Plasma tumor necrosis factor soluble receptors in chronic renal failure

The effect of fish oil on inflammation markers in adult patients undergoing hemodialysis: A meta-analysis

OBJECTIVE

This meta-analysis was to assess the effect of fish oil supplementation on inflammation markers in adult patients receiving hemodialysis.

METHODS

CENTRAL, EMBASE, MEDLINE databases were searched from inception to 10 April 2020. Two authors independently searched, selected, and screened the literature. The pooled results are represented by WMD or SMD with 95% confidence intervals. Subgroup analysis and meta-regression were used to explore sources of heterogeneity, and sensitivity analysis was used to assess the robustness of the pooled results. Funnel plots were used to assess publication bias.

RESULTS

Eleven RCT (randomized control trials) studies were included. The pooled results showed that fish oil supplementation caused a significant reduction of the CRP(C-reactive protein) level (random model: WMD, -3.36, 95%CI: -5.46 to -1.26, P = .002), especially in patients with baseline CRP ≥ 5 mg/L (random model: WMD, -4.43, 95%CI: -6.10 to -2.76, P = .00001, I²  = 41%). Meta-regression analyses showed that CRP baseline level (CRP < 5 mg/L) was the main source of heterogeneity (P = .036). Sensitive analyses revealed that the result was hardly changed. Fish oil supplementation might not reduce the level of IL-6 (random model: WMD, -2.26, 95%CI: -19.61 to 15.09, P = .80) in four studies or the level of TNF-α (random model: SMD, -2.51, 95%CI: -6.08 to 1.06, P = .17) in three studies.

CONCLUSIONS

Fish oil supplementation could reduce the level of CRP in hemodialysis patients, especially in patients with CRP ≥ 5 mg/L, but had no effects on IL-6 and TNF-α.

A profile of multiple circulating tumor necrosis factor receptors associated with early progressive kidney decline in Type 1 Diabetes is similar to profiles in autoimmune disorders

This study comprehensively evaluated the association between known circulating tumor necrosis factor (TNF) superfamily ligands and receptors and the development of early progressive kidney decline (PKD) leading to end-stage kidney disease (ESKD) in Type 1 diabetes. Participants for the study were from the Macro-Albuminuria Study (198 individuals), and the Micro-Albuminuria Study (148 individuals) of the Joslin Kidney Study. All individuals initially had normal kidney function and were followed for seven-fifteen years to determine the slope of the estimate glomerular filtration rate and to ascertain onset of ESKD. Plasma concentrations of 25 TNF superfamily proteins were measured using proximity extension assay applied in the OLINK proteomics platform. In the both studies risk of early PKD, determined as estimated glomerular filtration rate loss greater than or equal to three ml/min/1.73m2/year, was associated with elevated circulating levels of 13 of 19 TNF receptors examined. In the Macro-Albuminuria Study, we obtained similar findings for risk of progression to ESKD. These receptors comprised: TNF-R1A, -R1B, -R3, -R4, -R6, -R6B, -R7, -R10A, -R10B, -R11A, -R14, -R21, and -R27. Serial measurements showed that circulating levels of these TNF receptors had increased before the onset of PKD. In contrast, none of the six measured TNF ligands showed association with risk of early PKD. Of significance, the disease process that underlies PKD leading to ESKD in Type 1 diabetes has a profile also seen in autoimmune disorders. The mechanisms of this enrichment may be causally related to the development of PKD in Type 1 diabetes and must be investigated further. Thus, some of these receptors may be used as new risk predictors of ESKD.

Influence of Peritoneal Transport Rate, Inflammation, and Fluid Removal on Nutritional Status and Clinical Outcome in Prevalent Peritoneal Dialysis Patients

Objective

To evaluate the possible associations between peritoneal transport rate (PTR), fluid removal, inflammation, and nutritional status in patients treated with peritoneal dialysis (PD) for more than 6 months, and the impact of these factors on subsequent patient survival.

Design and Patients

A prospective study of 82 PD patients (48 males) that had been treated with PD more than 6 months. Based on the dialysate-to-plasma creatinine ratio at 4 hours of dwell (D/PCr; mean ± 1 SD), the patients were classified as having a high (H), high-average (HA), low-average (LA), or low (L) PTR.

Setting

Single PD unit in a university hospital.

Main Outcome Measures

The PTR, evaluation of adequacy of dialysis and nutritional status, and biochemical analyses were assessed at 10.8 ± 2.8 months after the start of PD.

Results

Compared to L and LA (L/LA) transporters, H and HA (H/HA) transporters had increased dialysate protein loss, glucose absorption from dialysate, and peritoneal creatinine clearance (CCr), and decreased night ultrafiltration volume and total Kt/V urea. However, nutritional variables, 24-hour total fluid removal (TFR), total CCr, and residual renal function were not significantly different between the two groups. The 24-hour TFR correlated significantly with D/PCr (rho = –0.25), mean arterial pressure (rho = –0.23), serum albumin (rho = 0.25), normalized protein equivalent of total nitrogen appearance (rho = 0.34), lean body mass (LBM) calculated from creatinine kinetics (rho = 0.41), total Kt/V urea (rho = 0.42), and total CCr (rho = 0.30). The group with serum C-reactive protein (sCRP) ⊕ 10 mg/L had a higher proportion of patients with reduced (< 1000 mL) TFR compared to the group with sCRP < 10 mg/(38% vs 16%, p = 0.04). Two-year patient survival rates from the time of the assessment were not different between the different transport groups (78% vs 73% for H/HA and L/LA, p = 0.99). Upon Cox proportional hazards multivariate analysis, age and high sCRP were independent predictors of mortality.

Conclusions

This study shows that, in a selected group of prevalent PD patients assessed after more than 6 months of PD therapy, ( 1 ) inflammation was an independent predictor for mortality; ( 2 ) reduced TFR was associated with impaired nutritional status, decreased small solute clearance, and inflammation; and ( 3 ) peritoneal transport status was not significantly associated with nutritional status and was not associated with subsequent patient survival. These results indicate that a high peritoneal solute transport rate, as such, should not be regarded as a relative contraindication for PD. Instead, the results suggest that more attention should be given to inflammation and inadequate fluid removal as predictors of mortality in PD patients.

Changes in soluble tumor necrosis factor receptor type 1 levels and early renal function decline in patients with diabetes

The relationship between serial changes in soluble tumor necrosis factor receptor type 1 (TNFR1) levels and an early decline in estimated glomerular filtration rate (eGFR) decline remains to be defined. We found that in patients with an early decline in renal function (n = 30), soluble TNFR1 values increased (2,595 ± 683 vs 3,596 ± 1,203 pg/mL, P < 0.001) as eGFR decreased (89 ± 1 vs 51 ± 2 mL/min/1.73m2 , P < 0.001) over an 8-year period. In contrast, there were no significant changes in soluble TNFR1 levels in patients with stable renal function (n = 17). In a multilevel mixed effects regression model, changes in soluble TNFR1 levels were found to be independently associated with eGFR decline (Z = -4.31, P < 0.001). An early decline in eGFR is associated with an increase in soluble TNFR levels; however, the factors driving this increase and the possible pathological role that soluble TNFR1 plays in progressive diabetic kidney disease remain to be determined.

Mechanisms of haemolysis-induced kidney injury

Intravascular haemolysis is a fundamental feature of chronic hereditary and acquired haemolytic anaemias, including those associated with haemoglobinopathies, complement disorders and infectious diseases such as malaria. Destabilization of red blood cells (RBCs) within the vasculature results in systemic inflammation, vasomotor dysfunction, thrombophilia and proliferative vasculopathy. The haemoprotein scavengers haptoglobin and haemopexin act to limit circulating levels of free haemoglobin, haem and iron - potentially toxic species that are released from injured RBCs. However, these adaptive defence systems can fail owing to ongoing intravascular disintegration of RBCs. Induction of the haem-degrading enzyme haem oxygenase 1 (HO1) - and potentially HO2 - represents a response to, and endogenous defence against, large amounts of cellular haem; however, this system can also become saturated. A frequent adverse consequence of massive and/or chronic haemolysis is kidney injury, which contributes to the morbidity and mortality of chronic haemolytic diseases. Intravascular destruction of RBCs and the resulting accumulation of haemoproteins can induce kidney injury via a number of mechanisms, including oxidative stress and cytotoxicity pathways, through the formation of intratubular casts and through direct as well as indirect proinflammatory effects, the latter via the activation of neutrophils and monocytes. Understanding of the detailed pathophysiology of haemolysis-induced kidney injury offers opportunities for the design and implementation of new therapeutic strategies to counteract the unfavourable and potentially fatal effects of haemolysis on the kidney.

