Glomerular vascular cell adhesion molecule-1 expression in renal vasculitis

Spatially Resolved Transcriptomes of Mammalian Kidneys Illustrate the Molecular Complexity and Interactions of Functional Nephron Segments

Available transcriptomes of the mammalian kidney provide limited information on the spatial interplay between different functional nephron structures due to the required dissociation of tissue with traditional transcriptome-based methodologies. A deeper understanding of the complexity of functional nephron structures requires a non-dissociative transcriptomics approach, such as spatial transcriptomics sequencing (ST-seq). We hypothesize that the application of ST-seq in normal mammalian kidneys will give transcriptomic insights within and across species of physiology at the functional structure level and cellular communication at the cell level. Here, we applied ST-seq in six mice and four human kidneys that were histologically absent of any overt pathology. We defined the location of specific nephron structures in the captured ST-seq datasets using three lines of evidence: pathologist's annotation, marker gene expression, and integration with public single-cell and/or single-nucleus RNA-sequencing datasets. We compared the mouse and human cortical kidney regions. In the human ST-seq datasets, we further investigated the cellular communication within glomeruli and regions of proximal tubules–peritubular capillaries by screening for co-expression of ligand–receptor gene pairs. Gene expression signatures of distinct nephron structures and microvascular regions were spatially resolved within the mouse and human ST-seq datasets. We identified 7,370 differentially expressed genes (p_adj < 0.05) distinguishing species, suggesting changes in energy production and metabolism in mouse cortical regions relative to human kidneys. Hundreds of potential ligand–receptor interactions were identified within glomeruli and regions of proximal tubules–peritubular capillaries, including known and novel interactions relevant to kidney physiology. Our application of ST-seq to normal human and murine kidneys confirms current knowledge and localization of transcripts within the kidney. Furthermore, the generated ST-seq datasets provide a valuable resource for the kidney community that can be used to inform future research into this complex organ.

Radix Paeoniae Rubra Ameliorates Lupus Nephritis in Lupus-Like Symptoms of Mrl Mice by Reducing Intercellular Cell Adhesion Molecule-1, Vascular Cell Adhesion Molecule-1, and Platelet Endothelial Cell Adhesion Molecule-1 Expression

OBJECTIVE

Vasculitis is the basic pathological change of systemic lupus erythematosus (SLE). Radix Paeoniae Rubra (RPR), a traditional Chinese herb with the function of reducing blood stasis, has anti-inflammatory and immunoregulatory properties. This study explored the effects of RPR on the kidneys of lupus-like symptoms of mrl (MRL/lpr) mice from the perspective of intercellular cell adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1) and platelet endothelial cell adhesion molecule-1 (PECAM-1).

METHODS

Eighteen MRL/lpr lupus model mice were randomly divided into three groups, the model control group, prednisone-treated group, and RPR-treated group, and 6 C57BL/ 6 mice were classified as a control group. After the mice had been treated for 12 weeks, the expression of ICAM-1, VCAM-1 and PECAM-1in the kidney was determined by immunohistochemistry and Reverse Transcription-Polymerase Chain Reaction (RT-PCR).

RESULTS

After 12 weeks, there were significant differences in body weight in the model, prednisone and RPR groups compared with the normal group (P <0.05). Pathological observation: Compared with the model group, the proliferation of inflammatory cells infiltrated glomeruli and interstitial cells in prednisone and RPR groups were reduced, and renal pathological damage was reduced. Compared with the model group, urine protein level of prednisone and RPR groups were reduced with no significance (P> 0.05). The mRNA expression levels of ICAM-1 and VCAM-1 were significantly reduced in the prednisone group and RPR group compared with the model group (P <0.05 or P <0.01). Meanwhile, the immunohistochemistry expressions of ICAM-1 and VCAM- 1 expressed in the kidney were significantly reduced in the prednisone group and RPR group (P <0.01 or P <0.05). However, The mRNA expression level and the immunohistochemistry expressions of PECAM-1 expressed in the kidney were reduced in each treatment group (prednisone group and RPR group), but these differences were not significant (P>0.05).

