Suppression of experimental crescentic glomerulonephritis by the interleukin-1 receptor antagonist

The role of interleukin-1 (IL-1) in the pathogenesis of experimental crescentic glomerulonephritis was investigated. Administration of the interleukin-1 receptor antagonist (IL-1ra) was used to block the action of IL-1 during disease development. Two groups of six rats were primed with rabbit IgG, followed five days later by injection of rabbit anti-GBM serum (day 0). Animals were treated with a constant infusion of recombinant human IL-1ra (plasma level approximately 100 to 200 ng/ml) or saline (untreated) from day -1 until being killed on day 14. Untreated animals exhibited severe proteinuria and development renal dysfunction shown by increased serum urea and serum creatinine and reduced creatinine clearance. In contrast, IL-1ra treated animals had significantly reduced proteinuria (IL-1ra vs. untreated, P < 0.05) and maintained normal renal function (IL-1ra vs. untreated, P < 0.05). Histologically, IL-1ra treatment markedly reduced glomerular hypercellularity, glomerular necrosis and crescent formation and almost completely abrogated tubular atrophy and fibrosis. IL-1ra treatment suppressed glomerular macrophage accumulation by 57% (P < 0.01), while macrophage accumulation in the interstitium was completely abrogated and immune activation of the interstitial T cell infiltrate was prevented. This study demonstrates that IL-1 plays a key role in the pathogenesis of anti-GBM glomerulonephritis, and blocking its effects may provide a novel therapeutic approach to the treatment of human progressive glomerulonephritis.

Delineation of pulmonary alveolar macrophage subpopulations by flow cytometry in normal subjects and in patients with lung cancer

We have previously described alterations in pulmonary alveolar macrophage (PAM) function in patients with lung cancer when compared with control subjects. This study examined PAM from five patients with lung cancer, seven normal volunteers and nine control patients, to assess whether any differences in surface phenotypic markers were present in lung cancer versus non-cancer subjects, and what changes might be induced with interferon-gamma (IFN-gamma) stimulation. After 3 days' culture with or without IFN-gamma no differences were seen in the percentages of cells staining positively in each group for HLA class I, class II and ICAM-1 (CD54) antigens. However, in 13 out of 14 control subjects, and only one out of the five cancer subjects, dual PAM populations were identified. The second PAM population (PAM-2) was larger and demonstrated a higher expression of class I and ICAM-1 antigens. Unlike the unfractionated PAM population, PAM-2 consistently responded to IFN-gamma stimulation with an increase in both class I (90 +/- 25%) and ICAM-1 (45 +/- 10%) antigens, while there was no change in class II antigen expression. In three subjects PAM-2 was found to induce a significantly greater mitogen response than the rest of the PAM population. If confirmed in a larger group of patients, the absence of PAM-2 in the majority of patients with lung cancer may underlie the functional PAM defects observed in these patients.

Involvement of activated periglomerular leukocytes in the rupture of Bowman's capsule and glomerular crescent progression in experimental glomerulonephritis

BACKGROUND

In an experimental model of crescentic glomerulonephritis, we have investigated whether periglomerular leukocytes are involved in (a), the disruption of Bowman's capsule (BC), and (b) the progression of cellular crescents.

EXPERIMENTAL DESIGN

Experimental crescentic glomerulonephritis was induced in inbred Sprague-Dawley rats using passive accelerated anti-glomerular basement membrane disease. Groups of 4 animals were sacrificed at 3, 7, 14, 21, and 28 days after administration of nephrotoxic serum.

