The cellular actions of interleukin-11 on bone resorption in vitro

The pleiotropic cytokine interleukin-11 (IL-11) stimulates osteoclast formation in vitro, but it is not known whether it influences other steps in the bone-resorptive cascade. Using a variety of in vitro model systems for studying bone resorption we have investigated the effects of IL-11 on 1) osteoclast formation, fusion, migration, and activity; and 2) osteoblast-mediated osteoid degradation. The involvement of matrix metalloproteinases (MMPs) and products of arachidonic acid metabolism in IL-11-mediated resorption were also assessed. We first examined the bone-resorptive effects of IL-11 by assessing 45Ca release from neonatal mouse calvarial bones. IL-11 dose-dependently stimulated bone resorption with an EC50 of 10(-10) M. The kinetics of IL-11-mediated 45Ca release demonstrated that it was without effect for the first 48 h of culture, but by 96 h, it stimulated 45Ca release to the same level as that produced by 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3] (a hormone that stimulates osteoclast formation and activity). IL-11 also produced a dose-dependent increase in osteoblast-mediated type I collagen degradation with a maximum of 58.0 +/- 6.2% at 5 x 10(-9) M; this effect of IL-11 was less than that produced by 1,25-(OH)2D3 (76.5 +/- 7.1%) and was prevented by an inhibitor of MMPs, but not those blocking arachidonic acid metabolism. We then tested the effects of IL-11 on isolated mouse osteoclasts cultured on ivory slices in the presence and absence of primary mouse osteoblasts. IL-11 had no effect on isolated osteoclast activity even in coculture with primary osteoblasts. We then examined the effects of IL-11 on the formation of osteoclast-like multinucleate cells in mouse bone marrow cultures and the resorptive activity of such cultures using ivory as a substrate. IL-11 dose-dependently increased 1) the number of tartrate-resistant acid phosphatase-positive osteoclast-like multinucleate cells and 2) the surface area of lacunar resorption, although the effects were less than that of 1,25-(OH)2D3. The effect of IL-11 on bone marrow lacunar resorption was prevented by a combination of inhibitors of 5-lipoxygenase and cyclooxygenase. In 17-day-old metatarsal bones, IL-11 prevented the migration of (pre)osteoclasts to future resorption sites, whereas their fusion was unaffected. These results provide strong evidence that IL-11 stimulates bone resorption by enhancing osteoclast formation and osteoblast-mediated osteoid degradation rather than stimulating osteoclast migration and activity. Our data also suggest that the stimulatory effects of IL-11 involve both MMPs and products of arachidonic acid metabolism.

A case of granulomatous dermatitis: cutaneous leishmaniasis

A case is reported of a 75-year-old woman, with a past clinical history of granuloma annulare, who developed groups of papulonodular skin lesions on the trunk and face six weeks after returning from a trip to the Mediterranean. The initial biopsy showed a granulomatous dermatitis which was considered consistent with the sarcoidal variant of granuloma annulare, and the lesions were treated with topical and intralesional steroid. A second biopsy performed four months later revealed large numbers of histiocytes containing diagnostic Leishman bodies. It is not clear whether the first biopsy was from a chronic lesion and the second from an acute lesion, or whether local steroid treatment enhanced proliferation of organisms and made a definitive diagnosis possible on the second biopsy.

Ultrastructural localisation of CD44 in the rat lung in experimental Goodpasture's syndrome

Although CD44 is known to be involved in a wide array of cell to cell and cell to matrix interactions, its role in immune-mediated disease is not well understood. Therefore, using immunogold electron microscopy we have determined the precise localisation of CD44 in the rat lung in experimental Goodpasture's (GP) syndrome, a model of immune-mediated pulmonary disease. In normal rat lung CD44 was present on the surface of alveolar macrophages but was not detectable on endothelium. In GP syndrome there was strong CD44 expression on all infiltrating inflammatory leucocytes, both adherent to endothelium and within the alveolar spaces and interstitium. However the most striking finding was the progressively strong antibody staining for CD44 on pulmonary endothelium of alveolar capillaries and larger vessels over the 21 days of GP syndrome. In situ hybridisation confirmed that the endothelial CD44 staining was due to local protein synthesis. All epithelial cell surfaces, including bronchial epithelium and type I and II alveolar epithelial cells, were negative in normal rat lung and GP syndrome. De novo CD44 expression by endothelial cells during the progression of GP syndrome may contribute to leucocyte recruitment and cell-mediated lung injury.

