Prolactin modulates IL-8 production induced by porins or LPS through different signaling mechanisms

The role of prolactin in central nervous system inflammation

Prolactin has been shown to favor both the activation and suppression of the microglia and astrocytes, as well as the release of inflammatory and anti-inflammatory cytokines. Prolactin has also been associated with neuronal damage in diseases such as multiple sclerosis, epilepsy, and in experimental models of these diseases. However, studies show that prolactin has neuroprotective effects in conditions of neuronal damage and inflammation and may be used as neuroprotector factor. In this review, we first discuss general information about prolactin, then we summarize recent findings of prolactin function in inflammatory and anti-inflammatory processes and factors involved in the possible dual role of prolactin are described. Finally, we review the function of prolactin specifically in the central nervous system and how it promotes a neuroprotective effect, or that of neuronal damage, particularly in experimental autoimmune encephalomyelitis and during excitotoxicity. The overall studies indicated that prolactin may be a promising molecule for the treatment of some neurological diseases.

Effect of pregnancy hormone mixtures on cytokine production and surface marker expression in naïve and LPS-activated THP-1 differentiated monocytes/macrophages

In pregnancy, maternal monocytes and macrophages acquire a specific phenotype that enables them to maintain immune tolerance and facilitate hormone–immune cell interactions, which are necessary for gestational progression. The aim of this study was to determine the effect of pregnancy hormone mixtures of the first and third trimesters on both resting and activated monocytes and macrophages. Pregnancy hormone levels (cortisol, estradiol, progesterone, and prolactin) were quantified at the first and third trimesters. The average of the levels obtained was used to prepare two mixtures of synthetic hormones: low and high. These mixtures were then used to stimulate THP-1 monocytes and macrophages, resting or activated with LPS. Cytokine production in the culture supernatants and surface marker expression (CD14, CD86, and CD163) were evaluated by ELISA and flow cytometry, respectively. We found that the hormones modulated the pro-inflammatory response of THP-1 cells, LPS-activated monocytes, and macrophages, inducing high levels of IL-10 and low levels of IL-8, IL-1-β, and IL-6. All hormone stimulation increased the CD163 receptor in both resting and LPS-activated monocytes and macrophages in a dose-independent manner, unlike CD14 and CD86. Pregnancy hormones promote the expression of the markers associated with the M2-like phenotype, modulating their pro-inflammatory response. This phenotype regulation by hormones could be a determinant in pregnancy.

Role and interactions of annexin A1 and oestrogens in the manifestation of sexual dimorphisms in cerebral and systemic inflammation

BACKGROUND AND PURPOSE

Gender differences in inflammation are well described, with females often showing more robust, oestrogen-associated responses. Here, we investigated the influence of gender, oestrogen and the anti-inflammatory protein annexin A1 (AnxA1) on lipopolysaccharide (LPS)-induced leukocyte-endothelial cell interactions in murine cerebral and mesenteric microvascular beds.

EXPERIMENTAL APPROACH

Intravital microscopy was used to visualize and quantify the effects of LPS (10 μg·per mouse i.p.) on leukocyte-endothelial interactions in male and female wild-type (WT) mice. The effects of ovariectomy ± oestrogen replacement were examined in WT and AnxA1-null (AnxA1(-/-) ) female mice.

KEY RESULTS

LPS increased leukocyte adherence in the cerebral and mesenteric beds of both male and female WT mice; females showed exacerbated responses in the brain versus males, but not the mesentery. Ovariectomy further enhanced LPS-induced adhesion in the brain but not the mesentery; its effects were reversed by oestrogen treatment. OVX AnxA1(-/-) mice also showed exaggerated adhesive responses to LPS in the brain. However, these were unresponsive to ovariectomy and, paradoxically, responded to oestrogen with a pronounced increase in basal and LPS-induced leukocyte adhesion in the cerebrovasculature.