Does inflammation affect outcomes in dialysis patients?

Chronic, low-grade inflammation is a common comorbid condition in chronic kidney disease (CKD), and particularly in chronic dialysis patients. In this review, we consider the question of whether inflammation affects outcomes in dialysis patients. Levels of proinflammatory cytokines, as well as C-reactive protein, are elevated in chronic dialysis patients. Multiple factors likely contribute to chronic inflammatory activation in kidney disease patients including the uremic milieu, lifestyle and epigenetic influences, infectious and thrombotic events, the dialysis process, and dysbiosis. Increased inflammatory markers in both CKD and chronic dialysis patients are associated with adverse clinical outcomes including all-cause mortality, cardiovascular events, kidney disease progression, protein energy wasting and diminished motor function, cognitive impairment, as well as other adverse consequences including CKD-mineral and bone disorder, anemia, and insulin resistance. Strategies that have been shown to reduce chronic systemic inflammation in CKD and chronic dialysis patients include both pharmacological and nonpharmacological interventions. However, despite evidence that systemic inflammatory markers can be lowered in kidney disease patients treated with various strategies, evidence that this improves clinical outcomes is largely unavailable and represents an important future research direction. Overall, there is strong observational evidence that inflammation is high in chronic dialysis patients and that this is independently associated with numerous adverse clinical outcomes. Targeting inflammation represents a potentially novel and attractive strategy if it can indeed improve adverse outcomes common in this population.

TNF Signaling in Peritoneal Mesothelial Cells: Pivotal Role of cFLIPL

♦ BACKGROUND: Peritoneal dialysis (PD) coincides with high concentrations of proinflammatory cytokines, such as tumor necrosis factor (TNF), in the peritoneal cavity. During treatment, chronic inflammatory processes lead to damage of the peritoneal membrane and a subsequent ultrafiltration failure. Human peritoneal mesothelial cells (HPMCs) play a central role as mediators and targets of PD-related inflammatory changes. Although TNF Receptor 1 (TNFR1) is expressed in high numbers on the cells, TNF-induced apoptosis is inhibited. Here, the underlying molecular mechanisms of TNFR1 signaling in HPMCs are investigated. ♦ METHODS: Human peritoneal mesothelial cells were isolated from the omentum of healthy donors and the dialysis solution of PD patients. Flow cytometry was applied to determine cell surface expression of TNFR1 on HPMCS from healthy donors in absence or presence of TNF or PD fluid (PDF) and were compared to TNFR1 expression on cells from PD patients. To investigate TNFR1-mediated signaling, HPMCs were treated with PDF or TNF, and expression patterns of proteins involved in the TNFR1 signaling pathway were assessed by western blot. ♦ RESULTS: Incubation with PDF led to a significant up-regulation of TNFR1 on the cell surface correlating with elevated TNFR1 numbers on HPMCs from PD patients. Investigations of underlying molecular mechanisms of TNFR1 signaling showed that PDF affects TNFR1 signaling at the proapoptotic signaling pathway by upregulation of IκBα and downregulation of cFLIP_L. In contrast, TNF exclusively induces the activation of NFκB by an increase of phosphorylated IκBα. ♦ CONCLUSIONS: Novel and relevant insights into the mechanisms of TNFR1-mediated signaling in HPMCs with an impact on our understanding of PD-associated damage of the peritoneal membrane are shown.

Eculizumab reduces complement activation, inflammation, endothelial damage, thrombosis, and renal injury markers in aHUS

Atypical hemolytic uremic syndrome (aHUS) is a genetic, life-threatening disease characterized by uncontrolled complement activation, systemic thrombotic microangiopathy (TMA), and vital organ damage. We evaluated the effect of terminal complement blockade with the anti-C5 monoclonal antibody eculizumab on biomarkers of cellular processes involved in TMA in patients with aHUS longitudinally, during up to 1 year of treatment, compared with in healthy volunteers. Biomarker levels were elevated at baseline in most patients, regardless of mutational status, plasma exchange/infusion use, platelet count, or lactate dehydrogenase or haptoglobin levels. Eculizumab reduced terminal complement activation (C5a and sC5b-9) and renal injury markers (clusterin, cystatin-C, β2-microglobulin, and liver fatty acid binding protein-1) to healthy volunteer levels and reduced inflammation (soluble tumor necrosis factor receptor-1), coagulation (prothrombin fragment F1+2 and d-dimer), and endothelial damage (thrombomodulin) markers to near-normal levels. Alternative pathway activation (Ba) and endothelial activation markers (soluble vascular cell adhesion molecule-1) decreased but remained elevated, reflecting ongoing complement activation in aHUS despite complete terminal complement blockade. These results highlight links between terminal complement activation and inflammation, endothelial damage, thrombosis, and renal injury and underscore ongoing risk for systemic TMA and progression to organ damage. Further research regarding underlying complement dysregulation is warranted. This trial was registered at www.clinicaltrials.gov as #NCT01194973.

Added value of soluble tumor necrosis factor-α receptor 1 as a biomarker of ESRD risk in patients with type 1 diabetes

OBJECTIVE

Recent studies have suggested that circulating levels of the tumor necrosis factor-α receptor 1 (sTNFαR1) may be a useful predictor for the risk of end-stage renal disease (ESRD) in patients with diabetes. However, its potential utility as a biomarker has not been formally quantified.

RESEARCH DESIGN AND METHODS

Circulating levels of sTNFαR1 were assessed in 429 patients with type 1 diabetes and overt nephropathy from the Finnish Diabetic Nephropathy (FinnDiane) cohort study. Predictors of incident ESRD over a median of 9.4 years of follow-up were determined by Cox regression and Fine-Gray competing risk analyses. The added value of sTNFαR1 was estimated via time-dependent receiver operating characteristic curves, net reclassification index (NRI), and integrated discrimination improvement (IDI) for survival data.

RESULTS

A total of 130 individuals developed ESRD (28%; ESRD incidence rate of 3.4% per year). In cause-specific modeling, after adjusting for baseline renal status, predictors of increased incidence of ESRD in patients with overt nephropathy were an elevated HbA1c, shorter duration of diabetes, and circulating levels of sTNFαR1. Notably, sTNFαR1 outperformed estimated glomerular filtration rate in terms of R(2). Circulating levels of the sTNFαR1 also remained associated with ESRD after adjusting for the competing risk of death. A prediction model including sTNFαR1 (as a -0.5 fractional polynomial) was superior to a model without it, as demonstrated by better global fit, an increment of R(2), the C index, and area under the curve. Estimates of IDI and NRI(>0) were 0.22 (95% CI 0.16-0.28; P < 0.0001) and 0.98 (0.78-1.23; P < 0.0001), respectively. The median increment in the risk score after including sTNFαR1 in the prediction model was 0.18 (0.12-0.30; P < 0.0001).

CONCLUSIONS

Circulating levels of sTNFαR1 are independently associated with the cumulative incidence of ESRD. This association is both significant and biologically plausible and appears to provide added value as a biomarker, based on the absolute values of NRI and IDI.

Patients with end-stage renal disease admitted to the intensive care unit: systematic review

The number of patients with end-stage renal disease (ESRD) is increasing worldwide, with a growing demand on healthcare services. A systematic review of the literature was performed to determine the requirement for intensive care unit (ICU) services, reasons for admission, predictors of mortality, and short- and long-term outcomes of ESRD patients admitted to ICU. Sixteen studies were identified, comprising 6591 ICU admissions. Cardiovascular disease and sepsis accounted for the majority of admissions. Acute illness severity scores tend to overestimate mortality among ESRD patients. Critical illness associated with acute kidney injury (AKI) requiring renal replacement therapy (RRT) is associated with significantly higher hospital mortality compared with ESRD patients admitted to the ICU [odds ratio (OR) 3.9; 3.5-4.4; P<0.0001]. However, hospital mortality of ESRD patients is less favourable compared with matched patients with mild AKI (OR 1.5; 1.4-1.6; P<0.0001). Although the mortality rate remains high shortly after hospital discharge, the duration of increased mortality risk is unclear. Patients with ESRD frequently benefit from ICU admission, despite chronic co-morbidity. Further studies are required to modify and validate existing illness severity scores for ESRD patients admitted to the ICU, and to establish the duration of increased mortality risk after discharge from ICU.

