Randomized, controlled trial of recombinant human interleukin-11 in patients with active Crohn's disease.

BACKGROUND: Interleukin-11 is a mesenchymally derived cytokine with pleiotropic activities. A pilot study suggested therapeutic benefit of recombinant human interleukin-11 (rhIL-11) in patients with Crohn's disease. AIM: To determine the safety and preliminary estimate of efficacy of rhIL-11 in treating active Crohn's disease. METHODS: Patients with mild to moderately active Crohn's disease, defined as a Crohn's disease activity index (CDAI) > or = 220 and < or = 450, were enrolled in a multicentre trial. Stable doses of 5-aminosalicylates, antibiotics, 6-mercaptopurine or azathioprine were permitted with appropriate wash-in periods. Oral, intravenous or rectally administered corticosteroids were not allowed. Patients were randomized to 6 weeks of subcutaneous injection with rhIL-11 15 microg/kg or placebo weekly, or rhIL-11 7.5 microg/kg or placebo twice weekly. The primary end-point was per cent change in CDAI at week 6; the major secondary end-point was the proportion of patients in remission, defined as a 100 point decrease in CDAI and absolute CDAI < or = 150. RESULTS: Baseline characteristics were similar among the 148 evaluated patients (49 placebo, 49 rhIL-11 15 microg/kg once weekly, 50 rhIL-11 7.5 microg/kg twice weekly). Treatment was well-tolerated, with mild injection site reactions occurring more frequently among patients treated with rhIL-11. Headache, oedema, and increased platelet count occurred significantly more often in the rhIL-11 7.5 microg/kg twice weekly group, but not the 15 microg/kg once weekly group. There was a trend toward decreased mean per cent change in CDAI in the rhIL-11 15 micro/kg once weekly group vs. placebo (-31.5% vs. -18.5%, 95% confidence interval for the difference -27.9-1.6%). A significantly greater proportion of patients receiving rhIL-11 15 microg/kg once weekly achieved remission compared to placebo (36.7% vs. 16.3%, 95% confidence interval for the difference 3.4-37.4%; 16.4% for rhIL-11 7.5 microg/kg, N.S.). CONCLUSIONS: Weekly subcutaneous injection with rhIL-11 15 microg/kg is safe and effective in inducing remission in a subset of patients with active Crohn's disease.

Results of a phase-I/II randomized, masked, placebo-controlled trial of recombinant human interleukin-11 (rhIL-11) in the treatment of subjects with active rheumatoid arthritis.

Interleukin-11 (IL-11) is a pleiotropic cytokine that regulates the growth and development of hematopoietic stem cells and decreases the proinflammatory mediators of cytokine and nitric oxide production. In animal models of arthritis, treatment with recombinant human IL-11 (rhIL-11) reduces both the level of synovitis and the histologic lesion scores in the joints. The goal of this phase-I/II study in adults with rheumatoid arthritis (RA) was to evaluate the safety and clinical activity of different doses and schedules of rhIL-11 in patients with active RA for whom treatment with at least one disease-modifying antirheumatic drug had failed. This was a multicenter, randomized, placebo-controlled trial that evaluated the safety and tolerability of rhIL-11 in 91 patients with active RA. rhIL-11 was administered subcutaneously; patients were randomized into one of five treatment groups (ratio of rhIL-11 to placebo, 4:1). Patients were treated for 12 weeks with either 2.5 or 7.5 microg/kg of rhIL-11 or placebo twice per week or 5 or 15 microg/kg of rhIL-11 or placebo once per week. The status of each subject's disease activity in accordance with the American College of Rheumatology (ACR) criteria was assessed before, during, and after completion of administration of the study drug. Administration of rhIL-11 was well tolerated at all doses and schedules. The most frequent adverse event was a reaction at the injection site. The data suggest a statistically significant reduction in the number of tender joints (P < 0.008) at the 15 microg/kg once-weekly dose schedule but showed no overall significant benefit at the ACR criterion of a 20% response. The trial showed rhIL-11 to be safe and well tolerated at a variety of doses and schedules over a 12-week treatment period in patients with active RA. The only adverse event clearly associated with rhIL-11 administration was reaction at the injection site.

Molecular classification of psoriasis disease-associated genes through pharmacogenomic expression profiling.

