Thymidine Phosphorylase: A Possible Marker of Cell Maturation in Acute Myeloid Leukaemia

Thymidine Phosphorylase activity has been measured in two populations of human Acute Myeloid Leukaemia cells (AML) and in normal human macrophages. During short-term culture in vitro of AML cells the activity of this enzyme increases progressively and approaches that of normal non-dividing macrophages at a time when the leukaemia cells in culture show evidence of maturation as assayed by functional, enzymatic and morphological criteria. It is suggested that the level of Thymidine Phosphorylase activity may be a marker of maturation in AML.

C5L2 and C5aR interaction in adipocytes and macrophages: insights into adipoimmunology

Obesity is associated with inflammation characterized by increased infiltration of macrophages into adipose tissue. C5aR-like receptor 2 (C5L2) has been identified as a receptor for acylation-stimulating protein (ASP) and the inflammatory factor C5a, which also binds C5aR. The present study examines the effects of ligands ASP and C5a on interactions between the receptors C5L2 and C5aR in 3T3-L1 adipocytes and J774 macrophages. BRET experiments indicate that C5L2 and C5aR form homo- and heterodimers in transfected HEK 293 cells, which were stable in the presence of ligand. Cell surface receptor levels of C5L2 and C5aR increased during 3T3-L1 adipocyte differentiation; both receptors are also highly expressed in J774 macrophages. Using confocal microscopy to evaluate endogenous receptors in adipocytes following stimulation with ASP or C5a, C5L2 is internalized with increasing perinuclear colocalization with C5aR. There is little C5a-dependent colocalization in macrophages. While adipocyte-conditioned medium (ACM) increased C5L2-C5aR colocalization in macrophages, this was blocked by C5a. ASP stimulation increased Akt (Ser(473)) phosphorylation in both cell types; C5a induced slight Akt phosphorylation in adipocytes with less effect in macrophages. ASP, but not C5a, increased fatty acid uptake/esterification in adipocytes. C5L2-C5aR homodimerization versus heterodimerization may thus contribute to differential responses obtained following ASP vs C5a stimulation of adipocytes and macrophages, providing new insights into the complex interaction between these two cell types within adipose tissue. Studying the mechanisms involved in the differential responses of C5L2-C5aR activation based on cell type will further our understanding of inflammatory processes in obesity.

Histiocytes in Familial and Infection-Induced/Idiopathic Hemophagocytic Syndromes May Exhibit Phenotypic Differences

Familial hemophagocytic syndrome (FHS) and infection-associated hemophagocytic syndrome (IAHS) usually present with fever, pancytopenia, hepatosplenomegaly, signs of hepatic dysfunction, bleeding diathesis, and neurological manifestations. FHS is almost uniformly fatal, and IAHS is associated with high mortality. The only distinguishing characteristics are lack of family history and association with infection in the latter. Despite this, sporadic cases of FHS and culture-negative examples of IAHS (idiopathic HS) can be difficult to distinguish and the distinction may have important implications for treatment and family planning. We evaluated the immunophenotype of the macrophages (M phi s) in frozen tissue sections from three cases of hemophagocytic syndrome using a very large panel of monocyte/M phi-associated monoclonal antibodies and an immunoperoxidase technique. The clinical and laboratory features suggested that two were examples of FHS (one with strong family history) and that the third was IAHS/idiopathic HS. The results supported the clinical impressions by showing that the antigenic phenotypes of the FHS cases were nearly identical and different from that of the case of presumed IAHS/idiopathic HS. Specifically, M phi s from the FHS cases expressed complement receptors, 1, 2, and 3 (CD35, CD21, and CD11b, respectively), the monocyte antigen CD36, and the "activation" antigens CD25 (IL2-R) and CD30 (Ki-1), while those from the IAHS/idiopathic case did not. These studies also demonstrated that the M phi s in these cases exhibited some phenotypic differences from those in control tissues, that is, expression of the pan-M phi antigen CD14, the M phi subset antigen identified by antibody G16/1, complement receptors, certain monocyte antigens, and M phi "activation" antigens.(ABSTRACT TRUNCATED AT 250 WORDS)

Characterization of foam cells in experimental atherosclerosis

A series of biochemical and morphological studies has focused on the properties and origins of lipid laden foam cells in experimentally induced atherosclerosis in rabbits. Lipids inclusions present in these cells occupy half or more of the cytoplasmic volume and are of two kinds: cytoplasmic lipid droplets composed predominantly of cholesteryl esters and lysosomes in which substantial quantities of free cholesterol have accumulated. The foam cells exhibit some properties of macrophages but not others. They possess high levels of acid hydrolases and catalase and Fc membrane receptors can be detected on their surface. Only about one third of the foam cells, however, exhibit C3 receptors and few if any of the cells appear to contain or secrete lysozyme.