Management of the dialysis patient in general intensive care

The incidence of end-stage renal disease (ESRD) is rising and represents an important group of patients admitted to intensive care units (ICU). ESRD patients have significant co-morbidities and specific medical requirements. Renal replacement therapy (RRT), cardiovascular disease, disorders of electrolytes, drug metabolism, and sepsis are discussed. This review provides a practical approach to problems specific to the ESRD patient and common problems on ICU that require special consideration in ESRD patients. ESRD patients are at risk of hyperkalaemia. I.V. insulin and nebulized salbutamol lower serum potassium until definitive treatment with RRT is instituted. ESRD patients are prone to hypocalcaemia, which requires i.v. replacement if associated with complications. Midazolam has delayed metabolism and elimination in renal impairment and should be avoided. Morphine and its derivatives accumulate in renal failure and shorter-acting opiates are preferable. The use of diuretics is limited to patients with residual urine output. When required, therapeutic systemic anticoagulation should be achieved with unfractionated heparin as it is reversible and its metabolism and clearance are independent of renal function. The risk of sepsis is higher among ESRD patients when compared with patients with normal renal function. Empiric treatment should include both Gram-positive and Gram-negative cover, and methicillin-resistant Staphylococcus aureus cover if the patient has a dialysis catheter. Cardiovascular events account for the majority of deaths among ESRD patients. Troponin-I and CK-MB in combination should be used as markers of acute myocardial damage in the appropriate context, whereas B-type natriuretic peptide and troponin-T values are of less value.

Difficulty in improving malnutrition and low-grade inflammation in diabetic patients on peritoneal dialysis

Continuous ambulatory peritoneal dialysis (CAPD) is commonly used for renal replacement therapy in diabetes mellitus (DM) patients. We investigated the changes of peritoneal transport characteristics, nutritional status, and adequacy and inflammation parameters in diabetic CAPD patients (N = 17) compared to non-diabetic patients (N = 23). Peritoneal equilibrium testing, nutritional, biochemical, and anthropometric parameters and adequacy were prospectively assessed at 1 (baseline), 6 and 12 months after initiating CAPD. The levels of several nutritional parameters were lower and did not change in DM patients over time (P < 0.05) and significantly improved in the non-DM patients over time (P < 0.05). Total weekly creatinine clearance and residual renal function exhibited a rapid decline (P < 0.05) and inflammation parameter levels were higher in DM patients (P < 0.05). Our results showed the difficulty in improvement of nutritional status and inflammatory parameters in diabetic patients during at least the first year of CAPD compared to non-DM patients.

Serum concentrations of markers of TNFalpha and Fas-mediated pathways and renal function in nonproteinuric patients with type 1 diabetes

BACKGROUND AND OBJECTIVES

The aim of our study was to examine serum markers of the TNF and Fas pathways for association with cystatin-C based estimated glomerular filtration rate (cC-GFR) in subjects with type 1 diabetes (T1DM) and no proteinuria.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

The study group (the 2nd Joslin Kidney Study) comprised patients with T1DM and normoalbuminuria (NA) (n = 363) or microalbuminuria (MA) (n = 304). Impaired renal function (cC-GFR <90 ml/min) was present in only 10% of patients with NA and 36% of those with MA. We measured markers of the tumor necrosis factor alpha (TNFalpha) pathway [TNFalpha, soluble TNF receptor 1 (sTNFR1), and 2 (sTNFR2)], its downstream effectors [soluble intercellular and soluble vascular adhesion molecules (sICAM-1 and sVCAM-1), interleukin 8 (IL8/CXCL8), monocytes chemoattractant protein-1 (MCP1), and IFNgamma inducible protein-10 (IP10/CXCL10)], the Fas pathway [soluble Fas (sFas) and Fas ligand (sFasL)], CRP, and IL6.

RESULTS

Of these, TNFalpha, sTNFRs, sFas, sICAM-1, and sIP10 were associated with cC-GFR. However, only the TNF receptors and sFas were associated with cC-GFR in multivariate analysis. Variation in the concentration of the TNF receptors had a much stronger impact on GFR than clinical covariates such as age and albumin excretion.

CONCLUSIONS

Elevated concentrations of serum markers of the TNFalpha and Fas-pathways are strongly associated with decreased renal function in nonproteinuric type 1 diabetic patients. These effects are independent of those of urinary albumin excretion. Follow-up studies are needed to characterize the role of these markers in early progressive renal function decline.

Elevated soluble tumor necrosis factor receptor 75 concentrations identify patients with liver cirrhosis at risk of death

BACKGROUND & AIMS

Elevated levels of the soluble 75-kd receptor for tumor necrosis factor-alpha (sTNF-R 75) are better predictors of mortality in cirrhosis than the Child-Turcotte-Pugh (CTP) score. Thus, we compared sTNF-R 75 with the Model for End-Stage Liver Disease (MELD), CTP, and the sTNF-R 75/55 ratio.

METHODS

Ninety-two patients with liver cirrhosis (mean age, 55 years; range, 19-76 years; male, 66%; CTP stage C, 41%) were included in our prospective single-center survival study. The study setting was a tertiary care university clinic. Soluble TNF-R levels were determined, and the primary end point was death.

RESULTS

During > or =730 days, 44 patients died. Multivariate Cox regression analysis revealed sTNF-R 75 (> or =14 ng/mL) as an independent predictor of mortality (hazard ratio, 2.53; P = .006). By receiver operating characteristic, MELD and sTNF-R 75 were more accurate in predicting 6-, 15-, and 24-month mortality than CTP and sTNF-R 75/55. This was significant for 6 months (MELD, 0.78; sTNF-R 75, 0.75 vs sTNF-R 75/55, 0.60). In patients with high MELD scores (> or =15), survival was further reduced if sTNF-R 75 values were elevated (P = .035).

CONCLUSIONS

Elevated sTNF-R 75 levels independently predicted mortality and improved MELD on the basis of evaluation of prognosis, especially in patients with high MELD scores. Thus, sTNF-R 75 levels might be a useful cytokine-based prognostic marker in patients with liver cirrhosis.

Improvement of gastric motility by hemodialysis in patients with chronic renal failure

BACKGROUND

Gastrointestinal (GI) symptoms are common in patients with chronic renal failure (CRF). We have previously demonstrated that patients with predialysis end-stage renal disease showed a high prevalence of GI symptoms and gastric hypomotility, and that gastric hypomotility appears to be an important factor in generating GI symptoms. However, it is not clear whether impaired gastric motor function would improve after hemodialytic treatment.

AIMS

To examine the relationship between gastric motor function and GI symptoms in CRF patients on hemodialysis.

METHODS

The study was performed in 19 patients with CRF treated with hemodialysis for more than six months and in 12 matched healthy controls. GI symptom severity was quantified in all patients. Gastric motility was evaluated with cutaneously recorded electrogastrography (EGG) and gastric emptying of semi-solid meals using the (13)C-acetic acid breath test.

RESULTS

Six patients had no symptoms, and 11 had slight GI symptoms with a total symptom score of less than 5. Compared with controls, CRF patients revealed no differences in gastric motility parameters, with the exception of a lower percentage of normogastria in EGG at fasting state. Eleven patients had normal gastric motor function (Group A), and eight showed abnormalities of either gastric myoelectrical activity or gastric emptying (Group B). There was no difference in symptom score between Group A and Group B.

CONCLUSIONS

More than half of the patients with CRF on hemodialysis demonstrated normal gastric motility, and no or slight GI symptoms. Hemodialytic treatment may improve impaired gastric motility and reduce GI symptoms in patients with CRF.

Inflammation, cardiovascular disease and nocturnal hemodialysis

PURPOSE OF REVIEW

There is a growing recognition that uremia is a proinflammatory condition. Chronic uremia-associated inflammation contributes to the pathogenesis of atherosclerosis, anemia and cardiovascular calcification in patients with end-stage renal disease (ESRD). Daily nocturnal hemodialysis (DNHD) is a form of frequent intensive renal replacement therapy that has multiple cardiovascular benefits. Here we will review the emerging data of DNHD on inflammation, coronary calcification and anemia management.

RECENT FINDINGS

Increasing the dose and frequency of dialysis by DNHD has been demonstrated, in both short and long-term studies, to reverse several important risk factors for adverse cardiovascular events in ESRD patients. In addition, there are preliminary data indicating the positive effects of DNHD on inflammatory cytokine profile, rate of coronary calcification progression and enhanced erythropoietin responsiveness.

SUMMARY

Augmentation of dialysis dose by DNHD may positively influence uremia-related inflammation. The role of intensive dialysis as a treatment for chronic inflammation requires further research.

