Interleukin-1 induces natriuresis in conscious rats: role of renal prostaglandins

A new immune disease: systemic hypertension

Systemic hypertension is the most common medical comorbidity affecting the adult population globally, with multiple associated outcomes including cerebrovascular diseases, cardiovascular diseases, vascular calcification, chronic kidney disease, metabolic syndrome and mortality. Despite advancements in the therapeutic field approximately one in every five adult patients with hypertension is classified as having treatment-resistant hypertension, indicating the need for studies to provide better understanding of the underlying pathophysiology and the need for more therapeutic targets. Recent pre-clinical studies have demonstrated the role of the innate and adaptive immune system including various cell types and cytokines in the pathophysiology of hypertension. Moreover, pre-clinical studies have indicated the potential beneficial effects of immunosuppressant medications in the control of hypertension. Nevertheless, it is unclear whether such pathophysiological mechanisms and therapeutic alternatives are applicable to human subjects, while this area of research is undoubtedly a rapidly growing field.

Responses to Ang II (Angiotensin II), Salt Intake, and Lipopolysaccharide Reveal the Diverse Actions of TNF-α (Tumor Necrosis Factor-α) on Blood Pressure and Renal Function

TNF-α (tumor necrosis factor-alpha) is the best known as a proinflammatory cytokine; yet, this cytokine also has important immunomodulatory and regulatory functions. As the effects of TNF-α on immune system function were being revealed, the spectrum of its activities appeared in conflict with each other before investigators defined the settings and mechanisms by which TNF-α contributed to both host defense and chronic inflammation. These effects reflect self-protective mechanisms that may become harmful when dysregulated. The paradigm of physiological and pathophysiological effects of TNF-α has since been uncovered in the lung, colon, and kidney where its role has been identified in pulmonary edema, electrolyte reabsorption, and blood pressure regulation, respectively. Recent studies on the prohypertensive and inflammatory effects of TNF-α in the cardiovascular system juxtaposed to those related to NaCl and blood pressure homeostasis, the response of the kidney to lipopolysaccharide, and protection against bacterial infections are helping define the mechanisms by which TNF-α modulates distinct functions within the kidney. This review discusses how production of TNF-α by renal epithelial cells may contribute to regulatory mechanisms that not only govern electrolyte excretion and blood pressure homeostasis but also maintain the appropriate local hypersalinity environment needed for optimizing the innate immune response to bacterial infections in the kidney. It is possible that the wide range of effects mediated by TNF-α may be related to severity of disease, amount of inflammation and TNF-α levels, and the specific cell types that produce this cytokine, areas that remain to be investigated further.

Hyponatremia in melioidosis: Analysis of 10-year data from a hospital-based registry

Introduction:

Methods:

Results:

Conclusion:

Beyond kidney stones: Why pediatricians should worry about hypercalciuria

The incidence of urolithiasis (UL) is increasing, and it has become more common in children and adolescents over the past few decades. Hypercalciuria is the leading metabolic risk factor of pediatric UL, and it has high morbidity, with or without lithiasis as hematuria and impairment of bone mass. The reduction in bone mineral density has already been described in pediatric idiopathic hypercalciuria (IH), and the precise mechanisms of bone loss or failure to achieve adequate bone mass gain remain unknown. A current understanding is that hypercalciuria throughout life can be considered a risk of change in bone structure and low bone mass throughout life. However, it is still not entirely known whether hypercalciuria throughout life can compromise the quality of the mass. The peak bone mass is achieved by late adolescence, peaking at the end of the second decade of life. This accumulation should occur without interference in order to achieve the peak of optimal bone mass. The bone mass acquired during childhood and adolescence is a major determinant of adult bone health, and its accumulation should occur without interference. This raises the critical question of whether adult osteoporosis and the risk of fractures are initiated during childhood. Pediatricians should be aware of this pediatric problem and investigate their patients. They should have the knowledge and ability to diagnose and initially manage patients with IH, with or without UL.

Induction of renal tumor necrosis factor-α and other autacoids and the beneficial effects of hypertonic saline in acute decompensated heart failure

Although administration of hypertonic saline (HSS) in combination with diuretics has yielded improved weight loss, preservation of renal function, and reduction in hospitalization time in the clinical setting of patients with acute decompensated heart failure (ADHF), the mechanisms that underlie these beneficial effects remain unclear and additional studies are needed before this approach can be adopted on a more consistent basis. As high salt conditions stimulate the production of several renal autacoids that exhibit natriuretic effects, renal physiologists can contribute to the understanding of mechanisms by which HSS leads to increased diuresis both as an individual therapy as well as in combination with loop diuretics. For instance, since HSS increases TNF-α production by proximal tubule and thick ascending limb of Henle's loop epithelial cells, this article is aimed at highlighting how the effects of TNF-α produced by these cell types may contribute to the beneficial effects of HSS in patients with ADHF. Although TNF-α produced by infiltrating macrophages and T cells exacerbates and attenuates renal damage, respectively, production of this cytokine within the tubular compartment of the kidney functions as an intrinsic regulator of blood pressure and Na⁺ homeostasis via mechanisms along the nephron related to inhibition of Na⁺-K⁺-2Cl^- cotransporter isoform 2 activity and angiotensinogen expression. Thus, in the clinical setting of ADHF and hyponatremia, induction of TNF-α production along the nephron by administration of HSS may attenuate Na⁺-K⁺-2Cl^- cotransporter isoform 2 activity and angiotensinogen expression as part of a mechanism that prevents excessive Na⁺ reabsorption in the thick ascending limb of Henle's loop, thereby mitigating volume overload.