Cleavage fragments of the third complement component (C3) enhance stromal derived factor-1 (SDF-1)-mediated platelet production during reactive postbleeding thrombocytosis

We hypothesized that the third complement component (C3) cleavage fragments (C3a and (des-Arg)C3a) are involved in stress/inflammation-related thrombocytosis, and investigated their potential role in reactive thrombocytosis induced by bleeding. We found that platelet counts are lower in C3-deficient mice in response to excessive bleeding as compared to normal littermates and that C3a and (des-Arg)C3a enhance stromal-derived factor-1 (SDF-1)-dependent megakaryocyte (Megs) migration, adhesion and platelet shedding. At the molecular level, C3a stimulates in Megs MAPKp42/44 phosphorylation, and enhances incorporation of CXCR4 into membrane lipid rafts increasing the responsiveness of Megs to SDF-1. We found that perturbation of lipid raft formation by statins decreases SDF-1/C3a-dependent platelet production in vitro and in an in vivo model statins ameliorated post-bleeding thrombocytosis. Thus, inhibition of lipid raft formation could find potential clinical application as a means of ameliorating some forms of thrombocytosis.

Human plasmacytoid dendritic cells express receptors for anaphylatoxins C3a and C5a and are chemoattracted to C3a and C5a

The presence of plasmacytoid dendritic cells (pDC) was recently demonstrated in lesions of inflammatory skin diseases. Since anaphylatoxins or their precursors were also found in such lesions, we investigated a possible interaction between pDC and anaphylatoxins C3a and C5a. pDC precursors isolated from peripheral blood did not express the receptors for C3a and C5a, complement C3a receptor (C3aR) and complement C3a receptor (C5aR). If these pDC precursors were cultured with IL-3, the resultant immature pDC expressed both receptors. Expression of C3aR and C5aR could also be demonstrated on pDC in lesions of cutaneous lupus erythematosus and allergic contact dermatitis. Such pDC were immature since they lacked the expression of the maturation marker CD83. Blood-derived pDC matured with CpG oligonucleotides downregulated the receptors. Immature pDC responded to C3a and C5a (but not C3adesArg) stimulation with increased F-actin polymerization and chemotactic migration. In contrast, interferon alpha production, surface molecule expression, and T-cell stimulatory capacity were not significantly modulated by C3a or C5a. Thus, immature pDC represent another type of antigen-presenting cell that express C3aR and C5aR, and respond to anaphylatoxins with chemotaxis. This might be relevant in the direction of pDC to cutaneous lesions of inflammation, for example, in lupus erythematosus or contact dermatitis.

C1qRP (CD93) expression on peripheral blood monocytes in patients with systemic lupus erythematosus

Aim of the study was to compare the expression of monocytes C1qRp (CD93) in patients with systemic lupus erythematosus (SLE) with that of healthy controls and to determine the influence of glucocorticoids and LPS on C1qRp expression. Thirty-six SLE patients and 20 healthy controls were analyzed by flow cytometry. Additionally, monocytes from five patients and five controls were cultured and stimulated with dexamethasone, interferon-gamma and LPS, respectively, before the measurement of C1qRp expression. There was no difference in C1qRp expression between SLE and HC. SLE patients with no or only low dose steroids had a significantly higher C1qRp expression than those with higher doses. However, in vitro dexamethasone did not stimulate or down-regulate C1qRp expression. Upon LPS stimulation, C1qRp was significantly up regulated on monocytes both from patients and from controls. In conclusion, C1qRp expression and regulation was not altered in SLE patients. Possible relations with disease activity and medication need further investigations.