CONCLUSIONS

ICAM-1, VCAM-1 and PECAM-1 expression in the model group was found to be significantly increased. In addition, RPR could reduce the expression of ICAM-1, VCAM-1 and PECAM-1 in MRL/lpr lupus mice as effectively as prednisone, which may result in the dosage reduction of prednisone, thus decreasing the toxicity and improving the efficacy of prednisone - based treatment of SLE.

Renal expression of adhesion molecules in anca-associated disease

INTRODUCTION

Anti-neutrophil cytoplasmic autoantibodies (ANCA)-associated disease among other manifestations can underlie rapidly progressive glomerulonephritis (RPGN), with crescentic and necrotizing GN. Differences in pathogenic immune mechanisms in RPGN may provide differences in the renal expression of adhesion molecules mediating these lesions.

METHODS

Renal intercellular adhesion molecule 1 (ICAM-1; CD54) and vascular cell adhesion molecule 1 (VCAM-1; CD106) were assessed in 40 patients with type I RPGN (anti-glomerular basement membrane antibodies, n = 4), type II (immune complexes, n = 17), and type III (ANCA, n = 19). Enzyme-linked immunosorbent assay (ELISA) for detection of immunoglobulin G antibodies against the Goodpasture's antigen and indirect immunofluorescence and ELISA for myeloperoxidase (MPO) and proteinase 3 (PR3) were performed for ANCA testing. Ten normal renal tissues were used as controls. Relationships between ICAM-1 and VCAM-1, histopathologic features, and CD18, CD14, and CD3 cells were analyzed.

RESULTS

Abnormal ICAM-1 and VCAM-1 in tubule was seen in >80% of biopsies with RPGN. Abnormal VCAM-1 in glomerular tuft was seen in >60% of biopsies with RPGN. Glomerular ICAM-1 was associated with less glomerulosclerosis (chi (2) = 6.719, p = 0.01), less interstitial fibrosis (chi (2) = 4.322, p < 0.05), and less tubular atrophy (chi (2) = 8.547, p < 0.005). Glomerular VCAM-1 was associated with glomerular leukocyte infiltration (chi (2) = 4.698, p < 0.05). Glomerular tuft stains of ++/+++ for VCAM-1 was observed in 10% from MPO-ANCA-GN patients but in 60% from PR3-ANCA-GN (Fi = 8.538, p = 0.03).

CONCLUSIONS

The following conclusions can be made from this study. (1) The renal expression of ICAM-1 and VCAM-1 is upregulated in RPGN, and this is associated with the histological activity. (2) De novo expression of VCAM-1 on glomerular tuft suggests that endothelial cells play a role in RPGN. (3) De novo tubular expression of ICAM-1 and VCAM-1 suggests that epithelial cells may participate in adhesive interactions in RPGN. (4) De novo expression of VCAM-1 at the glomerular tuft in PR3-ANCA positive patients seems greater than in MPO-ANCA positive patients, which suggests that testing specific immune activation mechanisms may play a role in ANCA-associated GN.

ANCA-associated vasculitis: new options beyond steroids and cytotoxic drugs

Small vessel vasculitic syndromes--Wegener's granulomatosis, microscopic polyangiitis and renal limited vasculitis (which are associated with circulating antineutrophil cytoplasmic autoantibodies)--are an important cause of renal failure. Present immunosuppressive regimens that are based on cyclophosphamide have significantly increased survival rates. However, these treatments are toxic, increase the risk of infection and do not cure disease. Therefore, newer approaches are required. Understanding disease pathogenesis has allowed rational use for newer therapies such as rituximab, which depletes B cells. Unfortunately, blockade of promising targets such as TNF-alpha, which was thought to be a pivotal cytokine in inflammation, has not shown benefit in a randomised controlled trial. Better understanding of the pathogenesis of the disease is the key to the development of novel targeted therapies, which are urgently required to improve patient prognosis. Gene therapy with targeted delivery of specific proteins is an exciting future prospect.

