Molecular identity, expression and functional analysis of interleukin-lα and its isoforms in rat testis

Interleukin-1α(IL-1α) is a proinflammatory cytokine that has also been found to act as a paracrine mediator involved in the regulation of testicular functions. The present review provides an overview of the role of IL-1α in testicular physiology. Bioactive IL-1α isolated from adult rat testis was found to consist of three distinct immunoreactive protein species with apparent sizes of 45, 24 and 19 kDa. These isoforms showed bioactivity in athymocyte proliferation and steroidogenesis assays with different biopotencies. The background of the molecular heterogeneity and processing, secretion and regulation of the isoforms of testicular IL-1α are discussed. All three isoforms have been found to be secreted into the testis tubular lumen and interstitial space. We have provided evidence that IL- 1α is a paracrine factor that may be of importance in, e.g., the regulation of Leydig cell steroidogenesis.Pathophysiologically, testicular IL-1α may contribute to testicular relapse of acute lymphocytic leukemia in boys.     

IL-1 receptor antagonist inhibits monocyte chemotactic peptide 1 generation by human mesangial cells.

The elicitation of neutrophils and monocytes from the circulation into the inflamed glomerulus is a key process in the pathogenesis of proliferative glomerulonephritis. The aim of this study was to determine the factors which regulate the expression and synthesis of the monocyte specific chemotaxin, monocyte chemotactic peptide 1 (MCP-1). Mesangial cells in culture did not constitutively express MCP-1, but could be induced to express both MCP-1 mRNA and antigenic MCP-1 by either stimulation with IL-1 alpha or TNF alpha, which are also stimuli for interleukin 8 (IL-8/NAP-1) expression and release. Pre-treatment of mesangial cells with the IL-1 receptor antagonist (IL-1ra) induced dose-dependent inhibition of both the expression of MCP-1 and IL-8 mRNA as well as the release of both chemotactic peptides in response to IL-1 alpha, while the receptor antagonist had no significant effect on TNF alpha induced MCP-1 and IL-8 generation. This study demonstrates that the IL-1 receptor antagonist was four times more effective at inhibiting the IL-1 induced expression and release of IL-8 compared to that of MCP-1. These results suggest that mesangial cell-derived MCP-1 may play an important role in the recruitment of monocytes in glomerular inflammation and that an IL-1 receptor antagonist may have therapeutic potential for the treatment of glomerulonephritis.     

The effect of 17beta-estradiol on production of cytokines in cultures of peripheral blood

Estrogen's action on bone may be mediated by cytokines produced by monocytes. We have reported a decreased ratio of interleukin-1beta (IL-1beta) to interleukin-1 receptor antagonist (IL-1ra) produced by whole blood cultures in vivo in women taking hormone replacement therapy (HRT). Also, one study has shown an effect of estradiol on tumor necrosis factor-alpha (TNF-alpha) secretion by separated monocytes in vitro. The aim of this study was to evaluate the effect of estrogen in vitro on the secretion of cytokines using whole blood cultures. Subjects consisted of 12 healthy postmenopausal women, ages 57-69 years, 4-20 years since menopause. Cytokines IL-1beta, interleukin-1alpha (IL-1alpha), IL-1ra, interleukin-6 (IL-6), TNF-alpha, and granulocyte macrophage-colony stimulating factor (GM-CSF) were measured in unstimulated and in stimulated (500 ng/mL lipopolysaccharide [LPS]) whole blood cultures treated with 17beta-estradiol (E(2)) at concentrations of 10(-12)--10(-6) mol/L. We found significant decreases in the spontaneous secretion of IL-6, TNF-alpha, IL-1ra, IL-1beta, and ratio of IL-1beta/IL-1ra compared with control, at physiological concentrations of E(2). The action of E(2) was blocked by the use of the antiestrogen ICI 182780 in coculture. A decrease in cytokine secretion was not observed when the inactive form of estrogen, 17alpha-estradiol, was used in place of 17beta-estradiol. GM-CSF and IL-1alpha were not detectable in unstimulated cultures. Cytokine levels measured in stimulated cultures were not attenuated by treatment with E(2). We conclude that E(2) inhibits the spontaneous secretion of cytokines measured in whole blood cultures at physiological concentrations, and that the powerful stimulatory effect of LPS prevents any significant inhibition by E(2) in stimulated cultures.     