Multiple extracellular signals promote osteoblast survival and apoptosis

Programed cell death (PCD) or apoptosis is a naturally occurring cell suicide pathway induced in a variety of cell types. In many cases, PCD apparently arises as a result of competition for limiting amounts of survival signals. In this study, we have investigated the potential role of growth factors (GF), cytokines, and osteotropic hormones on osteoblast survival in vitro. Our results indicate that in the absence of any of these factors, osteoblasts rapidly undergo PCD, as determined by cell morphology, mitochondrial function, and nuclei fragmentation. Osteoblast survival was promoted by insulin-like growth factor I (IGF-I), IGF-II, insulin, and basic fibroblast growth factor (bFGF). Platelet-derived growth factor had no effect on osteoblast survival, but this GF potentiated the survival-promoting effects of IGF-I, IGF-II, and insulin. A similar effect occurred when bFGF was added in combination with either of the IGFs or insulin. The effects of the IGFs were blocked by alphaIR-3, an antibody to the type I IGF receptor, whereas the effects of insulin were only partially blocked. This antibody blocked the potentiating effects of platelet-derived growth factor on IGF-I-mediated osteoblast survival, but only partially blocked those of bFGF. Although a 100% survival of osteoblasts was seen in the presence of 2% FCS, the highest level attained by any of the above GF combinations was approximately 75%. The monocyte-derived factor, tumor necrosis factor-alpha (TNF alpha) was the only agent that enhanced PCD in this study. These results suggest that osteoblast survival is promoted by those GFs sequestrated in bone matrix and that the type I, but not the type II, IGF receptor is involved in the response. Our data also indicate that other unidentified GFs or components of the extracellular matrix may be involved in promoting osteoblast survival and that TNF alpha may abrogate their effects in vivo. We propose that these GFs may be released from bone matrix during phases of bone resorption and promote osteoblast survival, thereby playing an important role in bone remodeling, and that PCD induced by TNF alpha may contribute to the bone loss in inflammatory bone disease.

CD44 and hyaluronan expression in the development of experimental crescentic glomerulonephritis

CD44 is a widely expressed cell surface glycoprotein which is involved in both cell-matrix and cell-cell interactions which regulate a variety of processes, including leucocyte migration and activation. Therefore, we examined the expression of CD44, and its major ligand hyaluronan, during the induction and progression of experimental glomerulonephritis. Antibody staining of normal rat kidney showed constitutive CD44 expression by resident glomerular macrophages, parietal epithelial cells, medullary and occasional cortical tubules. There was a marked increase in CD44 expression over days 1, 7 and 21 of rat crescentic anti-glomerular basement membrane (GBM) glomerulonephritis. Infiltrating monocytes and lymphocytes were CD44+, with ultrastructural studies showing high levels of CD44 expressed on the surface of lymphocytes adherent to activated endothelium. Marked hyaluronan deposition was seen in areas of fibrosis on days 7 and 21, such as glomerular crescents and the periglomerular area. Hyaluronan deposition was accompanied by the presence of many CD44+ cells. Double immunohistochemistry showed that both CD44+ED1+ macrophages and CD44+ myofibroblasts (identified by expression of alpha-smooth muscle actin) were present in areas of fibrosis. There was also a dramatic increase in cortical tubular CD44 expression, which was most evident in areas of tubular damage. Although tubular epithelial cells expressed CD44 upon both the basolateral and luminal surface, CD44 expression was most prominent within tightjunctions, suggesting a role for CD44-CD44 interactions in cell-cell adhesion within the tubule. Analysis of CD44 isoforms by reverse transcriptase-polymerase chain reaction (RT-PCR) showed that the standard form of CD44 predominated in both normal and diseased kidney. However, a series of alternatively spliced CD44 isoforms was also detected, whose expression was markedly increased during disease. At least seven isoforms containing the v6 domain were identified, with the smallest form representing activated T cells. In conclusion, CD44 is constitutively expressed in normal kidney and is dramatically up-regulated in rat anti-GBM disease, suggesting possible roles for the CD44-hyaluronan interaction in leucocyte recruitment, renal fibrosis and tubular cell-matrix and cell-cell interactions during the induction and progression of crescentic glomerulonephritis.