RESULTS

Periglomerular infiltration of macrophages and T cells was evident at day 3, although focal accumulation of activated mononuclear cells (IL-2R+) was not apparent in this area until day 14. BC rupture in some glomeruli was first evident at day 14, and this was seen in all 12 animals from days 14 to 28. Similarly, glomerular crescent formation was first apparent at day 14, and from days 14 to 28, 11 of 12 animals displayed crescent formation (25 to 74% crescentic glomeruli). Examination of glomeruli (> or = 200/animal) within periodic acid-Shiff stained sections found that BC disruption invariably occurred at sites of prominent focal periglomerular mononuclear cell infiltration. Monoclonal antibody labeling revealed that T cells and IL-2R+ cells were restricted to focal infiltrates at sites of BC rupture, whereas macrophages were more widely distributed throughout the periglomerular area. A key finding was that while BC disruption occurred in both the presence and the absence of crescent formation, it was always associated with prominent periglomerular leukocytic infiltration. In this model, most cellular crescents contained leukocytes (88.8 +/- 2.1%). In the presence of an intact BC, macrophages constituted the predominant leukocyte cell type within these crescents. However, when BC was ruptured, although the number of macrophages remained unchanged, a marked accumulation of both T cells and IL-2R+ cells occurred within crescents. Progressive fibrous organization of cellular crescents was observed only in those glomeruli in which BC was disrupted.

CONCLUSIONS

The results suggest that: (a) activated periglomerular mononuclear cells may cause disruption of BC via a delayed-type hypersensitivity mechanism, (b) rupture of BC facilitates entry of activated periglomerular T cells and fibroblasts into Bowman's space leading to progressive fibrous organization of cellular crescents, and (c) disruption of BC may be a general mechanism of progressive glomerular damage mediated by periglomerular leukocytes irrespective of crescent formation.

RAPID INDUCTION OF INTERCELLULAR ADHESION MOLECULE-1 ON MONOCYTES AND MYELOMONOCYTIC CELL LINES AFTER INTERFERON GAMMA TREATMENT

The ICAM-1 molecule is an important adhesion factor that facilitates lymphocyte activation as well as the movement of lymphocytes into solid tissues. It is poorly expressed on circulating monocytes but higher levels have been described following the use of some activation factors. While previous work has emphasized the role of interferon gamma in inducing increased ICAM-1 expression on nonleukocytic cells, we have demonstrated time- and dose-dependent increases on human monocytes and two myelomonocytic cell lines (Rc2A & U937). The increased level of ICAM-1 expression on the Rc2A cells was associated with higher accessory cell activity as determined by an increased mitogen and allogeneic response but specific antibody inhibition studies indicated only a partial dependence (up to 50%) on this molecule. Class II MHC expression and IL-1 production were not elevated by IFNg treatment of these cells, indicating that other factors account for the remainder of the incremental activity observed following this treatment.

Epidermal growth factor and transforming growth factor alpha stimulate or inhibit proliferation of a human renal adenocarcinoma cell line depending on cell status: differentiation of the two pathways by G protein involvement

Transforming growth factor alpha production by renal tumors, acting through the epidermal growth factor receptor, has been implicated in malignant transformation by studies which compared gene expression in neoplastic and normal human tissue. We sought confirmation of this hypothesis by measuring the growth responses of a human renal tumor cell line to the addition of epidermal growth factor and transforming growth factor alpha. Surprisingly, it was found that both growth factors could induce either mitogenic or inhibitory signals depending on the growth status of the cultures. Confluent cultures were stimulated by both growth factors, and nonconfluent cultures were inhibited, as determined by thymidine incorporation, cell cycle analysis, and direct cell counting. These signals appear to use different transduction pathways, as growth factor induced inhibition was reversed by Bordetella pertussis toxin (which affects G protein signaling), whereas the stimulatory effects were not reversed. Two clones isolated from these cells responded in the same manner as the main cell isolate. These data show that the same cell may display opposite responses to equivalent concentrations of the same growth factor, depending on the transduction pathway used after triggering by receptor occupancy of either ligand (epidermal growth factor or transforming growth factor alpha).

Nucleotide sequence of rat vascular cell adhesion molecule-1 cDNA

Vascular cell adhesion molecule 1 (VCAM-1) is an inducible transmembrane protein which is expressed by vascular endothelium following cytokine activation. VCAM-1 mediated the adhesion of certain blood leukocytes and tumor cells via the interaction with its counter-receptor, the integrin VLA4. When initially cloned from interleukin-1 (IL-1) stimulated human umbilical vein endothelial cells, VCAM-1 was reported to contain six immunoglobulin-like domains. However, subsequent cDNA clones and structural analysis of the human gene evealed an alternatively spliced seventh immunoglobulin domain. This seven domain form appears to be the predominant transcript in IL-1 activated endothelium. In this report, the cloning and nucleotide sequence of rat VCAM-1 is described.