Extracorporeal resuscitation with carbon monoxide improves renal function by targeting inflammatory pathways in cardiac arrest in pigs

Deleterious consequences like acute kidney injury frequently occur upon successful resuscitation from cardiac arrest. Extracorporeal life support is increasingly used to overcome high cardiac arrest mortality. Carbon monoxide (CO) is an endogenous gasotransmitter, capable of reducing renal injury. In our study, we hypothesized that addition of CO to extracorporeal resuscitation hampers severity of renal injury in a porcine model of cardiac arrest. Hypoxic cardiac arrest was induced in pigs. Animals were resuscitated using a conventional [cardiopulmonary resuscitation (CPR)], an extracorporeal (E-CPR), or a CO-assisted extracorporeal (CO-E-CPR) protocol. CO was applied using a membrane-controlled releasing system. Markers of renal injury were measured, and histopathological analyses were carried out. We investigated renal pathways involving inflammation as well as apoptotic cell death. No differences in serum neutrophil gelatinase-associated lipocalin (NGAL) were detected after CO treatment compared with Sham animals (Sham 71 ± 7 and CO-E-CPR 95 ± 6 ng/mL), while NGAL was increased in CPR and E-CPR groups (CPR 135 ± 11 and E-CPR 124 ± 5 ng/mL; P < 0.05). Evidence for histopathological damage was abrogated after CO application. CO increased renal heat shock protein 70 expression and reduced inducible cyclooxygenase 2 (CPR: 60 ± 8; E-CPR 56 ± 8; CO-E-CPR 31 ± 3 µg/mL; P < 0.05). Caspase 3 activity was decreased (CPR 1,469 ± 276; E-CPR 1,670 ± 225; CO-E-CPR 755 ± 83 pg/mL; P < 0.05). Furthermore, we found a reduction in renal inflammatory signaling upon CO treatment. Our data demonstrate improved renal function by extracorporeal CO treatment in a porcine model of cardiac arrest. CO reduced proinflammatory and proapoptotic signaling, characterizing beneficial aspects of a novel treatment option to overcome high mortality.

The idiopathic hypercalciuria reviewed. Metabolic abnormality or disease?

Idiopathic hypercalciuria (IH) is defined as that clinical situation in which an increase in urinary calcium excretion is observed, in the absence of hypercalcemia and other known causes of hypercalciuria. In recent years, its diagnosis in pediatric age has been more frequent because it has been known that it can debut with very different symptoms, in the absence of kidney stone formation. The discovery of genetic hypercalciuric stone-forming rats has allowed us to glimpse the pathophysiological mechanism of IH since they show many data in common with humans with IH as normal levels of blood calcium, intestinal calcium hyperabsorption, increased bone resorption and a defect in the renal tubular calcium reabsorption. In 1993, it was shown that in these animals there is an increase in the number of vitamin D receptors (VDR) in the intestine, which favors an increase in the functional capacity of calcitriol-VDR complexes that explains the increase in intestinal transport of calcium. The same happens at the bone level producing a greater resorption. In our opinion, IH is a 'metabolic anomaly' or, better, an inheritable constitutive metabolic characteristic. In this sense, what patients with IH would inherit is the availability of having a greater number of VDRs in their cells than those with normal urinary calcium excretion. IH cannot be considered a sensu stricto disease, so pharmacological treatment must be individualized.

Mechanisms of hypertension in autoimmune rheumatic diseases

Patients with autoimmune rheumatic diseases including rheumatoid arthritis and systemic lupus erythematosus have an increased prevalence of hypertension. There is now a large body of evidence showing that the immune system is a key mediator in both human primary hypertension and experimental models. Many of the proposed immunological mechanisms leading to primary hypertension are paralleled in autoimmune rheumatic disorders. Therefore, examining the link between autoimmunity and hypertension can be informative for understanding primary hypertension. This review examines the prevalent hypertension, the immune mediators that contribute to the prevalent hypertension and their impact on renal function and how the risk of hypertension is potentially influenced by common hormonal changes that are associated with autoimmune rheumatic diseases.

Linked Articles

This article is part of a themed section on Immune Targets in Hypertension. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.12/issuetoc

Renal-Specific Silencing of TNF (Tumor Necrosis Factor) Unmasks Salt-Dependent Increases in Blood Pressure via an NKCC2A (Na+-K+-2Cl- Cotransporter Isoform A)-Dependent Mechanism

We tested the hypothesis that TNF (tumor necrosis factor)-α produced within the kidney and acting on the renal tubular system is part of a regulatory mechanism that attenuates increases in blood pressure in response to high salt intake. Intrarenal administration of a lentivirus construct, which specifically silenced TNF in the kidney, did not affect baseline blood pressure. However, blood pressure increased significantly 1 day after mice with intrarenal silencing of TNF ingested 1% NaCl in the drinking water. The increase in blood pressure, which was continuously observed for 11 days, promptly returned to baseline levels when mice were switched from 1% NaCl to tap water. Silencing of renal TNF also increased NKCC2 (Na⁺-K⁺-2Cl^- cotransporter) phosphorylation and induced a selective increase in NKCC2A (NKCC2 isoform A) mRNA accumulation in both the cortical and medullary thick ascending limb of Henle loop that was neither associated with a compensatory decrease of NKCC2F in the medulla nor NKCC2B in the cortex. The NaCl-mediated increases in blood pressure were completely absent when NKCC2A, using a lentivirus construct that did not alter expression of NKCC2F or NKCC2B, and TNF were concomitantly silenced in the kidney. Moreover, the decrease in urine volume and NaCl excretion induced by renal TNF silencing was abolished when NKCC2A was concurrently silenced, suggesting that this isoform contributes to the transition from a salt-resistant to salt-sensitive phenotype. Collectively, the data are the first to demonstrate a role for TNF produced by the kidney in the modulation of sodium homeostasis and blood pressure regulation.

