Expression of cytokine mRNAs in mice cutaneously exposed to formaldehyde

In this study, we have investigated the expression of cytokine mRNAs in mice cutaneously exposed to formaldehyde using semiquantitative RT-PCR. We show that formaldehyde induced the long-lasting expression of IL-4 and IFN-gamma mRNAs and the transient expression of IL-13 mRNA in mouse spleen and draining lymph nodes. The transient increases in IL-2, IL-15, IL-12p40, IL-15 and IL-18 mRNAs, but long-lasting IL-15 mRNA were only seen in the formaldehyde-exposed mouse spleen. Moreover, a weak contact hypersensitivity (CH) and the significant increases in IL-4 and IFN-gamma mRNAs were detected in the ear skin of formaldehyde-cutaneously exposed mice when rechallenged mouse ears. Furthermore, CH as measured by mouse ear swelling response was positively correlated with IL-4 and IFN-gamma mRNA levels in the challenged ears. This study thus suggests that the induction of Th1 and Th2 cytokine mRNAs, particularly IL-4 and IFN-gamma, are a common immunological feature caused by contact allergens irrespective of strong or weak contact allergens. The analysis of IL-4 and IFN-gamma mRNAs may be useful markers in establishing the novel test for predicting chemical sensitizing potentials.     

Corticotropin-releasing hormone augments proinflammatory cytokine production from macrophages in vitro and in lipopolysaccharide-induced endotoxin shock in mice

Corticotropin-releasing hormone (CRH) exerts an anti-inflammatory effect indirectly, via cortisole production, and a proinflammatory effect directly on immune cells. The aim of the present work was to examine the effect of CRH on macrophage-derived cytokines both in vitro and in vivo. For the in vitro experiments we used two types of macrophages: (i) the RAW264.7 monocyte/macrophage cell line and (ii) thioglycolate-elicited peritoneal macrophages from BALB/c mice. We have found that CRH enhanced lipopolysaccharide (LPS)-induced tumor necrosis factor alpha (TNF-alpha), interleukin-1beta (IL-1beta), and IL-6 production. For the in vivo experiments we have used the LPS-induced endotoxin shock model in BALB/c mice, an established model for systemic inflammation in which macrophages are the major source of the proinflammatory cytokines responsible for the development of the shock. Administration of antalarmin, a synthetic CRH receptor 1 (CRHR1) antagonist, prior to LPS prolonged survival in a statistically significant manner. The effect was more evident at the early stages of endotoxin shock. CRHR1 blockade suppressed LPS-induced elevation of the macrophage-derived cytokines TNF-alpha, IL-1beta, and IL-6, confirming the role of CRH signals in cytokine expression. In conclusion, our data suggest that CRH signals play an early and crucial role in augmenting LPS-induced proinflammatory cytokine production by macrophages. Our data suggest that the diffuse neuroendocrine system via CRH directly affects the immune system at the level of macrophage activation and cytokine production.     

Negative regulation by SHPS-1 of Toll-like receptor-dependent proinflammatory cytokine production in macrophages

SHPS-1 is a transmembrane protein predominantly expressed in macrophages. The possible role of SHPS-1 in regulation of Toll-like receptor (TLR)-dependent production of proinflammatory cytokines by macrophages has remained unknown, however. We now show that expression either of a mutant version of mouse SHPS-1 (SHPS-1–4F) in which the four tyrosine phosphorylation sites in the cytoplasmic region are replaced by phenylalanine or of a chimeric protein comprising the extracellular and transmembrane regions of human CD8 fused to the cytoplasmic region of SHPS-1–4F (CD8–4F) markedly promoted the production of tumor necrosis factor-α (TNF-α) or interleukin-6 (IL-6) induced by lipopolysaccharide (LPS) or polyinosinic-polycytidylic acid [poly(I : C)] in RAW264.7 macrophages. In contrast, expression of a mutant form of SHPS-1 that lacks most of the cytoplasmic region did not promote such responses. Expression of SHPS-1–4F promoted the LPS- or poly(I : C)-induced activation of NF-κB. LPS and poly(I : C) each induced the tyrosine phosphorylation of SHPS-1 through a Src family kinase and the association of SHPS-1 with SHP-1 and SHP-2. These results suggest that LPS or poly(I : C) induces tyrosine phosphorylation of SHPS-1 and the association of SHPS-1 with SHP-1 and SHP-2 in a manner dependent on a Src family kinase. SHPS-1 then negatively regulates TLR4- or TLR3-dependent cytokine production through inhibition of NF-κB-dependent signaling.     

