Intraislet release of interleukin 1 inhibits beta cell function by inducing beta cell expression of inducible nitric oxide synthase

Cytokines, released in and around pancreatic islets during insulitis, have been proposed to participate in beta-cell destruction associated with autoimmune diabetes. In this study we have evaluated the hypothesis that local release of the cytokine interleukin 1 (IL-1) by nonendocrine cells of the islet induce the expression of inducible nitric oxide synthase (iNOS) by beta cells which results in the inhibition of beta cell function. Treatment of rat islets with a combination of tumor necrosis factor (TNF) and lipopolysaccharide (LPS), conditions known to activate macrophages, stimulate the expression of iNOS and the formation of nitrite. Although TNF+LPS induce iNOS expression and inhibit insulin secretion by intact islets, this combination does not induce the expression of iNOS by beta or alpha cells purified by fluorescence activated cell sorting (Facs). In contrast, IL-1 beta induces the expression of iNOS and also inhibits insulin secretion by both intact islets and Facs-purified beta cells, whereas TNF+LPS have no inhibitory effects on insulin secretion by purified beta cells. Evidence suggests that TNF+LPS inhibit insulin secretion from islets by stimulating the release of IL-1 which subsequently induces the expression of iNOS by beta cells. The IL-1 receptor antagonist protein completely prevents TNF+LPS-induced inhibition of insulin secretion and attenuates nitrite formation from islets, and neutralization of IL-1 with antisera specific for IL-1 alpha and IL-1 beta attenuates TNF+LPS-induced nitrite formation by islets. Immunohistochemical localization of iNOS and insulin confirm that TNF+LPS induce the expression of iNOS by islet beta cells, and that a small percentage of noninsulin-containing cells also express iNOS. Local release of IL-1 within islets appears to be required for TNF+LPS-induced inhibition of insulin secretion because TNF+LPS do not stimulate nitrite formation from islets physically separated into individual cells. These findings provide the first evidence that a limited number of nonendocrine cells can release sufficient quantities of IL-1 in islets to induce iNOS expression and inhibit the function of the beta cell, which is selectively destroyed during the development of autoimmune diabetes.     

Rapid and specific conversion of precursor interleukin 1 beta (IL-1 beta) to an active IL-1 species by human mast cell chymase

Secretory granules of human dermal mast cells contain a chymotrypsin-like serine proteinase called chymase. In this study, we demonstrate that the inactive cytokine, 31 kD interleukin 1 beta (IL-1 beta), can be converted rapidly to an 18 kD biologically active species by human mast cell chymase. The product formed is three amino acids longer at the amino terminus than the mature IL-1 beta produced by peripheral blood mononuclear cells and has comparable biological activity. Because chymase is a secretory granule constituent, it is likely to be released into the surrounding tissue when mast cells degranulate. It is also known that non-bone marrow derived cells resident in skin (keratinocytes, fibroblasts) produce but do not process 31 kD IL-1 beta. In this context, chymase may be a potent activator of locally produced 31 kD IL-1 beta. Mast cells lie in close apposition to blood vessels in dermis; therefore, chymase mediated conversion of 31 kD IL-1 beta might be expected to have a critical role in the initiation of the inflammatory response in skin.     

IL-10 inhibits metalloproteinase and stimulates TIMP-1 production in human mononuclear phagocytes.