Hyponatremia in patients with systemic lupus erythematosus

The aim of this study was to determine whether decreased serum sodium concentration could be associated with the disease activity in SLE. We retrospectively analyzed the data of the two independent cohorts of children and adults with SLE in two centers. Hyponatremia was associated with serum chloride (p = 0.004), albumin (p = 0.002) and SLE disease activity index (SLEDAI) (p = 0.026) in children with SLE. Serum sodium levels were correlated negatively with ESR (p =0.001) and positively with serum albumin levels (p < 0.0001) and C3 (p = 0.008) in children with SLE and those levels were correlated negatively with serum interleukin-6 levels (p = 0.003) in adults with SLE. Independent risk factors for the development of hyponatremia were the decreased serum C3 levels (OR 1.069, p = 0.031), the decreased serum chloride levels (OR 2.054, p = 0.006) and increased erythrocyte sedimentation rate (ESR) (OR 1.066, p = 0.03) in children with SLE and increased C-reactive protein (CRP) (OR 1.480, p = 0.023) in combined cohorts with SLE by multiple logistic regression analyses. Our study firstly showed that hyponatremia could reflect a disease activity and severe inflammation of SLE.

Epithelial transport during septic acute kidney injury

A goal for scientists studying septic acute kidney injury (AKI) should be to formulate a conceptual model of disease that is able to coherently reconcile the molecular and inflammatory consequences of sepsis with impaired epithelial tubular function, diminished glomerular filtration rate (GFR) and ultimately kidney failure. Recent evidence has shed light on how sepsis modulates the tubular regulation of ion, glucose, urea and water transport and acid-base homeostasis in the kidney. The present review summarizes recent discoveries on changes in epithelial transport under septic and endotoxemic conditions as well as the mechanisms that link inflammation with impaired tubular membrane transport. This paper also proposes that the tubular dysfunction that is mediated by inflammation in sepsis ultimately leads to increased sodium and chloride delivery to the distal tubule and macula densa, contributing to tubuloglomerular feedback and impaired GFR. We feel that this conceptual model resolves many of the physiologic and clinical paradoxes that septic AKI presents to practicing researchers and clinicians.

Hyponatremia and anti-diuretic hormone in Legionnaires' disease

Background

Medical textbooks often list Legionnaires’ disease as a differential diagnosis of the syndrome of inappropriate secretion of anti-diuretic hormone (ADH) (SIADH), but evidence supporting this association is largely lacking. We tested the hypothesis whether hyponatremia in patients with Legionnaires’ disease would be caused by increased CT-ProVasopressin.

Methods

We measured CT-ProVasopressin and sodium levels in a prospective cohort of 873 pneumonia patients from a previous multicentre study with 27 patients having positive antigen tests for Legionella pneumophila.

Results

Patients with Legionnaires’ disease more frequently had low sodium levels (Na < 130 mmol/L) (44.4% vs 8.2%, p < 0.01), but similar mean CT-ProVasopressin levels (pmol/l) (39.4 [±7] vs 51.2 [±2.7], p = 0.43) as compared to patients with pneumonia of other etiologies. In patients with Legionnaires’ disease, CT-ProVasopressin levels showed a positive correlation with sodium (r = 0.42, p < 0.05). Independent of pneumonia etiology, CT-ProVasopressin correlated significantly with the pneumonia severity index (r = 0.56, p < 0.05), ICU admission (adjusted odds ratio per decile, 95% CI) (1.6, 1.2 - 2.0), and 30-day-mortality (1.8, 1.3 - 2.4).

Conclusion

While Legionnaires’ disease was associated with hyponatremia, no concurrent increase in CT-ProVasopressin levels was found, which argues against elevated ADH levels as the causal pathway to hyponatremia. Rather, Vasopressin precursors were upregulated as response to stress in severe disease, which seems to overrule the osmoregulatory regulation of ADH.

Chronic elevation of IL-1β induces diuresis via a cyclooxygenase 2-mediated mechanism

Chronic renal inflammation is an increasingly recognized phenomenon in multiple disease states, but the impact of specific cytokines on renal function is unclear. Previously, we found that 14-day interleukin-1β (IL-1β) infusion increased urine flow in mice. To determine the mechanism by which this occurs, the current study tested the possible involvement of three classical prodiuretic pathways. Chronic IL-1β infusion significantly increased urine flow (6.5 ± 1 ml/day at day 14 vs. 2.3 ± 0.3 ml/day in vehicle group; P < 0.05) and expression of cyclooxygenase (COX)-2, all three nitric oxide synthase (NOS) isoforms, and endothelin (ET)-1 in the kidney (P < 0.05 in all cases). Urinary prostaglandin E metabolite (PGEM) excretion was also significantly increased at day 14 of IL-1β infusion (1.21 ± 0.26 vs. 0.29 ± 0.06 ng/day in vehicle-infused mice; P = 0.001). The selective COX-2 inhibitor celecoxib markedly attenuated urinary PGEM excretion and abolished the diuretic response to chronic IL-1β infusion. In contrast, deletion of NOS3, or inhibition of NOS1 with L-VNIO, did not blunt the diuretic effect of IL-1β, nor did pharmacological blockade of endothelin ETA and ETB receptors with A-182086. Consistent with a primary effect on water transport, IL-1β infusion markedly reduced inner medullary aquaporin-2 expression (P < 0.05) and did not alter urinary Na⁺ or K⁺ excretion. These data indicate a critical role for COX-2 in mediating the effects of chronic IL-1β elevation on the kidney.