Effect of inhaled glucocorticoids on IL-1 beta and IL-1 receptor antagonist (IL-1 ra) expression in asthmatic bronchial epithelium

BACKGROUND: Accumulating evidence suggests that the cytokine network is central to the immunopathology of bronchial asthma and the existence of naturally occurring cytokine antagonists has added to this complexity. Upregulation of both interleukin 1 beta (IL-1 beta) and its naturally occurring receptor antagonist, interleukin 1 receptor antagonist (IL- 1ra), has previously been observed on asthmatic bronchial epithelium compared with normal airways. METHODS: The effect of inhaled beclomethasone dipropionate (BDP) on asthmatic bronchial epithelial expression of IL-1 beta and IL-1ra was studied. Frozen bronchial biopsy specimens from nine asthmatic subjects receiving 1000 micrograms BDP daily for eight weeks and from six asthmatic subjects receiving matching placebo were stained with anti-IL-1 beta and anti-IL-1ra antibodies. Hue-saturation-intensity (HSI) colour image analysis was used to quantify the brown immunoperoxidase reaction colour present on the bronchial epithelium. RESULTS: There was a significant twofold decrease in the epithelial expression of IL-1 beta after treatment with BDP but no significant change was seen in IL-1ra (P = 0.175). CONCLUSION: The selective inhibition of IL-1 beta, without effect on IL- 1ra, provides a novel mechanism for the anti-inflammatory action of glucocorticosteroids.


     

Plasma and Urinary Cytokine Homeostasis and Renal Dysfunction during Cardiac Surgery

Background: Cardiac surgery induces changes in plasma cytokines. Proinflammatory cytokines have been associated with a number of renal diseases. The proinflammatory cytokines interleukin 8 (IL-8), tumor necrosis factor [alpha] (TNF[alpha]), and interleukin 1[beta] (IL-1[beta]) are smaller than the antiinflammatory cytokines interleukin 10 (IL-10), interleukin 1 receptor antagonist (IL-1ra), and TNF soluble receptor 2 (TNFsr2), and thus undergo glomerular filtration more readily. Accordingly, this study investigated the relation between plasma and urinary cytokines and proximal renal dysfunction during cardiac surgery.

Methods: Twenty patients undergoing coronary artery bypass grafting with cardiopulmonary bypass (CPB) were studied. Blood and urine samples were analyzed for proinflammatory and antiinflammatory cytokines. Proximal tubular dysfunction was measured using urinary N-acetyl-[beta]-d-glucosaminidase (NAG)/creatinine and [alpha]1-microglobulin/creatinine ratios.

Results: Plasma IL-8, IL-10, IL-1ra, and TNFsr2 values were significantly elevated compared with baseline. Urinary IL-1ra and TNFsr2 were significantly elevated. Urinary NAG/creatinine and [alpha]1-microglobulin/creatinine ratios were also elevated. Plasma TNF[alpha] at 2 h correlated with urinary NAG/creatinine ratio at 2 and 6 h (P < 0.05) and with urinary IL-1ra at 2 h (P < 0.05). Plasma IL-8 at 2 h correlated with NAG/creatinine at 6 h (P < 0.05). Urinary IL-1ra correlated with urinary NAG/creatinine ratio after cross-clamp release and 2 and 6 h after CPB (P < 0.05).     

