Elastase, α1-proteinase inhibitor, and interleukin-8 in pre-dialyzed and hemodialyzed patients with chronic kidney disease

The Direct Anti-Virulence but Not Bactericidal Activity of Human Neutrophil Elastase against Moraxella catarrhalis

Neutrophil elastase (NE) contributes to innate antibacterial defense at both the intracellular (phagocytosis) and extracellular (degranulation, NETosis) levels. Moraxella catarrhalis, a human respiratory pathogen, can exist in an inflammatory milieu which contains NE. No data are available on the action of NE against M. catarrhalis or on the counteraction of NE-dependent host defenses by this pathogen. Using time-kill assays we found that bacteria are able to survive and replicate in the presence of NE. Transmission electron microscopy and flow cytometry studies with NE-treated bacteria revealed that while NE admittedly destabilizes the outer membrane leaflet, it does not cause cytoplasmic membrane rupture, suggesting that the enzyme does not target components that are essential for cell integrity. Using LC-MS/MS spectroscopy we determined that NE cleaved at least three virulent surface proteins in outer membrane vesicles (OMVs) of M. catarrhalis, including OMP CD, McaP, and TbpA. The cleavage of OMP CD contributes to the significant decrease in resistance to serum complement in the complement-resistant strain Mc6. The cleavage of McaP did not cause any sensitization to erythromycin nor did NE disturb its drug action. Identifying NE as a novel but subtle anti-virulence agent together with its extracellularly not-efficient bactericidal activity against M. catarrhalis may facilitate the pathogen’s existence in the airways under inflammation.

Changes in FGF-23, Neutrophil/Platelet Activation Markers, and Angiogenin in Advanced Chronic Kidney Disease and Their Effect on Arterial Stiffness

AIMS

The aims of this study were to measure changes in fibroblast growth factor 23 (FGF-23), neutrophil (elastase, lactoferrin)/platelet activation marker (mean platelet volume-to-platelet count ratio [MPR]), and angiogenin according to the stage of chronic kidney disease (CKD), and to evaluate the association of FGF-23, elastase, lactoferrin, MPR, and angiogenin with arterial stiffness using brachial-ankle pulse wave velocity (ba-PWV) in CKD patients.

METHODS

According to the estimated glomerular filtration rate (eGFR) calculated using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation, the patients were allocated to five groups: (1) normal controls (eGFR ≥90 mL/min/1.73 m2 without pathologic, urine [proteinuria], blood [electrolyte], and imaging abnormalities; n = 22); (2) CKD stage 2 (eGFR 60-89 mL/min/1.73 m2; n = 17); (3) CKD stage 3 (eGFR 30-59 mL/min/1.73 m2; n = 22); (4) CKD stage 4 (eGFR 15-30 mL/min/1.73 m2; n = 17); and (5) CKD stage 5-hemodialysis (HD) (n = 30). All the patients were free of clinically apparent cardiovascular disease. Serum FGF-23, elastase, lactoferrin, and angiogenin concentrations and the MPR were measured to study the association of the above parameters with the clinical (age, sex, presence of diabetes mellitus, and blood pressure), biochemical (calcium, phosphorus, uric acid, intact parathyroid hormone [PTH], low-density lipoprotein cholesterol, and high-sensitivity C-reactive protein), and ba-PWV values of the CKD patients.

RESULTS

(1) The mean ba-PWV values were 1,497.2 ± 206.4 cm/s in the controls, 1,649.0 ± 247.9 cm/s in the CKD stage 2 group (p < 0.05 vs. controls), 1,655.8 ± 260.3 cm/s in the CKD stage 3 group (p < 0.05 vs. controls), 1,823.0 ± 402.4 cm/s in the CKD stage 4 group (p < 0.05 vs. controls and CKD stages 2 and 3), and 1,905.2 ± 374.1 cm/s in the CKD stage 5-HD group (p < 0.05 vs. controls and CKD stage 2). (2) The mean log10(FGF-23) concentration values were 0.77 ± 0.27, 0.97 ± 0.48, 1.10 ± 0.35 (p < 0.05 vs. controls and CKD stage 2), 1.35 ± 0.48 (p < 0.05 vs. controls and CKD stages 2 and 3), and 2.12 ± 0.82 (p < 0.05 vs. controls and CKD stages 2-4); the mean angiogenin levels were 230.6 ± 70.5 pg/mL, 283.0 ± 53.5 pg/mL (p < 0.05 vs. controls), 347.3 ± 76.9 pg/mL (p < 0.05 vs. controls and CKD stage 2), 445.9 ± 90.6 pg/mL (p < 0.05 vs. controls and CKD stages 2 and 3), and 370.9 ± 142.4 pg/mL (p < 0.05 vs. controls and CKD stages 2 and 3). (3) In the stage 3-4 CKD/HD patients, the mean elastase-to-neutrophil and lactoferrin-to-neutrophil ratios were significantly lower than in the controls and the stage 2 CKD patients. (4) Our multivariate linear regression analyses showed that age, pulse pressure, mean arterial pressure, PTH, and FGF-23 were independently associated with ba-PWV values.