Immune and inflammatory role in renal disease

Chronic and acute renal diseases, irrespective of the initiating cause, have inflammation and immune system activation as a common underlying mechanism. The purpose of this review is to provide a broad overview of immune cells and inflammatory proteins that contribute to the pathogenesis of renal disease, and to discuss some of the physiological changes that occur in the kidney as a result of immune system activation. An overview of common forms of acute and chronic renal disease is provided, followed by a discussion of common therapies that have anti-inflammatory or immunosuppressive effects in the treatment of renal disease.

Interleukin-1beta, but not interleukin-6, enhances renal and systemic endothelin production in vivo

The inflammatory cytokines IL-1beta and IL-6 have been shown to stimulate production of endothelin-1 (ET-1) by several cell types in vitro, but their effects on renal ET-1 production in vivo are not known. To test whether IL-1beta and IL-6 stimulate renal ET-1 production and release in vivo, urine was collected from male C57BL/6 mice over 24-h periods at baseline and on days 7 and 14 of a 14-day subcutaneous infusion of IL-1beta (10 ng/h), IL-6 (16 ng/h), or vehicle. By day 14, plasma ET-1 was significantly increased by IL-1beta infusion (1.7 +/- 0.1 vs. 0.8 +/- 0.1 pg/ml for vehicle, P < 0.001). Compared with vehicle infusion, IL-1beta infusion induced significant increases in urinary ET-1 excretion rate and urine flow but did not affect conscious mean arterial pressure (telemetry). IL-1beta infusion significantly increased renal cortical and medullary IL-1beta content (ELISA) and prepro-ET-1 mRNA expression (quantitative real-time PCR). In contrast, 14 days of IL-6 infusion had no significant effect on plasma ET-1 or urinary ET-1 excretion rate. To determine whether IL-1beta stimulates ET-1 release via activation of NF-kappaB, inner medullary collecting duct (IMCD-3) cells were incubated for 24 h with IL-1beta, and ET-1 release and NF-kappaB activation were measured (ELISA). IL-1beta activated NF-kappaB and increased ET-1 release in a concentration-dependent manner. The effect of IL-1beta on ET-1 release could be partially inhibited by pretreatment of IMCD-3 cells with an inhibitor of NF-kappaB activation (BAY 11-7082). These results indicate that IL-1beta stimulates renal and systemic ET-1 production in vivo, providing further evidence that ET-1 participates in inflammatory responses.

Changes in ion transport in inflammatory disease

Ion transport is essential for maintenance of transmembranous and transcellular electric potential, fluid transport and cellular volume. Disturbance of ion transport has been associated with cellular dysfunction, intra and extracellular edema and abnormalities of epithelial surface liquid volume. There is increasing evidence that conditions characterized by an intense local or systemic inflammatory response are associated with abnormal ion transport. This abnormal ion transport has been involved in the pathogenesis of conditions like hypovolemia due to fluid losses, hyponatremia and hypokalemia in diarrhoeal diseases, electrolyte abnormalities in pyelonephritis of early infancy, septicemia induced pulmonary edema, and in hypersecretion and edema induced by inflammatory reactions of the mucosa of the upper respiratory tract. Components of membranous ion transport systems, which have been shown to undergo a change in function during an inflammatory response include the sodium potassium ATPase, the epithelial sodium channel, the Cystic Fibrosis Transmembrane Conductance Regulator and calcium activated chloride channels and the sodium potassium chloride co-transporter. Inflammatory mediators, which influence ion transport are tumor necrosis factor, gamma interferon, interleukins, transforming growth factor, leukotrienes and bradykinin. They trigger the release of specific messengers like prostaglandins, nitric oxide and histamine which alter ion transport system function through specific receptors, intracellular second messengers and protein kinases. This review summarizes data on in vivo measurements of changes in ion transport in acute inflammatory conditions and in vitro studies, which have explored the underlying mechanisms. Potential interventions directed at a correction of the observed abnormalities are discussed.

Role of plasma ANG II in the excretion of acute sodium load in a bird with salt glands (Anas platyrhynchos)

This study was designed to further examine the role of plasma ANG II in the excretion of sodium in the Pekin duck, a bird with salt glands. Renal and extrarenal (salt gland) excretion of an intravenously administered isotonic saline load was monitored over a 4-h period in a group of eight birds under two conditions: the control condition, in which isotonic saline infusion decreased endogenous plasma ANG II from 102.6 to 16.5 pg/ml, and the experimental condition, in which ANG II suppression was prevented by intravenous infusion of a 3.5 ng. kg(-1). min(-1) dose of synthetic ANG II. ANG II infusion significantly decreased the total sodium excretion (by 15%), primarily via an inhibition of salt gland output. The results suggest that ANG II suppression facilitates the excretion of an administered sodium load in birds with salt glands.

Cyclooxygenase-2 expression and function in the medullary thick ascending limb

The medullary thick ascending limb (MTAL) metabolizes arachidonic acid (AA) via cytochrome P-450 (CyP450)- and cyclooxygenase (COX)-dependent pathways. In the present study, we demonstrated that the COX-2-selective inhibitor, NS-398, prevented tumor necrosis factor-alpha (TNF)- and phorbol myristate acetate (PMA)-mediated increases in PGE(2) production by cultured MTAL cells. Accumulation of COX-2, but not COX-1, mRNA increased when cells were challenged with TNF (1 nM) or PMA (1 microM). Pretreatment of cells for 30 min with actinomycin D (AcD, 1 microM) had little effect on COX-2 mRNA accumulation in unstimulated cells or in cells challenged with either TNF or PMA. Moreover, a posttranscriptional mechanism(s) appears to contribute significantly to COX-2 mRNA accumulation as pretreatment for 15 min with cycloheximide (CHX, 1 microM) caused a superinduction of COX-2 mRNA accumulation in unstimulated cells as well as in cells challenged with either TNF or PMA. Expression of COX-2 protein in unstimulated MTAL cells was attenuated by preincubation for 2 h with dexamethasone (Dex, 2 microM); however, Dex had little or no effect on COX-2 expression in cells challenged with either PMA or TNF. The time-dependent inhibition of 86Rb uptake by MTAL cells challenged with TNF was diminished by pretreating cells with NS-398. These data suggest that TNF-mediated induction of COX-2 protein expression accounted for the lag-time required for this cytokine to inhibit 86Rb uptake in MTAL cells.