Two new anti-rat macrophage monoclonal antibodies

There are relatively few monoclonal antibodies (MAbs) to rat monocyte/macrophages available. We describe here 2 new such antibodies. The first, 109.2, recognizes most rat monocyte/macrophages and all polymorphs. The antigen recognized by this antibody is upregulated by 15 mins exposure to PMA (Phorbol myristate acetate) but down regulated by overnight exposure to LPS (lipopolysaccharide). It is probably an adhesion molecule and is likely to represent the rat equivalent of CD11b. The second antibody, 112.1, recognizes lysozyme in rat macrophages, particularly alveolar macrophages. In addition it also recognizes lysozyme in hen, rabbit and human macrophages. It also recognizes lysozyme in other tissues such as Paneth cells and proximal renal tubular cells.

Campylobacter peritonitis in continuous ambulatory peritoneal dialysis: report of eight cases and a review of the literature

Continuous ambulatory peritoneal dialysis (CAPD)-associated peritonitis remains the most common complication of this form of renal replacement therapy and the potential causative organisms are many and varied. Campylobacter bacteria are unusual causes of peritonitis in CAPD patients and we report our experience with eight cases and review those cases reported in the literature. In many episodes, there is a strong association with acute enterocolitis, which may precede the onset of cloudy dialysate by many days. The method of spread of these organisms from the gastrointestinal tract to the peritoneal cavity remains speculative. Bacteremic transfer would appear the most likely route, although it is probable that no single mode of spread explains all episodes. The treatment of choice of Campylobacter peritonitis is with intraperitoneal aminoglycoside in combination with oral erythromycin. An awareness of the potential for Campylobacter to cause CAPD-associated peritonitis, particularly when diarrhea is a prominent feature, has resulted in this organism becoming increasingly isolated in our unit.

Renal allograft scintigraphy with Tc-99M-DTPA--its role during cyclosporine therapy

There are no accurate noninvasive methods to distinguish renal allograft dysfunction due to rejection or cyclosporine nephrotoxicity. We have studied the value of Tc-99M-DTPA renal scanning in 90 episodes of renal allograft dysfunction occurring in 44 patients subjected to 57 renal biopsies in whom a clear diagnosis could be established. Renal scintigrams were assessed qualitatively and quantitatively by a blinded observer. Rejection was diagnosed when deterioration in perfusion occurred in the presence of maintained or declining radionuclide excretion. The diagnosis of cyclosporine nephrotoxicity was made by exclusion. The final diagnosis was based on the clinical response to therapy and/or the findings on renal biopsy. The scintigraphic diagnosis of rejection had a specificity of 87.9% and significantly contributed to the exclusion of cyclosporine nephrotoxicity (negative predictive value of 90.6%). Furthermore, a scintigraphic diagnosis compatible with cyclosporine nephrotoxicity, in the presence of a drug level above the therapeutic range, indicated a 90.4% probability of true nephrotoxicity. We conclude that, even in cyclosporine-treated renal transplant patients, Tc-99M-DTPA scintigraphy is of clinical value and can be incorporated into an effective diagnostic algorithm for allograft dysfunction.

Ultrastructural localization of human kidney antigens using monoclonal antibodies

A highly sensitive method of ultrastructural-immunoperoxidase staining was developed for use with monoclonal antibodies which have been raised in this laboratory to a variety of antigens of the human kidney. Because of the susceptibility of the antigens to fixation and processing, a four layer, pre-embedding method of staining was used. Results confirmed and clarified previously reported light microscopy results, indicating that an antigen recognized by the PHM5 antibody was found on the podocyte cell membrane within the glomerulus and was not present within the glomerular basement membrane. The antigen was also present on the extraglomerular endothelial cell membrane. The study also demonstrated the presence of an antigen specific to endothelial cells throughout the renal cortex, and gave further insight into the precise localization of glomerular basement membrane components including fibronectin. The method of staining is now being used together with detailed ultrastructural studies to identify the cells produced from isolated glomeruli in tissue culture.

