Glucocorticosteroid inhibition of nonphagocytic discharge of lysosomal enzymes from human neutrophils

Understanding Long-term Remission Off Therapy in Antineutrophil Cytoplasmic Antibody-Associated Vasculitis

Introduction

In antineutrophil cytoplasmic antibody-associated (ANCA) vasculitis, relapse risk and long-term immunosuppressive therapy are problematic. Stopping immunotherapy has not been well described.

Methods

The Glomerular Disease Collaborative Network ANCA vasculitis inception cohort was evaluated. Patients who stopped all immunotherapy and those continuously on immunotherapy (≥2 years) were included. Time to first period off therapy was modeled with end-stage kidney disease and death as competing risks to understand influences of stopping therapy. Cause-specific hazard ratios (HRs) with 95% confidence intervals (CI) and P values are reported. Models controlled for age, sex, ANCA specificity, organ involvement, diagnosis era, and treatments (yes/no). Repeated events analysis was used to assess the time-dependent variable of time off treatment on recurrent relapse with HRs, 95% CIs, and P values are reported (same control variables without treatments).

Results

In 427 patients, 277 (65%) stopped therapy (median 20 months from initial induction); 14% for ≥2 different periods of time and 23% for periods ≥5 years. In multivariable models of time to discontinuation of treatment, women (HR 1.33; 95% CI 1.04-1.70; P = 0.024) and those treated with pulse methylprednisolone (HR 1.39; 95% CI 1.05-1.84; P = 0.020) were more likely to stop. The time-dependent variable of time off treatment was associated with fewer recurrent relapses (HR 0.51; 95% CI 0.41-0.63; P < 0.001).

Conclusions

Stopping immunotherapy was common. Women and those treated with methylprednisolone stop treatment more often, but underlying mechanisms are unknown. Stopping treatment was associated with fewer relapses, suggesting that even without guidelines there may be benefits without an untoward detriment of relapse.

In vitro effect of the reproductive hormones on the oxidative burst activity of polymorphonuclear leucocytes from cows: a flow cytometric study

In this study, the effect of reproductive hormones and substances with hormonal activity on the oxidative burst activity of blood polymorphonuclear leucocytes (PMN) high yielding dairy cows was evaluated. Different concentrations of: progesterone, oestradiol 17β, FSH, LH, GnRH, cortisol and PGF2α were incubated in vitro for 4 h with PMN of seven high milk yielding cows, during the period of anoestrous postpartum. Controls were run in parallel in which each hormone was replaced by its solvent. After incubation with hormones the competence of PMN to generate H(2) O(2) was monitored by flow cytometry. A down-regulation on the oxidative burst activity of PMA-stimulated PMN was observed when cells were incubated with progesterone. Significant (p ≤ 0.001) differences between control and progesterone incubated cells were observed from 6.56 μg/ml. The same predisposition was observed when PMNs were incubated with cortisol. Besides for all concentrations employed, a decrease in the burst activity was observed, only beyond 0.19 mg/ml, statistical differences between the results obtained by the control and the cortisol incubated cells were obtained. Concerning oestradiol 17β, an increase on H(2) O(2) -production was observed when PMN were incubated with 15 pg/ml and 45 pg/ml of this steroid (p ≤ 0.05), followed by a depression of the cell's activity when unphysiological concentrations were employed. Significant (p ≤ 0.05) differences between the obtained with the control and oestradiol 17β incubated cells were observed only in the highest concentration of oestradiol. No statistical differences were observed in the metabolic burst activity of PMN incubated with FSH, GnRH and LH when compared with the results obtained by the control.

Protease production by cultured microglia: substrate gel analysis and immobilized matrix degradation

The production of collagen-degrading proteases by cultured neonatal rat microglia was examined using an immobilized fibronectin-gelatin matrix coupled to a fluorescent marker and by substrate gel analysis. When microglia were plated onto the surface of the matrix and incubated under resting (nonstimulated) conditions, a small but visible amount of immobilized matrix was degraded. Treatment with lipopolysaccharide (LPS) or interleukin-1 (IL-1) significantly increased the number of microglia demonstrating substrate degradation. Substrate-SDS polyacrylamide gel electrophoresis of samples of supernatants from untreated cultured microglia indicated the presence of a 72 and a 92 kD metalloproteinase with characteristics corresponding to collagenases. Supernatants from untreated astrocyte cultures were shown to have primarily a 72 kD metalloproteinase. Proteinase activity increased on stimulation of the microglia with LPS and IL-1 in a dose-dependent fashion. These results indicate that cultured microglia release active proteases capable of degrading the extracellular matrix in a localized region. The production of proteases by activated microglia may have important physiological and pathophysiological consequences within the restricted extracellular matrix of the CNS.