Concerted actions of IL-1beta inhibit Na+ absorption and stimulate anion secretion by IMCD cells

Increasing evidence indicates that factors other than adrenocorticoid hormones can influence long-term regulation of Na+ transport by inner medullary collecting duct (IMCD) cells. We now report that, of 14 interleukins tested, only interleukin-1alpha (IL-1alpha) and IL-1beta inhibited Na+ transport by primary cultures of rat IMCD. IL-1beta reduced both basal and mineralocorticoid (MC)-stimulated Na+ transport by 50-70%; its effect on glucocorticoid (GC)-stimulated Na+ transport was significantly less. IL-1beta continued to blunt MC stimulation of Na+ transport even after it had been removed from the medium for 24 h. The onset of action to inhibit Na+ transport was within 20 min. The acute effect from the basolateral surface was greater than that from the apical surface, but the effect from each surface was additive. In addition to its inhibitory effect on Na+ transport, chronic IL-1beta exposure increased both basal and cAMP-stimulated anion secretion rates. IL-1beta had no acute effect on anion secretion. Monolayers chronically treated with IL-1beta had an increased capacity to secrete fluid, as predicted from its effects on ion transport. Inhibitors of cyclooxygenase did not blunt the actions of IL-1beta. Furthermore, IL-1beta did not produce a rise in intracellular Ca2+. These results suggest novel signaling pathways induced by IL-1beta regulating Na+ and Cl- transport by the IMCD.

Effects of systemic interleukin-1beta administration on daily drinking and renal excretory function in conscious rats

To elucidate the roles of interleukin-1beta (IL-1beta), a cytokine with several diverse actions, in the control of body fluid balance, its effects on daily drinking behavior and renal excretory function were examined in conscious rats. Administration of IL-1beta (4 microg/kg, I.P.) resulted in the suppression of both daily drinking and food intake and a decrease in daily urinary sodium and potassium excretion, but had no effect on urine volume. The IL-1beta-induced decrease in sodium excretion was abolished in renal-denervated rats. Kainic acid was then injected into the anteroventral third ventricle region, including the organum vasculosum of the lamina terminalis, to examine whether neurons in this region are involved in the IL-1beta-induced responses; the effects on daily drinking and urinary sodium and potassium excretion were abolished, whereas the effects on food intake, although attenuated, were still present. In contrast, electrical lesion of the subfomical organ did not affect the IL-1beta-induced responses. Thus, IL-1beta seems exert its effects on body fluid balance at several distinct sites in the central nervous system.

Effect of nephropathogenic infectious bronchitis viruses on renal function in young male broiler chickens

1. The acute effects of challenge with Australian T-strain infectious bronchitis virus (IBV) on renal function were evaluated, following primary vaccination in 1-d-old male broilers. 2. Challenge with T-strain IBV decreased body weight and induced kidney hypertrophy and kidney asymmetry. 3. Haematocrit was reduced in birds challenged with the Australian T-strain IBV and plasma uric acid was elevated in unvaccinated birds exposed to the IBV challenge. 4. Challenge with T-strain IBV caused significant increases in urinary water losses, accompanied by decreased urine osmolality and increased fractional excretion of sodium, calcium and potassium. 5. Vaccination at 1-d-old with Vic S-strain IBV provided a limited degree of protection against an heterologous challenge with T-strain IBV at 15 d of age.

Stimulation by interleukin-1 of renal calcium reabsorption in thyroparathyroidectomized rats

Recombinant human interleukin-1 (rhIL-1) can induce an elevation in calcium that has been ascribed exclusively to the stimulation of bone resorption. In the present study, we investigated whether rhIL-1 could also enhance the renal tubular reabsorption of calcium. The chronic influence of recombinant human rhIL-1 on renal calcium transport was investigated in thyroparathyroidectomized rats. Administration of rhIL-1 at the dose of 1.5 micrograms/day sc for 6 days induced a significant elevation in plasma calcium that was associated with a slight but significant decrease in the urinary excretion of calcium. Recording of the urinary calcium excretion expressed per ml glomerular filtrate at various plasma calcium levels, as achieved by acutely infusing calcium gluconate, indicates that rhIL-1 enhanced the tubular reabsorption of calcium. The calculated index of the tubular reabsorption of calcium (TRCal) was significantly increased by rhIL-1 (2.18 +/- 0.14 versus 1.79 +/- 0.07 mmol/l GFR, p < 0.05, in vehicle-treated rats). The change in the renal handling of calcium was not associated with stimulation of the tubular reabsorption of magnesium. Acute administration of a large dose (24 micrograms given in a bolus IV injection) of rhIL-1 enhanced within minutes the urinary excretion of prostaglandin E2. This effect was followed by a significant increase in urinary cAMP excretion and associated with a lower urinary calcium excretion. In conclusion, the results presented in this study indicate that rhIL-1 administered chronically selectively stimulated the tubular reabsorption of calcium. Experimental evidence suggests that this effect is mediated by prostaglandin-induced cAMP generation. These data strongly suggest that changes in the tubular handling of calcium could contribute to rhIL-1-induced hypercalcemia.