Inhibition of bone resorption in vitro by selective inhibitors of gelatinase and collagenase

Two low-molecular-mass inhibitors of matrix metalloproteinases (MMPs), CT1166, a concentration-dependent selective inhibitor of gelatinases A and B, and Ro 31-7467, a concentration-dependent selective inhibitor of collagenase, were examined for their effects on bone resorption and type-I collagenolysis. The test systems consisted of measuring (1) the release of [3H]proline from prelabelled mouse calvarial explants; (2) the release of 14C from prelabelled type-I collagen films by mouse calvarial osteoblasts; and (3) lacunar resorption by isolated rat osteoclasts cultured on ivory slices. In 24 h cultures, CT1166 and Ro 31-7467 inhibited both interleukin-1 alpha- (IL-1 alpha; 10(-10) M) and 1,25-dihydroxyvitamin D3 (10(-8) M)-stimulated bone resorption in cultured neonatal mouse calvariae at concentration selective for the inhibition of gelatinase (10(-9) M for CT1166) and collagenase (10(-8) M for Ro 31-7467) respectively. For each compound the inhibition was dose-dependent, reversible, and complete at a 10(-7) M concentration. However, CT1166 (10(-9) M) and Ro 31-7467 (10(-8) M) in combination were required to completely abolish IL-1 alpha-stimulated bone resorption in mouse calvariae throughout a 96 h culture period. Neither of the inhibitors affected protein synthesis, DNA synthesis nor the IL-1 alpha-stimulated secretion of the lysosomal enzyme, beta-glucuronidase. Both CT1166 and Ro 31-7467 partially inhibited IL-1 alpha-stimulated lacunar resorption by isolated osteoclasts, but were without effect on unstimulated lacunar resorption. Rodent osteoclasts produced collagenase and gelatinases-A and -B activity. In contrast the substrate used to assess osteoclast lacunar resorption contained no detectable collagenase or gelatinase activity. Both compounds dose-dependently inhibited 1,25-dihydroxyvitamin D3 (10(-8) M)-stimulated degradation of type-I collagen by mouse calvarial osteoblasts; however, complete inhibition of collagenolysis was only achieved at concentrations at which CT1166 and Ro 31-7467 act as general MMP inhibitors. This study demonstrates that collagenase and gelatinases A and/or B participate in bone resorption. While these MMPs may be primarily involved in osteoid removal, we conclude that they may also be released by osteoclasts, where they participate in bone collagen degradation within the resorption lacunae.

ICAM-1 and VCAM-1 in human renal allograft rejection

Light microscopy studies have demonstrated heightened ICAM-1 and VCAM-1 expression in renal allograft rejection in experimental animals and in humans, and administration of ICAM-1 blocking antibodies has been shown to prolong graft survival in nonhuman primates. We used a precise ultrastructural immunogold localization technique to identify the exact sites of expression of ICAM-1 and VCAM-1 in both normal human kidney and in renal allograft rejection. In the normal kidney ICAM-1 is moderately strongly expressed in glomeruli, on the endothelium and parietal epithelium and in the interstitium, on the endothelium of peritubular capillaries, arterioles and small arteries, on fibroblast-like interstitial cells and on the brush border of proximal tubules. In contrast, in normal kidney, VCAM-1 expression is restricted to the parietal epithelium and the basolateral surfaces of a few proximal tubule cells. In allograft rejection, although ICAM-1 expression appears to be increased, its pattern of distribution is similar to that seen in the normal kidney. However, VCAM-I in allograft rejection is widely expressed on the endothelium of peritubular capillaries and arterioles in association with adhesion of mononuclear leukocytes within these vessels. The tubular expression of VCAM-1, although still focal in nature, is increased on the basolateral surfaces in association with lymphocytic infiltration of tubules.(ABSTRACT TRUNCATED AT 250 WORDS)

Osteoblasts mediate insulin-like growth factor-I and -II stimulation of osteoclast formation and function