Human mononuclear phagocytes can modulate the turnover of extracellular matrix by producing metalloproteinases such as 92-kD gelatinase and interstitial collagenase as well as the tissue inhibitor of metalloproteinases (TIMP). We have previously reported that IL-4 and IFN gamma released by lymphocytes suppress metalloproteinase biosynthesis in macrophages without affecting TIMP production (Lacraz, S., L. Nicod, B. C. de Rochementeix, C. Baumberger, J. Dayer, and H. Welgus. 1992. J. Clin. Invest. 90:382-388.; Shapiro, S. D., E. J. Campbell, D. K. Kobayashi, and H. G. Welgus 1990. J. Clin. Invest. 86:1204-1210). Like IL-4, IL-10 is secreted by Th2 lymphocytes and is inhibitory to several macrophage functions. In the present study, IL-10 was tested and compared to IL-2, IL-4, IL-6, and IFN gamma for its capacity to modulate synthesis of 92-kD gelatinase, interstitial collagenase and TIMP in human macrophages and monocytes. We found that IL-10, just like IL-4, inhibited the production of 92-kD gelatinase and blocked LPS-, as well as killed Staphylococcus aureus-induced, interstitial collagenase production. The principal finding of this study, however, was that IL-10, in distinction to IL-4, produced a dose-dependent stimulation in the biosynthesis of TIMP-1. TIMP-2 production was not affected. IL-10 regulated the expression of 92-kD gelatinase and TIMP-1 at the pretranslational level. Furthermore, IL-10 regulation was cell type-specific, as it had no effect on the production of metalloproteinases or TIMP by human fibroblasts. In summary, IL-10 has a potent and unique effect upon tissue macrophages and blood monocytes by enhancing TIMP-1 production while decreasing metalloproteinase biosynthesis.     

IL-1beta stimulation induces paracrine regulation of PMN function and apoptosis

Polymorphonuclear leukocytes (PMN) play a crucial role in the primary immunological defense against infectious agents. PMN activation and function is influenced in a paracrine manner by cytokines and bacterial products. While cell-cell communication has been demonstrated between PMN and other cell types, little data is available addressing PMN-PMN communication. Therefore, the aim of this study was to determine whether PMN were able to affect PMN function in vitro in a cell-contact independent manner, and whether IL-1beta influenced this effect. Conditioned medias (CM) were prepared by incubating PMN in HBSS +/- IL-1beta for 1-4 h. Incubation of fresh PMN in these conditioned medias had little or no effect on the expression of cell surface FcgammaR expression or oxidative metabolism. However, incubation of PMN in CM-IL1beta, but not control CM, increased phagocytotic activity and suppressed apoptosis. Additionally, CM-IL1beta, but not control CM, slowed the changes in Mac-1 and CR1 cell surface expression that occurred in HBSS within 2 h of incubation. Finally, control CM down-regulated the cell surface expression of PSGL-1; an effect that was not observed with CM-IL1beta. In conclusion, we demonstrate that PMN are able to communicate with and influence the immunological function of other PMN independent of cell-cell contact, and that this influence is regulated by cytokines such as IL-1beta. The major impact of this paracrine regulation is to down-regulate PMN apoptosis with the potential for an upregulated inflammatory response.     

Tumor necrosis factor-alpha and interleukin-1beta synergistically depress human myocardial function.