A complement receptor for opsonized immune complexes on erythrocytes from Oncorhynchus mykiss but not Ictalarus punctatus

Immune complexes activate the classical pathway of complement resulting in the covalent deposition of fragments of the third (C3b) and fourth (C4b) components of complement, thus opsonizing the complexes for uptake by CD35 found on human erythrocytes. The complexes are then transported to and cleared from the circulation by the reticuloendothelial system. It has been shown that rainbow trout can remove immune complexes from the circulation in a complement-dependent manner similar to that found in the human. However, the cell or cell types involved have not been identified. The purpose of this study was to investigate whether a complement-dependent immune adherence receptor is expressed on erythrocytes from the rainbow trout (Oncorhynchus mykiss) and the channel catfish (Ictalarus punctatus). Coating fluorescent microparticles with BSA, and then binding them to anti-BSA created an artificial immune complex that was incubated with normal fish serum, normal human serum or EDTA-treated serum. The complement-coated immune complexes were then incubated with either fish or human erythrocytes and analyzed for binding by flow cytometry and further visualized by fluorescence microscopy. Our results indicate that erythrocytes from rainbow trout are capable of binding immune complexes when pretreated with serum from either the trout or human, but not when pretreated with serum containing EDTA. By contrast, erythrocytes from the channel catfish did not bind immune complexes pretreated with autologous or human serum. These data suggest that differences exist in receptor distribution between two closely related species of fish, and a potentially homologous relationship in receptor expression, and possibility function, exist between two highly divergent species.

Genetic deficiency of C3 as well as CNS-targeted expression of the complement inhibitor sCrry ameliorates experimental autoimmune uveoretinitis

In this report, we describe the effect of complement deficiency and inhibition on experimental autoimmune uveoretinitis (EAU). C57BL/6 mice genetically deficient in C3 (C3-/-) or expressing a soluble complement activation inhibitor (soluble complement receptor related protein Y or sCrry) in a CNS-targeted fashion, (sCrry/GFAP) were induced for EAU via peripheral immunisation with a peptide of amino acids 1-20 of human interphotoreceptor retinoid binding protein in complete Freund's adjuvant with concurrent intraperitoneal pertussis toxin. The incidence and severity of EAU in the mutant mice was compared with that in simultaneously induced C57BL/6 wild type mice. The sCrry protein was detected in retinal extracts from transgenic but not wild type mice by western blot. C3-/- mice had a significant reduction in the incidence of EAU compared with wild type mice (incidence 44 versus 89%, respectively, p=0.0417) and a significant reduction in the severity of EAU (median disease score values 0 versus 1.3, respectively, p=0.0253). Similarly, sCrry mice had a significant reduction in the incidence of EAU compared with wild type mice (incidence 57 versus 100% respectively, p=0.0033) and a significant reduction in the severity of EAU (median disease score values 0.18 versus 1.85, respectively, p=0.0054). A genetic deficiency of C3 and production of a soluble complement inhibitor targeted to the CNS and eye are protective against EAU.

Expression of the anaphylatoxin receptors C3aR and C5aR is increased in fatal asthma

BACKGROUND

The mechanisms leading to death from asthma are not completely understood. Recent studies suggest the involvement of the anaphylatoxins C3a and C5a, generated during complement activation, and their receptors C3aR and C5aR in the pathogenesis of asthma.

OBJECTIVE

The aim of our study was to investigate the expression of C3aR and C5aR in fatal asthma.

METHODS

We analyzed lung tissue from 14 subjects who died of asthma (fatal asthma; FA) and 14 subjects who died of nonpulmonary causes (controls) and bronchial biopsy specimens from 16 subjects with mild intermittent asthma (MIA). C3aR and C5aR expression was evaluated by immunohistochemistry, and a semiquantitative analysis of the intensity of staining was performed according to a visual analogue scale (score, 0-3).

RESULTS

C3aR was expressed on airway epithelium, smooth muscle, submucosal, and parenchymal vessels. C5aR was expressed on myeloid cells infiltrating the submucosa and on airway epithelium. Statistical analysis demonstrated higher expression of C3aR on submucosal vessels in FA compared with controls and MIA (median [minimum-maximum], controls, 0.24 [0-1.48]; MIA, 0.0 [0-1.00]; FA, 1.56 [0.13-3]; P = .002). C3aR was also increased on parenchymal vessels in FA (controls, 0.56 [0-2.00]; FA, 1.81 [0.5-3]; P = .0004). C5aR expression on airway epithelium was increased in FA compared with controls and MIA (controls, 1.25 [0.25-3]; MIA, 1.00 [0-2.00]; FA, 3.00 [1.13-3.00]; P = .001).

CONCLUSION

The results of our study suggest a role of complement in FA.