Insulin-like growth factor-I (IGF-I) and IGF-II have powerful, well defined effects on osteoblastic cells, stimulating their proliferation and inducing collagen synthesis, but the role of IGF-I and -II in modulating osteoclast differentiation and activity remains unclear. We first examined the bone-resorptive effects of IGF-I and IGF-II by assessing 45Ca2+ release from neonatal mouse calvarial bones. Both IGFs dose dependently stimulated bone resorption, with an EC50 of 8 x 10(-9) M for IGF-I and 2 x 10(-8) M for IGF-II. We then tested the effects of the IGFs on bone resorption by rat isolated osteoclasts cultured on ivory slices. Neither IGF-I nor IGF-II stimulated isolated osteoclast activity. However, in the presence of either primary mouse osteoblasts or human osteosarcoma MG 63 cells, both IGFs enhanced osteoclast resorptive activity, with an EC50 of 5 x 10(-10) M for IGF-I and 10(-9) M for IGF-II. Stimulation was not mediated by BALB/c/3T3 cells, a nonosteoblastic cell line. The effects of the IGFs were blocked by alpha IR-3, an antibody to the type I IGF receptor, but not by beta-galactosidase, a lysosomal enzyme that competes with IGF-II for the type II IGF receptor. We then examined the effects of the IGFs on the formation of osteoclast-like multinucleate cells (MNCs) in mouse bone marrow cultures. IGF-I and -II dose dependently increased the number of tartrate-resistant acid phosphatase (TRAP)-positive MNCs, although their effects were less than that of 1,25-dihydroxyvitamin D3 (a hormone that induces osteoclast differentiation). No TRAP-positive MNCs appeared in the absence of these hormones. Like authentic osteoclasts, the TRAP-positive MNCs formed in response to IGF-I and -II bound [125I]salmon calcitonin. When mouse bone marrow cells were cultured on ivory slices in the presence of either IGF-I or IGF-II for 10 days, numerous resorption lacunae were formed. beta-Galactosidase had no effect on IGF-mediated osteoclast formation. These results are strong evidence that both IGF-I and IGF-II stimulate bone resorption in vitro by enhancing osteoclast formation and function. Our data also suggest that the IGFs act through the intermediary of osteoblastic cells to stimulate osteoclast activity and that the type I, but not the type II, IGF receptor is involved in their responses. We propose that the local production of IGF-I and IGF-II may modulate both osteoblast-osteoclast interactions and osteoclast formation and play an important role in bone remodeling.

The purification and partial characterization of bone resorptive polypeptides from bovine bone matrix

Matrix proteins were extracted from bovine cortical bone with EDTA/Tris-HCl under non-dissociative conditions at neutral pH. Four distinct bone resorptive proteins with molecular masses of 14, 25, 29 and 40 kDa were purified and partially characterized using an in vitro neonatal mouse calvarial assay and a growth factor assay using BALB/c/3T3 cells. The 14 kDa protein was purified by anion exchange chromatography (Mono Q) and gel filtration (Superdex 75HR) using FPLC (fast protein liquid chromatography); this factor stimulated the proliferation of MCF-7 human breast cancer cells, a bioassay which is specific for the insulin-like growth factors (IGFs). The 25, 29 and 40 kDa proteins were purified by sequential chromatography as follows: anion-exchange (Mono Q), heparin-Sepharose, hydroxyapatite, concanavalin A-Sepharose, phenyl-Superose, reversed phase high performance liquid chromatography (HPLC) and sodium dodecylsulfate polyacrylamide gelelectrophoresis (SDS-PAGE). The 25 kDa protein was identified as TGF-beta by its inhibitory effect on the proliferation of mink lung cells. The 40 kDa protein enhanced the formation of multinucleate tartrate-resistant acid phosphatase positive cells in a murine bone marrow differentiation assay, but was without effect in an isolated osteoclast assay and had no growth factor activity; this protein is likely to be a colony stimulating factor. The 29 kDa protein was also without growth factor activity; it was, however, able to stimulate bone resorption in the isolated osteoclast assay, suggesting a direct action in osteoclast function. The 29 and 40 kDa proteins may be osteoblast gene products that have been sequestrated by the bone matrix in a similar fashion to TGF-beta and the IGFs. This is the first report of proteins isolated from bone matrix which directly stimulate osteoclast differentiation and activity.

The effects of selective inhibitors of matrix metalloproteinases (MMPs) on bone resorption and the identification of MMPs and TIMP-1 in isolated osteoclasts