Central effects of interleukin-1 on blood pressure, thermogenesis, and the release of vasopressin, ACTH, and atrial natriuretic peptide

To assess the central role of interleukin 1-beta (IL-1 beta) in the release of ACTH, vasopressin (AVP) and atrial natriuretic peptide (ANP) and in the regulation of blood pressure and thermogenesis, 3 ng (0.173 pM) x 100-1 x BW-1 (LIL), 30 ng (1.73 pM) x 100g-1 x BW-1 (MIL), and 150 ng (8.63 pM) x 100g-1 x BW-1 (HIL) of human IL-1 beta dissolved in sterile saline were injected intracerebroventricularly to conscious rats. In the control rats, saline alone (5 microliters) was administered. In three other groups, rats were pretreated with indomethacin, a cyclooxygenase inhibitor, given i.v. (1 mg x 100g-1 x BW-1); medium and high doses of IL-1 beta or its vehicle were given. In the LIL group, IL-1 beta increased blood pressure, body temperature and plasma AVP and ANP without any changes in heart rate (HR) and plasma ACTH. In the MIL group, plasma ACTH was increased, and changes in the other parameters were similar to those in the LIL group. In the HIL group, however, the pressor and thermogenetic responses were attenuated; plasma AVP, ACTH, and ANP were increased; and HR was unchanged. In the control (CON) group, none of these parameters was changed throughout the studies. Indomethacin abolished the AVP and ACTH responses to IL-1 beta, but potentiated the pressor and hypothermic responses and increased plasma ANP. These data suggest that the actions of IL-1 beta on AVP and ACTH release and thermogenesis, but not on blood pressure and the release of ANP, are modulated by the stimulated central production of prostaglandins.

Passive immunization against tumour necrosis factor-alpha (TNF-alpha) and IL-1 beta protects from LPS enhancing glomerular injury in nephrotoxic nephritis in rats

Glomerular injury caused by injection of heterologous anti-glomerular basement membrane antibodies (anti-GBM Ab) is increased in rats pretreated with small doses of bacterial lipopolysaccharide (LPS). We have investigated the involvement of tumour necrosis factor-alpha (TNF-alpha), IL-1 alpha and IL-1 beta in this phenomenon by passive immunization against these cytokines. Anti-TNF-alpha or anti-IL-1 beta antibodies given 1.5 h before the induction of nephritis significantly decreased injury in this model, whether assessed by the magnitude of albuminuria, the prevalence of glomerular capillary thrombi or the intensity of glomerular neutrophil infiltrate. Albuminuria in anti-GBM Ab alone was 11 +/- 3, LPS/anti-GBM Ab 87 +/- 22, and anti-TNF-alpha antibodies/LPS/anti-GBM Ab 21 +/- 6 mg/24 h (mean +/- s.e.) P < 0.05. Passive immunization with antibodies to IL-1 beta had a similar effect (anti-GBM Ab, 0.6 +/- 0.1, LPS/anti-GBM Ab, 92 +/- 19, anti-IL-1 beta antibodies/LPS/anti-GBM Ab 39 +/- 8 mg/24 h, P < 0.05). The prevalence of glomerular capillary thrombi was also reduced significantly by these treatments; from 22 +/- 5% to 4 +/- 1% in the case of anti-TNF-alpha antibodies and 28 +/- 5% to 13 +/- 4% with anti-IL-1 beta antibodies. Similarly, the glomerular neutrophil infiltrate was also reduced by these treatments; from 42 +/- 3 to 25 +/- 1 in the case of anti-TNF-alpha and 47 +/- 2 to 30 +/- 1 with anti-IL-1 beta antibodies. In contrast, passive immunization against IL-1 alpha had no effect on either albumin excretion (4 +/- 3, 83 +/- 22 and 77 +/- 24 mg/24 h), glomerular capillary thrombi (2 +/- 1; 19 +/- 5 and 16 +/- 3) or glomerular neutrophil infiltrate (22 +/- 3; 47 +/- 5 and 48 +/- 5 from the three groups respectively). These results demonstrate that enhanced antibody mediated injury in the kidney is modulated by TNF-alpha and IL-1 beta but not by IL-1 alpha.

In vitro and in vivo interleukin-8 production in human renal cortical epithelia

The signals resulting in leukocytes infiltrating the tubulointerstitial compartment during renal inflammatory disease are not well understood. A recently described cytokine, interleukin-8 (IL-8), has been demonstrated to be chemotactic for lymphocytes and neutrophils at picomolar and nanomolar concentrations, respectively. Cytokeratin positive, renal cortical epithelial cells (RCEC) with tubular attributes were cultured from kidney tissue from six human subjects. We report that these human renal cortical epithelial cells in primary cell culture respond to either IL-1 beta, TNF or LPS in both a time- and dose-dependent manner by expressing IL-8 mRNA and secreting antigenic IL-8 peptide. In addition, RCEC were found to be strongly positive for cell-associated antigenic IL-8 peptide by immunostaining after 24 hour incubation with IL-1 beta, TNF and LPS. To ascertain whether IL-8 was present in renal disease associated with infiltrating leukocytes, we performed immunohistochemistry on renal biopsy specimens from patients with acute allograft rejection. Both proximal and distal tubular epithelial cells were found to be strongly positive for cell-associated antigenic IL-8. These findings suggest that the human renal tubule epithelial cell may actively participate in acute inflammatory processes in the kidney, including allograft rejection, by effecting and directing leukocyte chemotaxis via the production of IL-8.

