Over the past decade, several studies have suggested that the complement system has an active role in both acute and chronic allograft rejection. These studies have been facilitated by improved techniques to detect antibody-mediated organ rejection, including immunohistological staining for C4d deposition in the allograft and solid-phase assays that identify donor-specific alloantibodies (DSAs) in the serum of transplant recipients. Studies with eculizumab, a humanized monoclonal antibody directed against complement component C5, have shown that activation of the terminal complement pathway is necessary for the development of acute antibody-mediated rejection in recipients of living-donor kidney allografts who have high levels of DSAs. The extent to which complement activation drives chronic antibody-mediated injury leading to organ rejection is less clear. In chronic antibody-mediated injury, early complement activation might facilitate chemotaxis of inflammatory cells into the allograft in a process that later becomes somewhat independent of DSA levels and complement factors. In this Review, we discuss the different roles that the complement system might have in antibody-mediated allograft rejection, with specific emphasis on renal transplantation.
Using an expression cDNA cloning approach, we examined human tumor cell lines for novel oncogenes that might evade detection by conventional techniques. We isolated a transforming sequence that was highly efficient in transforming NIH 3T3 mouse fibroblasts. DNA sequence analysis identified the gene as the human homolog of a recently cloned a subunit of mouse GTP-binding protein Gal2. NIH 3T3 cells transfected with Gal2 cDNA grew in soft agar and were tumorigenic in nude mice. There were no apparent mutations in the cloned cDNA in comparison with a Gal2 cDNA clone isolated from a normal human epithelial cell library, implying that overexpression alone was sufficient to cause NIH 3T3 cell transformation. The observed altered growth properties mediated by Gal2 showed a certain degree of dependency on serum factors, and its mitogenic potential was also potently inhibited by suramin treatment.
We identified a naturally occurring hepatocyte growth factor (HGF) variant, whose predicted sequence extends only through the second kringle domain of this plasminogen-related molecule. This smaller molecule, derived from an alternative HGF transcript, lacked mitogenic activity but specifically inhibited HGF-induced mitogenesis. Cross-linking studies demonstrated that the truncated molecule competes with HGF for binding to the HGF receptor, which has been identified as the c-met protooncogene product. Thus, the same gene encodes both a growth factor and its direct antagonist.
SummaryWe investigated the expression and distribution of keratinocyte growth factor (KGF) (FGF-7) and its receptor (KGFR.) during reepithelialization of human skin. KGF mR.NA levels increased rapidly by 8-10-fold and remained elevated for several days. In contrast, KGFP,. transcript levels decreased early but were significantly elevated by 8-9 d. A KGF-immunoglobulin G fusion protein (KGF-HFc), which specifically and sensitively detects the KGFR., localized the receptor to differentiating keratinocytes of control epidermis, but revealed a striking decrease in receptor protein expression during the intermediate period of reepithelization. Suramin, which blocked KGF binding and stripped already bound KGF from its receptor, failed to unmask KGFR.s in tissue sections from the intermediate phase of wound repair. The absence of KGFP,. protein despite increased KGFR. transcript levels implies functional receptor downregulation in the presence of increased KGF. This temporal modulation of KGF and KGFR.s provides strong evidence for the functional involvement of KGF in human skin reepithelialization.
Renal transplant candidates with high levels of donorspecific anti-HLA antibodies have low transplantation rates and high mortality rates on dialysis. Using desensitization protocols, good short-term outcomes are possible in "positive crossmatch kidney transplants (+XMKTx)" , but long-term outcome data are lacking. The aim of the current study was to determine actual 5-year graft outcomes of +XMKTx. We compared graft survival and the functional and histologic status of 102 +XMKTx to 204 −XMKTx matched for age and sex. Actual 5-year death-censored graft survival was lower in the +XMKTx group (70.7% vs. 88.0%, p < 0.01) and chronic injury (glomerulopathy) was present in 54.5% of surviving grafts. Graft survival was higher in recipients with antibody against donor class I only compared with antibody against class II (either alone or in combination with class I) (85.3% vs. 62.6%, p = 0.05) and was similar to −XMKTx (85.3 vs. 88.0%, p = 0.64). Renal function and proteinuria ranged across a wide spectrum in all groups reflecting the different histological findings at 5 years. We conclude that when compared to −XMKTx, +XMKTx have inferior outcomes at 5 years, however, almost half of the surviving grafts do not have glomerulopathy and avoiding antibodies against donor class II may improve outcomes.
Keratinocyte growth factor (KGF) is a member of the heparin-binding fibroblast growth factor family (FGF-7) with a distinctive pattern of target-cell specificity. Studies performed in cell culture suggested that KGF was mitogenically active only on epithelial cells, albeit from a variety of tissues. In contrast, KGF was produced solely by cells of mesenchymal origin, leading to the hypothesis that it might function as a paracrine mediator of mesenchymal-epithelial communication. Biochemical analysis and molecular cloning established that the KGF receptor (KGFR) was a tyrosine kinase isoform encoded by the fgfr-2 gene. Many detailed investigations of KGF and KGFR expression in whole tissue and cell lines largely substantiated the pattern initially perceived in vitro of mesenchymal and epithelial distribution, respectively. Moreover, functional assays in organ culture and in vivo and studies of KGF regulation by sex steroid hormones reinforced the idea that KGF acts predominantly on epithelial cells to elicit a variety of responses including proliferation, migration and morphogenesis.