We have compared the effects of a general matrix metalloproteinase (MMP) inhibitor (CT435) with those of a concentration-dependent specific gelatinase inhibitor (CT543; Ki < 20 nM) on bone resorption in vitro. The test systems consisted of measuring: (i) the release of 45Ca2+ from prelabelled mouse calvarial explants; (ii) the release of 45Ca2+ from prelabelled osteoid-free calvarial explants co-cultured with purified chicken osteoclasts; and (iii) lacunar resorption by isolated rat osteoclasts cultured on ivory slices. Both CT435 and CT543 dose-dependently inhibited the release of 45Ca2+ from neonatal calvarial bones stimulated by either parathyroid hormone or 1,25-dihydroxyvitamin D3. Moreover, CT543 produced a 40% inhibition at a concentration (10(−8) M) selective for the inhibition of human gelatinases A and B. CT435 (10(−5) M) and CT543 (10(−5) M) partially inhibited the release of 45Ca2+ from osteoid-free calvarial explants by chicken osteoclasts with a maximum of approximately 25% for unstimulated cultures, and approximately 36% for cultures stimulated by interleukin-1 alpha (IL-1 alpha; 10(−10) M). Neither inhibitor prevented lacunar resorption on ivory by unstimulated rat osteoclasts, but the compounds produced a partial reduction in both the number and total surface area of lacunae in IL-1 alpha-stimulated cultures, with maximal action at 10(−5) M. Neither of the inhibitors affected protein or DNA synthesis, nor the IL-1 alpha-stimulated secretion of the lysosomal enzyme beta-glucuronidase. Immunocytochemistry demonstrated that isolated rabbit osteoclasts constitutively expressed gelatinase A and synthesized gelatinase B, collagenase and stromelysin, as well as the tissue inhibitor of matrix metalloproteinases-1 (TIMP-1) following IL-1 alpha stimulation. These experiments have shown that in addition to collagenase, gelatinases A and B are likely to play a significant role in bone resorption. They further suggest that MMPs produced by osteoclasts are released into the sub-osteoclastic resorption zone where they participate in bone collagen degradation.

Inhibition of bone resorption by selective inactivators of cysteine proteinases

Inactivators of cysteine proteinases (CPs) were tested as inhibitors of bone resorption in vitro and in vivo. The following four CP inactivators were tested: Ep475, a compound with low membrane permeability which inhibits cathepsins B, L, S, H, and calpain; Ep453, the membrane-permeant prodrug of Ep475; CA074, a compound with low membrane permeability which selectively inactivates cathepsin B; and CA074Me, the membrane-permeant prodrug of CA074. The test systems consisted of 1) monitoring the release of radioisotope from prelabelled mouse calvarial explants and 2) assessing the extent of bone resorption in an isolated osteoclast assay using confocal laser microscopy. Ep453, Ep475, and CA074Me inhibited both stimulated and basal bone resorption in vitro while CA074 was without effect; the inhibition was reversible and dose dependent. None of the inhibitors affected protein synthesis, DNA synthesis, the PTH-enhanced secretion of beta-glucuronidase, and N-acetyl-beta-glucosaminidase, or the spontaneous release of lactate dehydrogenase. Ep453, Ep475, and CA074Me dose-dependently inhibited the resorptive activity of isolated rat osteoclasts cultured on bone slices with a maximal effect at 50 microM. The number of resorption pits and their mean volume was reduced, whilst the mean surface area remained unaffected. Again, CA074 was without effect. Ep453, Ep475, and CA074Me, but not CA074, when administered subcutaneously at a dose of 60 micrograms/g body weight inhibited bone resorption in vivo as measured by an in vivo/in vitro assay, by about 20%. This study demonstrates that cathepsins B, L, and/or S are involved in bone resorption in vitro and in vivo. Whilst cathepsin L and/or S act extracellularly, and possibly intracellularly, cathepsin B mediates its effects intracellularly perhaps through the activation of other proteinases involved in subosteoclastic collagen degradation.

Pulmonary expression of ICAM-1 and LFA-1 in experimental Goodpasture's syndrome

The functional importance of ICAM-1 and its ligands, the beta 2-integrins, in leukocytic accumulation in pulmonary injury has been recently demonstrated in experimental models of lung disease. However, the exact location of these adhesion molecules remains unknown. In the current study we have used immunogold ultrastructural techniques to define the precise location of ICAM-1 in the lung and its interaction with beta 2-integrin expressing leukocytes in the early stages of experimental Goodpasture's (GP) syndrome in the rat. In normal animals there is strong constitutive ICAM-1 expression on the luminal surface of the alveolar epithelium that is confined to type I cells and completely absent from type II cells. Constitutive expression of ICAM-1 on the pulmonary capillary endothelium is comparatively weak. In GP syndrome there is an increase in ICAM-1 expression, which is still confined to the alveolar type I epithelial cells and capillary endothelium. This is associated with an early (1.5 hours) influx of CD18 expressing polymorphonuclear leukocytes, which are seen migrating into alveoli and the pulmonary interstitium. There is a later (6-12 hours) influx of CD11a/CD18 expressing macrophages which are present in the interstitium and in large numbers in the alveolar spaces, where they are very closely apposed to and adherent to the alveolar epithelium. This is the first study to demonstrate the precise ultrastructural location of ICAM-1 in the normal rat lung and in disease. In vivo administered antibody to ICAM-1 gains access to the extravascular sites within the lung, in particular the surface of alveolar type I epithelial cells, and this raises the possibility that beneficial effects of such antibodies may extend beyond their ability to inhibit interactions between leukocytes and endothelial cells.