Exaggerated sickness behavior and brain proinflammatory cytokine expression in aged mice in response to intracerebroventricular lipopolysaccharide

Age-associated changes in glial reactivity may predispose individuals to exacerbated neuroinflammatory cytokine responses that are permissive to cognitive and behavioral complications. The purpose of this study was to determine if aging is associated with an exaggerated sickness response to central innate immune activation. Our results show that intracerebroventricular (i.c.v.) administration of lipopolysaccharide (LPS) caused a heightened proinflammatory cytokine response (IL-1beta, IL-6, and TNFalpha) in the cerebellum 2h post i.c.v. injection in aged mice compared to adults. This amplified inflammatory profile was consistent with a brain region-dependent increase in reactive glial markers (MHC class II, TLR2 and TLR4). Moreover, LPS caused a prolonged sickness behavior response in aged mice that was paralleled by a protracted expression of brain cytokines in the cerebellum and hippocampus. Finally, central LPS injection caused amplified and prolonged IL-6 levels at the periphery of aged mice. Collectively, these data establish that activation of the central innate immune system leads to exacerbated neuroinflammation and prolonged sickness behavior in aged as compared to adult mice.     

WSX-1 is required for resistance to Trypanosoma cruzi infection by regulation of proinflammatory cytokine production

WSX-1 is a class I cytokine receptor with homology to the IL-12 receptors and is essential for resistance to Leishmania major infection. In the present study, we demonstrated that WSX-1 was also required for resistance to Trypanosoma cruzi. WSX-1-/- mice exhibited prolonged parasitemia, severe liver injury, and increased mortality over wild-type mice. WSX-1-/- splenocytes produced enhanced levels of Th2 cytokines, which were responsible for the prolonged parasitemia. Massive necroinflammatory lesions were observed in the liver of infected WSX-1-/- mice, and IFN-gamma that was overproduced in WSX-1-/- mice compared with wild-type mice was responsible for the lesions. In addition, vast amounts of various proinflammatory cytokines, including IL-6 and TNF-alpha, were produced by liver mononuclear cells in WSX-1-/- mice. Thus, during T. cruzi infection, WSX-1 suppresses liver injury by regulating production of proinflammatory cytokines, while controlling parasitemia by suppression of Th2 responses, demonstrating its novel role as an inhibitory regulator of cytokine production.     

Escherichia coli K1 inhibits proinflammatory cytokine induction in monocytes by preventing NF-kappaB activation

Phagocytes are well-known effectors of the innate immune system to produce proinflammatory cytokines and chemokines such as tumor necrosis factor alpha (TNF-alpha), interleukin (IL)-1beta, and IL-8 during infections. Here, we show that infection of monocytes with wild-type Escherichia coli K1, which causes meningitis in neonates, suppresses the production of cytokines and chemokines (TNF-alpha, regulated on activation, normal T expressed and secreted, macrophage-inflammatory protein-1beta, IL-1beta, and IL-8). In contrast, infection of monocytes with a mutant E. coli, which lacks outer membrane protein A (OmpA- E. coli) resulted in robust production of cytokines and chemokines. Wild-type E. coli K1 (OmpA+ E. coli) prevented the phosphorylation and its degradation of inhibitor of kappaB, thereby blocking the translocation of nuclear factor (NF)-kappaB to the nucleus. OmpA+ E. coli-infected cells, subsequently subjected to lipopolysaccharide challenge, were crippled severely in their ability to activate NF-kappaB to induce cytokine/chemokine production. Selective inhibitors of the extracellular signal-regulated kinase (ERK) 1/2 pathway and p38 mitogen-activated protein kinase (MAPK), but not Jun N-terminal kinase, significantly reduced the activation of NF-kappaB and the production of cytokines and chemokines induced by OmpA- E. coli, indicating a role for these kinases in the NF-kappaB/cytokine pathway. It is interesting that the phosphorylation of ERK 1/2 and p38 MAPK was notably reduced in monocytes infected with OmpA+ E. coli when compared with monocytes infected with OmpA- E. coli, suggesting that the modulation of upstream events common for NF-kappaB and MAPKs by the bacterium is possible. The ability of OmpA+ E. coli K1 to inhibit the macrophage response temporarily may enable bacterial survival and growth within the host for the onset of meningitis by E. coli K1.     