Development of the seminal vesicle (SV) is elicited by androgens and is dependent on epithelialmesenchymal interactions. Androgenic signal trnsmission from the androgen-receptor-positive mesenchyme to the epithellum has been postulated to involve paracrine factors. Keratinocyte growth factor (KGF), a member of the fibroblast growth factor family, is produced by stromal/mesenchl cells and acts s ally on epithal cells. Seminal vesicles (SVs) are male sex-accessory glands derived from the caudal regions of the Wolffian ducts. The development and maintenance of the SV are dependent on epithelial-mesenchymal interactions that are directed by androgens (1-4). SV morphogenesis begins on embryonic day 15 in mice (5) subsequent to the onset of testosterone production by the fetal testes (6). Fetal development of the SV is driven by androgens acting directly on the mesenchyme that induces epithelial development. The mesenchyme must initially mediate the inductive action of androgens because it is the only source of androgen receptor until day 1 postnatally, when epithelial androgen receptors are first detected (7). This conclusion is reinforced by analysis of SV inductions employing normal androgen receptor-positive SV mesenchyme and androgen receptor-negative epithelium (testicular feminization) (8). Dependence on epithelial-mesenchymal interaction continues into adulthood, as demonstrated by homotypic and heterotypic recombination experiments. SV mesenchyme is capable of inducing SV differentiation, morphologically and functionally, from epithelia isolated from any portion of the fetal Wolffian duct (3, 4), adult epididymis (9), and adult ureter and adult ductus deferens (2). Thus, both prenatal and postnatal development depends on instructive signals from the mesenchyme to the epithelium.The identification of paracrine signals that mediate these cell-cell interactions has proven elusive. Recently, a growth factor whose properties are consistent with such an effector has been identified and molecularly cloned. This factor, designated keratinocyte growth factor (KGF), is a heparinbinding growth factor and member of the fibroblast growth factor (FGF) family (FGF-7) (10). KGF is secreted by mesenchymal cells and appears to act solely on epithelial cells (11,12). The present studies were undertaken to investigate the possibility that KOF is an important mediator of the epithelial-mesenchymal interactions required for androgendependent SV development. MATERIALS AND METHODSAnimals and Orgn Culte. SVs were dissected from newborn BALB/c mice obtained from either the Cancer Research Laboratory (University of California, Berkeley) or Simonsen Laboratories (Gilroy, CA). SVs were grown in an organ culture system as described (13). Briefly, the organs were placed on Millipore filters supported on tangula metal grids in 35-mm Petri dishes (Falcon). A basal medium of Dulbecco's modified Eagle's medium (DMEM)/Ham's F-12, 1:1 (vol/vol), supplemented with insulin (10 pg/ml), transferrin (10 ,ug/ml), cholera toxin (10 ng/ml), bov...
Abstract. In vitro studies have shown that keratinocyte growth factor (KGE also known as FGF-7) is secreted by fibroblasts and is mitogenic specifically for epithelial cells. Therefore, KGF may be an important paracrine mediator of epithelial cell proliferation in vivo. Because stromal cells are thought to influence glandular proliferation in the primate endometrium, we investigated the hormonal regulation and cellular localization of KGF mRNA expression in the rhesus monkey uterus. Tissues were obtained both from naturally cycling monkeys in the follicular and luteal phases of the cycle, and from spayed monkeys that were either untreated or treated with estradiol (F_a) alone, F_a followed by progesterone (P), F_a plus P, or Fa plus P plus an antiprogestin (RU 486). Northern blot analysis of total RNA with 32p-labeled probes revealed that the level of KGF mRNA in the endometrium was 70-100-fold greater in the luteal phase or after P treatment than in untreated, F_a-treated, or follicular phase animals. Northern analysis also showed that KGF mRNA was present in the myometrium but was unaffected by hormonal state. RU 486 treatment prevented the P-induced elevation of endometrial KGF mRNA. P-dependent elevation of endometrial KGF expression was confirmed by measurement of KGF protein in tissue extracts using a two-site enzyme-linked immunosorbent assay. In situ hybridization with nonradioactive digoxigenin-labeled eDNA probes revealed that the KGF mRNA signal, which was present only in stromal and smooth muscle cells, was substantially increased by P primarily in the stromal cells located in the basalis region. Smooth muscle cells in the myometrium and the walls of the spiral arteries also expressed KGF mRNA, but the degree of this expression did not differ with hormonal state. P treatment led to increased proliferation in the glandular epithelium of the basalis region and to extensive growth of the spiral arteries. We conclude that the P-dependent increase in endometrial KGF resulted from a dual action of P: (a) a P-dependent induction of KGF expression in stromal cells, especially those in the basalis (zones Ill and IV), and (b) a P-dependent increase in the number of KGF-positive vascular smooth muscle cells caused by the proliferation of the spiral arteries. KGF is one of the first examples in primates of a P-induced, stromally derived growth factor that might function as a progestomedin. MANY reports suggest that the actions of sex steroids in target tissues are mediated through locally produced growth factors in an autocrine/paracrine fashion. For example, EGF (23, 31), insulin-like growth factor I (IGF-I) t (15, 30), and TGF-ot (32) are all regarded as
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