Expression of ICAM-1, VCAM-1, E-selectin and TNF-alpha on the endothelium of femoral and iliac arteries in thromboangiitis obliterans

Immunohistochemical light and electron microscopical analysis of surgical biopsies obtained from femoral and iliac arteries of patients with thromboangiitis obliterans (TAO) were performed to investigate the presence of tumour necrosis factor-alpha (TNF-alpha) and expression of the endothelial cell adhesion molecules intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1) and E-selectin. Expression of ICAM-1, VCAM-1 and E-selectin was increased on endothelium and some inflammatory cells in the thickened intima in all TAO patients. Ultrastructural immunohistochemistry revealed contacts between mononuclear blood cells and ICAM-1-, and E-selectin-positive endothelial cells. These endothelial cells showed morphological signs of activation. The present data indicate that endothelial cells are activated in TAO and that vascular lesions are associated with TNF-alpha secretion by tissue-infiltrating inflammatory cells, ICAM-1-, VCAM-1- and E-selectin expression on endothelial cells and leukocyte adhesion via their ligands. The preferential expression of inducible adhesion molecules in microvessels and mononuclear inflammatory cells suggests that angiogenesis contributes to the persistence of the inflammatory process in TAO.

Expression of intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 in human crescentic glomerulonephritis

AIMS

In glomerulonephritis, intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) may play important roles in the formation of crescents. These studies are designed to evaluate the expression patterns of ICAM-1 and VCAM-1 in human crescentic glomerulonephritis and to determine the cellular origin of adhesion molecules in the crescentic lesions.

METHODS AND RESULTS

We examined the expression of ICAM-1 and VCAM-1 proteins in renal biopsies with cellular (n=7), fibrocellular (n=9) or fibrous (n=4) crescentic glomerulonephritis, and six controls by immunohistochemistry. mRNA expression of ICAM-1 and VCAM-1 was further evaluated by RNA in-situ hybridization. Cytokeratin or CD68 immunohistochemistry was performed on the same sections, where in-situ hybridization had been carried out. In cellular crescents, ICAM-1 and VCAM-1 proteins were over-expressed to a similar extent. Of the three types of crescents, the extent of ICAM-1 immunopositivity was the greatest in the cellular crescents and decreased towards the fibrous crescents (P < 0.05). Yet the extent of VCAM-1 immunoreactivity was not different between the types. Fibrous crescents still contained some epithelial cells and showed only VCAM-1 expression. In the glomeruli with cellular or fibrocellular crescents, the extent of ICAM-1 immunopositivity in the glomerular tufts was significantly larger than that of VCAM-1 (P < 0.05). In an in-situ hybridization study, the mRNA expression patterns of ICAM-1 and VCAM-1 paralleled their protein expressions. A double-labelling study showed that the signal for ICAM-1 and VCAM-1 mRNAs was mainly present in cytokeratin-positive and CD68-negative cells in the crescentic lesions.

CONCLUSIONS

These results suggest that glomerular parietal epithelial cells in cellular crescents up-regulate both ICAM-1 and VCAM-1, and that some epithelial cells retained in fibrous crescents persistently over-express VCAM-1, but not ICAM-1. They also suggest that ICAM-1 is involved in early leucocyte recruitment into glomeruli in crescentic glomerulonephritis.

Inhibition of LFA-1/ICAM-1 and VLA-4/VCAM-1 as a therapeutic approach to inflammation and autoimmune diseases

This review focuses on providing insights into the structural basis and clinical relevance of LFA-1 and VLA-4 inhibition by peptides and small molecules as adhesion-based therapeutic strategies for inflammation and autoimmune diseases. Interactions of cell adhesion molecules (CAM) play central roles in mediating immune and inflammatory responses. Leukocyte function-associated antigen (LFA-1, alpha(L)beta(2), and CD11a/CD18) and very late antigen (VLA-4, alpha(4)beta(1), and CD49d/CD29) are members of integrin-type CAM that are predominantly involved in leukocyte trafficking and extravasation. LFA-1 is exclusively expressed on leukocytes and interacts with its ligands ICAM-1, -2, and -3 to promote a variety of homotypic and heterotypic cell adhesion events required for normal and pathologic functions of the immune systems. VLA-4 is expressed mainly on lymphocyte, monocytes, and eosinophils, but is not found on neutrophils. VLA-4 interacts with its ligands VCAM-1 and fibronectin (FN) CS1 during chronic inflammatory diseases, such as rheumatoid arthritis, asthma, psoriasis, transplant-rejection, and allergy. Blockade of LFA-1 and VLA-4 interactions with their ligands is a potential target for immunosuppression. LFA-1 and VLA-4 antagonists (antibodies, peptides, and small molecules) are being developed for controlling inflammation and autoimmune diseases. The therapeutic intervention of mostly mAb-based has been extensively studied. However, due to the challenging relative efficacy/safety ratio of mAb-based therapy application, especially in terms of systemic administration and immunogenic potential, strategic alternatives in the forms of peptide, peptide mimetic inhibitors, and small molecule non-peptide antagonists are being sought. Linear and cyclic peptides derived from the sequences of LFA-1, ICAM-1, ICAM-2, VCAM-1, and FN C1 have been shown to have inhibitory effects in vitro and in vivo. Finally, understanding the mechanism of LFA-1 and VLA-4 binding to their ligands has become a fundamental basis in developing therapeutic agents for inflammation and autoimmune diseases.