miR-146a对THP-1细胞靶基因AUF1调控及细胞因子表达的影响

目的探讨miR-146a对人急性单核白血病细胞系(THP-1)靶基因AU碱基富集区结合降解因子1(AUF1)表达的调控及细胞因子表达的影响。方法构建miR-146a过表达及抑制表达慢病毒载体并转染THP-1细胞,以正常培养的THP-1细胞为对照。用实时定量PCR法检测THP-1细胞AUF1 mRNA表达;蛋白质印迹法检测THP-1细胞AUF1蛋白的表达;酶联免疫吸附试验检测THP-1细胞培养基上清液白细胞介素-8(IL-8)及白细胞介素-35(IL-35)浓度。结果过表达miR-146a,可导致THP-1细胞AUF1 mRNA及蛋白表达下调(P0.01,P0.05);THP-1细胞上清液IL-8及IL-35浓度降低(P0.01,P0.05)。抑制miR-146a表达,导致THP-1细胞上清液IL-8及IL-35浓度明显增高(P0.01,P0.01)。结论 AUF1是miR-146a的靶基因。miR-146a可以调控THP-1细胞上清液IL-8、IL-35浓度。IL-8的改变引起相应IL-35的改变,一起参与炎性反应。     

Attenuation of monocyte proinflammatory cytokine responses to Neisseria meningitidis in children by erythropoietin

Meningococcal disease is a leading infectious cause of death in children in industrialized countries. The induction of high levels of proinflammatory cytokines has been implicated in the pathogenesis of Neisseria meningitidis-related multi-organ failure. Here, we demonstrate that N. meningitidis serotypes A and B induce significantly higher levels of tumour necrosis factor (TNF)-alpha positive cells in vitro in infants and young children compared with adults (serotype A/B; infants: 64.9%/63.9%; children: 77.8%/64.3% versus adults: 27.7%/32%; P < 0.005). Serotype A induces also higher levels of interleukin (IL)-6 positive cells in neonates and infants compared with adults (serotype A; newborn 55.4%; infants 58.8% versus adults 49%; P < 0.05). Treatment with human recombinant erythropoietin in vitro resulted in significant attenuation of the N. meningitidis-induced proinflammatory response in all age groups (reduction rate of erythropoietin for IL-6 after stimulation with serotype B: newborn 28%, infants 15%, children 23% and adults 28% and for TNF-alpha after stimulation with serotype B: newborn 27%, infants 22%, children 20% and adults 28%; P < 0.05). We conclude that (i) Neisseria meningitidis induces a higher TNF-alpha response in infants and children compared with adults and (ii) erythropoietin was able to attenuate IL-6 and TNF-alpha production in all investigated age groups. These data may explain the high incidence of meningococcal infection in infants and makes erythropoietin a potentially attractive candidate for interventional strategies in an otherwise devastating course of the disease.     