Human p32, interacts with B subunit of the CCAAT-binding factor, CBF/NF-Y, and inhibits CBF-mediated transcription activation in vitro

To understand the role of the CCAAT-binding factor, CBF, in transcription, we developed a strategy to purify the heterotrimeric CBF complex from HeLa cell extracts using two successive immunoaffinity chromatography steps. Here we show that the p32 protein, previously identified as the ASF/SF2 splicing factor-associated protein, copurified with the CBF complex. Studies of protein-protein interaction demonstrated that p32 interacts specifically with CBF-B subunit and also associates with CBF-DNA complex. Cellular localization by immunofluorescence staining revealed that p32 is present in the cell throughout the cytosol and nucleus, whereas CBF is present primarily in the nucleus. A portion of the p32 colocalizes with CBF-B in the nucleus. Interestingly, reconstitution of p32 in an in vitro transcription reaction demonstrated that p32 specifically inhibits CBF-mediated transcription activation. Altogether, our study identified p32 as a novel and specific corepressor of CBF-mediated transcription activation in vitro.

Increased serum C3 levels in Crry transgenic mice partially abrogates its complement inhibitory effects

Complement receptor 1-related gene/protein y (Crry) is a potent murine complement regulator that inhibits C3 convertases. Transgenic mice that overexpress soluble Crry (sCrry), directed systemically by the metallothionein-I promoter, have been used as an animal model for chronic blockade of complement activation. Recently we have found that alternative pathway (AP) activity in Crry transgenic mice was not inhibited as much as expected. To elucidate the mechanism of this effect, we evaluated the AP activities and levels of sCrry and AP complement components in transgenic and non-transgenic mice. In transgenic mice, expression of sCrry was induced by feeding zinc sulphate solution to 70.1 +/- 42.7 micro g/ml mean serum level. Its corresponding level of purified sCrry inhibited 49% of AP activity of normal mice serum; however, the actual AP activities in transgenic mice were not decreased when compared to non-transgenic mice (130.2 +/- 9.0%versus 113.0 +/- 35.4%). Expressed sCrry was functional, as immunoprecipitation and removal of sCrry from transgenic sera with rabbit anti-Crry polyclonal antibody resulted in enhanced AP activity, consistent with initial levels of sCrry. We then compared the changes to C3, factor B, factor H and factor D serum levels in transgenic and non-transgenic mice after induction of sCrry expression. Of these only C3 was increased after zinc feeding in transgenic mice compared to non-transgenic mice (142.8 +/- 14.1%versus 121.4 +/- 15.1%, P = 0.023). These results suggest that the inhibitory effect of chronic exposure to sCrry is compensated by concomitant alteration in C3 levels. This result also suggests the presence of a complement regulatory protein controls the level of serum C3, which has potential importance in the design and interpretation of studies involving chronic use of complement inhibitors.

Membrane-bound complement regulatory proteins inhibit complement activation by an immunotherapeutic mAb in a syngeneic rat colorectal cancer model

MAb-mediated immunotherapy offers a potential tool for destroying metastasizing colorectal tumor cells. Promising results have been obtained by using xenograft models. However, overexpression of membrane-bound complement regulatory proteins (mCRP) impedes complement-mediated destruction of tumor cells in vitro. mCRP operate in a species selective manner. Therefore a syngeneic animal model is needed to investigate the contribution of mCRP in mAb-mediated immunotherapy. Here we present a syngeneic rat colorectal carcinoma model, which fulfills the conditions necessary to investigate the effect of mCRP expression on mAb-mediated immunotherapy of metastases of solid tumors.CC531 rat colorectal cancer cells were injected subcapsularly into the liver of syngeneic WAG/Rij rats. Four mAb (MG1(IgG2a), MG2(IgG2a), MG3(IgG3) and MG4(2a)(IgG2a)) directed against CC531 cells, were tested for their complement activating abilities in vitro and tumor homing capacities in vivo. Only MG4(2a) was found to activate complement in vitro and home to the tumor cells in vivo. This mAb induced C3-deposition and C-mediated lysis of CC531 cells in vitro when the effects of the C-inhibitors Crry/p65 and CD59 were neutralized. This implies an important role for these mCRP in restricting the effector functions of tumor-associated mAb on these cells. Although C activation could be induced by MG4(2a) in situ on tumor tissue sections, no deposition of C3 could be found on the tumor cells positive for MG4(2a) in vivo. This suggests that complement activation in vivo was inhibited by mCRP. The results indicate the suitability of this syngeneic animal model for studying the effects of mAb immunotherapy. However, the effect of mCRP on tumor cells need to be overcome, e.g. by the use of mAb against tumor antigens and mCRP.