Psoriasis is recognized as the most common T cell-mediated inflammatory disease in humans. Genetic linkage to as many as six distinct disease loci has been established but the molecular etiology and genetics remain unknown. To begin to identify psoriasis disease-related genes and construct in vivo pathways of the inflammatory process, a genome-wide expression screen of multiple psoriasis patients was undertaken. A comprehensive list of 159 genes that define psoriasis in molecular terms was generated; numerous genes in this set mapped to six different disease-associated loci. To further interpret the functional role of this gene set in the disease process, a longitudinal pharmacogenomic study was initiated to understand how expression levels of these transcripts are altered following patient treatment with therapeutic agents that antagonize calcineurin or NF-KB pathways. Transcript levels for a subset of these 159 genes changed significantly in those patients who responded to therapy and many of the changes preceded clinical improvement. The disease-related gene map provides new insights into the pathogenesis of psoriasis, wound healing and cellular-immune reactions occurring in human skin as well as other T cell-mediated autoimmune diseases. In addition, it provides a set of candidate genes that may serve as novel therapeutic intervention points as well as surrogate and predictive markers of treatment outcome.

Preclinical pharmacologic basis for clinical use of rhIL-11 as an effective platelet-support agent.

Preclinical studies have shown that rhIL-11, also known as oprelvekin (Neumega), stimulates early and later stages of megakaryocytopoiesis (including proliferation and differentiation of megakaryocyte precursors and maturation of megakaryocytes), to produce an increase in peripheral platelet count. Because of these effects, rhIL-11 must be administered to patients with cancer sufficiently in advance of the platelet nadir (within 6 to 24 hours postchemotherapy) to allow adequate time for megakaryocyte maturation and platelet formation. Therefore, the maximum platelet response coincides with the time when the platelet nadir would normally be experienced. In myelosuppressed, nonhuman primates, optimal platelet response occurred following 14 days of treatment at a dose equivalent to the 50-microgram/kg daily dose recommended in humans; lower doses and shorter durations were less effective. These data support the current dosing recommendation in humans, which states that rhIL-11 dosing continues until platelet recovery to > or = 50,000/microL has been achieved for 2 consecutive days or for a total of 10 to 21 days in each cycle. The nonhematopoietic effects of rhIL-11 include a renal effect, resulting in plasma-volume expansion, as well as potential beneficial clinical effects in damaged or inflamed intestinal mucosa, including potential mitigation of mucositis and a rationale for future studies in inflammatory bowel disease.

Mechanism and amelioration of recombinant human interleukin-11 (rhIL-11)-induced anemia in healthy subjects.

Recombinant human interleukin-11 (rhIL-11), or Neumega rhIL-11 Growth Factor, is a recombinant cytokine that stimulates megakaryocytopoiesis, increases platelet production, and also has shown anti-inflammatory and immune-modulating activity. Mild, reversible anemia was the most common adverse event observed in clinical studies and was demonstrated to be related to hemodilution. The purpose of this study was to examine the renal mechanisms of the rhIL-11-induced volume retention and devise a possible therapeutic intervention to ameliorate this effect. Eighteen healthy volunteers (9 male and 9 female) on a controlled sodium (180 mEq/day) and potassium (120 mEq/day) diet were randomized to one of six treatment sequences in a three-period crossover design. Each subject received 25 micrograms/kg IL-11 s.c. once daily, 25 micrograms/kg IL-11 s.c. once daily + Maxzide-25 twice daily, or placebo for 7 days in a crossover design. There was a 14-day washout period between treatment periods. Renal clearance parameters indicated that mean sodium excretion was decreased compared to placebo within 8 hours after dosing with rhIL-11, with these results reaching statistical significance 8 to 16 hours postdose (p < 0.01). The cumulative sodium excretion (mEq +/- SD) over the 7-day treatment period for each respective treatment group was the following: rhIL-11 = 833 +/- 154, rhIL-11 + Maxzide-25 twice daily = 1114 +/- 178, and placebo = 982 +/- 193 (p < 0.01). Hemoglobin concentration and hematocrit values, used as indicators of hemodilution, decreased in the rhIL-11-treated group as compared to the baseline and placebo groups (p < 0.01). Concurrent dosing with Maxzide-25 twice daily reduced the rhIL-11-associated hemodilution by about 50%.