OBJECTIVE: Proinflammatory cytokines such as tumor necrosis factor (TNF)-alpha and interleukin (IL)-1beta have been implicated in the pathogenesis of myocardial dysfunction in ischemia-reperfusion injury, sepsis, chronic heart failure, viral myocarditis, and cardiac allograft rejection. Although circulating TNF-alpha and IL-1beta are both often elevated in septic shock, it remains unknown whether TNF-alpha or IL-1beta are the factors induced during sepsis that directly depress human myocardial function, and if so, whether the combination synergistically depresses myocardial function. Furthermore, the mechanism(s) by which these cytokines induce human myocardial depression remain unknown. We hypothesized the following: a) TNF-alpha and IL-1beta directly depress human myocardial function; b) together, TNF-alpha and IL-1beta act synergistically to depress human myocardial function; and c) inhibition of ceramidase or nitric oxide synthase attenuates myocardial depression induced by TNF-alpha or IL-1beta by limiting proximal cytokine signaling or production of myocardial nitric oxide (NO). DESIGN: Prospective, randomized, controlled study. SETTING: Experimental laboratory in a university hospital. SUBJECTS: Freshly obtained human myocardial trabeculae. INTERVENTIONS: Human atrial trabeculae were obtained at the time of cardiac surgery, suspended in organ baths, and field simulated at 1 Hz, and the developed force was recorded. After a 90-min equilibration, TNF-alpha (1.25, 12.5, 125, or 250 pg/mL for 20 mins), IL-1beta (6.25, 12.5, 50, or 200 pg/mL for 20 mins), or TNF-alpha (1.25 pg/mL) plus IL-1beta (6.25 pg/mL) were added to the bath, and function was measured for the subsequent 100 mins after the 20-min exposure. To assess the roles of the sphingomyelin and NO pathways in TNF-alpha and IL-1beta cross-signaling, the ceramidase inhibitor N-oleoyl ethanolamine (1 microM) or the NO synthase inhibitor N(G)-monomethyl-L-arginine (10 microM) was added before TNF-alpha (125 pg/mL) or IL-1beta (50 pg/mL). MEASUREMENTS AND MAIN RESULTS: TNF-alpha and IL-1beta each depressed human myocardial function in a dose-dependent fashion (maximally depressing to 16.2 + 1.9% baseline developed force for TNF-alpha and 25.7 + 6.3% baseline developed force for IL-1beta), affecting systolic relatively more than diastolic performance (each p < .05). However, when combined, TNF-alpha and IL-1beta at concentrations that did not individually result in depression (p > .05 vs. control) resulted in contractile depression (p < .05 vs. control). Inhibition of myocardial sphingosine or NO release abolished the myocardial depressive effects of either TNF-alpha or IL-1beta. CONCLUSIONS: TNF-alpha and IL-1beta separately and synergistically depress human myocardial function. Sphingosine likely participates in the TNF-alpha and IL-1beta signal leading to human myocardial functional depression. Therapeutic strategies to reduce production or signaling of either TNF-alpha or IL-1beta may limit myocardial dysfunction in sepsis.     

Leptin- or troglitazone-induced lipopenia protects islets from interleukin 1beta cytotoxicity.

Interleukin 1beta (IL-1beta)-induced beta cell cytotoxicity has been implicated in the autoimmune cytotoxicity of insulin-dependent diabetes mellitus. These cytotoxic effects may be mediated by nitric oxide (NO). Since long-chain fatty acids (FFA), like IL-1beta, upregulate inducible nitric oxide synthase and enhance NO generation in islets, it seemed possible that islets might be protected from IL-1beta-induced damage by lowering their lipid content. We found that IL-1beta-induced NO production varied directly and islet cell viability inversely with islet triglyceride (TG) content. Fat-laden islets of obese rats were most vulnerable to IL-1beta, while moderately fat-depleted islets of food-restricted normal rats were less vulnerable than those of free-feeding normal rats. Severely lipopenic islets of rats made chronically hyperleptinemic by adenoviral leptin gene transfer resisted IL-1beta cytotoxicity even at 300 pg/ml, the maximal concentration. Troglitazone lowered islet TG in cultured islets from both normal rats and obese, leptin-resistant rats and reduced NO production and enhanced cell survival. We conclude that measures that lower islet TG content protect against IL-1beta-induced NO production and cytotoxicity. Leptin or troglitazone could provide in vivo protection against insulin-dependent diabetes mellitus.     

IL-1beta and IL-6 act synergistically with TNF-alpha to alter cardiac contractile function after burn trauma