New findings in pathogenesis of antineutrophil cytoplasm antibody-associated vasculitis

There has been a profusion of studies related to the pathogenesis of antineutrophil cytoplasm antibody-associated small vessel vasculitis. Further definition of epitopes on the major antigens, proteinase-3 and myeloperoxidase, has been sought, and intracellular signal transduction pathways after antineutrophil cytoplasm antibody-neutrophil interactions are beginning to be explored. Antineutrophil cytoplasm antibody stimulation of neutrophils has highlighted the functional importance of the accelerated death that follows the initial activation. The consequences of neutrophil and monocyte activation for endothelium and tissue damage continue to point toward an inflammatory process that has become dysregulated. Factors that initiate vasculitis are being identified slowly. The most secure identifiable environmental trigger is the antithyroid drug propylthiouracil. It is likely that environmental factors operate against a background genetic susceptibility, and polymorphisms in genes for proteins associated with inflammation are being tested for possible links with small vessel vasculitides.

Leukocyte-endothelial interactions in antineutrophil cytoplasmic antibody-associated systemic vasculitis

The etiology of ANCA-associated vasculitis is unknown. Currently, it is believed that disease may be triggered by infection with the release of proinflammatory cytokines in genetically susceptible individuals. Priming of PMNs and endothelial cells by these cytokines allows ANCAs to activate PMNs, with damage localized to the endothelium, resulting in early lesions. Damage and activation of endothelial cells produces proinflammatory chemokines and cytokines with influxes of monocytes and T cells that intensify endothelial damage. In the kidney, these changes eventually lead to crescent formation. Antigen-specific memory T cells persist after disease remission with the potential of reactivation and disease relapse. Although our understanding of the pathophysiologic mechanisms of ANCA-associated vasculitis is far greater now than when ANCAs were first identified in 1982, more experimental work in combination with clinical observations is required to further elucidate these mechanisms.

Expression of LFA-1 (CD11a/CD18) and ICAM-1 (CD54) in an animal model of renal interstitial fibrosis induced by unilateral ureteral obstruction

Unilateral ureteral obstruction (UUO) has been used as an experimental model to induce tubulointerstitial damage and interstitial fibrosis. UUO is characterized by cellular proliferation, accumulation of inflammatory cells, and subsequent replacement of renal parenchyma by fibrous tissue. The influx of inflammatory cells into the renal interstitium is mediated by adhesion molecules. In this study, the development of fibrosis in the UUO model of the rat was examined and its relation to the time course of LFA-1 and ICAM-1 expression was assessed by immunohistochemistry. An increase in interstitial connective tissue was detected on day 10 after UUO, with a maximum on day 35. After unilateral ureteral obstruction, LFA-1 was prominently expressed in interstitial infiltrates, and to a lesser degree in glomerular areas. An initial increase in LFA-1-positive cells was noted already on day 10, with a maximum on day 20 and a decline on day 25. During the time course of 35 days after UUO, we observed an increase in ICAM-1 expression in the vascular endothelium, in tubular epithelium and in interstitial areas. This study shows that LFA-1 expression and ICAM-1 expression are concordant and that this process is associated with increasing interstitial fibrosis. ICAM-1 interstitial tissue may facilitate the homing and persistence of an interstitial infiltrate by ICAM-1/LFA-1 interactions, thereby preceding the development of renal interstitial fibrosis.