Interleukin-11 therapy selectively downregulates type I cytokine proinflammatory pathways in psoriasis lesions.

Psoriasis is a chronic inflammatory skin disease in which epidermal hyperplasia results from skin infiltration by type I T lymphocytes and release of associated cytokines. A multifunctional cytokine, rhIL-11, modulates macrophage and type I T-lymphocyte function in cell culture and shows anti-inflammatory activity in animal models. We are testing subcutaneous delivery of rhIL-11 to patients with psoriasis in a phase 1 open-label dose-escalation clinical trial. Tissue was obtained from lesional and uninvolved skin before and during treatment with rhIL-11 and was examined by histology/immunohistochemistry and quantitative RT-PCR. Expression of over 35 genes was examined in all patients, and multiple genetic markers of psoriasis were identified. Expression of numerous proinflammatory genes was elevated in psoriatic tissue compared with nonlesional skin. Seven of 12 patients responded well to rhIL-11 treatment. Amelioration of disease by rhIL-11, as shown by reduced keratinocyte proliferation and cutaneous inflammation, was associated with decreased expression of products of disease-related genes, including K16, iNOS, IFN-gamma, IL-8, IL-12, TNF-alpha, IL-1beta, and CD8, and with increased expression of endogenous IL-11. We believe that this is the first study in humans to indicate that type I cytokines can be selectively suppressed by an exogenous immune-modifying therapy. The study highlights the utility of pharmacogenomic monitoring to track patient responsiveness and to elucidate anti-inflammatory mechanisms.

Analysis of factors that correlate with mucositis in recipients of autologous and allogeneic stem-cell transplants.

PURPOSE: To identify predictors of oral mucositis and gastrointestinal toxicity after high-dose therapy. PATIENTS AND METHODS: Mucositis and gastrointestinal toxicity were prospectively evaluated in 202 recipients of high-dose therapy and autologous or allogeneic stem-cell rescue. Of 10 outcome variables, three were selected as end points: the peak value for the University of Nebraska Oral Assessment Score (MUCPEAK), the duration of parenteral nutritional support, and the peak daily output of diarrhea. Potential covariates included patient age, sex, diagnosis, treatment protocol, transplantation type, stem-cell source, and rate of neutrophil recovery. The three selected end points were also examined for correlation with blood infections and transplant-related mortality. RESULTS: A diagnosis of leukemia, use of total body irradiation, allogeneic transplantation, and delayed neutrophil recovery were associated with increased oral mucositis and longer parenteral nutritional support. No factors were associated with diarrhea. Also, moderate to severe oral mucositis (MUCPEAK > or = 18 on a scale of 8 to 24) was correlated with blood infections and transplant-related mortality: 60% of patients with MUCPEAK > or = 18 had positive blood cultures versus 30% of patients with MUCPEAK less than 18 (P =.001); 24% of patients with MUCPEAK > or = 8 died during the transplantation procedure versus 4% of patients with MUCPEAK less than 18 (P =.001). CONCLUSION: Gastrointestinal toxicity is a major cause of transplant-related morbidity and mortality, emphasizing the need for corrective strategies. The peak oral mucositis score and the duration of parenteral nutritional support are useful indices of gastrointestinal toxicity because these end points are correlated with clinically significant events, including blood infections and treatment-related mortality.

Hematopoietic, immunomodulatory and epithelial effects of interleukin-11.