Although numerous studies have provided evidence that the inflammatory cytokines TNF-alpha and IL-1beta have significant negative inotropic effects, the role of the interleukins in burn-mediated cardiac dysfunction has not been defined. Furthermore, most studies examining the cardiotoxic effects of inflammatory cytokines have ignored the complex inflammatory milieu that occurs in the intact subject with trauma, sepsis, or ischemic heart disease. Therefore, this study examined the time course of IL-1beta and IL-6 secretion by cardiomyocytes after burn trauma, and additional studies examined the effects of these cytokines alone or in combination with TNF-alpha on cardiac contractile performance (Langendorff). Sprague-Dawley rats were given a full thickness burn injury over 40% of the total body surface area; fluid resuscitation was lactated Ringers solution, 4 mL/kg per burn percentage of burn area. Sham burn animals received identical anesthesia and handling, but no burn injury. Rats were sacrificed at several different times postburn, and isolated hearts (n = 4-5 rats/group/time period) were perfused with collagenase-containing buffer to prepare cardiomyocytes or were perfused in vitro to examine cardiac contractile function (n = 5-6 rats/group/time period). Additional naive control rats (n = 10) were included to prepare cardiomyocytes that, in turn, were challenged with different concentrations of either IL-1beta, IL-6, or TNF-alpha alone or in combination for several time periods (CO2 incubator at 37 degrees C for 1-3 h). Finally, inflammatory cytokines alone or in combination were added to the perfusate of hearts isolated from additional control rats (n = 6-7/group) to assess the cardiac contraction and relaxation effects of cytokine challenge. Despite aggressive fluid resuscitation, burn trauma produced a time-related increase in cardiomyocyte secretion of IL-1beta, IL-6, and TNF-alpha. Exposure of naive cardiomyocytes prepared from control rats to each cytokine alone or combined cytokine challenge produced a time-dependent and concentration-dependent decrease in cell viability and an increase in supernatant creatine kinase levels. Either IL-1beta or TNF-alpha produced greater cardiac defects than IL-6 when added separately to Langendorff-perfused hearts; dysfunction was maximal with combined cytokine challenge (IL-1beta plus TNF-alpha plus IL-6). The data confirm that burn trauma upregulates inflammatory cytokine secretion by cardiomyocytes and suggest that these inflammatory cytokines act in concert to produce burn-mediated cardiac contractile dysfunction.     

Effects of hemipancreatectomy on pancreatic alpha and beta cell function in healthy human donors.

To assess the metabolic consequences of hemipancreatectomy in humans, we determined pancreatic beta and alpha cell function in healthy donors. Donors examined cross-sectionally were found to have significantly decreased glucose-induced phasic insulin secretion and arginine-induced insulin and glucagon secretion as compared to age, sex, and body index-matched controls. However, their fasting glucose and insulin values were not different from controls. Similar observations were found in the prospective evaluation of eight donors before and 15 +/- 2 mo after hemipancreatectomy. Beta cell reserve, as measured by glucose potentiation of arginine-induced insulin secretion, was significantly decreased in donors (maximal acute insulin response [AIRmax]: donors = 666 +/- 84 pM vs controls = 1,772 +/- 234 pM) while the PG50 (the glucose value at which the half-maximal response was observed) was the same in the two groups. Donors and controls responded to 60-min continuous intravenous infusions of glucose by reaching identical serum glucose values, despite significantly lower insulin secretory responses in donors. We conclude that hemipancreatectomy in human donors is associated with decreased pancreatic alpha and beta cell function. Since donors generally maintain normoglycemia after hemipancreatectomy despite diminished insulin secretion, our data suggest that healthy humans may compensate for hemipancreatectomy by increasing glucose disposal.     

Transforming growth factor beta 1 selectively regulates early murine hematopoietic progenitors and inhibits the growth of IL-3-dependent myeloid leukemia cell lines

Transforming growth factor beta 1 (TGF-beta 1) has been shown to be associated with active centers of hematopoiesis and lymphopoiesis in the developing fetus. Therefore, the effects of TGF-beta 1 on mouse hematopoiesis were studied. TGF-beta 1 is a potent inhibitor of IL-3-induced bone marrow proliferation, but it does not inhibit the proliferation induced by granulocyte/macrophage, colony-stimulating factor (CSF), granulocyte CSF, and erythropoietin (Epo). TGF-beta 1 also inhibits IL-3-induced multipotential colony formation of bone marrow cells in soft agar, which includes early erythroid differentiation, while Epo-induced terminal differentiation is unaffected. In addition, IL-3-induced granulocyte/macrophage colonies were inhibited; however, small clusters of differentiated myeloid cells were consistently seen in cultures containing IL-3 and TGF-beta 1. Thus, TGF-beta 1 selectively inhibits early hematopoietic progenitor growth and differentiation but not more mature progenitors. TGF-beta 1 is also a potent inhibitor of IL-3-dependent and -independent myelomonocytic leukemic cell growth, while the more mature erythroid and macrophage leukemias are insensitive. Therefore, TGF-beta 1 functions as a selective regulator of differentiating normal hematopoietic cells, and suppresses myeloid leukemic cell growth.     