Defective phagocytosis, decreased tumour necrosis factor-alpha production, and lymphocyte hyporesponsiveness predispose patients with systemic lupus erythematosus to infections

Twenty-three patients with systemic lupus erythematosus (SLE) were studied in order to understand the mechanism of increased susceptibility to infection in SLE patients. We found that phagocytosis by polymorphonuclear leucocytes (PMN) was significantly defective in untreated (24.2 +/- 3.1%) and immunosuppressant-treated SLE patients (30.0 +/- 3.6%) compared with normals (47.9 +/- 0.6%), while the generation of superoxide anion radicals was normal. The defective phagocytosis in SLE could be increased by human recombinant tumour necrosis factor alpha (TNF-alpha). However, the percentages of phagocytosis in SLE before and after TNF-alpha stimulation were 56.6% and 60.7% of the normal values. This indicates that certain populations of PMN in SLE are not only defective as regards phagocytosis but also unresponsive to TNF-alpha stimulation. In an ELISA, TNF-alpha production by phorbol myristate acetate (PMA)-stimulated mononuclear cells from SLE patients was significantly decreased (181.4 +/- 22.7 pg/ml vs. 533.0 +/- 81.9 pg/ml, p = 0.002). In addition, the percentage of phytohaemagglutinin (PHA)-stimulated mononuclear cells in S phase in the cell cycle was deficient in patients with SLE (17.2 +/- 1.8% vs. 29.7 +/- 2.9%, p less than 0.001). These results lead us to propose that defective PMN in spontaneous and TNF-alpha-induced phagocytosis, decreased production of TNF-alpha, and lymphocyte hyporesponsiveness predispose patients with SLE to infections.

Mammary leukocyte response to drug therapy

The possibility exists that antibiotics and anti-inflammatory agents will be used indiscriminately in attempts to reduce leukocyte or somatic cell counts in mammary secretions to conform with Interstate Milk Shippers quality standards for raw milk to be implemented July 1, 1986. Recent in vivo studies evaluating the effect of intramammary drug injection on milk leukocytes confirmed previous in vitro investigations demonstrating that certain drugs have a significant effect on leukocyte antimicrobial activity. Antibiotics commonly included in commercial infusion products used in this country such as penicillin G, semisynthetic penicillins, the mycins, cephalosporins, and sulfonamides did not affect leukocyte function. However, some drugs were detrimental, notably chloramphenicol, tiamulin, tetracycline, gentamicin, rifampicin, amikacin, and nitrofurantoin. In vitro investigations on the use of anti-inflammatory agents demonstrated that methylprednisolone had a stabilizing effect on leukocytes by maintaining viability and reducing degranulation, whereas flumethasone was detrimental to cell viability. The nonsteroid agent, ibuprofen, decreased viability and increased degranulation but also increased phagocytosis and bacterial killing. Intramammary infusion of anti-inflammatory agents was generally ineffective in lowering somatic cell counts of endotoxin-infused quarters, but certain drugs may be advantageous in limiting milk production losses during udder inflammation.

Inhibition of neutrophil superoxide production by fanetizole

The effects on neutrophil function of the new immunomodulatory agent fanetizole mesylate were studied. Fanetizole did not affect random or stimulated migration, phagocytosis, or degranulation by normal human neutrophils. Production of superoxide in response to the chemotactic factor formyl-methionyl-leucyl-phenylalanine (f-Met-Leu-Phe) was markedly inhibited (41.3 +/- 3.9%) by 250 microM fanetizole. This inhibition was not due to scavenging of superoxide by fanetizole, as there was no impairment of superoxide detection in a cell-free xanthine-xanthine oxidase system. Inhibition was dose dependent (no effect seen with 1 or 10 microM fanetizole) and stimulus specific (no impairment of superoxide production in response to phorbol myristate acetate). Washing the cells after fanetizole treatment partially restored their superoxide response to f-Met-Leu-Phe. Suppression of neutrophil production of toxic oxygen metabolites may partially explain the antiarthritic effect of fanetizole, and study of such selective inhibitors may be useful in probing the contribution of neutrophils to inflammatory tissue damage.

Effect of high-dose methylprednisolone therapy on phagocyte function in systemic lupus erythematosus

Circulating phagocytes play a major role in the defence of the host against microbial infection. In an attempt to identify the reason for the unusual susceptibility to infection of patients with systemic lupus erythematosus (SLE) various parameters of phagocytic cell function were assessed kinetically in whole blood, and the accumulation of cells in areas of inflammation was studied in vivo with the skin window technique. The effect on these parameters of conventional therapy with glucocorticoids and pulse therapy with large doses of methylprednisolone were examined. Patients on conventional doses of steroids had no abnormality of phagocyte function that might have predisposed to infection, apart from a reduced accumulation of monocytes in areas of inflammation and decreased lactoferrin secretion. Pulse therapy with methylprednisolone considerably delayed the secretion of lactoferrin and the adherence of neutrophils in most of the patients, as well as impairing bacterial killing and digestion.

The effects of in vivo hydrocortisone on lymphocyte-mediated cytotoxicity

To examine the effects of in vivo hydrocortisone sodium succinate (HC) on natural killer (NK) cell and antibody-dependent cellular cytotoxicity (ADCC), 11 normal adults received a single intravenous bolus of 400 mg hydrocortisone. Lymphocytes were tested for NK activity and ADCC using 51chromium (51Cr)-release and single cell cytotoxicity assays against Molt-4 and sensitized RL O leads to target cells, respectively. Four hours after injection, both NK and ADCC activity were transiently increased in the 51Cr-release system (P less than 0.05). At 4 hours, there was a twofold increase in the relative frequency of potentially cytotoxic target binding cells (P less than 0.001) but the absolute number of these cells did not change (P less than 0.1). However, the percentage lysis of bound targets at 4 hours was not altered (P greater than 0.1). These data suggest that: 1) lymphocytes participating in NK and ADCC reactions are refractory to the kinetic and functional effects of HC; 2) the increased lytic activity observed at 4 hours is due to a selective depletion of noncytotoxic cells from the circulation; and 3) NK and ADCC activity did not differ in their responses to HC.

Lysosomal enzymes in ocular tissues and diseases

Lysosomal enzymes are distributed widely in various ocular tissues. Among these tissues, the uvea and retina show the higher enzyme activities of acid phosphates, beta-blucuronidase, alpha-fucosidase, alpha-mannosidase, arylsulfatase, cathepsin D, cathepsin B and others. The particular role of lysosomal enzymes in the pathogenic processes of ocular diseases such as storage disease, uveitis, retinal degeneration, retinal detachment, corneal dystrophy and glaucoma is strongly suggested. The enzymes also have additional importance in ocular physiopathology.

Effect of bioflavonoids on lysosomal acid hydrolases and lysosomal stability in adjuvant-induced arthritis

In rats with adjuvant-induced arthritis, the effect of (+)-catechin (CA) and 0-(beta-hydroxyethyl) rutosides (HR) on the activity of certain lysosomal acid hydrolases, viz., beta-glucuronidase, beta-N-acetyl glucosaminidase and cathepsin D in serum, liver, kidney and spleen and the stability of liver lysosomes was studied. The activity of these enzymes in arthritic tissues and serum increased significantly. The total activity of beta-glucuronidase in the lysosome-rich fraction from arthritic liver was appreciably decreased, while its release was significantly increased. These results demonstrate the fragility of lysosomes in arthritic tissues. Administration of CA or HR to the arthritic animals was found to have a prophylactic action by stabilizing liver lysosomes and reducing the free lysosomal enzyme activities in serum, liver, kidney and spleen. CA was more effective than HR.

Metabolic and secretory properties of peripheral and synovial granulocytes in rheumatoid arthritis

The metabolic and secretory properties of peripheral and synovial granulocytes of patients with rheumatoid arthritis were investigated with serum- or immunoglobulin-treated zymosan as activators of cell metabolism. During isolation of the synovial cells precautions were taken to prevent in vitro phagocytosis of immune materials present in the synovial fluids. Oxygen uptake, extracellular release of lysosomal enzymes under resting and activated conditions, yield of the isolated granulocytes, and the granule enzyme content of peripheral and synovial cells did not differ significantly from those of peripheral granulocytes from healthy volunteers. In agreement with the biochemical results, intracellular inclusions could be detected in only a few synovial cells with a direct immunofluorescence technique. The possibility that formation of "ragocytes" may be an in vitro phenomenon is discussed.

Release of cartilage proteoglycan degrading enzyme activity by thioglycollate stimulated mouse peritoneal macrophages in culture

Media from cultured mouse peritoneal macrophages were tested for cartilage proteoglycan degrading activity using S35-labelled rabbit ear cartilage. Media samples collected at 2-day intervals contained increasing amounts of activity between days two and six. This activity was activated by trypsin and antagonized by chelating agents. The macrophage products induced release of the proteoglycan component of cartilage as determined by biochemical and histological methods without affecting the collagen component. Media from cells incubated with hydrocortisone were devoid of proteoglycan degrading activity.

Glucocorticoids and lysosomes

Steroids in general and glucocorticoids in particular affect lysosomes in various ways. The explanation of these effects remains in dispute, however. Theories include the view that steroids interact directly with lysosomal membranes, that steroids provoke induced changes in lysosomes, and that classical steroid receptors originate in lysosomes. Experiments pertaining to these views are discussed, particularly with respect to steroid specificity and tissue specificity of effects and to dose-response considerations.

Mechanisms of the immunosuppressive and anti-inflammatory effects of glucocorticosteroids

Corticosteroids have multifaceted effects on various phases of inflammatory and immunological activity. These include effects on vascular and tissue responses, effects on the movement or traffic of inflammatory or immunologically reactive cells, direct effects on functional capabilities of cells, and direct or indirect effects on various soluble factors mediating inflammation or immunologic activity. It is clear that there is a differential sensitivity of various populations and subpopulations of cells to the corticosteriod modulation of cellular kinetic patterns, cellular interactions, and functional capabilities. In general, corticosteroids have a much greater and more obvious effect on the traffic and kinetics than on the functional properties of cells involved in inflammation and immunologic activity. Hypotheses concerning the precise mechanisms of many of these effects have been proposed, but still await verification and possibly amplification.