Release of anti-inflammatory mediators after major torso trauma correlates with the development of postinjury multiple organ failure

BACKGROUND: Soluble tumor necrosis factor receptor (sTNFr) and interleukin-1 receptor antagonist (IL-1ra) have been identified as endogenous inhibitors of TNF-alpha and IL-1beta. While TNF-alpha and IL-1beta levels are not systematically elevated in postinjury patients who developed multiorgan failure (MOF), their involvement at the tissue level has been suggested. Our study hypothesis was that levels of sTNFr-I and IL-1ra would discriminate patients at risk for postinjury MOF. METHODS: Serial plasma levels of sTNFr and IL-1ra were measured in 29 trauma patients at high risk for postinjury MOF. RESULTS: sTNFr-I levels were higher in MOF compared with non-MOF patients at 12, 84, and 132 hours postinjury. MOF patients also had higher IL-1ra values 36, 60, 84, and 132 hours postinjury. CONCLUSIONS: Anti-inflammatory mechanisms are activated after trauma. Since increased levels of sTNFr and IL-1ra correlate with postinjury MOF, they may contribute to our understanding of the pathogenesis as well as prediction of outcome. High levels of antagonists to TNF-alpha and IL-1beta suggest tissue level involvement of these cytokines in postinjury hyperinflammation.     

Inflammation in human brain injury: intracerebral concentrations of IL-1alpha, IL-1beta, and their endogenous inhibitor IL-1ra

Following traumatic brain injury (TBI), cascades of inflammatory processes occur. Laboratory studies implicate the cytokines interleukin-1alpha (IL-1alpha) and IL-1beta in the pathophysiology of TBI and cerebral ischemia, whilst exogenous and endogenous interleukin-1 receptor antagonist (IL-1ra) is neuroprotective. We analyzed IL-1alpha, IL-1beta, and IL-1ra in brain microdialysates (100-kDa membrane) in 15 TBI patients. We also analyzed energy-related molecules (glucose, lactate, pyruvate, glutamate, and the lactate/pyruvate ratio) in these brain microdialysates. Mean of mean (+/-SD) in vitro microdialysis percentage recoveries (extraction efficiencies) were IL-1alpha 19.7+/-7.6%, IL-1beta 23.9+/-10.5%, and IL-1ra 20.9+/-6.3%. In the patients' brain microdialysates, mean of mean cytokine concentrations (not corrected for percentage recovery) were IL-1alpha 5.6+/-14.8 pg/mL, IL-1beta 10.4+/-14.7 pg/mL, and IL-1ra 2796+/-2918 pg/mL. IL-1ra was consistently much higher than IL-1alpha and IL-1beta. There were no significant relationships between IL-1 family cytokines and energy-related molecules. There was a significant correlation between increasing IL-1beta and increasing IL-1ra (Spearman r=0.59, p=0.028). There was also a significant relationship between increasing IL-1ra and decreasing intracranial pressure (Spearman r=-0.57, p=0.041). High concentrations of IL-1ra, and also high IL-1ra/IL-1beta ratio, were associated with better outcome (Mann Whitney, p=0.018 and p=0.0201, respectively), within these 15 patients. It is unclear whether these IL-1ra concentrations are sufficient to antagonize the effects of IL-1beta in vivo. This study demonstrates feasibility of our microdialysis methodology in recovering IL-1 family cytokines for assessing their inter-relationships in the injured human brain, and suggests a neuroprotective role for IL-1ra. It remains to be seen whether exogenous IL-1ra or other agents can be used to manipulate cytokine levels in the brain, for potential therapeutic effect.     

Lower urinary-interleukin-1 receptor-antagonist excretion in IgA nephropathy than in Henoch-Sch?nlein nephritis.

