Subclinical chorioamnionitis as a targetable risk factor for vertical transmission of HIV-1

Innate immunity including epithelial and nonspecific host factors: workshop 1B

The majority of HIV infections are initiated at mucosal sites. The oral mucosal tissue has been shown to be a potential route of entry in humans and primates. Whereas HIV RNA, proviral DNA, and infected cells are detected in the oral mucosa and saliva of infected individuals, it appears that the oral mucosa is not permissive for efficient HIV replication and therefore may differ in susceptibility to infection when compared to other mucosal sites. Since there is no definitive information regarding the fate of the HIV virion in mucosal epithelium, there is a pressing need to understand what occurs when the virus is in contact with this tissue, what mechanisms are in play to determine the outcome, and to what degree the mechanisms and outcomes differ between mucosal sites. Workshop 1B tackled 5 important questions to define current knowledge about epithelial cell-derived innate immune agents, commensal and endogenous pathogens, and epithelial cells and cells of the adaptive immune system and how they contribute to dissemination or resistance to HIV infection. Discovering factors that explain the differential susceptibility and resistance to HIV infection in mucosal sites will allow for the identification and development of novel protective strategies.

Increased Risk of Intrauterine Transmission of HIV-1 Associated With Granulocyte Elastase in Endocervical Mucus

BACKGROUND

One of the remaining challenges in the prevention of mother-to-child transmission of HIV is to reduce the risk of the transmission during pregnancy. It remains to be investigated which factors affect intrauterine HIV transmission and how they can be identified and addressed during pregnancy.

METHODS

Granulocyte elastase in the endocervical mucus of HIV-positive pregnant women in Zambia was measured, and its association with intrauterine transmission of HIV-1 from the mother to the fetus was investigated.

RESULTS

The intrauterine transmission rate determined by polymerase chain reaction assay of DNA from neonates at birth was 15.3%. The risk for intrauterine transmission was 8.65-fold higher in women who were positive for granulocyte elastase than in those who were negative.

CONCLUSION

We suggest that the women showing positive granulocyte elastase at delivery be strongly suspected of having and if having had chorioamnionitis during pregnancy, which could affect the intrauterine transmission of HIV.

Acute and chronic chorioamnionitis and the risk of perinatal human immunodeficiency virus-1 transmission

OBJECTIVE

This study was undertaken to examine the prevalence of acute and chronic chorioamnionitis among women infected with human immunodeficiency virus-1 (HIV-1) and to determine the relative contribution of each to perinatal HIV-1 transmission.

STUDY DESIGN

In 227 HIV-infected women receiving intrapartum/neonatal nevirapine prophylaxis, we examined associations between fetal membrane histology, cord blood interleukin-6 (IL-6), and perinatal HIV-1 transmission.

RESULTS

Acute chorioamnionitis was present in 122 of 227 specimens; chronic chorioamnionitis in 64 of 227. There was a positive correlation between acute chorioamnionitis and labor length (r = 0.208; P = .002), time of ruptured membrane (r = 0.177; P = .008), and cord IL-6 (r = 0.390; P < .001). Chronic chorioamnionitis was associated with high viral load (P = .05) and low cord IL-6 (P < .001). Severe chronic chorioamnionitis was associated with intrauterine HIV-1 transmission (odds ratio [OR] = 7.61; 95% CI = 1.04-85.5), but no correlation was demonstrated between acute chorioamnionitis and vertical transmission.

CONCLUSION

In a setting of high perinatal nevirapine use, acute chorioamnionitis was not associated with vertical HIV-1 transmission. Risk for intrauterine transmission increased significantly when chronic chorioamnionitis was present.

Chorioamnionitis is associated with placental transmission of human immunodeficiency virus-1 subtype E in the early gestational period

The frequency and the cellular basis for HIV-1 transmission from mother to child in the early gestational period are poorly understood. We compared the placentas of 24 women seropositive for HIV-1 subtype E and who had not received any antiretroviral drugs, to placentas of 25 seronegative women. All placentas were obtained during therapeutic abortion at 6-23 weeks gestation. Placentas and fetal organs were examined by routine light microscopy, immunostaining for p24 capsid protein, and in situ PCR to localize which cells were infected with HIV-1 subtype E. The number of previous abortions was not a factor in placental HIV infection since this number was higher in seronegative women (P < 0.01). There were no significant differences between the placentas of the two groups with respect to presence of chorioamnionitis, villitis, villous stromal fibrosis, infarction, abnormal villous maturation, deciduitis or decidual necrosis. HIV-1 subtype E was detected in up to 83% of placentas, either by immunostaining or in situ PCR, in trophoblast, villous stromal cells, Hofbauer cells, decidual and decidual glandular epithelium. Fetal organs were positive for HIV in 30% (6/20) of cases. There was a significant association between transmission of HIV to the fetus and the histologic findings of chorioamnionitis, plasmacellular deciduitis and decidual cell necrosis. This is the first report showing an association of chorioamnionitis with early in utero transmission of HIV-1 subtype E. This may help explain the cases of in utero transmission that persist despite antiretroviral prophylaxis, given that therapy is started in the late gestational period.