Association between C-reactive protein levels and N-terminal pro-B-type natriuretic peptide in pre-dialysis patients

BACKGROUND

The prevalence of inflammation is high among patients with chronic renal failure but the reason of inflammation is unclear. We test the hypothesis that inflammation in chronic renal failure could be the consequence of an increased left-ventricular wall tension related to ventricular dysfunction, hypervolemia or both.

METHODS

For assessing left-ventricular filling pressure, plasma level of N-terminal pro-B-type natriuretic peptide (N-BNP) was used, as B-type natriuretic peptide is secreted from the cardiac ventricles in response to increased wall tension. N-BNP levels and C-reactive protein (CRP) were measured on the same day in 75 pre-dialysis patients. A previous history of cardiomiopathy with systolic dysfunction was present in 27 (36%) of them.

RESULTS

The levels of N-BNP were not normally distributed (mean: 2,589 +/- 4,514 pg/ml; median: 789 pg/ml). The distribution of CRP levels was also not normal (mean: 15 +/- 27 mg/l; median: 5 mg/l). Both parameters correlated significantly (r: 0.41; p < 0.005). N-BNP was higher (p < 0.001) in patients with known ventricular dysfunction. Excluding these patients, the correlation between N-BNP and CRP was stronger (r: 0.88; p < 0.001). Univariate analysis in these patients without known cardiomyopathy showed that N-BNP levels also correlated with systolic and diastolic blood pressure (r: 0.54; p < 0.005) and inversely with creatinine clearance (r: -0.43; p < 0.01), serum albumin (r: 0.6; p < 0.001) and hemoglobin levels (r: 0.37; p < 0.05). CRP levels correlated significantly (p < 0.01) with the same parameters as N-BNP in univariate analysis. However, in multiple stepwise regression analysis in which CRP was the dependent variable, only the association with N-BNP remained significant (r: 0.87; p < 0.001).

CONCLUSIONS

Our results suggest a link between left-ventricular filling pressure and inflammation in patients with advanced renal insufficiency. The importance of strict volume control in these patients, in order to reduce left-ventricular pressure and therefore inflammation, should be considered.

Chronic systemic inflammation in uremia: Potential therapeutic approaches

Systemic inflammation characterizes several chronic diseases including uremia. Inflammation may contribute to morbidity and mortality by enhancing protein-calorie malnutrition, infectious complications, and atherosclerosis and cardiovascular disease. Although inflammation in renal disease can be caused, at least in part, by reduced renal clearance of proinflammatory mediators (tumor necrosis factor [TNF]-alpha, interleukin [IL]-6), several pathogenetic mechanisms are likely to contribute to direct activation of the inflammatory process under these conditions. These mechanisms include accumulation of advance glycoxidation end products, production of reactive oxygen species and oxidative damage, and chronic infection. Support for direct activation of systemic inflammation provides a strong rationale for use of anti-inflammatory treatments in uremia. The current article describes the association between uremia and inflammation, provides evidence for activation of inflammatory process, and provides potential therapeutic approaches.

Tumor necrosis factor alpha, its soluble receptor I, and -308 gene promoter polymorphism in patients with rheumatoid arthritis with or without amyloidosis: implications for the pathogenesis of nephropathy and anemia of chronic disease in reactive amyloidosis

OBJECTIVE

To study tumor necrosis factor alpha (TNFalpha) -308 gene promoter polymorphism and circulating levels of TNFalpha and soluble TNF receptor type I (sTNFRI) in rheumatoid arthritis (RA) patients with and without reactive amyloidosis.

METHODS

In a retrospective study, we examined 55 RA patients with biopsy-proven reactive amyloidosis and 55 control RA patients without amyloidosis (matched for age, sex, rheumatoid factor titer, and RA duration). Inflammatory activity was assessed by measuring the erythrocyte sedimentation rate and C-reactive protein level. TNFalpha gene promoter polymorphism was studied using polymerase chain reaction-restriction fragment length polymorphism assay. Cytokine and receptor levels were measured by enzyme-linked immunoassays.

RESULTS

Patients with RA and amyloidosis had significantly higher TNFalpha and sTNFRI levels than did the control RA patients. The increased circulating levels of TNFalpha correlated with interleukin-18 levels, but not with the serum amyloid A protein levels or with TNFalpha -308 gene promoter polymorphism (reported to be associated with high TNFalpha levels and certain disease susceptibilities). In the patients with RA and amyloidosis, those with anemia had significantly higher TNFalpha and sTNFRI levels than did those without anemia, and circulating TNFalpha and sTNFRI levels correlated negatively with hemoglobin concentrations. In the patients with RA and amyloidosis, those with nephropathy had significantly higher TNFalpha and sTNFRI levels than did those without nephropathy; in patients with isolated proteinuria (but no creatinine elevation) the TNFalpha level was also significantly increased, indicating that the TNFalpha elevation was not merely a consequence of impaired renal function.

CONCLUSION

This study shows that circulating levels of TNFalpha and sTNFRI are significantly increased in RA patients with amyloidosis as compared with control RA patients without amyloidosis and that the increased levels may be implicated in the pathogenesis of certain disease manifestations, including anemia of chronic disease and renal pathology in reactive amyloidosis.

Habitual dietary intake of n-3 and n-6 fatty acids in relation to inflammatory markers among US men and women

BACKGROUND

Polyunsaturated fatty acid intake favorably affects chronic inflammatory-related diseases such as cardiovascular disease; however, high intake of n-6 fatty acids may attenuate the known beneficial effects of n-3 fatty acids.

METHODS AND RESULTS

We investigated habitual dietary n-3 fatty acid intake and its interaction with n-6 fatty acids in relation to the plasma inflammatory markers C-reactive protein, interleukin 6, and soluble tumor necrosis factor receptors 1 and 2 (sTNF-R1 and R2) among 405 healthy men and 454 healthy women. After adjustment for other predictors of inflammation, intake of the n-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) was inversely associated with plasma levels of sTNF-R1 and sTNF-R2 (P=0.03 and P<0.001, respectively) and somewhat less so for C-reactive protein (P=0.08). n-3 alpha-linolenic acid and n-6 cis-linoleic acid were not significantly related to the inflammatory markers. We found little if any association between n-3 fatty acid (EPA+DHA) intake and tumor necrosis factor receptors among participants with low intake of n-6 but a strong inverse association among those with high n-6 intake (P=0.04 and 0.002 for interaction of n-3 with n-6 on sTNF-R1 and sTNF-R2, respectively).

CONCLUSIONS

These results suggest that n-6 fatty acids do not inhibit the antiinflammatory effects of n-3 fatty acids and that the combination of both types of fatty acids is associated with the lowest levels of inflammation. The inhibition of inflammatory cytokines may be one possible mechanism for the observed beneficial effects of these fatty acids on chronic inflammatory-related diseases.

Absence of peripheral blood mononuclear cells priming in hemodialysis patients

As a consequence of the proinflammatory environment occurring in dialytic patients, cytokine overproduction has been implicated in hemodialysis co-morbidity. However, there are discrepancies among the various studies that have analyzed TNF-alpha synthesis and the presence of peripheral blood mononuclear cell (PBMC) priming in this clinical setting. We measured bioactive cytokine by the L929 cell bioassay, and evaluated PBMC TNF-alpha production by 32 hemodialysis patients (HP) and 51 controls. No difference in TNF-alpha secretion was observed between controls and HP (859 +/- 141 vs 697 +/- 130 U/10(6) cells). Lipopolysaccharide (5 microg/ml) did not induce any further TNF-alpha release, showing no PBMC priming. Paraformaldehyde-fixed HP PBMC were not cytotoxic to L929 cells, suggesting the absence of membrane-anchored TNF-alpha. Cycloheximide inhibited PBMC cytotoxicity in HP and controls, indicating lack of a PBMC TNF-alpha pool, and dependence on de novo cytokine synthesis. Actinomycin D reduced TNF-alpha production in HP, but had no effect on controls. Therefore, our data imply that TNF-a production is an intrinsic activity of normal PBMC and is not altered in HP. Moreover, TNF-alpha is a product of de novo synthesis by PBMC and is not constitutively expressed on HP cell membranes. The effect of actinomycin D suggests a putative tighter control of TNF-alpha mRNA turnover in HP. This increased dependence on TNF-alpha RNA transcription in HP may reflect an adaptive response to hemodialysis stimuli.

Elevated serum levels of the type I and type II receptors for tumor necrosis factor-alpha as predictive factors for ARF in patients with septic shock

BACKGROUND

Acute renal failure (ARF), a common and serious complication in patients with septic shock, has high mortality. Recent data suggest that proinflammatory cytokines may contribute to sepsis-associated ARF.