TGF-beta(1) down-regulates inflammatory cytokine-induced VCAM-1 expression in cultured human glomerular endothelial cells

BACKGROUND

Endothelial cells are active participants in the processes controlling coagulation, inflammation and the immune response. Variations are recognized between endothelia isolated from different vascular beds as well as from different species. Though transforming growth factor-beta(1) (TGF-beta(1)) has been known to have an anti-inflammatory action, little is known about its effect on expression of cellular adhesion molecules during the inflammatory process in human glomerular endothelial cells. The aim of this study was to determine the effect of TGF-beta(1) on the inflammatory cytokine-induced expression of vascular cell adhesion molecule-1 (VCAM-1) in cultured human glomerular endothelial cells.

METHODS

The culture of human glomerular endothelial cells was established using the normal portion of nephrectomized renal tissues and identified by factor VIII staining and cellular uptake of fluorescent-labelled acetylated low-density lipoprotein (LDL). The endothelial cells were stimulated by interleukin-1beta (IL-1beta), tumour necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) with or without TGF-beta(1). Cellular expression of VCAM-1 was measured by enzyme-linked immunosorbent assay (ELISA) and flow cytometry, and VCAM-1 mRNA was measured by Northern blot analysis.

RESULTS

TGF-beta(1) (1, 10 and 25 ng/ml) blunted IL-1beta- (5 ng/ml) induced VCAM-1 expression significantly (OD=1.08+/-0.14, 1. 10+/-1.16 and 1.05+/-0.14 vs IL-1beta=1.97+/-0.29, n=6, P<0.05) in ELISA. The addition of TGF-beta(1) (1, 10 and 25 ng/ml) also suppressed TNF-alpha- (10 ng/ml) induced VCAM-1 expression (OD=1. 14+/-0.15, 1.17+/-0.17 and 1.18+/-0.16 vs TNF-alpha=1.96+/-0.26, n=6, P<0.05). The same results were obtained by flow cytometry. TGF-beta(1) (10 ng/ml) inhibited both IL-1beta- (5 ng/ml) and TNF-alpha-(10 ng/ml) induced expression of VCAM-1 (MFI: IL-1beta=90. 8+/- 17.6, IL-1beta+TGF-beta(1)=37.8+/-14.9, TNF-alpha=113.6+/- 12.4, TNF-alpha+TGF-beta(1)=64.3+/-13.8, mean+/-SD, n=3, P<0.05). By Northern blot analysis, TGF-beta(1) (10 ng/ml) significantly suppressed the stimulatory effect of IL-1beta and TNF-alpha.

CONCLUSIONS

These results show that TGF-beta(1) down-regulates the inflammatory cytokine-induced expression of VCAM-1 in human glomerular endothelial cells, which could be a novel mechanism for the anti-inflammatory action of TGF-beta(1) during the inflammatory processes in human glomerular diseases.

Pathogenesis of ANCA-associated systemic vasculitis

The aetiology of primary systemic vasculitides remains unknown. Recent advances have been made in the understanding of relevant mechanisms of inflammation, particularly the role of the endothelium and interactions with inflammatory mediators and immune effector cells. In Wegener's granulomatosis and microscopic polyangiitis the evidence suggests an autoimmune inflammatory process, characterized by an early lesion involving neutrophils and endothelial cells as both targets and active participants; priming of neutrophils and endothelial cells allows ANCA to activate neutrophils with damage localized to the endothelium. In the absence of immune complex deposition, the role of the ANCA is particularly intriguing. Endothelial cell damage and activation produces pro-inflammatory mediators with influx monocytes and T cells intensifying damage. Increased understanding of the pathogenesis of systemic vasculitis is likely to provide the basis for the use of more selective immunomodulatory therapies in the future.