[Changes of ECR1 genomic density polymorphism, quantitative expression and the activity of ECR1 natural adhesion in patients with chronic hepatitis]

OBJECTIVE

To study the changes of genomic density polymorphism, quantitative expression and the adhesion activity of complement receptor type 1 (ECR1) on erythrocytes in patients with chronic hepatitis.

METHODS

Polymerase chain reaction (PCR) and Hind restriction enzyme digestion, the quantitative assay of ECR1 and the activity of erythrocytes immune adhesion test were applied.

RESULTS

The spot mutation rate (25.0%-30.3%) of ECR1 density gene in patients with chronic hepatitis was not significantly different from that of healthy individuals (28.0%). The amount of ECR1 in patients with chronic hepatitis, except for the diseases with normal liver function, was significantly lower than that of healthy individuals (t=9.87,P<0.000 1). The quantitative expression of ECR1 in decompensated cirrhosis was obviously lower than that of compensated cirrhosis (t=2.21,P<0.05).

CONCLUSIONS

Defective expression of ECR1 in chronic hepatitis B may be acquired through central and/or peripheral mechanisms. It is very important to study the quantitative expression in the patients with chronic hepatitis.

Distribution of rat C5a anaphylatoxin receptor

The anaphylatoxin, complement 5a (C5a), plays a key role in mediating various inflammatory reactions following complement activation. Several investigators have reported that C5a receptor (C5aR) is expressed in non-myeloid cells under certain conditions or in different cell lines. In our study, the abundance of C5aR-positive myeloid cells in rats depended on the organs examined. C5aR was usually expressed at the site of exposure to pathogens, such as in salivary gland or lung, and was up-regulated in liver in the inflammatory state induced by lipopolysaccharide (LPS) administration. Furthermore, the increased expression of C5aR antigen was not accompanied by an increase in C5aR mRNA in Kupffer cells following LPS challenge.

Overexpression of complement receptors and related antigens on the surface of bone marrow mast cells in patients with systemic mastocytosis

Depending on their stage of maturation and other factors, mast cell (MC) subsets differ from each other in terms of the expression of complement-associated antigens. This study analysed the expression of various complement-related cell surface antigens (CD11b/CR3, CD11c/CR4, CD35/CR1, CD55/DAF, CD59/MIRL, CD88/C5aR) on bone marrow mast cells (BMMC) in patients suffering from systemic mastocytosis (SM), other haematological diseases and non-haematological disorders (control groups). Expression of complement-associated cell surface antigens was analysed by flow cytometry. There were clear immunophenotypic differences between BMMC obtained from patients with SM and those from the control subjects: the percentage of patients expressing surface CD11c, CD35 and CD88 was significantly higher in patients with SM (76%, 100%, 54%) than in the control subjects (58%, 11%, 18%) (P < 0.05). In addition, the levels of CD11c, CD35 and CD88 expressed per MC (sites per cell) were significantly higher (P < 0.05) in SM than in the control group. Expression of the complement regulatory molecules CD55 and CD59 was detected in BMMC in all patients analysed. However, the levels of CD59 per BMMC were higher in patients with SM as compared with the control subjects, which could help to explain the formation of BMMC aggregates in the former group of individuals. Together, our results showed that BMMC in systemic mastocytosis overexpressed the cell surface membrane receptors involved in binding of complement components and complement-mediated cell activation. Whether this pathological expression of complement receptors is of pathophysiological significance remains to be determined.

A simple method for accurate quantification of complement receptor 1 on erythrocytes preserved by fixing or freezing

The mean number of complement receptor 1 (CR1) molecules on erythrocytes differs between normal individuals within the range of 100-1000 molecules per cell. In some disease states such as systemic lupus erythematosus (SLE), acquired immune deficiency syndrome (AIDS), insulin-dependent diabetes mellitus and malaria, erythrocyte CR1 levels are reduced and CR1 function may be impaired. Current methods for determining erythrocyte CR1 levels by flow cytometry require the use of freshly drawn blood samples because CR1 is lost from erythrocytes during storage. In order to facilitate field studies of associations between erythrocyte CR1 levels and disease, we have developed and validated an assay to quantify CR1 on both healthy and diseased erythrocytes that have been fixed in 5% formaldehyde or frozen in glycerol. These methods enable blood samples to be collected in areas lacking the facilities for flow cytometry and stored for later accurate quantification of CR1. Such procedures will be of particular benefit for future investigations of erythrocyte CR1 expression level and malaria susceptibility.