重组腺病毒介导的BCL-X1基因过表达治疗急性肝衰竭大鼠的研究

目的明确肝细胞凋亡与急性大鼠肝衰竭模型肝组织损伤程度的关系;明确BCL—X1过表达对急性肝衰竭大鼠肝脏的治疗保护作用。方法将60只Wistar大鼠随机分为正常对照组、模型组、处理组三组。正常对照组及模型组给予门静脉注射生理盐水,处理组予门静脉注射重组BCL-Xl腺病毒。预处理7d后模型组及处理组予D-氨基半乳糖＋脂多糖建立肝衰竭模型,观察各组大鼠的BCL-X1蛋白的表达、ALT、AST水平、肝细胞凋亡率及死亡率。结果BCL．XI基因在处理组的表达高于在模型组中的表达;建立大鼠肝衰竭后6h,处理组的血清ALT、AST水平低于模型组（P〈0．05）。处理组的肝细胞凋亡率低于模型组（P〈0．05）。处理组的大鼠死亡率低于模型组（P〈0．05）。结论在急性肝衰竭大鼠中,肝细胞的凋亡率与大鼠的死亡率呈正相关;BCL-XI在肝组织中的过表达能减少急性肝衰竭模型大鼠的肝细胞凋亡率,降低急性肝衰竭大鼠的死亡率。     

Interleukin-1beta modulates proinflammatory cytokine production in human epithelial cells

Periodontitis is a chronic human inflammatory disease initiated and sustained by dental plaque microorganisms. A major contributing pathogen is Porphyromonas gingivalis, a gram-negative bacterium recognized by Toll-like receptor 2 (TLR2) and TLR4, which are expressed by human gingival epithelial cells (HGECs). However, it is still unclear how these cells respond to P. gingivalis and initiate inflammatory and immune responses. We have reported previously that HGECs produce a wide range of proinflammatory cytokines, including interleukin-6 (IL-6), IL-8, granulocyte-macrophage colony-stimulating factor, tumor necrosis factor alpha (TNF-alpha), and IL-1beta. In this study, we show that IL-1beta has a special role in the modulation of other inflammatory cytokines in HGECs challenged with P. gingivalis. Our results show that the increased production of IL-1beta correlates with the cell surface expression of TLR4, and more specifically, TLR4-normal HGECs produce fourfold more IL-1beta than do TLR4-deficient HGECs after challenge. Moreover, blocking the IL-1beta receptor greatly reduces the production of "secondary" proinflammatory cytokines such as IL-8 or IL-6. Our data indicate that the induction of IL-1beta plays an important role in mediating the release of other proinflammatory cytokines from primary human epithelial cells following challenge with P. gingivalis, and this process may be an inflammatory enhancement mechanism adopted by epithelial cells.     

Specific inhibition of T-cell adhesion to extracellular matrix and proinflammatory cytokine secretion by human recombinant galectin-1

The migration of immune cells through the extracellular matrix (ECM) towards inflammatory sites is co-ordinated by receptors recognizing ECM glycoproteins, chemokines and proinflammatory cytokines. In this context, galectins are secreted to the extracellular milieu, where they recognize poly-N-acetyllactosamine chains on major ECM glycoproteins, such as fibronectin and laminin. We investigated the possibility that galectin-1 could modulate the adhesion of human T cells to ECM and ECM components. T cells were purified from human blood, activated with interleukin-2 (IL-2), labelled, and incubated further with intact immobilized ECM and ECM glycoproteins in the presence of increasing concentrations of human recombinant galectin-1, or its more stable, related, C2-S molecule obtained by site-directed mutagenesis. The presence of galectin-1 was shown to inhibit T-cell adhesion to intact ECM, laminin and fibronectin, and to a lesser extent to collagen type IV, in a dose-dependent manner. This effect was specifically blocked by anti-galectin-1 antibody and was dependent on the lectin's carbohydrate-binding properties. The inhibition of T-cell adhesion by galectin-1 correlates with the ability of this molecule to block the re-organization of the activated cell's actin cytoskeleton. Furthermore, tumour necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) production was markedly reduced when IL-2-activated T cells were incubated with galectin-1 or its mutant. This effect was prevented by beta-galactoside-related sugars. The present study reveals an alternative inhibitory mechanism for explaining the suppressive properties of the galectin-1 subfamily on inflammatory and autoimmune processes.     

Temporal sequence and kinetics of proinflammatory and anti-inflammatory cytokine secretion induced by toxic shock syndrome toxin 1 in human peripheral blood mononuclear cells.