METHODS

To examine the role of proinflammatory cytokines, we evaluated 537 patients enrolled in the placebo arm of the Norasept II study, of whom 112 patients (20%) developed ARF.

RESULTS

By univariate analysis, the following factors were significantly associated with the development of ARF: male sex, younger age, increased heart rate, higher Acute Physiology and Chronic Health Evaluation II score, oliguria, increased blood urea nitrogen level, increased serum creatinine (Scr) level, decreased arterial pH, and increased serum potassium level. Although there were no statistically significant differences in serum levels of tumor necrosis factor-alpha (TNF-alpha) or interleukin-6 between patients with and without ARF, elevated serum levels of the two soluble TNF-alpha receptors (S-TNF-RI and S-TNF-RII) were strongly associated with the development of ARF (S-TNF-RI, 25 +/- 16 versus 18 +/- 13 ng/mL; P = 0.00006; S-TNF-RII, 25 +/- 21 versus 18 +/- 17 ng/mL; P = 0.0007). Using forward stepwise regression analysis, elevated S-TNF-R level remained an independent predictor for ARF, even when we limited our analysis to patients with Scr levels of 1.4 mg/dL or less (< or =124 micromol/L) at study entry, suggesting that decreased renal clearance of S-TNF-R alone cannot account for this association. Elevated S-TNF-R level also was an independent predictor of mortality among patients developing ARF.

CONCLUSION

S-TNF-R level is an independent predictor for the development of ARF and mortality. We speculate that elevated S-TNF-R levels may reflect a more intense inflammatory response.

Inflammation in end-stage renal disease: sources, consequences, and therapy

Cardiovascular disease (CVD) remains the main cause of morbidity and mortality in patients with end-stage renal disease (ESRD). Although traditional risk factors are common in ESRD patients, they alone may not be sufficient to account for the high prevalence of CVD in this condition. Recent evidence demonstrates that chronic inflammation, a nontraditional risk factor which is commonly observed in ESRD patients, may cause malnutrition and progressive atherosclerotic CVD by several pathogenetic mechanisms. The causes of inflammation in ESRD are multifactorial and, while it may reflect underlying CVD, an acute-phase reaction may also be a direct cause of vascular injury by several pathogenetic mechanisms. Available data suggest that proinflammatory cytokines play a central role in the genesis of both malnutrition and CVD in ESRD. Thus it could be speculated that suppression of the vicious cycle of malnutrition, inflammation, and atherosclerosis (MIA syndrome) would improve survival in dialysis patients. Recent evidence has demonstrated strong associations between inflammation and both increased oxidative stress and endothelial dysfunction in ESRD patients. As there is not yet any recognized, or even proposed, treatment for ESRD patients with chronic inflammation, it would be of obvious interest to study the long-term effect of various anti-inflammatory treatment strategies on the nutritional and cardiovascular status as well as outcome in these patients.

Peritoneal dialysis in anuric patients: concerns and cautions

Most recent studies have found an equivalent survival for patients on peritoneal dialysis (PD) and hemodialysis (HD); evidence even suggests that PD might be the preferred modality during the first 3-4 years of renal replacement therapy. This is probably related to the continuous and minimally invasive character of PD as compared to HD, resulting in better preservation of residual renal function (RRF) and less cardiovascular strain. On the other hand, blood pressure control, fluid balance, and adequacy targets may be difficult to obtain in long-term PD patients. The question arises whether PD is a feasible option in anuric patients. It is clear that the answer depends on the body size and the peritoneal membrane transport characteristics of the patient, so that PD will be feasible in some anuric patients, whereas in others it will not be. Evaluation of the peritoneal transport characteristics and adaptation of the PD prescription is warranted. A constant evaluation of the fluid balance, nutritional, and cardiovascular status is needed. This article reviews the physiologic insights and clinical evidence necessary for a good PD prescription in anuric patients.

Soluble tumor necrosis factor receptor p55 predicts cytokinemia and systemic inflammatory response after cardiopulmonary bypass

OBJECTIVES

To examine the behavior of soluble tumor necrosis factor (TNF) receptors in circulation before and after cardiopulmonary bypass and the relationship to the development of cytokinemia and acute complications comprising systemic inflammatory response syndrome (SIRS) and multiple organ dysfunction syndrome (MODS). The predictive value of soluble TNF receptor is assessed herein.

DESIGN

Prospective study comparing prebypass and postbypass levels in patients with and without complications indicative of SIRS and MODS.

SETTING

Cardiac surgical intensive care unit in a tertiary care hospital.

PATIENTS

A total of 20 pediatric patients who underwent cardiopulmonary bypass during open heart surgery.

INTERVENTIONS

Blood samples were collected from catheters before and 2 hrs and 24 hrs after the onset of bypass.

MEASUREMENTS AND MAIN RESULTS

We measured plasma levels of soluble TNF receptors by using enzyme-linked immunosorbent assay in 20 patients before and after cardiopulmonary bypass. Clinical data, including duration of bypass and tests or signs indicative of SIRS/MODS, were collected. Soluble TNF receptor I (p55 sR), significantly increased (2241 +/- 312 pg/mL) at 2 hrs after bypass (p <.0005) and remained elevated (2826 +/- 695 pg/mL) at 1 day after bypass (p <.005) when compared with prebypass levels (725 +/- 130 pg/mL). Patients with the acute complications of SIRS/MODS had a higher ratio of postbypass to prebypass p55 sR levels (5.0-fold, p <.001) when compared with patients with no SIRS/MODS (1.75-fold). Remarkably, before surgery, levels of TNF p55 sR predict both cytokinemia (r =.67 to.73, p <.05) and SIRS/MODS (p <.01). The prebypass levels of TNF p55 sR were consistently higher (range, 1000-1400 pg/mL) in patients who subsequently developed SIRS/MODS than the levels (range, 400-570 pg/mL) in patients who did not develop SIRS/MODS. Hypotension, respiratory dysfunctions, and coagulopathy were particularly more prevailing (p <.005) among the complications that were associated with high prebypass levels of TNF p55 sR.

CONCLUSIONS

Soluble TNF receptor p55 can be employed as a predictive marker for cytokinemia and the development of SIRS/MODS that may arise from a major insult to the body such as cardiopulmonary bypass.

Association between inflammation and changes in residual renal function and peritoneal transport rate during the first year of dialysis

BACKGROUND

Peritoneal transport rate, a major determinant of peritoneal dialysis (PD) patient survival, increases in most patients starting on PD, while in other patients peritoneal transport rate may decline. Although several factors may contribute to changes in peritoneal transport rate, inflammation is known to be associated with a high peritoneal transport rate, and residual renal function (RRF), which often declines after start of PD, may also be related to inflammation. Therefore, we hypothesized that changes in peritoneal transport rate during patients' first year on PD and declining RRF may be linked with inflammation.

METHODS

A total of 76 PD patients (40 males, mean age 56.8+/-14.1 years), who underwent two peritoneal equilibration tests at a mean of 0.4 months and 1 year after beginning PD, were included in the study. Based on the change in dialysate to plasma creatinine concentration ratio at 4-h dwell (D/P Cr) during first year on PD, the patients were divided into decreased or unchanged (group DUC; n=22) and increased (group I; n=54) groups.

RESULTS

Initially, group I had a lower proportion of high transporters and more often high serum C-reactive protein (sCRP, > or =10 mg/l) and lower RRF compared with the DUC group. In group I, serum albumin and RRF decreased significantly and dialysate protein loss and glucose absorption increased significantly during the first year on PD. When patients were divided into two groups based on median change in RRF (1.9 ml/min), patients with a decrease in RRF >1.9 ml/min during first year on PD had a higher proportion of high sCRP, higher D/P Cr, and higher changes in D/P Cr compared to patients with a decrease in RRF < or =1.9 ml/min. Patients with elevated sCRP at one year included a higher proportion of patients who had high sCRP at the start of PD, higher increase in D/P Cr, lower serum albumin, lower RRF, and more decrease in RRF during first year on PD compared with patients having normal sCRP. RRF was inversely correlated with changes in D/P Cr during the first year on PD (r=-0.28, P=0.02). Multiple regression analysis revealed that the only factors affecting changes in D/P Cr were high sCRP and a low RRF.

CONCLUSIONS

Our preliminary short-term study suggests that changes in peritoneal transport rate during patients' first year on PD may be linked with inflammation and declining residual renal function. Inflammation and residual renal function were identified as the only independent factors determining peritoneal transport rate during the first year on PD. It is possible that inflammation may cause both an increase in peritoneal transport rate and a decline in residual renal function, or that the decline in residual renal function and the increase in peritoneal transport rate may induce or aggravate inflammation. Further studies are needed to confirm these findings.