Endothelial Expression of VCAM-1 in Experimental Crescentic Nephritis and Effect of Antibodies to Very Late Antigen-4 or VCAM-1 on Glomerular Injury

The migration of leukocytes into glomeruli in crescentic glomerulonephritis is fundamental to pathogenesis, and offers important therapeutic opportunities. We addressed the importance of VCAM-1, and its leukocyte ligand very late antigen-4 (VLA-4), in such leukocyte migration. In a rat model of nephrotoxic nephritis, glomerular expression of VCAM-1, studied by immunohistochemistry, was up-regulated by day 6 of nephritis. To quantify kidney endothelial VCAM-1 expression, a differential radiolabeled mAb technique was used, which demonstrated that protein expression was not up-regulated by day 2 of nephritis, but rose threefold between days 2 and 5, and remained elevated until at least day 28. An in vivo study was then performed, using blocking mAbs to either VCAM-1 or VLA-4, starting mAb treatment on the day prior to disease induction, and continuing until animals were sacrificed at day 7. mAbs to VLA-4 significantly attenuated renal injury (albuminuria, glomerular fibrinoid necrosis, and crescent formation), but mAbs to VCAM-1 had no significant effect. Surprisingly, the number of leukocytes within glomeruli was unaffected by anti-VLA-4 mAb therapy, despite the reduction in renal injury. Paradoxically, classical markers of macrophage activation were increased in the anti-VLA-4- and anti-VCAM-1-treated animals. This study demonstrates that kidney endothelial VCAM-1, in contrast to ICAM-1, is not up-regulated by day 2 of nephrotoxic nephritis, and plays little part in early leukocyte influx into glomeruli. However, VLA-4 is an important mediator of glomerular injury, operating after transendothelial leukocyte migration, and presumably binding to alternate ligands within the kidney.

T lymphocyte adhesion mechanisms within inflamed human kidney: studies with a Stamper-Woodruff assay

Renal inflammatory conditions are characterized by mononuclear cell recruitment to sites of inflammation. We have developed a modified Stamper-Woodruff assay system to analyze mechanisms of functional T cell adhesion to cryostat sections of renal biopsy material from patients with vasculitic glomerulonephritis (GN) and acute allograft rejection. Peripheral blood T cells adhered to intraglomerular, periglomerular, and tubulointerstitial regions of the cortex. Blocking monoclonal antibodies against tissue expressed ICAM-1, VCAM-1, and the CS-1 domain of fibronectin (CS-1Fn) differentially attenuated T cell adhesion. Glomerular adhesion in vasculitic GN and tubulointerstitial adhesion in acute rejection were particularly sensitive to both anti-ICAM-1 and anti-VCAM-1 antibodies, indicating a prominent role for ICAM-1 and VCAM-1 at glomerular sites in vasculitis and at tubulointerstitial sites in rejection. Furthermore, using KL/4 cells (LFA-1 expressing) and Jurkat cells (VLA-4 expressing), we demonstrated specific LFA-1/ICAM-1- and VLA-4/VCAM-1-mediated interactions within glomerular and tubulointerstitial compartments. Jurkat cells also adhered to VCAM-1-free sites, and binding was inhibitable by anti-CS-1Fn antibody, thereby demonstrating a role for VLA-4/fibronectin interactions especially at intraglomerular sites in acute rejection where VCAM-1 is notably absent. We therefore propose a prominent functional role for ICAM-1, VCAM-1, and CS-1 domain fibronectin in T cell recruitment to the inflamed kidney.

Interferon enhances tumor necrosis factor-induced vascular cell adhesion molecule 1 (CD106) expression in human endothelial cells by an interferon-related factor 1-dependent pathway