Essential role for the C5a receptor in regulating the effector phase of synovial infiltration and joint destruction in experimental arthritis

A characteristic feature of rheumatoid arthritis is the abundance of inflammatory cells in the diseased joint. Two major components of this infiltrate are neutrophils in the synovial fluid and macrophages in the synovial tissue. These cells produce cytokines including tumor necrosis factor alpha and other proinflammatory mediators that likely drive the disease through its effector phases. To investigate what mechanisms underlie the recruitment of these cells into the synovial fluid and tissue, we performed expression analyses of chemoattractant receptors in a related family that includes the anaphylatoxin receptors and the formyl-MetLeuPhe receptor. We then examined the effect of targeted disruption of two abundantly expressed chemoattractant receptors, the receptors for C3a and C5a, on arthritogenesis in a mouse model of disease. We report that genetic ablation of C5a receptor expression completely protects mice from arthritis.

Complement-induced impairment of innate immunity during sepsis

This study defines the molecular basis for defects in innate immunity involving neutrophils during cecal ligation/puncture (CLP)-induced sepsis in rats. Blood neutrophils from CLP rats demonstrated defective phagocytosis and defective assembly of NADPH oxidase, the latter being due to the inability of p47(phox) to translocate from the cytosol to the cell membrane of neutrophils after cell stimulation by phorbol ester (PMA). The appearance of these defects was prevented by in vivo blockade of C5a in CLP rats. In vitro exposure of neutrophils to C5a led to reduced surface expression of C5aR and defective assembly of NADPH oxidase, as defined by failure in phosphorylation of p47(phox) and its translocation to the cell membrane, together with failure in phosphorylation of p42/p44 mitogen-activated protein kinases. These data identify a molecular basis for defective innate immunity involving neutrophils during sepsis.

6-Sulfo LacNAc, a novel carbohydrate modification of PSGL-1, defines an inflammatory type of human dendritic cells

The monoclonal antibody M-DC8 defines a major subset of human blood dendritic cells (DCs). Here we identify the M-DC8 structure as 6-sulfo LacNAc, a novel carbohydrate modification of the P selectin glycoprotein ligand 1 (PSGL-1). In contrast to previously described blood DCs, M-DC8+ DCs lack the cutaneous lymphocyte antigen (CLA) on PSGL-1 and fail to bind P and E selectin. Yet they express anaphylatoxin receptors (C5aR and C3aR) and the Fcgamma receptor III (CD16), which recruit cells to inflammatory sites. While sharing with DC1 the expression of myeloid markers and a potent capacity to prime T cells in vitro, M-DC8+ DCs produce far more TNF-alpha in response to the bacterial endotoxin lipopolysaccharide (LPS). Thus, 6-sulfo LacNAc-expressing DCs appear as a novel proinflammatory DC subset.

Phagocytosis by emigrated, intra-abdominal neutrophils is depressed during human secondary peritonitis

The phagocytic function of neutrophils is a crucial element in host defense against invading microorganisms. Patients with diffuse peritonitis depend on adequate reactivity of neutrophils, in particular locally in the peritoneal cavity as well as in the circulation. This study examined phagocytosis as well as numerical expression of Fcgamma I-III (CD16, CD32, CD64) and complement receptors (CD18, CD35) of emigrated, intra-abdominal and circulating neutrophils during human secondary peritonitis using fluorescence-activated cell analysis. Optimally opsonized E. coli bacteria were used independently of the well-known low level of opsonic molecules during peritonitis. Compared with controls (abdominal surgery without peritonitis), the percentage of emigrated neutrophils which engulfed E. coli bacteria was significantly depressed until 48 h after diagnosis of, and surgery for, peritonitis. When patients with complicated peritonitis (septic shock, multiple organ failure) were compared with patients without complications, phagocytosis was even more depressed in patients with complications. Numerical expression of CD64 (Fcgamma RI) and CD35 (CR1) increased significantly on emigrated polymorphonuclear leukocytes (PMNs) during peritonitis when compared to controls. There was no difference in CD18 and CD32 (Fcgamma RII) expression between the two groups. Numerical expression of CD16 (Fcgamma RIII) on emigrated PMNs decreased significantly in peritonitis. This was more pronounced in patients with complicated peritonitis. We conclude that there is a long-lasting depression of phagocytosis by emigrated PMNs during peritonitis, independent of the opsonic activity. Our data suggest that decreased phagocytosis might be correlated to the profound drop in CD16 on these cells.

Mucosal type mast cells express complement receptor type 2 (CD21)

Fragments of complement component C3 generated upon activation of the cascade play an important role in the induction and regulation of immune responses. