T cell regulation, anti-idiotypic immunity, and the nephritogenic immune response

Renal failure associated with alternative medical therapies

Because the kidney is the major excretory organ for drugs and toxins, it is especially susceptible to damage from such agents. While alternative medical therapies appear to be on an increase worldwide, there have been few case reports regarding their nephrotoxicity. However we have recently observed three patients who developed irreversible renal impairment, which we believe was due to such therapies.

Activation of autoreactive T-lymphocytes by cultured syngeneic glomerular mesangial cells

The capacity of intrinsic, glomerular mesangial cells (MC) to cause an autoreactive response of syngeneic lymphocytes in vitro are presented. Initial experiments demonstrated the MHC class II dependent capacity of MC to present exogenous antigen to sensitized lymph node lymphocytes (LN) and to activate naive, allogeneic LN in the absence of a nominal antigen. However, the most striking finding of the present investigation was that mouse MC (C57BL/6 or DBA/2) augmented a significant activation of naive, syngeneic lymphocytes. The extent of the proliferative lymphocyte response was comparable to that observed after stimulation with allogeneic MC. Moreover, during syngeneic coculture substantial amounts of interferon bioactivity were generated. Equipotent concentrations of rm IFN-gamma were sufficient to induce class II MHC expression of mouse MC. In control experiments the macrophage cell line, IC-21 (C57BL/6), or freshly prepared DBA/2 mouse peritoneal macrophages did not elicit a syngeneic LN response. Using MC, which had not been pretreated, the MC-specific LN stimulation occurred after prolonged periods of coculture. The stimulation index (S.I.) was 9.77 after 144 hours compared with LN controls (S.I. = 1). However, a 48 hour pretreatment of MC with either rm IFN-gamma alone or in combination with rh TNF-alpha and/or the continuous presence of rm IL-1 alpha during coculture periods from 72 to 144 hours substantially enhanced the proliferative LN response. Analysis of non-adherent LN by flow cytometry (FACS) after 96 or 120 hours coculture with MC revealed an increased ratio of Thy1.2+ to B220+ cells with a predominant rise of L3T4+ T-helper cells compared to Lyt2+ cytotoxic T-cells. Furthermore, immune fluorescence microscopy showed that a fraction of Thy1.2+ lymphoblasts adhered to MC. FACS analysis of these adherent LN after detachment demonstrated that in comparison to cocultures with untreated MC, cocultures of LN with IFN-gamma/TNF-alpha pre-treated MC resulted in a 24.4% increase of Thy1.2+ cells, with 89% of these being L3T4+ T-helper lymphocytes. In conclusion, autoreactivity of preferentially T-helper cells to cocultured glomerular MC was shown, which may represent a useful model of T-lymphocyte dependent glomerulonephritis.

Immune modulation of biologic systems in renal somatic cells

The various theories discussed here suggest that somatic renal cells are susceptible to biologic modulation by the immune system independent of an inflammatory effect. (1) The mode of repression of type IV collagen synthesis by novel, soluble antigen-binding proteins, the down-regulation of class II MHC expression with interruption of antigen presentation to epithelia after selective gene regulation by antibody, and the diverse interactions of antibody with renal glomerular cells producing functional disturbances in endocytosis and permselectivity; (2) modification of surface-antigen composition; (3) alteration of matrix deposition, remodeling and composition; (4) biophysical perturbation of cytoskeletal and cell membrane components; (5) and lastly, alterations in cell adhesion through cell-surface alterations, all lend testimony to the richness of the signal transduction pathways in somatic cells. Although the preceding examples represent only a small fraction of those which may take place within the glomerular and tubular microenvironments, these paradigms may nevertheless serve as new models upon which one can consider the multitude of potential communications between disparate biologic systems that connect in complex organisms.