Effect of poly DL-lactide--co-glycolide implants and xenogeneic bone matrix-derived growth factors on calvarial bone repair in the rabbit

Polymer implant discs composed of 50:50 poly DL-lactide-co-glycolide (molecular weight about 9000) were used to repair 5 mm calvarial defects in 2 kg rabbits and osseous repair compared to spontaneous healing (control). After 4 weeks the implants had undergone substantial degradation with little evidence of residual polymer. The extent to which the defects had been replaced by bone showed individual variation. In some animals a layer of bone with normal cancellous architecture had bridged the defect, but at no time was bone observed in intimate contact with the polymer matrix, suggesting that the material had acted as a tissue spacer rather than an osteoconductive substrate. Non-osseous tissue consisted of a highly vascular fibrous connective tissue containing variable numbers of inflammatory cells. In some sites numerous macrophages and multinucleate giant cells were observed, the majority of which were shown by immunocytochemistry to be MHC class II-positive. Histomorphometric analysis demonstrated no statistically significant difference in osseous repair between control and polymer implant groups after 1, 2 or 3 months. Incorporation of bone matrix proteins extracted from bovine cortical bone into the discs, however, provoked a cellular and humoral immune response which had a significant inhibitory effect on osseous repair. These data suggest, first, that while synthetic polymers have potential as bone graft substitutes, improvements in their performance in vivo are needed and, second, it is advisable to use allogeneic proteins in rabbit models of bone regeneration.

Suppression of experimental glomerulonephritis by the interleukin-1 receptor antagonist: inhibition of intercellular adhesion molecule-1 expression

Interleukin-1 is a proinflammatory cytokine produced in glomerulonephritis. Blocking the action of interleukin-1 by the administration of the interleukin-1 receptor antagonist (IL-1ra) has been shown to prevent renal function impairment, reduce glomerular injury, inhibit leukocyte infiltration, and suppress tubulointerstitial damage in experimental antiglomerular basement membrane disease. A key mechanism in the entry of leukocytes into the kidney is the interaction between the interleukin-1 inducible intercellular adhesion molecule-1 (ICAM-1; CD54) and lymphocyte function-associated antigen-1 (CD11a/CD18). Therefore, this study investigated whether the inhibition of this mechanism was the means by which IL-1ra suppressed leukocyte infiltration in rat accelerated antiglomerular basement membrane glomerulonephritis. Disease was induced in two groups of six rats; animals were treated by constant sc infusion of recombinant human IL-1ra or saline from the initiation of disease until being euthanized 14 days later. In saline-treated animals, there was marked up-regulation of ICAM-1 in the glomerulus and interstitium, In which was associated with leukocyte infiltration. In particular, focal accumulation of CD11a+ and CD18+ cells was apparent in areas of tubulointerstitial damage exhibiting intense ICAM-1 expression. IL-1ra treatment partially reduced glomerular ICAM-1 expression and leukocyte infiltration. However, IL-1ra treatment resulted in a dramatic inhibition of interstitial ICAM-1 expression, interstitial leukocyte infiltration, and tubulointerstitial damage. In conclusion, this study has shown that interleukin-1 is a major inducer of ICAM-1 expression within the renal tubulo-interstitium--a process associated with focal leukocyte infiltration and tubulointerstitial damage.(ABSTRACT TRUNCATED AT 250 WORDS)

The ICAM-1/LFA-1 interaction in glomerular leukocytic accumulation in anti-GBM glomerulonephritis

Recent studies of rat anti-glomerular basement membrane (anti-GBM) disease have demonstrated a functional role for ICAM-1 in the entry of leukocytes into the glomerulus, both in the early polymorphonuclear (PMNL) influx and the more delayed monocyte/macrophage infiltration. In the current study we used immunogold ultrastructural techniques to identify the exact sites of expression of ICAM-1 (CD54) in the glomerulus and the expression of CD11a and CD18 by infiltrating glomerular leukocytes in the first 24 hours of accelerated anti-GBM disease in rats. In normal rats there was constitutive ICAM-1 expression on the luminal surface of the glomerular endothelium and parietal epithelium of Bowman's capsule. In disease ICAM-1 expression was progressively increased over 24 hours on a thickened, reactive glomerular endothelium, being most prominent on endothelium adjacent to the mesangial stalks. Mesangial cells demonstrated surface ICAM-1 expression only in focal areas of superficial mesangiolysis. PMNL, the predominant glomerular inflammatory cell in the first 12 hours of accelerated anti-GBM GN, expressed abundant surface CD18 which was present at the sites of adhesion of the PMNL to the glomerular endothelium. In contrast PMNL expressed only very sparse surface CD11a, suggesting that another beta 2 integrin, Mac-1, which shares a common beta chain with LFA-1 may be the more important PMNL counter receptor for ICAM-1 in the glomerulus. Glomerular monocyte/macrophage infiltration became evident within glomerular capillary loops and the mesangium from 6 to 24 hours. These adherent and migrating leukocytes expressed abundant surface CD11a and moderate CD18 particularly at their sites of adhesion to glomerular endothelium.(ABSTRACT TRUNCATED AT 250 WORDS)