Initiation and evolution of interstitial leukocytic infiltration in experimental glomerulonephritis

Most forms of glomerulonephritis have a significant interstitial leukocytic infiltrate which is associated with disease progression. However, there is little data concerning the timing, initial location, and development of this interstitial component. Therefore, we have addressed these issues in a study of passive accelerated anti-GBM glomerulonephritis in the rat. In this model, interstitial leukocytic infiltration was an early event in the disease process with a significant infiltrate apparent at 12 hours after administration of nephrotoxic serum (NTS). This initial infiltrate was restricted to a perivascular sheath surrounding the hilar arterioles. The sheath infiltrate then spread to include the whole hilar area by day 1, the entire periglomerular area by day 3, and became widespread throughout the cortical tubulointerstitium by day 7. The early sheath infiltrate was composed of macrophages and T cells. Both cell types continued to increase as the infiltrate expanded, and a significant accumulation of activated cells (IL-2R+) was evident from day 7 onwards. There was a highly significant correlation between interstitial macrophage infiltration and renal function impairment, proteinuria, and histologic damage. Interstitial T cell infiltration correlated with proteinuria and histologic damage, while the appearance of immune-activated mononuclear cells (IL-2R+) exhibited a highly significant correlation with all disease parameters. This study demonstrates the importance of the glomerular hilar arteriolar region as a focus for mononuclear leucocytic migration and accumulation which not only affects the structure and function of the glomerulus but subsequently the entire tubulointerstitium.

Differential control of mesangial cell proliferation by interferon-gamma

Rat mesangial cells were shown to be sensitive to recombinant interferon-gamma (IFN-gamma). IFN-gamma reduced thymidine uptake by these cells and inhibited cell proliferation. Incubation of the cells with 1000 U/ml IFN-gamma decreased thymidine uptake by up to 64% and cell numbers were decreased by 17%. The effects of IFN-gamma were dose and time dependent and were partially reversible by the anti-IFN-gamma monoclonal antibody DB-1. This lymphokine did not reduce incorporation of RNA and protein precursors however. Measurements of 3H-uridine and 3H-leucine incorporation indicated significant increases in RNA and protein synthesis (37% and 45%, respectively) on a per cell basis. The mitogenic effects of IL-1 and platelet-derived growth factor (PDGF) were also susceptible to IFN-gamma-mediated inhibition but the mitogenic response to epidermal growth factor (EGF) was much less sensitive. We conclude that while IFN-gamma may act to modulate the mitogenic signals provided by some factors such as IL-1 and PDGF, the response to EGF appears to be unaffected.

Deoxyspergualin inhibits cytotoxic T lymphocytes but not NK or LAK cells

Deoxyspergualin (DOSP) is a new immunosuppressive agent which probably inhibits various functions of monocytes, B cells and T cells. We examined the effects of deoxyspergualin on cellular cytotoxicity, including cytotoxic T lymphocyte (CTL) mediated killer, natural killer (NK) cell and lymphokine activated killer (LAK) cell killing. Deoxyspergualin inhibited cellular cytotoxicity generated by 7 days allo-antigenic challenge; it also inhibited cell killing if added on day 6 of this 7 day culture period. The drug did not significantly inhibit NK or LAK cell killing. The inhibitory effects of deoxyspergualin, however, were dependent on the serum used in the culture medium. Normal human serum (NHS) was associated with less inhibition than fetal calf serum (FCS). Finally, interleukin 2 (IL-2) was able to prevent the inhibitory effects of deoxyspergualin on antigen-specific cytotoxicity.