Activated T-lymphocytes induce growth inhibition and prostaglandin E2 release from syngeneic glomerular mesangial cells

The concept of an active role of T lymphocytes in the initiation and development of autoimmune glomerulonephritis has gradually evolved from recent investigations. In the present study we started in a murine coculture system to directly examine cellular interactions of intrinsic glomerular mesangial cells (MC) and syngeneic T lymphocytes. Lymph node lymphocytes and, moreover, cloned T helper cells specifically affected syngeneic proliferating MC, causing growth inhibition and prostaglandin E2 (PGE2) release. The T cell specificity of mesangial cell responses was confirmed by demonstrating (i) that MC cocultured with other cell types showed no reaction and (ii) that additional activation of T lymphocytes by IL-2 or concanavalin A significantly enhanced the MC responses. Subsequently, we confirmed the presence of T cell factors in the supernatants responsible for the observed effects: interferon-gamma (IFN-gamma) and tumour necrosis factor (TNF). Experiments with combinations of recombinant mouse IFN-gamma and human lymphotoxin or TNF-alpha showed that these lymphokines could substitute for the direct T lymphocyte effects causing a synergistic growth inhibition and PGE2 release from mouse MC. The observed lymphokine activities were not due to mesangiolysis as shown by neutral red uptake of MC. Pointing to the essential role of T helper cell-specific products, IFN-gamma antibodies abolished both the IFN-gamma and the combined IFN-gamma/TNF-alpha effect. Thus, our investigations with syngeneic MC-lymphocyte cocultures demonstrated that cultured MC specifically responded to T lymphocytes and their products.

Thymocytes reacting with heterologous antibodies against GP 330 in autologous immune complex glomerulopathy (AICG) in the rat. The relation between susceptibility for AICG and anti-GP 330-binding thymocytes

Autologous immune complex glomerulopathy (AICG) is induced by immunizing rats with a crude brushborder fraction of rat kidney tubules (Fx1A) or with the purified GP 330 antigen. In these animals, anti-brushborder antibodies develop, leading to subepithelial immune complexes along the glomerular capillary wall. In rats with AICG, thymocytes sensitized against Fx1A as well as thymocytes recognizing anti-Fx1A are present. These latter cells might play a role in the specific tolerance against the pathogenetic antigen GP 330. To substantiate this notion, immunofluorescence studies were performed in which the number of anti-GP 330 binding cells was quantified in thymus cell suspensions of rats with AICG, in control rats and in naive rats with different genetic background. It is shown that increased numbers of anti-GP 330-binding thymocytes in rats with AICG are associated with a decline in the serum anti-brushborder titer. Furthermore, it appears that the number of anti-GP 330-binding thymocytes in naive rats of the non-responder Brown Norway strain is significantly higher as compared to the PVG/c and Lewis strains, which are susceptible for AICG. The correlation between the numbers of anti-GP 330-binding thymocytes and the susceptibility for AICG suggests a role for these cells in maintaining the tolerance against the Fx1A (GP 330) antigen.

Characterization of interstitial infiltrating cells in Berger's disease

The role of infiltrating blood-borne cells in the pathogenesis of renal damage in human glomerulonephritis is under active investigation. We have evaluated leukocyte infiltrates (number of cells/mm2) in the renal interstitium of 21 patients with Berger's disease and eight normal kidneys with monoclonal antibodies and a four-layer immunoperoxidase technique. In our population of patients, the number of infiltrating T-lymphocytes (OKT11+ cells) was significantly higher (median, 132) than in the normal kidneys (median, 60). This increase was mainly due to T-suppressor/cytotoxic lymphocytes (OKT8+ cells; median, 68), while T-helper/inducer lymphocytes (Leu 3A+ cells) and monocytes were in the normal range. T-lymphocyte infiltration was more marked in ten patients with impaired glomerular filtration rate (GFR) at the time of biopsy (median, 167) than in patients with normal GFR (median, 88). In addition, ten patients who showed deterioration of renal function during the subsequent follow-up, whatever their serum creatinine levels at the time of biopsy, had significantly more total T cells (median, 269), OKT8+ cells (median, 143), and Leu 3A+ cells (median, 105) than 11 patients with persistently stable GFR and normal controls. More data are necessary to establish whether this T-lymphocyte infiltration is the consequence of a cell-mediated mechanism acting in the interstitium, concomitant with the immune-complex-mediated mechanism acting in the glomerulus, or is a nonspecific consequence of the tubulointerstitial damage induced by the immunologically mediated glomerular disease.