Interleukin 11 (IL-11) is a pleiotropic cytokine with biological activities on many different cell types. Recombinant human IL-11 (rhIL-11) is produced by recombinant DNA technology in Escherichia coli. Both in vitro and in vivo, rhIL-11 has shown effects on multiple hematopoietic cell types. Its predominant in vivo hematopoietic activity is the stimulation of peripheral platelet counts in both normal and myelosuppressed animals. This activity is mediated through effects on both early and late progenitor cells to stimulate megakaryocyte differentiation and maturation. rhIL-11 has been approved for the treatment of chemotherapy-induced thrombocytopenia. The hematopoietic effects of rhIL-11 are most likely direct effects on progenitor cells and megakaryocytes in combination with other cytokines or growth factors. rhIL-11 also induces secretion of acute phase proteins (ferritin, haptoglobin, C-reactive protein, and fibrinogen) from the liver. The induction of heme oxidase and inhibition of several P450 oxidases have been reported from in vitro studies. In vivo, rhIL-11 treatment decreases sodium excretion by the kidney by an unknown mechanism and induces hemodilution. rhIL-11 also exhibits anti-inflammatory effects in a variety of animal models of acute and chronic inflammation, including inflammatory bowel disease, inflammatory skin disease, autoimmune joint disease, and various infection-endotoxemia syndromes. rhIL-11 has trophic effects on non-transformed intestinal epithelium under conditions of mucosal damage. The mechanism of the anti-inflammatory activity of rhIL-11 has been extensively studied. rhIL-11 directly affects macrophage and T cell effector function. rhIL-11 inhibits tumor necrosis factor-alpha (TNF alpha), interleukin 1beta (IL-1beta), interleukin 12 (IL-12), interleukin 6 (IL-6), and nitric oxide (NO) production from activated macrophages in vitro. The inhibition of cytokine production was associated with inhibition of nuclear translocation of the transcription factor, nuclear factor kappa B (NF-kappaB). The block to NF-kappaB nuclear translocation correlates with the ability of rhIL-11 to maintain or enhance production of the inhibitors of NF-kappaB, IkappaB-alpha and IkappaB-beta. In addition to effects on macrophages, rhIL-11 also reduces CD4+ T cell production of Th1 cytokines, such as IFN gamma induced by IL-12, while enhancing Th2 cytokine production. rhIL-11 also blocks IFN gamma production in vivo. The molecular effects of rhIL-11 have also been studied in a clinical trial. Molecular analysis of skin biopsies of patients with psoriasis before and during rhIL-11 treatment demonstrates a decrease in mRNA levels of TNF alpha, IFN gamma and iNOS. These activities suggest that in addition to its thrombopoietic clinical use, rhIL-11 may also be valuable in the treatment of inflammatory diseases. The clinical utility of the anti-inflammatory properties of rhIL-11 is being investigated in patients with Crohn's disease, psoriasis and rheumatoid arthritis. These diseases are believed to be initiated and maintained by activated CD4+ Th1 cells in conjunction with activated macrophages.

Preliminary evaluation of safety and activity of recombinant human interleukin 11 in patients with active Crohn's disease.

BACKGROUND & AIMS: Recombinant human interleukin 11 (rhIL-11) is a cytokine with thrombocytopoietic activity and anti-inflammatory and mucosal protective effects. The objectives of this study were to investigate the safety and tolerability of rhIL-11 in patients with Crohn's disease and to explore the effects of dose and schedule on platelet count and Crohn's disease activity. METHODS: A multicenter, double-masked, placebo-controlled, dose-escalation study of 76 patients with active Crohn's disease was performed. Patients were randomized to receive subcutaneous placebo or rhIL-11 at doses of 5, 16, or 40 microgram. kg-1. wk-1 given 2 or 5 times weekly for 3 weeks. Clinical and laboratory safety data were recorded, and disease activity was measured at each visit. RESULTS: Subcutaneous injection of rhIL-11 generally was well tolerated. Significantly greater increases in platelet counts were found among patients receiving rhIL-11 40 microgram. kg-1. wk-1 as 2 or 5 weekly doses and 16 microgram. kg-1. week-1 as 5 weekly doses compared with patients receiving placebo (P < 0.05). Patients receiving 16 microgram. kg-1. wk-1 had the highest clinical response rates, with a response seen in 42% of patients (5/12) receiving 5 weekly doses and 33% of patients (4/12) receiving 2 weekly doses, compared with 7% of patients (1/15) receiving placebo. CONCLUSIONS: Short-term treatment with rhIL-11 is well tolerated in patients with active Crohn's disease. The thrombocytopoietic effect of rhIL-11 seems to be both dose and schedule dependent and may be minimized with retained clinical benefit in Crohn's disease at 16 microgram. kg-1. wk-1 given in 2 equal doses.

Mitigating effects of interleukin 11 on consecutive courses of 5-fluorouracil-induced ulcerative mucositis in hamsters.