Activated (IL-2R+) intraglomerular mononuclear cells in crescentic glomerulonephritis

We recently reported evidence for the involvement of local cellular immune activation in the immunopathogenesis of human IgA nephropathy, particularly in cases of IgA disease featuring crescent formation. In the current study, using monoclonal antibodies, we investigated whether mononuclear cells bearing receptors for interleukin 2 (IL-2R+ MNC) were present within glomeruli or associated crescents in biopsies from patients with crescentic glomerulonephritis (greater than 60% crescents, N = 19), IgA disease with crescents (N = 9), or other types of proliferative glomerulonephritis with crescents (10 to 44%, N = 6), compared with normal control kidneys (N = 10). Biopsies were further classified into those showing active (cells, fibrin) (N = 15) or inactive (sclerosed) crescents (N = 19), to determine whether IL-2R+ MNC were particularly associated with active crescent formation. Few leucocytes were found within glomerular tufts of normal kidneys (2.4 +/- 0.7 cells/glomerular cross-section; mean +/- SEM). By contrast, in biopsies from patients with active crescentic glomerulonephritis, total intraglomerular tuft leucocytes were increased to 14.0 +/- 1.7 (P less than 0.01 vs. normal kidneys), largely due to increased numbers of intraglomerular monocytes (10.4 +/- 1.1, P less than 0.01) and T cells (3.7 +/- 0.6, P less than 0.01). Biopsies with active crescents also contained significantly increased numbers of intraglomerular tuft IL-2R+ MNC (4.0 +/- 0.7, 29% of total intraglomerular leucocytes), and there was a strong correlation between the numbers of intraglomerular IL-2R+ MNC and T cells (P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Leukocyte involvement in the pathogenesis of pulmonary injury in experimental Goodpasture's syndrome

To investigate the role of leukocytes in the pathogenesis of pulmonary injury after antibody deposition on the alveolar basement membrane, we have induced experimental Goodpasture's syndrome in the rat using passive accelerated anti-glomerular basement membrane (GBM) disease. Animals were immunized with normal rabbit IgG and given either rabbit anti-rat GBM serum or normal rabbit serum (control) 5 days later. In this model, leukocytic infiltration, severe hemorrhage, and granulomatous-like lesions developed in the lung, while a rapidly progressive glomerulonephritis was evident in the kidney. Within 30 minutes of injection of anti-GBM serum, strong linear deposition of antibody on both glomerular and alveolar basement membranes was evident. In the lung, a transient influx of polymorphonuclear cells during the first 12 hours was closely followed by macrophage infiltration, with T cell infiltration not evident until day 3. Pulmonary hemorrhage correlated with ED1+ macrophage infiltration (p less than 0.001), but not with OX-19+ T cell accumulation. Many activated mononuclear cells were found in the lung infiltrate from day 14 onward and were associated with areas of tissue damage. This study demonstrates the feasibility of using passive accelerated anti-GBM disease as a model of Goodpasture's syndrome, and suggests that inflammatory macrophages are the major cellular participants in progressive pulmonary injury after antibody deposition.

Anthropometry underestimates body protein depletion in haemodialysis patients

The body composition of 62 haemodialysis patients (41 males) and 63 controls (30 males) was assessed using anthropometry and in vivo neutron activation analysis of body nitrogen. There was no significant difference between patients and controls in body mass index (BMI) and percentage body fat. Arm muscle circumference was significantly reduced in males. Lean body mass was strongly correlated with body nitrogen in controls (r = 0.951) but less so in patients (r = 0.876). The mean standardised body nitrogen index (NI) was reduced in male patients by 13% (95% confidence interval -9 to -17%) and in females by 4% (95% confidence interval +4 to -12%). Of the 16 patients with a NI below the control range, arm muscle circumference was below the control range in only 3 and BMI less than 18 kg/m2 in 2. NI was correlated negatively with the duration of renal replacement therapy, duration of haemodialysis, the number of previous failed transplants and the total dose of steroids received but not with current energy or protein intakes. Steroid dose was the only significant independent variable. Anthropometry underestimates body protein depletion in haemodialysis patients and the degree of protein loss is related to the cumulative dose of corticosteroids previously received.