Soluble CD40 in the serum of healthy donors, patients with chronic renal failure, haemodialysis and chronic ambulatory peritoneal dialysis (CAPD) patients

CD40 and its ligand CD40L are key players in T cell-B cell interaction and T cell-antigen-presenting cell (APC) interaction. Inhibition of CD40-CD40L interaction leads to severe humoral and cellular immunodeficiency. In this study we examined the presence of soluble CD40 (sCD40) in the serum of haemodialysis (HD) patients, CAPD patients, chronic renal failure (CRF) patients and healthy donors in order to evaluate the possible involvement of CD40 in uraemic immunodeficiency. Soluble CD40 was detected in the serum of healthy donors (n = 41) with a mean of 0.14 +/- 0.12 ng/ml and in the urine of healthy donors with a mean of 1.80 +/- 0.74 ng/ml. Soluble CD40 was highly elevated in all patients with impaired renal function. HD patients (n = 22) had up to 100-fold elevated sCD40 levels with a mean concentration of 8.32 +/- 4.11 ng/ml, whereas CAPD patients (n = 10) had considerably lower levels of sCD40 with a mean of 3.58 +/- 2.40 ng/ml. A strong correlation between sCD40 and serum creatinine levels was noted in CRF patients (n = 66). The highly elevated levels of sCD40 may point to the involvement of CD40 and its ligand CD40L in the clinical manifestation of uraemic immunodeficiency.

Differential expression of tumor necrosis factor receptor subtypes on leukocytes in systemic inflammatory response syndrome

OBJECTIVE

To determine the expression of tumor necrosis factor (TNF) receptor in patients with systemic inflammatory response syndrome (SIRS).

DESIGN

Prospective study.

SETTING

Intensive care unit and central laboratory.

PATIENTS

Blood specimens from 18 healthy volunteers (controls) and 16 patients with SIRS.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Using monoclonal antibodies, fluorescence labeling, and high sensitivity flow cytometry, we measured the expression of membrane TNF receptor subtypes TNF-R55 and TNF-R75 on peripheral blood leukocytes. Receptor expression is expressed as mean fluorescence intensity +/- SD (units: detection channel number). In controls, TNF-R55 was only weakly expressed (monocytes: 2.5+/-1.8; neutrophils: 0.7+/-0.8), whereas expression of TNF-R75 was higher (monocytes: 28.6+/-9.0; neutrophils: 4.8+/-1.0) and was also found on lymphocytes (on CD8+ lymphocytes: 5.7+/-1.8; CD16+: 5.5+/-1.2; CD4+: 9.7+/-3.7). In SIRS, we observed increased expression of TNF-R55 on monocytes (6.9+/-3.4, p<.001) and neutrophils (2.2+/-1.9, p<.01), as well as decreased expression of TNF-R75 on monocytes (17.3+/-13.2; p<.001). The extent of TNF-R55 up-regulation did not correlate with that of TNF-R75 down-regulation. TNF-R55 on monocytes and neutrophils strongly correlated with body temperature but not with survival, whereas monocyte TNF-R75 was considerably lower in nonsurvivors, albeit not significantly (12.3+/-7.1 vs. 23.9+/-16.7; p = .07).

CONCLUSIONS

These data indicate that leukocyte TNF-R55 and TNF-R75 react differentially and probably serve different functions in SIRS, which prompts the investigation of receptor subtype-specific therapeutic approaches.

Etanercept, a novel drug for the treatment of patients with severe, active rheumatoid arthritis

The US adult rheumatoid arthritis (RA) population numbers approximately 2.1 million, with a greater proportion of cases in women. RA is a disease of the immune system that has no known cure, and current drugs do not affect the underlying cause. The side effects such drugs produce limit their usefulness, and many patients stop responding to these treatments over time. Etanercept, a biologic inflammation modulator, is a novel human recombinant version of the soluble p75 tumor necrosis factor (TNF) receptor that is linked to the Fc receptor of human immunoglobulin G subclass 1. It acts as a competitive inhibitor of the binding of TNF-alpha to cell-surface TNF receptors and thereby inhibits TNF-alpha-induced proinflammatory activity in the joints of RA patients. Etanercept acts as a cytokine "carrier" and TNF-alpha antagonist, rendering TNF-alpha biologically inactive, even though prolonging its half-life. In Phase I, II, and III clinical studies in patients with active, severe RA who had not responded to disease-modifying antirheumatic drug (DMARD) therapy, etanercept treatment decreased disease activity, increased functional activity, and improved health-related quality of life. In a recent 12-month continuation of an earlier 6-month study, 105 patients who received etanercept 25 mg subcutaneously twice weekly demonstrated rapid and sustained improvements in disease activity. The US Food and Drug Administration has approved etanercept for marketing for the treatment of moderately to severely active RA in patients who have not responded adequately to other DMARDs.

Elevated SCF levels in the serum of patients with chronic renal failure

Serum stem cell factor (SCF) and soluble KIT (sKIT) levels were estimated in patients with chronic renal failure (CRF) and anaemia, and compared with clinical parameters of blood cells and renal function. Serum SCF levels in CRF patients were 5-fold higher than those in healthy controls. However, serum sKIT levels in haemodialysis (HD)-CRF patients were only slightly higher than those of healthy controls. In untreated CRF patients and healthy controls, serum SCF levels were significantly correlated with blood urea nitrogen (BUN), creatinine. haemoglobin, red blood cell (RBC) count and sKIT. In untreated CRF patients, serum SCF levels were significantly correlated with BUN, creatinine, and sKIT. These results suggest that serum SCF levels increased with the deterioration of renal function and might be related to erythropoiesis.

Levels of inhibitors of tumor necrosis factor alpha and interleukin 1beta in urine and sera of patients with urosepsis

The antiinflammatory cytokine response during urosepsis was determined by measurement of concentrations of soluble tumor necrosis factor receptor (sTNFR) types I and II, interleukin 1 receptor antagonist (IL-1ra), soluble IL-1 receptor type II (sIL-1RII), and interleukin 10 in sera and urine of 30 patients with culture-proven urinary tract infections before and 4, 24, 48, and 72 h after initiation of antibiotic therapy and in 20 healthy individuals. In serum, the levels of sTNFR types I and II, IL-1ra, and IL-10 were higher in patients than in controls. In urine, only sTNFR type I and II levels were elevated in patients. The ratios of concentrations of both types of sTNFR in urine to concentrations in serum were higher in patients than in controls. These findings indicate that during urosepsis, the antiinflammatory cytokine response is generated predominantly at the systemic level.

Soluble tumor necrosis factor receptor (p75) fusion protein (ENBREL) as a therapy for rheumatoid arthritis

Soluble tumor necrosis factor (TNF) receptor fusion protein (p75) (Enbrel) is a reversible inhibitor of the biologic effects of TNF. Enbrel has been shown in placebo-controlled trials to significantly improve the signs and symptoms of rheumatoid arthritis. Clinical trials are now in progress to assess the safety and efficacy of Enbrel in combination with methotrexate in refractory rheumatoid arthritis along with trials to compare Enbrel to methotrexate in patients with early rheumatoid arthritis.

Serum levels of soluble tumor-necrosis-factor receptors in patients with benign and malignant HPV-associated anogenital lesions

The levels of type-I and type-II soluble TNF-alpha receptors (sTNF-Rs) were evaluated in sera from patients with various human-papillomavirus-(HPV)-associated benign and malignant anogenital lesions using specific enzyme-linked immunobiological assays. In patients with benign HPV6/11-associated condylomata acuminata, the levels of sTNF-RI were significantly increased, while sTNF-RII were in normal range. Both types of sTNF-Rs were in normal range in patients with benign HPV16-associated grade-I/II and grade-III cervical intra-epithelial neoplasia. However, their levels were significantly increased in patients with HPV16/18-associated squamous cervical cancer and anogenital Bowen's carcinoma. Sera from patients with condylomata acuminata and anogenital carcinomas displayed significantly increased TNF-alpha-inhibitory activity, as revealed by L929 cell-cytotoxicity assay. Increased serum TNF-alpha-inhibitory activity correlated with higher levels of sTNF-Rs. Furthermore, this inhibitory activity could be specifically abrogated by htr9 and utr1 monoclonal antibodies recognizing TNF-RI and TNF-RII respectively. Our results strongly suggest that serum sTNF-Rs may protect tumor cells from cytotoxic/cytostatic effects of locally released TNF-alpha, and that elevated levels of circulating sTNF-Rs may facilitate the growth of HPV-associated anogenital lesions.