Analysis of renal fibrosis in a rabbit model of crescentic nephritis

The pathogenesis of renal fibrosis in crescentic nephritis is incompletely understood. To improve our understanding of this process, crescentic nephritis was induced in New Zealand White rabbits by administration of guinea pig antiglomerular basement membrane IgG after sensitization with guinea pig IgG, and their kidneys were analyzed for the development of fibrosis. Collagen synthesis in renal cortical tissue was significantly elevated by day 3, peaked at days 7-15, and returned towards baseline by day 21. Collagen content of both glomeruli and cortex were increased starting on days 14-16, and remained constant in cortex thereafter. Light microscopic analysis was much less sensitive, revealing fibrosis only after day 21. Immunofluorescence revealed that type IV collagen was distributed primarily in the glomerulus, while types I and III were increased in the glomerulus and interstitium. Thus, in this model of crescentic nephritis, fibrosis, as assessed biochemically, developed early at time points when morphologic analysis failed to detect such a development. Hence early therapeutic intervention, before morphologic evidence of fibrosis is evident, may be more successful in arresting the progression of this disease before it reaches irreversible terminal stages.

Intraglomerular T cells and monocytes in nephritis: study with monoclonal antibodies

Intraglomerular T cells, monocytes, total leucocytes and other mononuclear subsets were sought in renal biopsies from patients with glomerulonephritis, using monoclonal antibodies and immunoperoxidase techniques. Twenty-four biopsies with no significant glomerular proliferation on optical microscopy, thirty-two with only endocapillary hypercellularity, and twenty-one with extra capillary crescentic glomerular disease were studied. Few intra-glomerular leucocytes were seen in the non-proliferative group. In contrast, when compared with this group, biopsies with glomerular hypercellularity and particularly those with crescents showed increased numbers of intra-glomerular total leucocytes and monocytes/macrophages, as well as an excess of T lymphocytes and T cytotoxic/suppressor cells; T helper/inducer lymphocytes were significantly increased only in the crescentic group. Only small numbers of B lymphocytes and NK cells were found in all groups. The numbers of total glomerular T-cells and monocytes per glomerular cross section were highly correlated in the crescentic group. Only idiopathic IgA nephropathy failed to show a significant increase in the numbers of intra-glomerular leucocytes, in comparison with the non-proliferative group, Henoch-Schönlein purpura biopsies in contrast had an excess of both monocytes and T cell subsets. The finding of T lymphocytes as well as monocytes in glomeruli of proliferative nephritis suggests that cellular immune mechanisms may play a role in their pathogenesis, especially when crescents are present.

Experimental strategies for the study of cellular immunity in renal disease

This overview has examined some of the current experimental options available for the study of cellular immunity in the immunopathogenesis of renal disease. T cell immunity, where it has been examined, seems to have a particularly pivotal role in orchestrating and regulating functional patterns of renal injury. The use of the research methods presented here for the study of cell-mediated interactional events in kidney disease, however, has lagged behind similar efforts in other organ systems. We hope, therefore, this report will serve to stimulate and strengthen further interest in the cell biology of the nephritogenic immune response.

Cell-mediated immunity in renal disease

It has been shown in experimental models that cell-mediated immunologic mechanisms can lead to glomerular as well as tubulointerstitial renal injury, with or without concomitant antibody-mediated effects. The glomerular lesions are characterized by varying combinations of monocyte and, to a lesser extent, lymphocyte influx, necrosis, and proliferation of intrinsic glomerular cells. The tubulointerstitial lesions have generally been characterized by interstitial infiltrates containing numerous T lymphocytes and, often, numerous macrophages, sometimes with invasion of tubules and tubular cell damage. Although similar renal abnormalities are seen in several human renal diseases, further evidence is obviously required to establish a pathogenetic role for cellular immunity. Analyses of infiltrating mononuclear cells by immunohistochemical methods, with monoclonal antibodies that identify subsets of T cells, have indirectly supported a role for delayed hypersensitivity reactions in tubulointerstitial nephritis resulting from drugs or associated with anti-TBM antibodies, as well as a role for both delayed hypersensitivity and cytolytic lymphocyte effects in renal allografts. However, only with the development of methods that permit the identification of subsets of lymphocytes with unique functions, as well as the identification of the antigen specificity of the cells, will it be possible to understand fully the renal lesions that are now suspected of being cell-mediated.