Ulcerative mucositis is a painful, debilitating and dose-limiting toxicity of cancer chemotherapy. Current treatment is largely palliative and no adequate preventive treatment exists. Recently, we reported that recombinant human(rh) interleukin 11 (IL-11) favourably modified the course of mucositis following a single stomatotoxic regimen of 5-fluorouracil in hamsters. Although potentially beneficial, the clinically relevant issue of mucositis and myelosuppression during multicourse chemotherapy treatment was not addressed. The present study was undertaken to evaluate the effect of rhIL-11 on two consecutive courses of mucositis and myelosuppression in hamsters. Ulcerative mucositis was induced using a standardized protocol consisting of 5-fluorouracil (60 mg/kg) on days 1 and 2 followed by superficial irritation of the buccal mucosa on day 4. Animals treated with 100 microg of rhIL-11 for 12 consecutive days following each regimen of chemotherapy experienced a reduction in the incidence, severity, and duration of mucositis, a reduction in weight loss, and less morbidity and mortality relative to control animals. Bone marrow cellularity and function was not adversely affected by rhIL-11 treatment. The present study is consistent with the potential use of rhIL-11 treating patients at risk of developing ulcerative mucositis while undergoing intensive multicourse chemotherapy treatment.

The renin angiotensin aldosterone system and frusemide response in congestive heart failure.

1. To test the hypothesis that basal renin angiotensin aldosterone system (RAAS) activity impairs the acute natriuretic response to frusemide in patients with mild or moderate congestive heart failure (CHF), we studied eight adult volunteers with preserved renal function, stable New York Heart Association Class II or III CHF, and echocardiographic evidence of left ventricular dysfunction due to myocardial infarction, hypertension, or both causes. 2. All patients received three dosing regimens administered in random order: (a) intravenous frusemide: 40 mg bolus then 40 mg h-1 for 3 h, (b) captopril: two 12.5 mg oral doses separated by 2 h, (c) combined dosing: the first captopril dose preceded the frusemide bolus by 30 min. Sodium balance on an 80 mmol day-1 sodium diet was documented prior to each dosing regimen. Sodium excretion was quantitated in urine collected at intervals until 3.5 h after initiating drug administration. During this time, urine output was replaced intravenously with an equivalent volume of 0.45% saline. 3. Captopril significantly lowered plasma angiotensin converting enzyme (ACE) activity and plasma aldosterone concentration, and raised inulin clearance. The drug had essentially no effect on the time course of magnitude of frusemide's natriuretic effect. Maximal fractional sodium excretion during frusemide infused by itself and in combination with captopril was 24.7 +/- 1.9% vs 28.2 +/- 3.8%, respectively (difference 3.5%; 95% CI, -4.0 to 11.0%; P > 0.05). Cumulative sodium excretion ending at 3.5 h was 429 +/- 53 mmol when frusemide was given alone and 455 +/- 69 mmol when captopril was added (difference, 26 mmol; CI, -121 to 174 mmol; P > 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of tibenelast (a phosphodiesterase inhibitor) and theophylline on isoproterenol-stimulated heart rate, cyclic AMP and norepinephrine levels.

The effect of the phosphodiesterase inhibitors (tibenelast, theophylline) and placebo on isoproterenol-induced changes in heart rate, cAMP and norepinephrine levels in normal male volunteers was studied. Heart rates in response to isoproterenol dosing were fitted by linear regression, and horizontal shifts in the regression lines were examined between the three treatments. The shift of the regression line after placebo compared to the preplacebo line was to the right by 2.6 +/- 2.2 ng ISO/kg/min, theophylline pretreatment shifted this line to the left by 2.4 +/- 1.8 ng/kg/min (p < 0.05) and tibenelast by 3.7 +/- 1.9 ng/kg/min (p < 0.02). Both tibenelast and theophylline increased the heart rate response to isoproterenol infusion, whereas norepinephrine and cAMP levels were not different in any treatment.

Nonimmunological alterations of glomerular filtration by s-PAF in the rat kidney.