The staphylococcal superantigen toxic shock syndrome toxin 1 (TSST-1) induces massive cytokine production, which is believed to be the key factor in the pathogenesis of TSS. The temporal sequence and kinetics of both proinflammatory and anti-inflammatory cytokines induced by TSST-1 in human peripheral blood mononuclear cells were investigated. A panel of loss-of-function single-amino-acid-substitution mutants of TSST-1, previously demonstrated to be defective in either major histocompatibility complex (MHC) class II binding (G31R) or T-cell receptor (TCR) interaction (H135A, S14N), was studied in parallel to further elucidate the mechanisms of cytokine secretion. Wild-type recombinant (WT r) TSST-1 induced a biphasic pattern of cytokine secretion: an early phase with rapid release of proinflammatory cytokines (especially gamma interferon, interleukin-2 [IL-2], and tumor necrosis factor alpha [TNF-alpha]) within 3 to 4 h poststimulation, and a later phase with more gradual production of both proinflammatory (IL-1beta, IL-12, and TNF-beta) and anti-inflammatory (IL-6, IL-10) cytokines within 16 to 72 h poststimulation. G31R, which is defective in MHC class II binding, induced a cytokine profile similar to that of WT rTSST-1, except that secretion of the early-phase proinflammatory cytokines was delayed and production of IL-1beta and IL-12 was markedly reduced. In contrast, mutant toxins defective in TCR interaction either demonstrated complete absence of any cytokine secretion during the entire observation period (H135A) or resulted in complete abolishment of IL-2 and other early-phase proinflammatory cytokines, while secretion of IL-10 appeared unaffected (S14N). Neither WT rTSST-1 nor the mutant toxins induced IL-4 or transforming growth factor beta. Our data indicate that effective TCR interaction is critical for the induction of the early-phase proinflammatory cytokine response, thus underscoring the importance of T-cell signaling in TSS.     

Mutative expression in Candida albicans infection and cytokine signaling network in gene knockout mice

The interactions of Candida species with host cells are crucial for candidiasis. Recognition and adherence to host constituents are the keys to initial colonization of mucosal surfaces and the invasion of host cells. Resistance to mucosal candidiasis is mediated by cell-mediated immunity. Knowledge about host receptors on immune cells and the adhesins on the surface of C. albicans are more redundant, respectively, than about the ligands on the fungal surface and the structures on the host cells bound by adhesions. Silencing or disrupting specific genes both in the pathogen and the host are developing optimistically. The research on IL-12/23 p40 knockout (KO) mice is sound in providing preliminary array data about the principal pathways in oral C. albicans infection and clues about the molecular differences between wild-type (WT) and p40 KO mice of candidiasis in different sites, thus, hints that certain specific drug targets accessible to topical agents for the clinical treatment of oral candidiasis and relevant mucocutaneous precancerous lesions.     

Fmr1基因敲除小鼠的ABR阈值观察

目的对不同周龄的KO与WT小鼠听阈进行检测并对比,了解KO小鼠的听阈变化。方法采用PCR法鉴定FMR1基因敲除型(KO)纯合子(-/-)及其野生型(WT)纯合子(+/+)FVB近交系小鼠,实验动物150只分两组:(1)KO组(3、4、6、8、10周龄,每周龄15只,共75只;②WT组(3、4、6、8、10周龄,每周龄15,共75只,用于听性脑干反应(ABR)测试。数据及图像的采集:以ABR图形中Ⅱ波的阈值为小鼠的ABR阈值。结果 ABR阈值:3周及4周年龄组小鼠各基因型间KO小鼠的ABR阈值显著高于WT小鼠,差异有统计学意义(P<0.01);6、8、10周各组中各基因型小鼠的KO小鼠和WT小鼠的ABR阈值的差异无统计学意义(P>0.05)。结论幼年期FMR-1 KO小鼠听阈提高,成熟期FMR-1 KO小鼠听阈无异常,KO小鼠ABR的结果与AGS发生的年龄依赖性相一致。     

Transforming growth factor-beta 1 knockout mice. A mutation in one cytokine gene causes a dramatic inflammatory disease.