Interleukin-6 as an endogenous pyrogen: induction of prostaglandin E2 in brain but not in peripheral blood mononuclear cells

Fever induced by endogenous as well as exogenous pyrogens is often prevented by cyclooxygenase inhibitors; endogenous pyrogens stimulate prostaglandin E2 (PGE2) in or near the thermoregulatory centers of the brain. The cytokines, interleukin-1 (IL-1) and tumor necrosis factor (TNF), are two pyrogens which stimulate brain PGE2 formation during fever and also increase PGE2 synthesis in human mononuclear cells in vitro. In the present study, we examined whether interleukin-6 (IL-6) stimulates PGE2 formation in a manner similar to IL-1 and TNF. Both glycosylated and non-glycosylated forms of recombinant human IL-6 were tested. Following intravenous injection into rabbits, the glycosylated IL-6 was more pyrogenic than the non-glycosylated form and there was no evidence of synergy in the production of fever when IL-6 and IL-1 were given simultaneously. IL-6 fever was blocked by prior administration of the cyclooxygenase inhibitor ibuprofen. IL-6 was also pyrogenic in the cat by either the systemic or the intraventricular route. However, in both species, IL-6 was less effective than IL-1 beta. When given intraventricularly to cats, IL-6 produced an increase in PGE2 levels of the cerebrospinal fluid in parallel with the rise in body temperature. In the latter respect, IL-6 imitated IL-1 beta; however, IL-6 from 0.15-15 micrograms/ml did not increase mononuclear cell PGE2 production in vitro whereas IL-1 beta induced 20-30-fold increases in PGE2 at 100 ng/ml.(ABSTRACT TRUNCATED AT 250 WORDS)

Excretion of metabolites of prostacyclin and thromboxane by rats with nephrotoxic nephritis: effects of interleukin-1

1. To obtain direct evidence of abnormal eicosanoid biosynthesis in rats injected with anti-glomerular-basement-membrane antibodies (a-GBM), products derived from thromboxane A2 (TXA2) and prostacyclin (PGI2) were measured in 24 h urine collections before and after a-GBM. 2. Administration of a-GBM (9.5 mg) caused albuminuria, decreased creatinine clearance, increased numbers of intra-glomerular neutrophils and increased excretion of TXB2, 2,3-dinor-TXB2 (products of TXA2) and 6-oxo-PGF 1 alpha and 2,3-dinor-6-oxo-PGF 1 alpha (products of PGI2) at 24 h. 3. Interleukin-1 (IL-1 beta; 5 micrograms) alone caused an increase in PGI2 metabolite excretion but had no effect on TXA2 metabolites. It had no effect on creatinine clearance but increased numbers of glomerular neutrophils by approximately 4-5 fold compared to a-GBM. 4. Pretreatment of rats with IL-1 beta before a-GBM synergistically increased albumin excretion but only additively increased eicosanoid excretion. Numbers of intra-glomerular neutrophils and creatinine clearance were unchanged compared to IL-1 beta alone. 5. The cyclo-oxygenase inhibitor, ibuprofen (10 mgkg-1 i.p., twice daily for 4 days) inhibited both serum TXB2 production and urinary prostaglandin excretion. It also caused an almost complete attenuation of albumin excretion. Creatinine clearance and glomerular neutrophils remained unchanged after a-GBM/IL-1 beta. 6. We conclude that the 50% inhibition of thromboxane production induced by ibuprofen does not modify the fall in creatinine clearance of accumulation of neutrophils in the glomerulus caused by the a-GBM. This degree of inhibition of eicosanoid production was associated with a striking decrease in proteinuria, but this may reflect a haemodynamic rather than a disease modifying action.

Role of prostaglandins in the behavioral changes induced by murine interleukin 1 alpha in the rat

Continuous infusion of murine recombinant interleukin 1 alpha (rIL-1 alpha) produces weight loss, appetite suppression, reduction in horizontal locomotor activity (crossovers) and vertical locomotor activity (rears), and an increase in drinking behavior in the rat. The role of prostaglandins (PG) in the elicitation of these effects was studied. Infusion of rIL-1 alpha produced a transient increase in serum (PGs) which peaked at 24 to 48 h. This increase was completely inhibited by piroxicam. However, inhibition of circulating PG by piroxicam did not block the reductions in appetite, crossover, and rears induced by rIL-1 alpha; it restored normal drinking behavior and only partially restored body weight. Continuous intraperitoneal infusion of PGE2 at 24 micrograms/day exposed the animals to serum levels of PGE2 comparable to those produced by infusion with rIL-1 alpha. Yet, at the point of maximum weight loss induced by rIL-1 alpha (72 h), PGE2 infusion resulted in only a quarter of the weight loss. Compared with rIL-1 alpha, continuously infused PGE2 produced significantly smaller reductions in appetite, crossovers, and rears, and had no effect on drinking behavior. From these observations, we conclude that the rIL-1 alpha-induced increase in drinking behavior was fully dependent on products of the cyclooxygenase pathway, but not necessarily PGE2. However, because of the failure of piroxicam to fully reverse rIL-1 alpha effects on eating, mobility, and weight loss, there must also be a significant PG-independent component to account for the full range of rIL-1 alpha effects.