BACKGROUND: IgA nephropathy (IgAN) and Henoch-Sch?nlein nephritis (HSN) share many clinical, histological and immunological features. It has been postulated that these two conditions have a common pathogenesis and that HSN might be a systemic form of IgAN. Activity of interleukin-1beta (IL-1beta) in urine has been found to be higher in IgAN and HSN patients than in healthy controls. Interaction between IL-1beta and interleukin-1 receptor antagonist (IL-1ra) plays a significant role in the regulation of inflammatory responses. We studied levels of urinary excretion of IL-1beta and IL-1ra in patients with IgAN and HSN. METHODS: Amounts of IL-1beta and IL-1ra excreted in 24-h urine samples collected from 241 IgAN, 26 HSN patients and from 33 healthy controls were determined. Results were expressed as cytokine/creatinine (ng/mmol) ratios. RESULTS: Urinary IL-1beta excretion by the IgAN and HSN patients was no greater than urinary IL-1beta excretion by healthy controls. Urinary IL-1ra excretion by the IgAN patients was lower than urinary IL-1ra excretion by healthy controls (P < 0.05) and by the HSN patients (P < 0.01). In both patients and controls women had significantly higher IL-1ra, IL-1beta excretion levels and IL-1ra/IL-1beta ratios. The differences in urinary excretions of IL-1ra by the healthy controls and by the IgAN and HSN patients were significant in both sexes. Excretion of IL-1beta or IL-1ra did not correlate with excretion of urinary protein, duration of the disease or any histopathological variable. However, histopathological changes in renal biopsy specimens from patients with IL-1ra/IL-1beta ratios above normal were significantly milder than in renal biopsy specimens from patients with low or normal IL-1ra/IL-1beta ratios. CONCLUSION: Urinary IL-1ra levels in IgAN patients were lower than urinary IL-1ra levels in healthy controls or HSN patients, a finding which may indicate that the two diseases have a different pathogenesis. Whether the male predominance in IgAN and HSN and the worse outcomes in males that have been reported previously in IgAN and HSN are connected with the lower excretion of IL-1ra and consequently lower IL-1ra/IL-1beta ratios in male patients than in female patients needs more thorough investigation.     

Plasma and urinary cytokine homeostasis and renal dysfunction during cardiac surgery

BACKGROUND: Cardiac surgery induces changes in plasma cytokines. Proinflammatory cytokines have been associated with a number of renal diseases. The proinflammatory cytokines interleukin 8 (IL-8), tumor necrosis factor alpha (TNFalpha), and interleukin 1beta (IL-1beta) are smaller than the antiinflammatory cytokines interleukin 10 (IL-10), interleukin 1 receptor antagonist (IL-1ra), and TNF soluble receptor 2 (TNFsr2), and thus undergo glomerular filtration more readily. Accordingly, this study investigated the relation between plasma and urinary cytokines and proximal renal dysfunction during cardiac surgery. METHODS: Twenty patients undergoing coronary artery bypass grafting with cardiopulmonary bypass (CPB) were studied. Blood and urine samples were analyzed for proinflammatory and antiinflammatory cytokines. Proximal tubular dysfunction was measured using urinary N-acetyl-beta-d-glucosaminidase (NAG)/creatinine and alpha1-microglobulin/creatinine ratios. RESULTS: Plasma IL-8, IL-10, IL-1ra, and TNFsr2 values were significantly elevated compared with baseline. Urinary IL-1ra and TNFsr2 were significantly elevated. Urinary NAG/creatinine and alpha1-microglobulin/creatinine ratios were also elevated. Plasma TNFalpha at 2 h correlated with urinary NAG/creatinine ratio at 2 and 6 h (P < 0.05) and with urinary IL-1ra at 2 h (P < 0.05). Plasma IL-8 at 2 h correlated with NAG/creatinine at 6 h (P < 0.05). Urinary IL-1ra correlated with urinary NAG/creatinine ratio after cross-clamp release and 2 and 6 h after CPB (P < 0.05). CONCLUSIONS: Cardiac surgery using CPB leads to changes in plasma and urinary cytokine homeostasis that correlate with renal proximal tubular dysfunction. This dysfunction may be related to the renal filtration of proinflammatory mediators. Renal autoprotective mechanisms may involve the intrarenal generation of antiinflammatory cytokines.     