Oral ACTH (H.P. ActharGel) inhibits IL-1 and IL-17 secretion in humans

Objective

We have shown that oral corticotropin hormone (ACTH) decreased clinical score, inflammatory foci and T_eff IL-17 in fed and adoptive transferred recipient mice with experimental autoimmune encephalomyelitis (EAE). Therefore, we determined whether oral administration of ACTH had immunological and endocrinological effects and was safe in humans.

Methods

Three groups of three healthy adult volunteers were assayed for total serum ACTH, cortisol and a set of pro-inflammatory and counter-regulatory cytokines after ingested dose(s) of ACTH 4 IU (n = 3), 41 IU (n = 3), or 123 IU (n = 3) over 5 days.

Results

There were no safety issues during the trial. There was no increase in total ACTH levels after day 1 or day 5. There was no significant increase in total cortisol among the groups comparing day 1 to day 5. There were significant decreases in the inflammatory cytokine IL-1 and IL-17 secretion at day 6 compared to baseline with the 123 IU dose but not after the 4 IU and 41 IU doses.

Conclusions

These data provide evidence for the safety and an immunological effect of oral ACTH in humans. It is unknown if the change in IL-1 and IL-17 reflects a local GI-mediated effect or effects following systemic absorption of ACTH.     

转化生长因子β1抑制人肾小管上皮细胞的增殖

背景：慢性肾衰竭进展过程中的一个重要病理改变是炎症和纤维化,主要包括肾小球和肾小管的炎症和纤维化。目前大多数研究主要集中于肾小球,对于肾小管病变的研究相对较少。但实际上部分疾病的肾小管病变出现在肾小球病变之前,其对于疾病预后更具有指导意义。目的：观察转化生长因子β1对人类肾小管上皮细胞HK-2增殖的影响,探索转化生长因子β1在肾小管炎症和纤维化方面的作用。方法：将传代培养的HK-2细胞分成空白对照组和转化生长因子β1作用组,分别使用DMEM／F12培养液,以及含转化生长因子β1（2,5,10#g／L）的DMEM／F12培养液培养,在倒置显微镜下观察各组细胞形态的改变,并使用MTT法检测细胞增殖情况。结果与结论：转化生长因子β1能显著抑制人。肾小管上皮细胞的增殖,并促使细胞向纤维样改变,与空白对照组相比差异有显著性意义（P〈0．05）,其抑制增殖作用并不随转化生长因子β1质量浓度的增大而显著增强,作用时间可持续至72h。结果可见转化生长因子β1能够抑制人肾小管上皮细胞的增殖,并具有促进肾间质纤维化的作用。     

Bone regeneration by transforming growth factor beta1 released from a biodegradable hydrogel.

This paper describes the sustained release of transforming growth factor beta1 (TGF-beta1) from a biodegradable hydrogel based on polyion complexation for the enhancement of bone regeneration activity. Basic TGF-beta1 was adsorbed onto the biodegradable hydrogel of acidic gelatin with an isoelectric point of 5.0 by an electrostatic interaction. The TGF-beta1 could not be adsorbed onto basic gelatin. When acidic gelatin hydrogels incorporating 125I-labeled TGF-beta1 were implanted into the back subcutis of mice, the radioactivity decreased with time and the in vivo retention of TGF-beta1 was prolonged with a decrease in the water content of hydrogels. The higher the water content of hydrogels, the faster their biodegradation. The in vivo retention of TGF-beta1 correlated well with that of gelatin hydrogels, indicating that TGF-beta1 was released from the gelatin hydrogel as a result of hydrogel biodegradation. The ability of TGF-beta1-incorporated into acidic gelatin hydrogels to induce bone regeneration was evaluated in a rabbit calvarial defect model. Eight weeks after treatment, the gelatin hydrogels with water contents of 90 and 95 wt% induced significantly high bone regeneration compared with those with lower and higher water contents and free TGF-beta1. This indicates that the sustained release of TGF-beta1 from the hydrogel with suitable in vivo degradability is necessary to effectively enhance its osteoinductive function. Rapid hydrogel degradation will result in a retention time of TGF-beta1 which is too short to induce bone regeneration. It is possible that the slow degradation of the hydrogel physically blocked TGF-beta1-induced bone regeneration at the skull defect. It can be concluded that the gelatin hydrogel is a promising matrix of TGF-beta1 release to induce skull bone regeneration.     