Macrophages in renal injury

There is good evidence from experimental studies that glomerular macrophages are important in acute renal injury and an increasing acceptance that they also play a role in chronic glomerular injury by stimulating mesangial cell proliferation and glomerulosclerosis. However, it is now evident that the contribution of macrophages and T cells within the interstitium must be taken into account. Indeed, if it is proved that progressive renal injury occurs via interstitial DTH mechanisms, regardless of the nature of the initial glomerular insult, then such mechanisms may provide a suitable target for the development of novel therapeutic strategies.

ICAM-1 directs migration and localization of interstitial leukocytes in experimental glomerulonephritis

Recent studies of rat anti-GBM disease have demonstrated a functional role of the ICAM-1/LFA-1 interaction in the entry of leukocytes into the glomerulus and an association between interstitial ICAM-1 expression, leukocyte infiltration and tubulointerstitial damage. In the current study, we used immunogold ultrastructural techniques to identify ICAM-1/LFA-1 interactions in the initiation of interstitial leukocyte infiltration during the first 24 hours of rat accelerated anti-GBM disease. In normal rats, there was weak constitutive ICAM-1 expression in the interstitium: on the endothelial luminal surface of interstitial capillaries, venules and arterioles, on the entire surface of interstitial fibroblast-like cells and confined to the brush border of proximal tubules. As early as 1.5 hours after injection of anti-GBM serum, there was a marked increase in the intensity of ICAM-1 expression, most notably on capillary endothelium, fibroblast-like cells and brush borders of proximal tubules, particularly in the periglomerular/perihilar areas. Mononuclear leukocytes exhibiting strong surface LFA-1 (CD11a and CD18) expression were seen adherent to the endothelium of interstitial capillaries, with ICAM-1 and LFA-1 antigens present at sites of contact. In addition, mononuclear cells migrating into the interstitium showed areas of close apposition to interstitial fibroblast-like cells, and here ICAM-1 and LFA-1 expression were also prominent at the sites of contact. This is the first study to demonstrate sites of ICAM-1/LFA-1 interaction in mononuclear cell migration and localization in glomerulonephritis. The results suggest that up-regulation of periglomerular/peritubular capillary ICAM-1 expression is important for mononuclear cell entry into the interstitium, while interaction with fibroblast-like cells may facilitate movement and subsequent focal accumulation of mononuclear cells at sites within the interstitium.

Regulation of human renal adenocarcinoma cell growth by retinoic acid and its interactions with epidermal growth factor

Retinoic acid (RA) is a natural derivative of vitamin A which regulates the growth and differentiation of epithelia. We have previously proposed that RA participates in compensatory kidney growth and reported that RA inhibits rat mesangial cell growth. This paper describes the effects of RA on a human renal adenocarcinoma cell line (PAD) under different growth conditions, and its interactions with epidermal growth factor (EGF). PAD cells were shown to express RA receptors alpha and beta by Northern blot analysis. In serum free cultures, addition of RA (10(-7) M) markedly increased thymidine incorporation by PAD cells (155 +/- 7% mean +/- SE vs. control in 6 separate experiments; P < 0.0001). RA also caused a significant increase in thymidine incorporation by PAD cells under conditions of rapid growth in serum supplemented medium (115 +/- 2% vs. control; P < 0.001). RA by itself was unable to reverse contact inhibition of PAD cell growth (NS vs. control), but it synergistically enhanced the mitogenic effect of EGF on confluent monolayers (110 +/- 0.6% vs. EGF alone; P < 0.05). Northern blot analysis demonstrated that PAD cells express EGF receptor mRNA, and this was not significantly modified by the addition of RA. Growth arrested (serum starved) PAD cells expressed RAR-alpha mRNA which was upregulated eightfold at three hours following the addition of 10% FCS. Thus, our data show that RA is directly mitogenic for serum starved human renal adenocarcinoma cells and that it exerts complex modulation of cell growth in the presence of EGF and serum components.