Rat kidneys were isolated and perfused with a cell-free perfusion buffer containing 4% albumin. Infusion of platelet activating factor (s-PAF) into the isolated perfused kidney caused a dose-dependent fall in renal vascular resistance (RVR): 12 +/- 6% at 10 nM s-PAF, 18 +/- 3% at 100 nM s-PAF and 20 +/- 7% at 1 microM s-PAF. Glomerular filtration rate fell by 32 +/- 5% at 10 nM, 38 +/- 6% at 100 nM, and 52 +/- 10% at 1 microM. s-PAF (50 nM) increased urinary protein excretion after 20 minutes. Because GFR fell to a greater extent than RVR, possible changes in glomerular permeability after s-PAF treatment were assessed morphologically using native ferritin. After s-PAF treatment (100 nM), the number of ferritin particles/micron2 increased from 1.2 +/- 0.9 (control) to 795 +/- 69 in the glomerular basement membrane (GBM) and from 0.2 +/- 0.06 (control) to 98 +/- 29 in lamina rara externa (LRE). To quantitate changes in fixed anionic charges, polyethylenimine (PEI) was quantitated morphologically in GBM. No significant change between s-PAF treated and untreated kidneys was seen. s-PAF did not alter the sialoglycoprotein pattern in the perfused kidney as assessed by lysozyme staining. These results are in contrast to findings with s-PAF in vivo where in addition to increased glomerular permeability, a reduction of fixed anionic charges is seen.(ABSTRACT TRUNCATED AT 250 WORDS)

Platelet-activating factor-induced homologous and heterologous desensitization in cultured vascular smooth muscle cells.

Intracellular free Ca2+ concentrations were monitored in vascular smooth muscle cells (VSMC) using the Ca2+-sensitive dye fura II. Superfusion of VSMC with platelet-activating factor (S-PAF; 1-100 nM) increased cytosolic Ca2+ in a dose-dependent manner. The response was transient and returned to base line even though the agonist was still present. A second, higher dose of PAF did not elicit a response. The inactive optical isomer, R-PAF, was ineffective suggesting that the S-PAF response is specific and receptor-mediated. Pretreatment of VSMC with PAF attenuated angiotensin II-stimulated Ca2+ mobilization but not vasopressin-stimulated Ca2+ mobilization. Treatment of VSMC with PAF (10 nM) stimulated inositol trisphosphate and inositol tetrakisphosphate formation above control by 260 +/- 15% and 195 +/- 11%, respectively. Diacylglycerol levels also rose during PAF stimulation and remained increased over 15 min. Pretreatment of VSMCs with phorbol-12,13-myristate acetate (10 nM) for 30 min abolished both the PAF- and angiotensin II-induced increases in cytosolic Ca2+, but not the vasopressin-induced increase. Pretreatment of VSMC with dioctanoylglycerol (10 microM) abolished the S-PAF-, angiotensin II-, and vasopressin-induced elevation in cytosolic Ca2+. We propose that this desensitization is possibly mediated by diacylglycerol formed in response to PAF.

L-platelet activating factor induces changes on renal vascular resistance, vascular reactivity, and renin release in the isolated perfused rat kidney.

Rat kidneys were isolated and perfused with a modified Krebs-Henseleit buffer containing 4% albumin. Perfusate recirculated except during L-platelet activating factor (L-PAF), angiotensin II (ang II), and norepinephrine (NE) infusions. L-PAF caused a dose-dependent decrease in renovascular resistance (RVR): -6 +/- 3% at 10(-9)M, -12 +/- 6% at 10(-8)M, -18 +/- 3% at 10(-7) and -20 +/- 7% at 10(-6)M. L-PAF increased immunoreactive PGE (iPGE) and thromboxane (iTXB) release into the venous effluent from 2.4 +/- 0.2 to 3.9 +/- 0.4 ng/min (p less than 0.05) and from 2.1 +/- 0.4 to 3.5 +/- 0.5 ng/min (p less than 0.05), respectively. Vasodilation by L-PAF (10(-7) M) in the presence of indomethacin (INDO) (5 microM) was enhanced compared to the non-INDO response (RVR change: L-PAF = -18 +/- 3% vs. L-PAF = -26 +/- 3%; p less than 0.05). As a control for specificity, the was infused at 10(-9) M, 10(-8) M, and 10(-7) M. None of these concentrations changed renal vascular resistance. To study the vascular receptor responsible for L-PAF-induced vasodilation, dose-response curves to NE and ang II were established with and without L-PAF (10(-7) M). The NE dose-response curve was unchanged by L-PAF, whereas the ang II dose-response curve was shifted to the right by one order of magnitude. In kidneys pretreated with INDO (5 microM), the L-PAF-induced shift of the ang II dose-response relation was increased to 2-3 orders of magnitude.(ABSTRACT TRUNCATED AT 250 WORDS)

Hemodynamic effects of platelet activating factor in the dog kidney in vivo.

