaired by our limited knowledge of the basic mechanisms of HIV-1 transmission as well as by the inadequacy of the systems in which microbicides are tested in preclinical studies.

Herpes simplex virus-induced epithelial damage and susceptibility to human immunodeficiency virus type 1 infection in human cervical organ culture

Normal human premenopausal cervical tissue has been used to derive primary cell populations and to establish ex vivo organ culture systems to study infections with herpes simplex virus (HSV-1 or HSV-2) and human immunodeficiency virus type 1 (HIV-1). Infection with either HSV-1 or HSV-2 rapidly induced multinuclear giant cell formation and widespread damage in mucosal epithelial cells. Subsequent exposure of the damaged mucosal surfaces to HIV-1 revealed frequent co-localization of HSV and HIV-1 antigens. The short-term organ culture system provides direct experimental support for the epidemiological findings that pre-existing sexually transmitted infections, including primary and recurrent herpes virus infections at mucosal surfaces, represent major risk factors for acquisition of primary HIV-1 infection. Epithelial damage in combination with pre-existing inflammation, as described here for overtly normal human premenopausal cervix, creates a highly susceptible environment for the initiation and establishment of primary HIV-1 infection in the sub-mucosa of the cervical transformation zone.