The immune response to sub‑clinical mastitis is impaired in HIV‑infected women

BACKGROUND : Subclinical mastitis (SCM) is relatively common in lactating women and may be associated with HIV shedding in breast milk. The potential association between HIV infection and breast milk immunologic factors and immune response to SCM needs to be addressed. METHODS : In this cross-sectional study, SCM (Na/K ratio > 1) was tested in 165 mature breast milk samples collected from 40 HIV-infected women who didn’t transmit HIV to their child by breastfeeding and 43 HIV-uninfected women enrolled in an interventional cohort in South-Africa (Vertical Transmission Study). The level of 33 immune markers related to Th1/Th2 related response, inflammation and bacterial exposure were compared in ART-naive HIV-infected versus HIV-uninfected women. The associations between HIV infection and SCM on the concentration of immune factors were tested separately by Wilcoxon rank-sum test and corrected for false discovery rate. To control for potential confounder effects and take into account the clustering of breast milk samples from a single woman, multivariate mixed linear models adjusted on child age at the time of sampling were performed for each immune factor. RESULTS : Subclinical mastitis was detected in 15 (37.5%) HIV-infected women and 10 (23.3%) HIV-uninfected women. In the absence of SCM, the breast milk levels of IP-10 and MIG were higher and IL1-RA lower in HIV-infected women than in HIV-uninfected women (respectively p < 0.001, p = 0.001, p = 0.045). In HIV-uninfected women, SCM was characterized by a robust immune response with higher concentrations of a broad panel of Th1 and inflammatory related immune markers than in samples without SCM. By contrast, in HIV-infected women a limited number of immune markers were increased and lower increases were observed in samples with SCM than without SCM. CONCLUSION : HIV infection in ART-naïve women was associated with elevated breast milk levels of IP-10 and MIG, which areTh1-related cytokines induced by IFN-γ. During SCM, a lower and narrower immune response was observed in HIV-infected than HIV-uninfected women, suggesting that HIV infection affects the capacity of the mammary gland to respond to SCM.Additional file 1: Table S1. Detection rates of immune factors in samples with and without sub-clinical mastitis, by HIV group. This table compares the detection rates of immune factors measured in mature breast milk samples with and without sub-clinical mastitis, separately for samples from HIV-infected and HIV-uninfected women. There were no detection rate differences between samples with and without SCM in samples from HIV-infected women. In comparison, in samples from HIV-uninfected women, interferon-α, interferon-γ, interleukin-4, α-defensin, Tumor Necrosis Factor-α and interleukin-6 were more frequently detected in samples with SCM compared to samples without SCM.Additional file 2: Table S2. Multivariate models assessing the effect of HIV on immunologic factor concentration in samples without SCM. This table indicates the adjusted regression coefficients and associated p-values of multivariate mixed linear models assessing the effect of HIV infection on each breast milk soluble immunologic factor concentration, in samples without sub-clinical mastitis, adjusted on child age at the time of sampling. HIV infection was associated with an increase of monokine induced by gamma interferon, inflammatory protein-10, C-reactive protein and ß2-microglobuline, and a decrease of receptor antagonist of interleukin 1ß and soluble CD14.Additional file 3: Table S3. Correlations between breast milk immune factor concentration, HIV plasma parameters and breast milk HIV RNA. This table indicates the Spearman’s non parametric correlations and associated p-values between breast milk soluble immunologic factor concentration and plasma HIV viral load (approximately 6 months after delivery), plasma CD4 count (approximately 6 months after delivery) and breast milk HIV RNA (at the time of breast milk sampling), in samples from HIV-infected women only. There are only a few weak correlations (maximum |ρ| = 0.44).Additional file 4: Table S4. Breast milk immune factor comparisons between samples with sub-clinical mastitis from HIV-uninfected and HIV-infected women. This table compares the concentration of immune factors measured in mature breast milk samples with sub-clinical mastitis, between samples from HIV-infected and HIV-uninfected women. There were no statistically significant concentration differences in samples with sub-clinical mastitis between HIV-infected and HIV-uninfected women.Additional file 5: Table S5. Multivariate models assessing the effect of SCM on immunologic factor concentration, by HIV group. This table indicates the adjusted regression coefficients and associated p-values of multivariate mixed linear models assessing the effect of sub-clinical mastitis on each breast milk soluble factor concentration, adjusted on child age at the time of sampling, separately for samples from HIV-infected and HIV-uninfected women. Sub-clinical mastitis was associated with and increase of 9/13 immune factors analyzed in samples from HIV-uninfected women compared to 7/17 immune factors analyzed in samples from HIV-infected women.Wellcome Trust and Agence Nationale de Recherche sur le SIDA (ANRS) (Grant Numbers VTS 063009/Z/00/Z, ANRS 1271).https://translational-medicine.biomedcentral.comam2019Medical Virolog