The effect of platelet activating factor (PAF) on renal hemodynamics and function was examined in anesthetized dogs. The infusion of PAF into the renal artery at 5, 10, and 20 ng X min-1 X kg-1 body weight resulted in dose-dependent reductions in renal blood flow, glomerular filtration rate, urine volume, and urinary sodium excretion, whereas the infusion of vehicle alone in the contralateral kidney did not result in significant changes in these parameters. The maximum decrease expressed as the percent change from baseline was 22.2 +/- 1.7% for renal blood flow, 50.8 +/- 11% for glomerular filtration rate, 67.3 +/- 4.2% for urine volume, and 69.0 +/- 8.5% for urinary sodium excretion, respectively. These renal effects were not accompanied by significant alterations in systemic arterial blood pressure and heart rate. Pretreatment with indomethacin to block prostaglandin synthesis enhanced the effect of PAF on kidney function. Our data demonstrate that, unlike the rat kidney, intrarenal PAF infusion into the intact dog results in vasoconstriction and serve reduction in glomerular filtration rate.

A dual effect of nonsteroidal anti-inflammatory drugs on renal water handling in humans.

The role of renal prostaglandins (PGs) in the induction and maintenance of a sustained water diuresis was studied by using two different nonsteroidal anti-inflammatory drugs (NSAIDs), indomethacin and meclofenamate given either before or during the diuresis. Urinary PGE2 excretion increased with the initiation of a water diuresis (from 2.5 +/- 0.7 to 6.1 +/- 1 pg/kg/min during the 2nd hr, P less than .01) but then fell back to control levels when water diuresis was established. Pretreatment with NSAIDs abolished the initial increase in PGE excretion and delayed the onset of the water diuresis so that 1 hr after the initiation of the diuresis, the urine osmolality in the control subjects was 205 +/- 50 mosm/kg as compared with 440 +/- 55 mosm/kg (P less than .05) for the NSAID-treated subjects. In contrast, the urine osmolality did not change when subjects were given the NSAIDs 5 hr after the onset of the water diuresis. However, the NSAIDs did decrease urine volume and free water clearance for as long as the urinary PG excretion was suppressed, regardless of when the drugs were given. This action of the NSAIDs to decrease the urine volume and free water clearance was due to a decrease in delivery of water and solute to the diluting segments of the nephron. These data imply that the transient increase in urinary PGE excretion occurring at the onset of a water diuresis has functional significance, as NSAIDs block the increase in PG synthesis and also interfere with the onset of a water diuresis by delaying the attainment of a maximally dilute urine.(ABSTRACT TRUNCATED AT 250 WORDS)

Beneficial effects of calcium channel blockers and calmodulin binding drugs on in vitro renal cell anoxia.

Proximal tubules (PSTs) of the S1, S2 and S3 segments and cortical collecting tubules (CCTs) were microdissected individually from rabbit kidneys and cultured for 7 days in hormonally defined media. Anoxia was induced by incubation of cultures in normal medium for 45 min at 25 degrees C in an atmosphere of nitrogen and cell death was measured by nigrosine dye uptake. After 45 min of anoxia and a 4- to 6-hr incubation in normal Ca++-containing media, cells from all segments were dead. Addition of calcium channel blockers verapamil and nifedipine (5 X 10(-7) and 10(-6) M, respectively) for the first 2 hr after anoxia to the incubation media was associated with a 60 +/- 8 and 33 +/- 7% survival of PST cells (5 hr after anoxia), p less than .05. Verapamil at 5 X 10(-8) M caused a 42 +/- 4% survival whereas nifedipine at 10(-7) M was not effective on the survival rate of PST cells (5 hr after anoxia). These calcium channel blockers also afforded protection from anoxic cell death for CCT cells. The role of calmodulin in anoxic cell injury was studied by means of calmodulin binding drugs, trifluoperazine and W7 [N-(6-aminohexyl)-5-chloronapthalene-sulfonamide]. Addition of trifluoperazine (5 X 10(-7) M) and W7 (5 X 10(-7) M to both PST and CCT cells during the 2-hr reflow period after 45 min of anoxia increased viability by 58 +/- 3 and 62 +/- 3%, respectively (P less than .05) at 5 hr postanoxia.(ABSTRACT TRUNCATED AT 250 WORDS)