Concentrations of soluble tumor necrosis factor and interleukin-6 receptors in heatstroke and heatstress

OBJECTIVE

Increased proinflammatory cytokine concentrations have been implicated in the pathogenesis of heatstroke. Soluble cytokine receptors can modulate circulating cytokine activities. We examined the possible role of soluble tumor necrosis factor receptors (sTNFR 60, sTNFR 80) and interleukin-6 receptor (sIL-6R) in heatstroke by determining their concentrations before and after cooling, as well as in heatstressed controls.

DESIGN

Prospective controlled study.

SETTING

Heatstroke Center, Makkah, Saudi Arabia (1993 pilgrimage).

PATIENTS

Twenty-five consecutive heatstroke patients before and after cooling, 14 heatstressed controls (HSC), and 13 normal controls (NC).

MEASUREMENTS AND MAIN RESULTS

Concentrations of sTNFR 60, sTNFR 80, and sIL-6R, as well as their ligands, were measured using commercially available enzyme-linked immunosorbent assay kits. Mean sTNFR 60 concentration was increased in heatstroke (p <.0001, vs. NC; p < .0001, vs. HSC) and in HSC (p = .004, vs. NC). Mean sTNFR 80 concentration was increased in heatstroke and decreased in HSC (p = .01, heatstroke vs. HSC). Mean sIL-6R concentration was decreased in heatstroke and increased in HSC (p = .04, heatstroke vs. NC; p = .001, heatstroke vs. HSC). IL-6 was undetectable in NC and mean IL-6 concentration was more increased in heatstroke than in HSC (p = .001). Rectal temperature and creatinine concentrations correlated significantly with sTNFR 60, sTNFR 80, sIL-6R, and IL-6 concentrations. After cooling, mean concentrations of sIL-6R and sTNFR 80 increased significantly, whereas the mean sTNFR 60 concentration did not change. Residual neurologic deficits were associated with higher precooling IL-6 (p = .002) and postcooling sTNFRs (p < .0001) concentrations.

CONCLUSIONS

Significant changes in cytokine receptor concentrations are associated with heatstress. In heatstroke, the changes are more pronounced, and for some cytokine receptors, the changes are in the opposite direction (compared with changes in heatstress). Concentrations of IL-6 and sTNFRs correlate with hyperthermia and outcome. Cooling did not normalize sTNFR concentrations, suggesting failure to control the inflammatory response.

Treatment of rheumatoid arthritis with a recombinant human tumor necrosis factor receptor (p75)-Fc fusion protein

BACKGROUND

Tumor necrosis factor (TNF) is a proinflammatory cytokine involved in the pathogenesis of rheumatoid arthritis, and antagonism of TNF may reduce the activity of the disease. This study evaluated the safety and efficacy of a novel TNF antagonist - a recombinant fusion protein that consists of the soluble TNF receptor (p75) linked to the Fc portion of human IgG1 (TNFR:Fc).

METHODS

In this multicenter, double-blind trial, we randomly assigned 180 patients with refractory rheumatoid arthritis to receive subcutaneous injections of placebo or one of three doses of TNFR:Fc (0.25, 2, or 16 mg per square meter of body-surface area) twice weekly for three months. The clinical response was measured by changes in composite symptoms of arthritis defined according to American College of Rheumatology criteria.

RESULTS

Treatment with TNFR:Fc led to significant reductions in disease activity, and the therapeutic effects of TNFR:Fc were dose-related. At three months, 75 percent of the patients in the group assigned to 16 mg of TNFR:Fc per square meter had improvement of 20 percent or more in symptoms, as compared with 14 percent in the placebo group (P<0.001). In the group assigned to 16 mg per square meter, the mean percent reduction in the number of tender or swollen joints at three months was 61 percent, as compared with 25 percent in the placebo group (P<0.001). The most common adverse events were mild injection-site reactions and mild upper respiratory tract symptoms. There were no dose-limiting toxic effects, and no antibodies to TNFR:Fc were detected in serum samples.

CONCLUSIONS

In this three-month trial TNFR:Fc was safe, well tolerated, and associated with improvement in the inflammatory symptoms of rheumatoid arthritis.

Metabolism in patients with small cell lung carcinoma compared with patients with non-small cell lung carcinoma and healthy controls

BACKGROUND

Weight loss is a frequently occurring problem in patients with lung cancer due to an increased resting energy expenditure (REE) and a decreased energy intake. The aim of the present study was to compare the metabolic and inflammatory characteristics of patients with small cell lung carcinoma (SCLC) and non-small cell lung carcinoma (NSCLC). The metabolic parameters of the lung cancer population were compared with those of a healthy control group.

METHODS

REE was measured in 66 patients with lung cancer, subdivided according to their histology, and in 33 healthy controls matched for sex, age, and fat free mass (FFM). Inflammatory mediators were measured in the plasma of the patients with lung cancer.

RESULTS

An increased REE adjusted for FFM was found in the patients with lung cancer. Those with small cell lung carcinoma (SCLC) had an increased REE adjusted for FFM (mean 1925 kcal/day) compared with those with non-small cell lung carcinoma (NSCLC) (mean 1789 kcal/day, 95% CI for difference 36 to 236). FFM accounted for 69% and 48% of the inter-individual variation in REE in controls and those with NSCLC, respectively, while FFM accounted for only 25% of the variation in REE in patients with SCLC in whom the fat mass (FM) also contributed significantly (28%) to the variation in REE. Increased concentrations of soluble TNF-receptor 75 (sTNF-R75) and cortisol were found in patients with SCLC compared with those with NSCLC. Lipopolyasccharide binding protein (LBP) and sTNF-R55 were related to plasma levels of cortisol.

CONCLUSION

An enhanced REE adjusted for FFM occurred in patients with SCLC compared with those with NSCLC.

Preclinical safety assessment of the recombinant TNF receptor-immunoglobulin fusion protein

The tumor necrosis factor (TNF) is now recognized as one of the most pleiotropic mediators of host defense, immune regulation, and inflammatory response. Due to its broad spectrum of effects, TNF has been implicated as a key mediator in the pathogenesis of acute and chronic inflammatory conditions. The inhibition of bioactive TNF could therefore provide a substantial therapeutic benefit. One approach to a potent TNF antagonist is to use recombinant protein technology in the design of a molecule in which the heavy-chain sequences of an immunoglobulin are fused with the ligand-binding region of the TNF receptor. This paper describes some aspects of the preclinical safety evaluation of the recombinant human TNF receptor-immunoglobulin fusion protein (TENEFUSE). Specific emphasis was placed on transgenic and gene-deleted mice models as central sources of information in the safety evaluation of this TNF antagonist.

The effects of treatment with chemotherapy on energy metabolism and inflammatory mediators in small-cell lung carcinoma

A disturbed energy balance has been demonstrated in lung cancer patients. Both an enhanced resting energy expenditure (REE) and a decreased energy intake contribute to weight loss. Enhanced systemic levels of inflammatory mediators were found to be related to the enhanced REE in lung cancer. The aim of the present study was to investigate energy metabolism and systemic levels of inflammatory mediators in small-cell lung carcinoma (SCLC) patients before and after treatment with chemotherapy. Hypermetabolism and an enhanced inflammatory response have already been demonstrated in SCLC by our group before. Twelve newly diagnosed SCLC patients were consecutively included in the study. REE was measured by indirect calorimetry and body composition was determined by bioelectrical impedance (BIA) before and 1 month after treatment. To assess the inflammatory state the acute-phase proteins, C-reactive protein (CRP) and lipopolysaccharide-binding protein (LBP), both soluble tumour necrosis factor (TNF) receptors, (sTNF-R)-55 and sTNF-R75, and soluble intercellular adhesion molecule (sICAM)-1 were measured in plasma before and 1 month after treatment. CRP was assessed by turbidemetry, whereas the other inflammatory parameters were measured by enzyme-linked immunosorbent assay (ELISA). A significant reduction in REE was found irrespective of therapeutic outcome, whereas body weight and body composition remained stable. The acute-phase proteins CRP and LBP were reduced significantly after treatment with chemotherapy, whereas both sTNF receptors and sICAM-1 remained enhanced. No correlation, however, existed between the decrease in REE and the decrease in the acute-phase proteins. In conclusion, chemotherapeutic treatment attenuates the tumour-related metabolic derangements and acute-phase response.

