Chronic inflammation is associated with higher risk of cardiovascular disease (CVD) in people living with HIV (PLWH). We have previously shown that interleukin-32 (IL-32), a multi-isoform proinflammatory cytokine, is chronically upregulated in PLWH and is linked with CVD. However, the mechanistic roles of the different IL-32 isoforms in CVD are yet to be identified. In this study, we aimed to investigate the potential impact of IL-32 isoforms on coronary artery endothelial cells (CAEC), whose dysfunction represents a major factor for atherosclerosis. Our results demonstrated that the predominantly expressed IL-32 isoforms (IL-32β and IL-32γ) have a selective impact on the production of the proinflammatory cytokine IL-6 by CAEC. Furthermore, these two isoforms induced endothelial cell dysfunction by upregulating the expression of the adhesion molecules ICAM-I and VCAM-I and the chemoattractants CCL-2, CXCL-8 and CXCL-1. IL-32-mediated expression of these chemokines was sufficient to drive monocyte transmigration in vitro. Finally, we demonstrate that IL-32 expression in both PLWH and controls correlates with the carotid artery stiffness, measured by the cumulated lateral translation. These results suggest a role for IL-32-mediated endothelial cell dysfunction in dysregulation of the blood vessel wall and that IL-32 may represent a therapeutic target to prevent CVD in PLWH.

People with HIV (PWH) have an increased risk of developing cardiovascular disease (CVD). Our recent data demonstrated that the multi-isoform proinflammatory cytokine IL-32 is upregulated in PWH and is associated with arterial stiffness and subclinical atherosclerosis. However, the mechanisms by which IL-32 contributes to the pathogenesis of these diseases remain unclear. Here, we show that while the less expressed IL-32α isoform induces the differentiation of human classical monocytes into the calcium-resorbing osteoclast cells, the dominantly expressed isoforms IL-32β and IL-32γ suppress this function through the inhibition of TGF-β and induce the differentiation of monocytes into the calcium-depositing osteocalcin+ osteoblasts. These results aligned with the increase in plasma levels of osteoprotegerin, a biomarker of vascular calcification, and its association with the presence of coronary artery subclinical atherosclerosis and calcium score in PWH. These findings support a novel role for the proinflammatory cytokine IL-32 in the pathophysiology of CVD by increasing vascular calcification in PWH.

Purpose: Breast cancer diagnosed within 10 years following childbirth is defined as postpartum breast cancer (PPBC) and is highly metastatic. Interactions between immune cells and other stromal cells within the involuting mammary gland are fundamental in facilitating an aggressive tumor phenotype. The MNK1/2-eIF4E axis promotes the translation of pro-metastatic mRNAs in tumor cells, but its role in modulating the function of non-tumor cells in the PPBC microenvironment, and in particular its activity in human PPBC, has not been explored. Experimental design: We used a combination of in vivo PPBC models and in vitro assays to study the effects of phospho-eIF4E deficiency on the pro-tumor function of select cells of the TME. Furthermore, we employed Imaging Mass Cytometry on PPBC and non-PPBC patient samples, to chart the expression of the MNK1/2-eIF4E axis components in the TME. Results: Here, we show that phospho-eIF4E deficient (eIF4E ^S209A ) PPBC mice are protected against lung metastasis and reveal differences in the lung immune microenvironment of the WT and eIF4E ^S209A mice. Moreover, we show that the expression of fibroblast-derived IL-33, an alarmin known to induce invasion, was repressed upon MNK1/2-eIF4E axis inhibition. Imaging Mass Cytometry results indicated that human PPBC contain phospho-eIF4E high-expressing tumor cells and CD8+ T cells displaying an activated dysfunctional phenotype. Finally, we block lung metastasis in PPBC mice, using combined MNK1/2 inhibition and anti-PD-1 therapy. Conclusions: These findings implicate the involvement of the MNK1/2-eIF4E axis during PPBC metastasis and suggest a promising immunomodulatory route to enhance the efficacy of immunotherapy by blocking phospho-eIF4E. Translational relevance: Postpartum breast cancer (PPBC) is highly aggressive. It is hypothesized that involution-induced changes in the postpartum breast microenvironment, which include an influx of inflammatory immune cells and activation of resident fibroblasts, facilitate the invasiveness of an existing neoplasm. We used imaging mass cytometry to do an in-depth profiling of the MNK1-eIF4E axis in the TME of a unique cohort of PPBC and non-PPBC patients. We observed patterns of phospho-eIF4E in non-tumor cells that were specific to the TME of PPBC. We also noted that the CD8 ⁺ T cells present in PPBC express an activated dysfunctional phenotype characterized by the co-expression of HLA-DR and PD-1. This study represents a first look at the expression of the MNK1-eIF4E axis in the stromal cells of metastatic breast cancer and has therapeutic implications as we show, in an animal model of PPBC, that MNK1/2 inhibition can be used to sensitize tumors to anti-PD1 immunotherapy.