Effects of vitamin D3 on the expression of growth-related oncogene-α in THP-1 cells and human primary monocytes.

Asthma and many autoimmune diseases, such as systemic lupus erythematosus, have been reported to associate with vitamin D deficiency recently. Growth-related oncogene-α (GRO-α)/CXCL1, a neutrophil-related chemokine, have an important influence on the chronic inflammation of these diseases. It is unknown whether vitamin D has regulatory effects on GRO-α expression in human monocytes. To this end, the human monocytic leukemia cell line, THP-1, and human primary monocytes were pretreated with 1α, 25-(OH)(2)D(3), and was stimulated with lipopolysaccharide (LPS). Supernatants were collected to determine GRO-α level by ELISA. The intracellular signaling was investigated by nuclear factor (NF)-κB inhibitor, the mitogen-activated protein kinase (MAPK) inhibitors, and Western blot. In our studies, LPS-induced GRO-α was significantly enhanced in THP-1 cells, but suppressed in human primary monocytes by 1α, 25-(OH)(2)D(3). Western blotting revealed that 1α, 25-(OH)(2)D(3) increased LPS-stimulated pp38 expression in THP-1 cells, but suppressed LPS-stimulated pMEK1/2-pERK and pJNK in human primary monocytes. In conclusion, the opposite effects of 1α, 25-(OH)(2)D(3) on GRO-α expression in THP-1 cells and human primary monocytes indicated that the data from THP-1 cells should be further confirmed by human primary monocytes. Moreover, vitamin D3 may have potentiality in treating GRO-α-related chronic inflammatory diseases, like asthma and autoimmune diseases.

Suppressive effects of imidapril on Th1- and Th2-related chemokines in monocytes.

BACKGROUND: Angiotensin-converting enzyme inhibitors (ACEIs) are used to control hypertension and are superior to other antihypertensive agents in protecting the progressive deterioration of autoimmune-related nephritis. An imbalance of T helper 1 (Th1)/Th2 is thought to contribute to the pathogenesis of autoimmune diseases and their related glomerulonephritis. I-309 is a Th2-related chemokine involved in the recruitment of Th2 cells toward Th2-related inflammation. Tumor necrosis factor α (TNF-α) and Th1-related chemokines, interferon-inducible protein 10 (IP-10)/CXCL10 are also involved in autoimmune glomerulonephritis. However, the modulatory effects and the mechanisms of ACEIs on TNF-α and Th1- and Th2-related chemokines in monocytes remain poorly defined. OBJECTIVE: We investigated the effects of imidapril and perindopril, 2 ACEIs, on the expression of IP-10, I-309, and TNF-α in human monocytes and also the associated intracellular mechanism. RESULTS: Imidapril and perindopril significantly downregulated lipopolysaccharide (LPS)-induced TNF-α, I-309, and IP-10 in THP-1 cells and human primary monocytes. All 3 mitogen-activated protein kinase inhibitors suppressed LPS-induced TNF-α and I-309 expression in human primary monocytes. Only extracellular signal-regulated kinases and c-Jun N-terminal kinases (JNK) mitogen-activated protein kinase inhibitors suppressed LPS-induced IP-10 expression. Lipopolysaccharide-induced mitogen-activated protein kinase kinase 4 (MKK4), p-JNK, and c-Jun expression in human primary monocytes was suppressed by imidapril. CONCLUSIONS: These data demonstrate that ACEI is effective in downregulating LPS-induced TNF-α, I-309, and IP-10, which play important roles in the pathogenesis of inflammation. Its suppressive effect on TNF-α, I-309, and IP-10 may, at least in part, involve the down-regulation of LPS-induced MKK4-JNK-c-Jun expression.

Inhibitory effects of albuterol and fenoterol on RANTES and IP-10 expression in bronchial epithelial cells.