Immunoelectron microscopic localization of antigens which react with islet cell cytoplasmic antibodies within human pancreatic beta cells.

The presence of circulating autoantibody to islet cell cytoplasm is considered to be an important marker of Type 1 (insulin-dependent) diabetes mellitus. In the present study using islet cell cytoplasmic antibody positive patient sera as the first antibody, we studied the intracellular distribution of its antigen at the electron microscopic level using the pre-embedding immunoperoxidase method. Specific immunoreactivity was found in the membranes of beta cell-secretory granules and cytoplasmic membranes. This result is compatible with the interpretation that the antigen(s) on the membranes of beta cell secretory granules is (are) the target of islet cell cytoplasmic antibody.     

Interaction between phagocytosis and IL-1beta production by rat peritoneal macrophages.

The capacity of rat peritoneal macrophages to produce interleukin-1beta (IL-1beta) following phagocytosis of latex particles in vivo and in vitro was examined. In both cases, a marked increase in IL-1beta secretion was observed, although the level of the cytokine secreted in vivo was higher than that observed after incubation of the cells with latex beads in vitro. It is presumed that this difference is due to stimulation of the peritoneal macrophages by endogenous produced factors/cytokines prior and during phagocytosis in vivo. Macrophages stimulated with LPS showed a level of IL-1beta almost identical to that obtained after incubation with latex. Following phagocytosis in vivo and further stimulation with LPS in vitro, the cells showed an additional increase in IL-1beta production, whereas this additive effect could not be observed when incubation with both latex and LPS was carried out in vitro.The results suggest different patterns for IL-1beta production by rat peritoneal macrophages, depending on the way they are stimulated for phagocytosis.     

Interleukin 10 (IL-10) inhibits the release of proinflammatory cytokines from human polymorphonuclear leukocytes. Evidence for an autocrine role of tumor necrosis factor and IL-1 beta in mediating the production of IL-8 triggered by lipopolysaccharide

In this study we have examined the effects of interleukin 10 (IL-10) on polymorphonuclear leukocytes (PMN), and found that it is a potent inhibitor of tumor necrosis factor (TNF), IL-1 beta, and IL-8 secretion triggered by lipopolysaccharide (LPS). Cytokine production by phagocytosing PMN was also inhibited by IL-10, but to a lesser extent than the LPS-induced production. As shown by Northern blot analysis, IL- 10 diminished the levels of TNF, IL-1 beta, and IL-8 mRNAs late after the onset of stimulation of PMN with LPS. In addition, we provide evidence that the kinetics of LPS-induced IL-8 production by PMN is composed of two distinct phases. Specifically, our experiments demonstrated that in the first phase, the production of IL-8 is a process directly induced by LPS that lasts for some hours. After this early wave, a second phase begins that is sustained and leads to an elevated production of IL-8 that appears to be due to the endogenous release of TNF and IL-1 beta. This second wave can in fact be blocked by anti-TNF and anti-IL-1 beta neutralizing antibodies, and by IL-10 as the consequence of its downregulatory effects on TNF and IL-1 beta release. Taken together, these findings identify novel biological actions of IL-10 as a suppressor of the inflammatory response.