Interleukin-1beta and adverse effects on cerebral blood flow during long-term global hypoperfusion

OBJECT: The effects of interleukin (IL)-1beta on the cerebral vasculature are complex and incompletely understood. Many pathophysiological states in which inflammatory cascades have been implicated also have varying degrees of cerebral hypoperfusion. The purpose of this investigation was to examine the long-term effects of this proinflammatory cytokine and its antagonist on cerebral blood flow (CBF) following global cerebral hypoperfusion. METHODS: Sprague-Dawley rats were randomly assigned to 12 groups and given continuous intracerebroventricular (ICV) infusions of IL-1beta, the IL-1 receptor antagonist (IL-1ra), or saline vehicle (control). Global cerebral hypoperfusion was produced by occlusion of both carotid arteries and one vertebral artery. Cerebral blood flow was measured at baseline and again after initiation of the infusions by performing a 133Xe clearance study. Prolonged ICV administration of IL-1beta resulted in a significant decrease in CBF compared with that in controls. Prolonged administration of the antagonist IL-1ra resulted in significant increases in CBF compared with that in both IL-1beta-treated animals and controls. CONCLUSIONS: This experiment demonstrates that long-term treatment with the proinflammatory cytokine IL-1beta adversely affects CBF.     

Leucocyte response and anti-inflammatory cytokines in community acquired pneumonia

BACKGROUND: In the host defence of the lung neutrophils (PMN) play a central role. Apart from antimicrobial properties, recent data indicate that PMN also exert anti-inflammatory effects by stimulation and release of cytokine antagonists such as interleukin-1 receptor antagonist (IL-1ra). METHODS: Cytokine release from lipopolysaccharide stimulated whole blood was studied in 18 patients with community acquired pneumonia (CAP) and severe co-morbidities at admission and after 24 hours. Release of IL-1ra, interleukin-1beta (IL-1beta), tumour necrosis factor alpha (TNFalpha), soluble TNF receptor type I (sTNF-RI), and IL-8 was determined by ELISA. RESULTS: The mean (SD) leucocyte level at admission was 12.5 (4.1)/nl. There was a significant correlation between the release of anti-inflammatory cytokines such as IL-1ra and sTNF-RI and the leucocyte count at admission and after 24 hours. Additional in vitro experiments showed that co-incubation of peripheral blood mononuclear cells with autologous PMN led to a marked dose dependent increase in IL-1ra and sTNF-RI release. CONCLUSION: These results indicate that PMN may be responsible for the increase in anti-inflammatory cytokines in CAP. Strategies to increase neutrophil counts may exert beneficial effects, not only by augmenting the antimicrobial activity but also by modulating the inflammatory cytokine response.     

Improved recovery and delayed cytokine induction after closed head injury in mice with central overexpression of the secreted isoform of the interleukin-1 receptor antagonist

The acute inflammatory response following traumatic brain injury (TBI) has been shown to play an important role in the development of secondary tissue damage. The proinflammatory cytokines interleukin-1 (IL-1) and tumor necrosis factor-alpha (TNFalpha), are induced early after brain injury and have been implicated in the delayed damage. The IL-1 receptor antagonist (IL-1ra) has been shown to modulate the proinflammatory cytokine cascade by blocking the binding of IL-1 to its signaling receptor. In this study, we investigated the effect of transgenic overexpression of IL-1ra on the cytokine expression and neurological damage in a closed head injury (CHI) model of TBI. The neurological recovery, as analyzed by neurological severity score (NSS), was significantly higher in transgenic mice overexpressing the human secreted form of IL-1ra in astrocytes, directed by the murine glial fibrillary acidic protein promoter, as compared to wild-type mice. Analysis of tissue levels of cytokines by ELISA showed increased levels of TNFalpha in the cerebral cortex from the wild type mice 1 h after injury. After 4 h significant increases in the levels of IL-1beta and IL-6 were observed in the wild type mice. In the transgenic mice, on the other hand, no effect on TNFalpha levels was observed and no significant increases in IL-1beta and IL-6 levels could be detected until 6 h after injury. Thus, it can be concluded that blockage of IL-1 signaling by elevated levels of IL-1ra has a neuroprotective effect, in agreement with previous reports, and that central overexpression of IL-1ra results in delayed proinflammatory cytokine induction and improved neurological recovery after traumatic brain injury.     