Cytokines in fluids from polycystic kidneys

We sought evidence of cytokine presence and interleukin-1 beta (IL-1 beta) bioactivity in 104 aerobic culture negative cyst fluids (CFs) from 13 kidneys of 13 patients with symptomatic normal to end-stage autosomal dominant polycystic kidney disease (ADPKD). ELISAs were used to detect IL-1 beta, interleukin-2 (IL-2), tumor necrosis factor alpha (TNF alpha) and stromelysin. Prostaglandin E2 (PGE2) was detected by radioimmunoassay. IL-1 beta was present in 65 of 94 (less than 20 to 419 pg/ml, TNF alpha in 54 of 75 (less than 10 to 73 pg/ml), stromelysin in 18 of 23 (less than 1.0 to 56 ng/ml), IL-2 in 7 of 23 (0.1 to 1.3 ng/ml) and PGE2 in 9 of 10 fluids (0.03 to 0.49 ng/ml). Of 51 fluids with immunoreactive IL-1 beta, 36 were mitogenic for thymocytes. IL-1 beta concentrations correlated directly with those of IL-2; IL-1 beta presence was associated with higher stimulation indices, higher mean concentrations of TNF alpha, IL-2, stromelysin, and PGE2, and with positive endotoxin assays, suggesting activation of the cytokine cascade in vivo. Cytokine, stromelysin and PGE2 concentrations did not correlate with sodium or non-sodium solute concentrations, nor with CF blood, osmolality, or endotoxin activity, indicating that differences in concentrations among fluids could not be explained by differences in water content. These data identify cytokines as candidate contributors to the morbidity and pathogenesis of ADPKD.

Secretion of plasminogen activator and its inhibitor by glomerular epithelial cells

The effects of thrombin, interleukin-1 (IL-1), tumor necrosis factor (TNF) and gamma-interferon (gamma-IFN) on the release of plasminogen activator (PA) and inhibitor (PAI) were studied using cultivated human glomerular epithelial cells (GECs). Species of PAs and PAI secreted from the GECs were urokinase-type PA (u-PA) and tissue-type PA (t-PA), while the major species was a single chain u-PA in the amount of 28.6 +/- 2.34 ng/10(5) cells for 24 hours (N = 4, mean +/- SD), and PAI-1. The addition of increased concentrations of thrombin (0.1 to 31.6 U/ml) into confluent cultures enhanced the GECs to release u-PA, t-PA and PAI-1 in a dose- and time-dependent manner. The incubation of the GECs with 10 U/ml thrombin resulted in about a fourfold increase in the concentration of u-PA, threefold in t-PA and twofold in PAI-1. All thrombin effects, however, were suppressed by the simultaneous addition of cycloheximide, indicating that the enhancing effects of thrombin were due to an increase in the production of PAs and PAI-1, via protein synthesis. These thrombin effects appeared to be dependent upon the enzymatically active site of thrombin because DFP-thrombin had no effect. In the conditioned medium which was under continuous thrombin stimulation for 24 hours, no u-PA activity was detectable, even after the plasmin treatment, because a single chain u-PA was degraded by the thrombin. The stimulation of cultured GECs with thrombin only for the first three hours in 24 hour cultivation showed an apparent increase in the antigenic amount of u-PA. IL-1 enhanced the release of t-PA and PAI-1, and TNF did that of u-PA and t-PA, while gamma-IFN showed no significant effects. These findings indicate that the GECs participate in the regulation of extracapillary fibrinolysis in the glomerular microenvironment, as being modulated by thrombin and two cytokines, IL-1 and TNF.

Interleukin 1- and tumor necrosis factor-stimulation of prostaglandin E2 synthesis in MDCK cells, and potentiation of this effect by cycloheximide

The effects of interleukin (IL)-1 alpha, IL-1 beta and TNF alpha on prostaglandin-E2 synthesis in Madin-Darby canine kidney (MDCK) cells were investigated. IL-1 beta time- and dose-dependently stimulated prostaglandin-E2 synthesis. While TNF alpha produced a comparatively small but significant stimulation of PGE2 release, coincubation of IL-1 beta with TNF alpha produced a marked synergistic stimulation of PGE2 release. The effect of IL-1 beta and of IL-1 beta and TNF alpha was apparent as early as after 2 h of incubation. The enhanced PGE2 synthesis was inhibited by indomethacin as well as actinomycin D, while cycloheximide surprisingly potentiated PGE2 synthesis in response to both IL-1 beta and TNF alpha. IL-1 alpha alone was ineffective in stimulating a significant release of PGE2 at concentrations as high as 10 nM. However, it also showed a marked synergistic interaction with TNF alpha in stimulating PGE2 release.

Interleukin 1: the first interleukin

The name 'interleukin' and the designation of interleukin 1 (IL-1) derived from the Second International Lymphokine Workshop held in Switzerland in 1979. Since then interest in the original interleukin (IL-1) has increased exponentially as measured by the numbers of publications and meetings. The main reasons for this can be seen in the accompanying centrefold. The perception of IL-1 as a biological mediator in every organ system has attracted scientists from widely different backgrounds into this area and a steady succession of important and often surprising insights into IL-1 biology has ensured that interest has been sustained at a high level. This overview of the biology of IL-1 on the tenth anniversary of its turbulent life has been compiled by Franco di Giovine and Gordon Duff. It is of necessity selective and biased towards human IL-1 and begins with some general points (mainly cautionary) as a backdrop to the centrefold.

Peptide-dependent regulation of epithelial nephron functions

It has become evident that the nephron is an important target organ of many of the regulatory peptides; this brief overview will not attempt to consider the vast amount of work on peptide-dependent kidney functions; instead, it will emphasize recent work directed towards understanding intracellular signal pathways between peptide ligand-receptor interaction and expression of physiological transport responses in renal epithelial cells. The awareness that peptide hormones of differing origin, e.g., intestinal and cardiac, share at least some of the signal steps in nephron cells, has stimulated work on nephron segmental analysis of receptor binding, of second messengers, of membrane G proteins, of protein phosphorylation, and of final membrane transport responses, such as peptide-dependent ion channel regulation. Peptides involved in cell growth and differentiation, e.g., growth factors, appear to act through part of the signal pathway shared by other peptides. The peptides selected for the purpose of this review, then, are those that have been linked, by experimental evidence, to intracellular messenger systems in nephron epithelia.