Inhibition of stimulated bone resorption in vitro by TIMP-1 and TIMP-2

Recombinant human TIMP-1 and TIMP-2 (tissue inhibitors of metalloproteinases) inhibited bone resorption induced by either parathyroid hormone or 1,25-dihydroxyvitamin D3 in cultured neonatal mouse calvariae. The inhibition was reversible, dose-dependent and complete at 1 microgram/ml inhibitor concentration. TIMP-2 was more potent than TIMP-1. TIMP-1 and TIMP-2 also inhibited basal bone resorption. Neither metalloproteinase inhibitor affected protein synthesis, DNA synthesis, the PTH-enhanced secretion of beta-glucuronidase or the spontaneous release of lactate dehydrogenase. These results suggest that endogenous TIMPs play a central role in regulating both physiological and pathological bone resorption.

The prevalence and severity of malocclusion and the need for orthodontic treatment in 9-, 12-, and 15-year-old Glasgow schoolchildren

An epidemiological investigation involving 765 Glasgow schoolchildren aged nine, twelve, and fifteen years was undertaken to assess the severity of malocclusion, the need for orthodontic treatment, and the proportion of children in each age group who had previously received treatment. An index termed the Malocclusion Severity Index (MSI) was developed to establish objectively the severity of malocclusion in each individual. Fifty sets of orthodontic study models and six orthodontists assessed the reproducibility and validity of the index. Although there was a significant reduction in the proportion of children in need of orthodontic treatment between 9 and 15 years of age, a considerable number were still in need of treatment; crowding of their dentitions being responsible for the majority of the treatment requirement. The MSI was found to be as precise and valid as previously developed occlusal indices, for estimating the treatment needs of sample populations.

Ultrastructural changes in renal tubules associated with glomerular bleeding

Renal biopsies from ten patients presenting with macroscopic or heavy microscopic hematuria, shown to be glomerular in origin, were examined by light and electron microscopy. All biopsies showed erythrocytes within tubules by light microscopy and, in five cases, there were morphologic features of acute tubular necrosis. In four biopsies there was clear evidence by electron microscopy of uptake of erythrocytes by renal tubular epithelial cells, associated with some blunting of epithelial microvilli, vacuolar change and increased lysosomal content. Associated with erythrophagocytosis, the subsequent pathway of erythrocyte destruction within renal tubular epithelial cells closely resembled the hemolytic pathway described in macrophages of the reticuloendothelial system.

Morphologic changes in the renal glomerulus and the juxtaglomerular apparatus in human preeclampsia

The renal biopsies of ten women with preeclampsia without other underlying renal disease were examined in detail using light and electron microscopy and immunofluorescence. Characteristic preeclamptic glomerular lesions with endocapillary cell swelling, subendothelial and mesangial deposits, and mesangial interposition were detected in each patient. Juxtaglomerular regions were not prominent and were poorly granulated on light microscopy; ultrastructurally, they showed myoepithelioid cells with sparse renin granulation and considerable heterogeneity of granule size and density in association with relatively meagre granular endoplasmic reticulum and Golgi profiles. These morphologic findings suggest that, in patients with clinical and renal biopsy evidence of preeclampsia, there is no significant stimulation of the renin-angiotensin system.

Osteoporosis with hip fracture: changes in calcium regulating hormones

It has been suggested that there are two distinct types of involutional osteoporosis in women. Loss of ovarian function causes spine and wrist fractures in middle-aged women whilst a decline in renal endocrine function and bone formation is responsible for fractures, especially of the hip, in elderly women. We have investigated calcium regulation in post-menopausal women with hip fractures in their seventh decade together with non-osteoporotic controls of similar age. The major findings were reduced secretion of calcitonin (P less than 0.01) and 1,25 dihydroxy-vitamin D (P less than 0.025) in the osteoporotics as compared with controls. No differences in plasma levels of calcium, parathyroid hormone and 25 hydroxyvitamin D were observed. Our results show some similarities with those reported in both proposed types of osteoporosis, suggesting considerable overlap between them. Secondary hyperparathyroidism does not appear to be a usual feature of osteoporotic women with hip fracture up to age 75 years. Our hormonal findings are more in keeping with marked oestrogen deficiency, suggesting that loss of ovarian function is a major determinant of the osteoporosis in these women.