Unopposed interleukin-1 is necessary for increased plasma cytokine and eicosanoid levels to develop in severe sepsis.

OBJECTIVE: The purpose of the study was to identify the changes in plasma prostaglandin, leukotriene, and cytokine levels during clinical severe sepsis for which interleukin-1 was necessary. SUMMARY BACKGROUND DATA: Circulating prostaglandins, leukotrienes, and cytokines have been implicated as causative agents of systemic inflammation due to sepsis. However, interactions between interleukin-1 and the other cytokine and eicosanoid mediators of severe sepsis are not well-defined. METHODS: As part of two sequential multisite, prospective, randomized, double-blind, placebo-controlled clinical trials, 37 patients with severe sepsis received interleukin-1 receptor antagonist (IL-1ra) 100-mg bolus followed by 2 mg/kg per hour intravenously for 72 hours (n = 20) or placebo (n = 17). Plasma thromboxane B2 (TxB2), prostaglandin 6-keto-F1alpha (PGI), leukotriene B4 (LTB4), leukotriene C4D4E4 (LTC4D4E4), interleukin-1 beta (IL-1), interleukin-6 (IL-6), and tumor necrosis factor alpha (TNF-alpha) were measured by enzyme-linked immunosorbent assay before study drug infusion (baseline) and at 24, 48, and 72 hours after the beginning of the study drug infusion. RESULTS: Differences between placebo and IL-1ra for plasma LTB4 were not significant, but only IL-1ra LTB4 increased from baseline. Plasma TxB2, PGI, LTC4D4E4, TNF, and IL-6, expressed as % baseline, decreased significantly in patients receiving IL-1ra compared with the placebo group (p < 0.05), whereas plasma IL-1 increased significantly. CONCLUSIONS: Interleukin-1 may be a necessary mediator of increased circulating PGI, TxB2, LTC4D4E4, TNF, and IL-6 levels in patients with severe sepsis. Plasma IL-1 and LTB4 are increased with infusion of IL-1 receptor antagonist. The clinical significance of IL-1 in modifying circulating eicosanoid and cytokine concentrations in clinical sepsis is not clear from the data.     

Identification of estrogen-regulated genes of potential importance for the regulation of trabecular bone mineral density.

Estrogen is of importance for the regulation of trabecular bone mineral density (BMD). The aim of this study was to search for possible mechanisms of action of estrogen on bone. Ovariectomized (OVX) mice were treated with 17beta-estradiol. Possible effects of estrogen on the expression of 125 different bone-related genes in humerus were analyzed using the microarray technique. Estrogen regulated 12 of these genes, namely, two growth factor-related genes, 8 cytokines, and 2 bone matrix-related genes. Five of the 12 genes are known to be estrogen-regulated, and the remaining 7 genes are novel estrogen-regulated genes. Seven genes, including interleukin-1 receptor antagonist (IL-1ra), IL-1receptor type II (IL-1RII), insulin-like growth factor-binding protein 4 (IGFBP-4), transforming growth factor beta (TGF-beta), granulocyte colony-stimulating factor receptor (G-CSFR), leukemia inhibitory factor receptor (LIFR), and soluble IL-4 receptor (sIL-4R) were selected as probable candidate genes for the trabecular bone-sparing effect of estrogen, as the mRNA levels of these genes were highly correlated (r2 > 0.65) to the trabecular BMD. The regulation of most of these seven genes was predominantly estrogen receptor alpha (ER-alpha)-mediated (5/7) while some genes (2/7) were regulated both via ER-alpha and ER-beta. In conclusion, by using the microarray technique, we have identified four previously known and three novel estrogen-regulated genes of potential importance for the trabecular bone-sparing effect of estrogen.