CONCLUSIONS AND IMPLICATIONS

Our data confirm the fundamental role of AnxA1 in limiting the inflammatory response in the central and peripheral microvasculature. They also (i) show that oestrogen acts via an AnxA1-dependent mechanism to protect the cerebral, but not the mesenteric, vasculature from the damaging effects of LPS and (ii) reveal a paradoxical and potentially toxic effect of the steroid in potentiating the central response to LPS in the absence of AnxA1.

HIV-1 activates proinflammatory and interferon-inducible genes in human brain microvascular endothelial cells: putative mechanisms of blood-brain barrier dysfunction

The mechanisms underlying blood-brain barrier (BBB) dysfunction seen in human immunodeficiency virus 1 (HIV-1) infection are poorly understood; however, they are believed to be caused by interactions of human brain microvascular endothelial cells (HBMEC) with virus-infected macrophages. Using a transwell system and Affymetrix arrays, we investigated HIV-1-induced genomic changes in HBMEC after coculture with HIV-1-infected or -uninfected monocyte-derived macrophages (MDM). Differentially expressed genes were determined by linear modeling and then were grouped by hierarchical clustering. Compared to HBMEC cocultured with noninfected MDM, 184 probe sets corresponding to 84 genes were differentially expressed in HBMEC cocultured with HIV-infected MDM. Genes activated in HIV-1 MDM-exposed HBMEC included proinflammatory cytokines and chemokines, tumor necrosis factor-alpha-induced proteins, interferon (IFN)-inducible genes, intercellular adhesion molecule-1, transcription factors of the nuclear factor-kappaB family, and signal transducer and activator of transcription 1. Analysis of molecular networks and canonical pathways associated with differentially expressed genes suggest that HIV-1 causes BBB impairment by mechanisms involving inflammation, cytokine, and IFN signaling in HBMEC.

Interleukin-22, a member of the IL-10 subfamily, induces inflammatory responses in colonic subepithelial myofibroblasts

BACKGROUND & AIMS

Interleukin (IL)-22, a member of the IL-10 subfamily, is a recently identified T-cell-derived cytokine. We investigated IL-22 expression in the inflamed mucosa of patients with inflammatory bowel disease (IBD) and analyzed its biologic activities in human colonic subepithelial myofibroblasts (SEMFs).

METHODS

Mucosal IL-22 expression was evaluated by immunohistochemical procedures. The effects of IL-22 on colonic SEMFs were investigated by cDNA microarrays, Northern blots, enzyme-linked immunosorbent assay, and electrophoretic gel mobility shift assays (EMSAs).

RESULTS

IL-22 was not detectable in normal colonic mucosa. In IBD mucosa, IL-22 expression was detectable in CD4-positive T cells. IL-22-positive cells were increased in ulcerative colitis and even more so in Crohn's disease. IL-22 receptor expression colocalized with a marker of SEMFs. IL-22 did not modulate SEMF proliferation and collagen synthesis. cDNA microarray analyses demonstrated that, in colonic SEMFs, IL-22 increased the messenger RNA (mRNA) expression of inflammatory cytokines (IL-6, IL-8, IL-11, and leukemia inhibitory factor [LIF]), chemokines, and matrix metalloproteinases. IL-22 induced an activation of nuclear factor (NF)-kappaB and activating protein (AP)-1 within 1 hour, and a blockade of NF-kappaB and AP-1 activation markedly reduced IL-22 induction of IL-6, IL-8, IL-11, and LIF mRNA. MAP-kinase inhibitors (PD98059, U0216, and SB202190) significantly reduced IL-22 induction of cytokine secretion. The combination of either IL-17 plus IL-22 or IL-19 plus IL-22 additively up-regulated cytokine secretion.

CONCLUSIONS

IL-22 derived from activated T cells acts on SEMFs to elicit expression of proinflammatory cytokines and matrix-degrading molecules indicating proinflammatory/remodeling roles in IBD.