T-lymphocyte response to cytokines in B-chronic lymphocytic leukemia

The mechanisms underlying abnormal T-cell function in B-chronic lymphocytic leukemia (B-CLL) are unknown. We have studied B-CLL T-cell activation pathways in the rigorous absence of leukemic cells and with controlled numbers of accessory cells present. The responsiveness to added recombinant IL-1 and IL-2 was assessed. We have found that under optimal culture conditions B-CLL T cells had a normal PHA-induced proliferative response in terms of incorporated 3H-thymidine per T cell. Also the capacity of mitomycin-C treated B-CLL monocytes to support autologous T-cell mitogenesis was normal. However, a subtle difference between normal and B-CLL T cells emerged with respect to cytokine responsiveness. While the PHA response of purified normal T cells in the absence of monocytes was augmented by rIL-1, this could not be demonstrated for B-CLL T cells. A much greater degree of augmentation occurred with added rIL-2 in the case of both normal and B-CLL T cells. In the presence of 20% autologous monocytes rIL-1 and rIL-2 had no effect on mitogenesis. We conclude that B-CLL T cells have an abnormal profile of cytokine responsiveness which is consistent with observed abnormalities of subset distribution, and which may contribute to the clinical immunodeficiency in B-CLL.

The evolution of the interstitial infiltrate in rejecting rat renal allografts: with particular reference to the production of gamma-interferon

This study aimed to examine the evolution of the leucocytic infiltrate in rat renal allografts in the first 5 days of rejection. Immunohistology was used to assess the absolute numbers of infiltrating leucocytes in the rejecting allografts. The total infiltrate approximately doubled daily from day 1 through to day 4 (370 +/- 15 total leucocytes/mm2 of tissue on day 1 vs 5055 +/- 135 on day 4, p less than 0.05 for all days) and increased only a minor degree on day 5 (5485 +/- 535 leucocytes/mm2, p = n.s.). CD4 positive cells predominated until day 3, after which time CD8 positive cells greatly outnumbered CD4 positive cells (CD4:CD8 ratio day 3 1.83 vs day 5 0.53, p less than 0.05). Gamma-interferon was positive in T cells on day 2 (73% of all T cells) and was slightly positive on day 3 (5% of all T cells) but was negative on days 4 and 5. Activation markers such as IL-2Rs increased markedly from day 3. These findings favour a pivotal role for CD4 positive cells in the early phase of rejection and suggest that the early release of lymphokines by these cells is associated with the recruitment of CD8 positive cells to the allograft and the activation of those leucocytes present.

Defective cytostatic activity of pulmonary alveolar macrophages in primary lung cancer

Macrophages are thought to play an important immune effector cell role in antitumor host defense. It remains unclear whether PAM antitumor activity in patients with lung cancer is normal or impaired. We examined PAM cytostasis in patients with lung cancer and in control subjects and determined whether the in vitro PAM response could be enhanced by gamma-interferon. Nineteen patients with primary lung carcinoma and 15 control patients underwent BAL. Five patients with cancer underwent lavage of both lungs to assess whether any abnormality found related to tumor proximity or was part of a more generalized defect. Cytostatic activity was assessed by measuring inhibition of incorporation of tritiated thymidine into the target cell U937. There was a significant difference in baseline cytostatic activity between patients with cancer (mean +/- SE, 59 +/- 7 percent) and control patients (92 +/- 2 percent) (p less than 0.0002). The increase in cytostatic function after stimulation with gamma-interferon (1,250 units/ml) was higher in the group with cancer (28 +/- 5 percent increase from baseline) than in controls (5 +/- 1 percent) (p less than 0.0005). Cytostasis after stimulation was not significantly different between the groups. In the bilaterally lavaged group, baseline cytostatic activity was not different between cancerous and noncancerous lungs and was again significantly lower than in control subjects. These results indicate (a) that PAM baseline cytostatic activity in patients with cancer is lower than in controls, (b) that gamma-interferon can significantly augment cytostatic function in patients with cancer, to levels comparable with those achievable in control patients, and (c) that the PAM abnormality is part of a generalized immune defect in lung cancer and does not simply reflect a local response to the carcinoma. It may be inferred from these results that PAMs from patients with primary lung cancer are not fully stimulated in vivo and that a defect of T cell lymphokine production may underlie the macrophage dysfunction.