Tumor necrosis factor (TNF) and interleukin 1 are known to initiate endothelial vascular cell adhesion molecule (VCAM)-1 transcription primarily by activating nuclear factor (NF)-kappaB, which translocates to the nucleus. In addition to two NF-kappaB elements found within the minimal cytokine-inducible VCAM-1 promoter, an interferon-related factor (IRF) element (IRF-1) has been identified close to the transcription initiation site, suggesting that cytokines that induce IRF-1 might affect VCAM-1 expression levels. We therefore investigated the effects of interferons (IFNs), which strongly induce IRF-1, on VCAM-1 transcription and expression. We show that IFN-alpha and -gamma enhance TNF-induced VCAM-1 mRNA transcription and protein expression in human endothelial cells. IFN enhancement of TNF-induced expression is also seen using chloramphenicol acetyl transferase reporter genes linked to the minimal cytokine inducible VCAM-1 promoter. Nuclear IRF-1 is the molecular basis of IFN enhancement, because (a) IFN plus TNF-treated cells displayed increased nuclear IRF-1 levels and increased IRF-1 binding to the VCAM-1 promoter, compared with cells treated with TNF alone; (b) kinetics of nuclear IRF-1 levels correlated with VCAM-1 mRNA levels; (c) transfection with an IRF-1 construct substituted for IFN treatment; and (d) transfection with an expression construct encoding IRF-2, a competitive inhibitor of IRF-1, reduced TNF-induced VCAM-1 expression. Our experiments show that IFN amplifies TNF-induced VCAM-1 expression at the transcriptional level by an IRF-1-dependent pathway.

Intercellular adhesion molecule-1 (ICAM-1), leucocyte function-associated antigen-1 (LFA-1) and leucocyte infiltration in proliferative human glomerulonephritis

The expression of the intercellular adhesion molecule-1 (ICAM-1), infiltrating cells positive for its ligand leucocyte adhesion molecule-1(LFA-1), and the markers of total leucocytes (CD45RB), T cells (CD45RO), and monocytes/macrophages (CD68) were examined by an indirect immunoperoxidase method on renal biopsy specimens from 20 patients with mesangial proliferative glomerulonephritis-IgA negative (MesProGN) and 20 with IgA nephropathy (IgAN). Histologically, normal portions of the kidney tissue (n = 15) obtained from patients with renal trauma or renal tumours were used as controls. The expression of ICAM-1 was evident and extended in mesangium, on endothelial cells of peritubular capillaries, interstitial cells, several infiltrating immune cells and on tubular epithelial cells, particularly on atrophic tubuli in renal biopsies of MesProGN and IgAN. In both types of glomerulopathies a significant increase in the number of glomerular and interstitial LFA-1-positive cells correlated positively with the expression of ICAM-1. The number of glomerular and interstitial LFA-1-positive cells correlated positively with the number of monocytes/macrophages in glomeruli and interstitium. The strong correlation between expression of ICAM-1 and LFA-1 and between LFA-1-positive cells and immune cells makes these adhesion molecules useful markers of activity and suggest that they are involved in recruitment of leucocytes in the studied types of proliferative glomerulopathies.

Active Wegener’s Granulomatosis Is Associated with HLA-DR+ CD4+ T Cells Exhibiting an Unbalanced Th1-Type T Cell Cytokine Pattern: Reversal with IL-10

Wegener’s granulomatosis (WG) is a granulomatous vasculitis that affects the upper respiratory tract, lung, and kidney. Since T cells make up a significant proportion of cells infiltrating granulomatous lesions in WG, we investigated the proliferative response and cytokine profile of T cells from these patients. PBMCs were isolated from 12 patients with active WG, 7 patients with inactive disease, and 12 healthy normal donors. PBMCs from clinically active WG patients exhibited increased proliferation following stimulation with either PMA/ionomycin or anti-CD2 and anti-CD28, when compared with normal donors. In addition, these PBMCs exhibited increased secretion of IFN-γ, but not of IL-4, IL-5, or IL-10. Furthermore, TNF-α production from PBMCs and CD4+ T cells isolated from patients with WG was elevated, when compared with healthy donors. In further studies, we investigated the ability of WG patients’ monocytes to produce IL-12 and showed that both inactive and active patients produced increased amounts of IL-12. Finally, the in vitro IFN-γ production by WG PBMC is inhibited in a dose-dependent manner by exogenous IL-10. These data suggest that T cells from WG patients overproduce IFN-γ and TNF-α, probably due to dysregulated IL-12 secretion, and that IL-10 may therefore have therapeutic implications for this disease.

Dynamic pattern of endothelial cell adhesion molecule expression in muscle and perineural vessels from patients with classic polyarteritis nodosa

OBJECTIVE

To investigate endothelial cell adhesion molecule expression in vessels from patients with classic polyarteritis nodosa (PAN).