Short-acting ß2-adrenoreceptor agonist (SABA) is the major asthma reliever as indicated in the GINA guidelines. Regulated on activation, normal T expressed and secreted (RANTES) is a chemokine that attracts eosinophils, mast cells, and basophils toward site of allergic inflammation. Interferon γ-inducible protein (IP)-10 is a Th1-related chemokine that is also important in asthmatic inflammation and also involved in our immune defense against pathogens. Bronchial epithelial cells are first-line barrier against invasive pathogen and also have immunomodulatory function. However, whether albuterol and fenoterol (two SABAs) have modulatory effects on RANTES and IP-10 expression in bronchial epithelial cells is unknown. The human bronchial epithelial cell lines, BEAS-2B cells, were pre-treated with different concentrations of albuterol, fenoterol or dibutyryl-cAMP (a cyclic AMP analog) before polyinosinic-polycytidylic acid (poly I:C) stimulation. In some condition, BEAS-2B cells were pre-treated with ICI-118551, a selective ß2-adrenoreceptor antagonist, 30 min before albuterol or fenoterol treatment. The levels of RANTES and IP-10 were measured by ELISA. Intracellular signaling was investigated using cAMP assay, mitogen-activated protein kinase (MAPK) inhibitor, nuclear factor (NF)-κB inhibitor, and western blot. Albuterol and fenoterol suppressed poly I:C-induced RANTES and IP-10 expression of BEAS-2B cells. ICI-118551 could partly reverse the suppressive effects of albuterol and fenoterol on RANTES and IP-10 expression. Albuterol and fenoterol increased intracellular cAMP levels. Dibutyryl-cAMP conferred the similar effects of albuterol and fenoterol. Western blot revealed that albuterol suppressed p-ERK, p-JNK and pp38, and also their associated kinase expression. Albuterol had no effect on pp65 expression. Albuterol and fenoterol could suppress poly I:C-induced RANTES and IP-10 expression in human bronchial epithelial cells via at least partly the ß2-adrenoreceptor-cAMP and the MAPK pathways, implicating that albuterol and fenoterol could exert anti-inflammatory effect and benefit asthmatic patients by suppressing RANTES and IP-10 expression. However, these suppressive effects of albuterol and fenoterol may inhibit the defense against viral infection.

Effects of PGI2 analogues on Th1- and Th2-related chemokines in monocytes via epigenetic regulation.

Chemokines play important roles in asthma. Prostaglandin I(2) (PGI(2)) analogue is recently suggested as a candidate for treating asthma. However, the effects of PGI(2) analogues on the expression of Th1- and Th2-related chemokines are unknown. To this end, we investigated the in vitro effects of PGI(2) analogues on the expression of Th1-related chemokine interferon-γ-inducible protein-10 (IP-10/CXCL10) and Th2-related chemokine macrophage-derived chemokine (MDC/CCL22) in human monocytes. The human monocytes were pretreated with iloprost and treprostinil before lipopolysaccharide (LPS) stimulation. IP-10 and MDC were measured by ELISA. Intracellular signaling was investigated by cyclic adenosine monophosphate (cAMP) assay, western blot and chromatin immunoprecipitation. PGI(2) analogues enhanced MDC, but suppressed IP-10 expression in LPS-stimulated monocytes. These effects were reversed by the I prostanoid (IP) receptor antagonist (CAY10449), peroxisomal proliferators-activated receptor (PPAR)-α antagonist (GW6741) and PPAR-γ antagonist (GW9662). PGI(2) analogues increased intracellular cAMP levels. Forskolin, an adenyl cyclase activator, conferred similar effects. PGI(2) analogue-enhanced MDC expression was reduced by nuclear factor (NF) κB inhibitor (BAY 117085) and mitogen-activated protein kinase (MAPK)-p38 inhibitor (SB203580). PGI(2) analogues up-regulated phospho-p65 and phospho-p38 but down-regulated phospho-ERK expression. Iloprost enhanced H3 acetylation in MDC promoter area and suppressed H3 acetylation, H3K4, and H3K36 trimethylation in IP-10 promoter area. PGI(2) analogues enhanced MDC expression via the I prostanoid-receptor-cAMP, PPAR-α and PPAR-γ, NFκB-p65, MAPK-p38-ATF2 pathways and increasing histone acetylation, and suppressed IP-10 expression via the IP-receptor-cAMP, PPAR-γ, MAPK-ERK-ELK1 pathways and inhibiting histone acetylation and trimethylation in LPS-stimulated monocytes. PGI(2) analogues may therefore increase Th2 recruitment and inflammation.

The natural flavonoid apigenin suppresses Th1- and Th2-related chemokine production by human monocyte THP-1 cells through mitogen-activated protein kinase pathways.