A monoclonal antibody (Ki-S1) has been raised that reacts with the nuclei of proliferating cells. The antigen recognized is resistant to formalin fixation and can be detected in frozen tissues as well as in routinely processed specimens. In immunohistochemistry, nuclear staining can be seen in those tissues and cellular compartments known to be actively proliferating. Peripheral blood lymphocytes are negative but show a strong increase in antigen expression after mitogen stimulation. Flow cytometric determination of DNA content and antigen expression revealed negativity of G0 cells and positivity of G1 to G2/M cells. A cytoplasmic co-reactivity, not associated with proliferation, was confined to Langerhans islands of the pancreas. The nuclear localized antigen has a molecular mass of 160 kd and therefore seems to be different from all other known immunohistochemical markers of proliferating cells. We conclude that the monoclonal antibody Ki-S1 might provide a useful tool for studying cell proliferation in situ under normal and pathological circumstances.     

Alpha-synuclein-induced neurodegeneration is exacerbated in PINK1 knockout mice

Loss-of-function mutations in the PINK1 gene lead to recessive forms of Parkinson's disease. Animal models with depleted PINK1 expression have failed to reproduce significant nigral dopaminergic neurodegeneration and clear alpha-synuclein pathology, main characteristics of the disease. In this study, we investigated whether alpha-synuclein pathology is altered in the absence of PINK1 in cell culture and in vivo. We observed that downregulation of PINK1 enhanced alpha-synuclein aggregation and apoptosis in a neuronal cell culture model for synucleinopathy. Silencing of PINK1 expression in mouse substantia nigra using recombinant adeno-associated viral vectors did not induce dopaminergic neurodegeneration in a long-term study up to 10 months, nor did it enhance or accelerate dopaminergic neurodegeneration after alpha-synuclein overexpression. However, in PINK1 knockout mice, overexpression of alpha-synuclein in the substantia nigra resulted in enhanced dopaminergic neurodegeneration as well as significantly higher levels of alpha-synuclein phosphorylation at serine 129 at 4 weeks postinjection. In conclusion, our results demonstrate that total loss of PINK1 leads to an increased sensitivity to alpha-synuclein-induced neuropathology and cell death in vivo.     

Renal autoregulation in P2X1 knockout mice

Autoregulation of renal blood flow is an established physiological phenomenon, however the signalling mechanisms involved remain elusive. Autoregulatory adjustments in preglomerular resistance involve myogenic and tubuloglomerular feedback (TGF) influences. While there is general agreement on the participation of these two regulatory pathways, the signalling molecules and effector mechanisms have not been identified. Currently, there are two major hypotheses being considered to explain the mechanism by which TGF signals are transmitted from the macula densa to the afferent arteriole. The adenosine hypothesis proposes that the released adenosine triphosphate (ATP) is hydrolysed to adenosine and this product stimulates preglomerular vasoconstriction by activation of A(1) receptors on the afferent arteriole. Alternatively, the P2 receptor hypothesis postulates that ATP released from the macula densa directly stimulates afferent arteriolar vasoconstriction by activation of ATP-sensitive P2X(1) receptors. This hypothesis has emerged from the realization that P2X(1) receptors are heavily expressed along the preglomerular vasculature. Inactivation of P2X(1) receptors impairs autoregulatory responses while afferent arteriolar responses to A(1) adenosine receptor activation are retained. Autoregulatory behaviour is markedly attenuated in mice lacking P2X(1) receptors but responses to adenosine A(1) receptor activation remain intact. More recent experiments suggest that P2X(1) receptors play an essential role in TGF-dependent vasoconstriction of the afferent arteriole. Interruption of TGF-dependent influences on afferent arteriolar diameter, by papillectomy or furosemide treatment, significantly attenuated pressure-mediated afferent arteriolar vasoconstriction in wild-type mice but had no effect on the response in P2X(1) knockout mice. Collectively, these observations support an essential role for P2X(1) receptors in TGF-mediated afferent arteriolar vasoconstriction.     