Inhibitory role of dietary protein restriction on the development and expression of immune-mediated antitubular basement membrane-induced tubulointerstitial nephritis in rats

The protective effect of dietary protein restriction on the development and expression of immune-mediated interstitial nephritis was evaluated in Brown Norway rats with anti-tubular basement membrane disease. In the first series of experiments, pair-fed rats received low protein (LP) (3% casein) or normal protein (NP) (27% casein), normocaloric diets. After 6 wk, each group was immunized with renal tubular antigen in adjuvant to produce anti-tubular basement membrane antibody (alpha TBM-Ab) and tubulointerstitial nephritis. The kidneys harvested from NP rats after four more weeks on the diet had histologically more severe interstitial disease than the LP rats (histologic severity; NP = 3.1 +/- 0.2 vs. LP = 1.1 +/- 0.3; P less than 0.001), and serum creatinine values were concordantly different (NP = 1.34 +/- 0.02 vs. LP = 0.82 +/- 0.03). Titers of alpha TBM-Ab were similar in both groups, while the T cell-mediated immune response, as measured by delayed-type hypersensitivity (DTH), was nonspecifically impaired in LP rats when compared with the NP group. Admixture cotransfers of LP plus NP cells failed to demonstrate active suppression as an explanation for the depressed DTH in LP rats. The therapeutic role of dietary protein restriction was also examined in rats with established alpha TBM disease. In these experiments, rats were first immunized and fed NP diets for 4 wk (histologic severity = 3.0 +/- 0.2; creatinine = 1.78 +/- 0.02), and then were divided into two groups and followed for six more weeks on either LP or NP diets. LP rats, under these conditions, developed less disease than those fed NP diet (histologic severity; NP = 3.2 +/- 0.3 vs. LP = 1.4 +/- 0.2; P less than 0.001), and serum creatinine values were concordantly different (NP = 1.92 +/- 0.05 vs. LP = 0.97 +/- 0.02). Again, the titers of alpha TBM-Ab in both LP and NP groups were similar. These data collectively suggest that LP diet has a protective effect both on the development and extent of tubulointerstitial nephritis that is perhaps, in part, related to the selective abrogation of effector T cell immunity.

Pathogenesis and treatment of immune-mediated renal disease

There is now convincing evidence to suggest that most forms of glomerulonephritis and tubulointerstitial nephropathy involve the immune system in the destructive process. Such involvement can be mediated by a humoral immune response, a cell-mediated immune response, or a coordinated response of both limbs of the immune system derived from complementary T- and B-cell interactions.

Tubular antigen-derivatized cells induce a disease-protective, antigen-specific, and idiotype-specific suppressor T cell network restricted by I-J and Igh-V in mice with experimental interstitial nephritis

The nephritogenic effector T cell response producing interstitial nephritis in mice can be largely inhibited by the adoptive transfer of suppressor T cells before or after the induction of disease. These suppressor T cells are harvested from donor mice primed with tubular antigen-derivatized syngeneic lymphocytes, and two subsets of suppressor cells can be characterized within this donor cell population. The first suppressor cell in this network is an L3T4+, I-J+, RE-Id+ cell (Ts-1). Ts-1 cells are antigen-binding suppressor cells that inhibit afferent phase immune responses and, in the presence of tubular antigen, specifically induce Lyt-2+, I-J+ cells (Ts-2) that are antiidiotypic (RE-Id-binding) suppressors. The Ts-2 cell is functionally restricted in its suppressive effect by I-J and Igh-V gene products, and acts on the effector limb of the cell-mediated anti-tubular basement membrane immune response. These studies provide an experimental basis for further efforts to use immunoregulatory modulation in the control of autoimmune renal disease.

Analysis of renal cell populations using monoclonal antibodies

Monoclonal antibodies have proved invaluable in identification and characterization of hemopoietic cell surface macromolecules. We have used a number of these monoclonal antibody probes for immunohistochemical analysis of interstitial cell populations in diseased human kidney tissues and in certain prototypic cutaneous cellular immune reactions. The studies demonstrate that the relative proportions of T-cell subpopulations present in graft rejection (OKT8+ exceeding OKT4+) differ from those observed in drug nephrotoxicity and end-stage kidney disease. In this regard rejection resembles graft versus host disease of skin but not delayed-type hypersensitivity. However, analysis of cell populations in interstitial infiltrates from various forms of chronic renal disease (glomerulonephritis, end-stage renal disease of varied etiologies) failed to demonstrate any unique or characteristic profile. These studies led to the recognition that certain monoclonal antibodies directed against B- and leukemic cell surface antigens also bind to normal renal cells and that nephron development in the human fetus is characterized by differential binding of these probes.