METHODS

Frozen sections of 21 muscle and 16 nerve samples from 30 patients with biopsy-proven PAN and 12 histologically normal muscle and 2 histologically normal nerve samples from 12 controls were studied immunohistochemically, using specific monoclonal antibodies (MAb) that recognize adhesion molecules. Adhesion molecules identified were intercellular adhesion molecule 1 (ICAM-1), ICAM-2, ICAM-3, vascular cell adhesion molecule 1 (VCAM-1), platelet endothelial cell adhesion molecule 1 (PECAM-1), E-selectin, P-selectin, L-selectin, lymphocyte function-associated antigen 1 (LFA-1), and very late activation antigen 4 (VLA-4). Neutrophils were identified with a MAb recognizing neutrophil elastase. Endothelial cells were identified with the lectin ulex europaeus.

RESULTS

In early lesions, expression of PECAM-1, ICAM-1, ICAM-2, and P-selectin was similar to that in control samples, and VCAM-1 and E-selectin were induced in vascular endothelium. In advanced lesions, immunostaining for adhesion molecules diminished or disappeared in luminal endothelium, whereas these molecules were clearly expressed in microvessels within and surrounding inflamed vessels. Staining in endothelia from vessels in a healing stage tended to be negative. A high proportion of infiltrating leukocytes expressed LFA-1 and VLA-4, and only a minority expressed L-selectin. No relationship between the expression pattern of adhesion molecules and clinical features, disease duration, or previous corticosteroid treatment was observed.

CONCLUSION

Endothelial adhesion molecule expression in PAN is a dynamic process that varies according to the histopathologic stage of the vascular lesions. The preferential expression of constitutive and inducible adhesion molecules in microvessels suggests that angiogenesis contributes to the persistence of inflammatory infiltration in PAN.

Upregulation and co-localization of connexin43 and cellular adhesion molecules in inflammatory renal disease

Connexin43 (Cx43) is a major component of gap junctions. These are widely distributed in the human kidney and are thought to be involved in the inflammatory response and in the regulation of cell growth. Cellular adhesion molecules (CAMs) are also thought to be important in these processes, where they possibly facilitate gap junction formation. The aims of the current study were to define for the first time the expression of Cx43 in inflammatory glomerulonephritis and to compare the localization of this connexin with that of the intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and E-selectin. Human renal biopsies and control sections of normal human kidney were stained using the alkaline phosphatase/anti-alkaline phosphatase immunohistochemical technique, demonstrating that Cx43 was strongly expressed on inflammatory cells, on damaged tubular cells, and on interstitial cells. This pattern of expression was paralleled closely by that of ICAM-1 and, to a lesser extent, by that of VCAM-1. Cx43 is therefore primarily implicated in tubulointerstitial inflammation.

Cell adhesion molecule expression within human glomerular and kidney organ culture

A glomerular and kidney organ culture method was developed to study cytokine inducibility of adhesion molecules and MHC antigen expression. Glomerular cells showed constitutive expression of intercellular cell adhesion molecule-1 (ICAM-1) and MHC class I and II antigens, but not vascular cell adhesion molecule-1 (VCAM-1), E-selectin, or P-selectin. Expression of E-selectin on glomerular endothelial cells (ECs) was induced by interleukin-1 (IL-1), tumour necrosis factor (TNF), interferon-gamma (IFN-gamma) and granulocyte/ macrophage-colony stimulating factor (GM-CSF); this induction was inhibited by transforming growth factor beta (TGF beta) and by IL-4. P-selectin expression was never seen within glomeruli. VCAM-1 was constitutively expressed by Bowman's capsule and proximal tubules and was weakly induced on glomerular ECs by TNF and IL-4 in combination. Glomerular endothelial ICAM-1 expression was increased by IL-1, TNF, IFN-gamma, and GM-CSF, while TGF beta inhibited induction by TNF and IL-1. Expression of MHC class I and II antigens by glomerular ECs was constitutive; further upregulation of MHC class II by IFN-gamma was observed. These studies suggest that leukocyte-endothelial cell interactions that occur within the kidney follow broadly similar principles as are proposed to occur elsewhere in the body but, in addition, there are subtle differences that reflect local conditions.