Systemic cytokine response in moribund mice of streptococcal toxic shock syndrome model

Streptococcus pyogenes causes severe invasive disease in humans, including streptococcal toxic shock syndrome (STSS). We previously reported a mouse model that is similar to human STSS. When mice were infected intramuscularly with 10⁷ CFU of S. pyogenes, all of them survived acute phase of infection. After 20 or more days of infection, a number of them died suddenly accompanied by S. pyogenes bacteremia. We call this phenomenon “delayed death”. We analyzed the serum cytokine levels of mice with delayed death, and compared them with those of mice who died in the acute phase of intravenous S. pyogenes infection. The serum levels of TNF-α and IFN-γ in mice of delayed death were more than 100 times higher than those in acute death mice. IL-10 and IL-12, which were not detected in acute death, were also significantly higher in mice of delayed death. IL-6 and MCP-1 (CCL-2) were elevated in both groups of mice. It was noteworthy that not only pro-inflammatory cytokines but also anti-inflammatory cytokines were elevated in delayed death. We also found that intravenous TNF-α injection accelerated delayed death, suggesting that an increase of serum TNF-α induced S. pyogenes bacteremia in our mouse model.     

Attenuation of Th1 effector cell responses and susceptibility to experimental allergic encephalomyelitis in histamine H2 receptor knockout mice is due to dysregulation of cytokine production by antigen-presenting cells

Histamine, a biogenic amine with both neurotransmitter and vasoactive properties, is well recognized as an immunomodulatory agent in allergic and inflammatory reactions. It also plays a regulatory role in the development of antigen-specific immune responses. CD4+ T-cells from histamine H1 receptor (H1R)-deficient (H1RKO) mice produce significantly less interferon-gamma and more interleukin (IL)-4 in in vitro recall assays compared to wild-type controls. H1RKO mice are also less susceptible to acute early-phase experimental allergic encephalomyelitis indicating that H1R signaling in CD4+ T cells plays a central role in regulating pathogenic T-cell responses. In this study, we show that mice lacking histamine H2 receptor (H2RKO) are similar to H1RKO mice in that they develop encephalitogen-specific T-cell responses as assessed by proliferation and IL-2 production and present with less severe acute early-phase experimental allergic encephalomyelitis. However, unlike T cells from H1RKO mice, which exhibit a strong Th2 bias, T cells from H2RKO mice do not. Rather, they are uniquely characterized by a significant inhibition of Th1 effector cell responses. Given that both histamine and adjuvants such as pertussis toxin modulate antigen-presenting cell (APC) maturation and function, including T-cell-polarizing activity, we analyzed the cytokines/chemokines secreted by APCs from wild-type, H1RKO, and H2RKO mice. Significant differences in cytokine/chemokine production by APCs from unimmunized and immunized mice were delineated. APCs from H2RKO mice produce significantly less IL-12 and IL-6 and markedly greater amounts of MCP-1 compared to wild-type and H1RKO mice. Because MCP-1 is known to inhibit IL-12 production, the failure of H2RKO mice to generate encephalitogenic Th1 effector cell responses is consistent with inhibition of negative regulation of MCP-1 secretion by H2R signaling in APCs.     

Suppression of cytokine production by glucocorticoids is mediated by MKP-1 in human lung epithelial cells

Mitogen-activated protein kinase phosphatase 1 (MKP-1) expression is induced by inflammatory factors and serves as an endogenous p38 MAPK suppressor to limit inflammatory response. Glucocorticoids are very effective anti-inflammatory drugs and they are used for the treatment of many inflammatory diseases, such as asthma and COPD. We investigated the role of MKP-1 in the inhibition of cytokine production by dexamethasone in human A549 bronchial epithelial cells. We found that dexamethasone increased MKP-1 expression, inhibited p38 MAPK phosphorylation, and suppressed TNF and MIP-3α production in A549 cells. Interestingly, the suppression of p38 MAPK phosphorylation and the inhibition of TNF expression by dexamethasone were attenuated in cells, where MKP-1 expression was silenced by siRNA. In conclusion, these data suggest that dexamethasone increases MKP-1 expression and this results in the suppression of p38 MAPK signaling leading to the inhibition of cytokine production in human bronchial epithelial cells. These results point to the role of MKP-1 as an important factor in the therapeutic effects of glucocorticoids in the treatment of inflammatory lung diseases.