Azotemia, TNF alpha, and LPS prime the human neutrophil oxidative burst by distinct mechanisms

The oxidative burst of neutrophils from azotemic patients (AzoPMNs) is primed for an enhanced response compared to neutrophils from normal subjects (NorPMNs). The mechanism for this priming is unknown, although TNF alpha does not further prime AzoPMNs. The present study examines the hypothesis that azotemia and TNF alpha prime neutrophils by the same mechanism. Formyl peptide receptor expression and degranulation were not primed in AzoPMNs, but were primed by both LPS and TNF alpha. LPS was also able to prime the AzoPMN oxidative burst. Guanine nucleotide exchange by multiple guanine nucleotide binding proteins, including heterotrimeric G-proteins and low molecular weight GTP-binding proteins (LMWGs), was increased in AzoPMNs, as demonstrated by GTP gamma S binding and azidoanilide GTP photoaffinity labeling. The plasma membrane density of G-protein alpha i2, alpha i3, and alpha s subunits and the density in the cytosol of the LMWG, Rap1A, was present in significantly greater amounts on plasma membranes from AzoPMNs. FMet-Leu-Phe-stimulated phospholipase D activity, but not basal activity, was significantly greater in AzoPMNs. Finally, incubation of NorPMNs in plasma from azotemic patients resulted in a significant increase in basal GTP gamma S binding. These results demonstrate that priming of AzoPMNs is restricted to oxidative burst activity and that it occurs by a mechanism distinct from that utilized by TNF alpha and LPS. While the exact mechanism remains unknown, it appears to involve a plasma factor and changes in LMWG expression or activity.

TNF-receptors on human peritoneal mesothelial cells: regulation of receptor levels and shedding by IL-1 alpha and TNF alpha

Human peritoneal mesothelial cells (HPMC) respond to tumor necrosis factor alpha (TNF alpha) by releasing various cytokines that may activate the endothelium and induce recruitment of leukocytes during peristonitis. We characterized the receptors for TNF on HPMC to elucidate their functions in peritonitis. Scatchard analysis determined the presence of 70 x 10(3) TNF receptors/cell with a kDa of 0.44 nM. TNF receptor 1 (TNF-R1, p55) and TNF-R2 (p75) mRNA were demonstrated by reverse-transcriptase-PCR (RT-PCR). TNF-R1 protein was solely detected by flow cytometry (FCM). Interleukin-1 alpha (IL-1 alpha) induced down-regulation of TNF-R1. This was concomitant with accumulation of soluble TNF-R1 (sTNF-R1) detected by specific ELISA. LPS had a lower TNF-R1-shedding activity while TNF alpha did not induce shedding. The IL-1-induced-sTNF-R1-shedding was suppressed by the protein-kinase-A (PKA) inhibitor, H-8, or by H-7, the inhibitor of both PKC and PKA, but not by the specific PKC inhibitor GF. These experiments suggest a role for PKA in the IL-1-shedding signal. No change in TNF-R1 mRNA levels was observed after IL-1 alpha or TNF alpha stimulation while TNF-R2 (p75) mRNA basal levels transiently increased three to fivefold, reaching a peak after four hours followed by an accumulation of sTNF-R2 in the supernatant. Our data suggest that the main receptor expressed on HPMC is TNF-R1. Down-regulation and shedding of TNF-R1 induced by IL-1, and the transient expression of TNF-R2 induced by IL-1 and TNF, may regulate the responses to TNF by HPMC. These results may be important in understanding the inflammatory process of peritonitis were TNF plays a major role.

Soluble TNF alpha receptors are increased in chronic renal insufficiency and hemodialysis and inhibit neutrophil priming by TNF alpha

The oxidative burst of neutrophils from azotemic patients is refractory to priming by tumor necrosis factor-alpha (TNF alpha). Soluble TNF alpha binding protiens (sTNFR) accumulate in the plasma of azotemic patients. To test the hypothesis that these increased sTNFR concentrations inhibit TNF alpha priming of oxidative burst activity, we measured plasma sTNFR concentrations in nondialyzed azotemic patients, hemodialysis patients, and normal subjects, and determined TNF alpha priming of fMet-Leu-Phe-stimulated superoxide production in neutrophils incubated in plasma with differing levels of sT-NFR. These sTNFR concentrations increased significantly as creatinine clearance decreased and were significantly greater in hemodialysis patients than could be accounted for by loss of renal function alone. TNF alpha primed superoxide production by normal neutrophils in normal plasma, but this effect was significantly reduced in plasma with increased concentrations of sTNFR. Neutrophils from azotemic and hemodialysis patients were refractory to priming by TNF alpha in autologous plasma, and incubation in normal plasma only partially corrected this defect. We conclude that sTNFR accumulate as a result of the loss of renal function and hemodialysis and inhibit TNF alpha priming of neutrophils in azotemic and hemodialysis patients, but that these cells also have an intrinsic functional defect.

Soluble tumor necrosis factor-receptors are not a useful marker of acute allograft rejection: a study in patients with renal or cardiac allografts

In this study, we investigated soluble tumor necrosis factor receptor (sTNF-R) levels in plasma of patients with either a kidney or cardiac allograft when clinical suspicion of acute rejection was raised. In plasma of patients with acute renal graft rejection, the sTNF-R levels were strongly enhanced (20-150 ng/ml) as compared to plasma of patients with stable renal function. Following successful treatment of the rejection, a gradual decline in sTNF-R levels occurred with improving renal function, and an inverse correlation between creatinine clearance and sTNF-R was found. To determine whether the increase was caused by an accumulation of constitutively released sTNF-R and lack of clearance by the kidney, or whether the immunological process of the rejection caused the enhancement, we measured sTNF-R in patients suffering from acute cardiac graft rejection but with predominantly stable kidney function. Rejection of a cardiac graft did not lead to a significant enhancement of sTNF-R levels. However, treatment with ATG or OKT3 did cause enhanced sTNF-R levels, followed by a decline that reached starting values after 7 days. These results provide evidence that the immune reaction that occurs during rejection of a graft does not per se induce discernible changes in sTNF-R levels, whereas that induced by ATG or OKT3 does. Thus, sTNF-R levels are not reliable marker in transplant recipient monitoring.

Nutrition support affects the distribution and organ uptake of cachectin/tumor necrosis factor in rats

BACKGROUND

We have previously observed a potentiation of the metabolic response to cachectin/tumor necrosis factor (TNF) by total parenteral nutrition (TPN) but not in anorexic orally fed animals. We hypothesized that nutritional status might affect TNF clearance kinetics.

METHODS

We compared the clearance of a bolus of labeled TNF in TPN-fed animals given sufficient nutrients to grow called weight-gaining rats (WGR) with those given 50% of the WGR called weight-losing rats (WLR) and with orally fed rats (OFR). Data were analyzed using a two-compartment open system model and by linear systems analysis.

RESULTS

The data from both types of analysis indicator that although metabolic clearance was similar, WGR had a slower fractional TNF clearance rate (FCR) as well as a larger volume of distribution than WLR or OFR. Further analysis showed that an increased proportion of the total mass of TNF resided in a plasma-associated compartment in WGR compared with WLR and OFR. In addition, WGR had reduced uptake of labeled TNF by the kidney.

CONCLUSION

The data suggest that nutrition support influences either the distribution of TNF or the FCR, resulting in a greater retention in the plasma-associated compartment with intact absolute removal rates. This study has important implications concerning the type of nutrition support provided to the critically ill patient because our data suggest that clinical states with increased circulating TNF levels may be adversely affected by currently available nutritional practices.

A metalloprotease inhibitor blocks shedding of the 80-kD TNF receptor and TNF processing in T lymphocytes

TNF is synthesized as a 26-kD membrane-anchored precursor and is proteolytically processed at the cell surface to yield the mature secreted 17-kD polypeptide. The 80-kD tumor necrosis factor (TNF) receptor (TNFR80) is also proteolytically cleaved at the cell surface (shed), releasing a soluble ligand-binding receptor fragment. Since processing of TNF and TNFR80 occurs concurrently in activated T cells, we asked whether a common protease may be involved. Here, we present evidence that a recently described inhibitor of TNF processing N-(D,L-[2-(hydroxyaminocarbonyl)methyl]-4-methylpentanoyl)L- 3-(2'naphthyl)- alanyl-L-alanine, 2-aminoethyl amide (TAPI) also blocks shedding of TNFR80, suggesting that these processes may be coordinately regulated during T cell activation. In addition, studies of murine fibroblasts transfected with human TNFR80, or a cytoplasmic deletion form of TNFR80, reveal that inhibition of TNFR80 shedding by TAPI is independent of receptor phosphorylation and does not require the receptor cytoplasmic domain.