Dietary flavonoids have various biological functions, and there is increasing evidence that reduced prevalence and severity of allergic reactions are associated with the intake of flavonoids. Among natural flavonoids, apigenin is a potent anti-inflammatory agent. However, the mechanisms of apigenin's effect remain uncertain. Monocyte-derived chemokine (MDC) plays a pivotal role in recruiting T-helper (Th) 2 cells in the allergic inflammation process. In the late phase of allergic inflammation, the Th1 chemokine interferon-inducible protein 10 (IP-10) has also been found in elevated levels in the bronchial alveolar fluid of asthmatic children. We used human THP-1 monocyte cells, pretreated with or without apigenin, prior to lipopolysaccharide stimulation. By means of enzyme-linked immunosorbent assay, we found that apigenin inhibited production of both MDC and IP-10 by THP-1 cells and that the suppressive effect of apigenin was not reversed by the estrogen receptor antagonist ICI182780. The p65 phosphorylation of nuclear factor kappaB remained unaffected, but the phosphorylation of p38, c-Jun N-terminal kinase, and extracellular signal-regulated kinase mitogen-activated protein kinase pathways were all blocked. We found that inhibition of c-raf phosphorylation might be the target of apigenin's anti-inflammation property.

Natural flavone kaempferol suppresses chemokines expression in human monocyte THP-1 cells through MAPK pathways.

There is increasing evidence that daily intake of flavonoids reduced severity and prevalence of allergic diseases. However, the mechanism of its antiinflammatory effects in allergic diseases remains uncertain. Kaempferol, which belongs to the flavone group, is a strong antioxidant among natural flavonoids and is the essential component of many beverages and vegetables. Because chemokine is one of the key mediators in allergic inflammatory process, we investigated the effect of kaempferol on chemokines expression in monocytes. Our data demonstrated that kaempferol significantly inhibited the lipopolysaccharide (LPS)-induced production of monocyte-derived chemokine (MDC), interferon gamma-induced protein 10 (IP-10), and interleukin-8 (IL-8) in THP-1 cells. Growth-related oncogene-α (GRO-α) was also suppressed at a higher concentration. We also found that kaempferol was able to suppress LPS-induced mitogen-activated protein kinase (MAPK) pathways, as well as the phosphorylation of upstream c-raf and MEK1/2. In brief, kaempferol suppressed LPS-induced T helper 1 (Th1), T helper 2 (Th2), and neutrophil-related chemokines production in monocytes might be via the MAPK pathways.

Suppressive effect on MDC and IP-10 expression in monocytes by endocrine disruptor chemicals.

The expression of chemokines is critical in leukocyte recruitment and inflammation, but the regulatory mechanisms involved remain incompletely defined. While endocrine disrupter chemicals (EDCs) are known to be ubiquitous in the environment and often associated with altered inflammatory response, their potential impact on chemokine expression in monocytes is at present unknown. To this end, the effects of EDCs on the expression of Th1- and Th2-related chemokines in a human monocytic cell line, THP-1, were investigated. THP-1 cells were pre-treated with varying concentrations of EDCs (nonylphenol and 4-octylphenol) with or without the addition of an estrogen receptor (ER) antagonist, ICI 182,780 and then stimulated by lipopolysaccharide (LPS). The levels of chemokines, CXCL10/ IFN-alpha-inducible protein 10 (IP-10, a Th1 chemokine) and monocyte-derived chemokine (MDC)/CCL22, a Th2 chemokine) were measured by ELISA. EDC-mediated signaling events and histone modifications were examined by the use of Western blotting and chromatin immunoprecipitation (ChIP) assay. Nonylphenol and 4-octylphenol were able to suppress LPS-induced MDC and IP-10 expression. This suppressive effect was not reversed by the addition of ICI 182,780. Nonylphenol and 4-octylphenol reduced LPS-induced activation of MAPK signaling pathway, MKK1/2 and ERK, concomitant with decreased levels of LPS-induced acetylated histone 4 (H4) at the IP-10 and MDC gene loci. Nonylphenol and 4-octylphenol suppressed LPS-induced MDC expression in monocytes via, at least in part, the MKK1/2-ERK MAPK pathway and histone H4 acetylation, but not the estrogen receptor.