CONCLUSIONS

Circulating FGF-23 and angiogenin concentrations gradually increased as CKD advanced, whereas neutrophil activation markers were significantly lower in the stage 3-4 CKD/HD patients than in the controls and stage 2 CKD patients. FGF-23 was weakly associated with ba-PWV values in patients with CKD/HD and no previous cardiovascular disease.

Neutrophil Elastase Inhibitors and Chronic Kidney Disease

End-stage renal disease (ESRD), the last stage of chronic kidney disease (CKD), is characterized by chronic inflammation and oxidative stress. Neutrophils are the front line cells that mediate an inflammatory response against microorganisms as they can migrate, produce reactive oxygen species (ROS), secrete neutrophil serine proteases (NSPs), and release neutrophil extracellular traps (NETs). Serine proteases inhibitors regulate the activity of serine proteases and reduce neutrophil accumulation at inflammatory sites. This review intends to relate the role of neutrophil elastase in CKD and the effects of neutrophil elastase inhibitors in predicting or preventing inflammation.

Evidence for anti-inflammatory effects of exercise in CKD

CKD is associated with a complex state of immune dysfunction characterized by immune depression, predisposing patients to infections, and immune activation, resulting in inflammation that associates with higher risk of cardiovascular disease. Physical exercise may enhance immune function and exert anti-inflammatory effects, but such effects are unclear in CKD. We investigated the separate effects of acute and regular moderate-intensity aerobic exercise on neutrophil degranulation (elastase release), activation of T lymphocytes (CD69 expression) and monocytes (CD86 and HLA-DR expression), and plasma inflammatory markers (IL-6, IL-10, soluble TNF-receptors, and C-reactive protein) in patients with predialysis CKD. A single 30-minute (acute) bout of walking induced a normal pattern of leukocyte mobilization and had no effect on T-lymphocyte and monocyte activation but improved neutrophil responsiveness to a bacterial challenge in the postexercise period. Furthermore, acute exercise induced a systemic anti-inflammatory environment, evidenced by a marked increase in plasma IL-10 levels (peaked at 1 hour postexercise), that was most likely mediated by increased plasma IL-6 levels (peaked immediately postexercise). Six months of regular walking exercise (30 min/d for 5 times/wk) exerted anti-inflammatory effects (reduction in the ratio of plasma IL-6 to IL-10 levels) and a downregulation of T-lymphocyte and monocyte activation, but it had no effect on circulating immune cell numbers or neutrophil degranulation responses. Renal function, proteinuria, and BP were also unaffected. These findings provide compelling evidence that walking exercise is safe with regard to immune and inflammatory responses and has the potential to be an effective anti-inflammatory therapy in predialysis CKD.

Elastase, α1-proteinase inhibitor, and interleukin-8 in children and young adults with end-stage kidney disease undergoing continuous ambulatory peritoneal dialysis

Peritoneal dialysis is one of the main modality of treatment in end-stage kidney diseases (ESKD) in children. In our previous work in chronic kidney disease patients, in pre-dialyzed period and on hemodialysis, the neutrophils were highly activated. The aim of this study was to assess an inflammatory condition and neutrophil activation in ESKD patients undergoing continuous ambulatory peritoneal dialysis (CAPD). Thirteen CAPD patients without infection, both sexes, aged 2.5–24 years, and group of healthy subjects (C) were studied. For comparative purposes the conservatively treated (CT) group of ESKD patients was included. Neutrophil elastase in complex with α₁-proteinase inhibitor (NE-α₁PI; ELISA), α₁-proteinase inhibitor (α₁PI; radial immunodiffusion) and interleukin-8 (IL-8; ELISA) were measured in the blood samples from CAPD, CT, and C group and in the peritoneal dialysate fluid (PDF) samples of patients on CAPD. A significantly increased plasma NE-α₁PI levels (median 176.5 μg/L, range 85.2–373.2 μg/L; p < 0.00005), serum IL-8 (median 18.6 pg/mL, range 15.73–35.28 pg/mL; p < 0.05), and slightly decreased serum α₁PI (median 1,540 mg/L, range 1,270–1,955; p ≤ 0.05) compared to the control groups were found. There were no significant differences of analyzed parameters between CAPD and CT patients. The concentration ratio of NE-α₁PI, α₁PI and IL-8 in blood/PDF was 29.97, 8.24, and 4.48, respectively. There were significantly positive correlations between serum and PDF concentration of α₁PI and IL-8 (r = 0.613, p < 0.05; r = 0.59; p < 0.005, respectively). The results of our study demonstrate that neutrophils are highly activated in non-infected CAPD patients. The pivotal marker of this activation is NE-α₁PI. It may contribute to chronic inflammation and tissues injury.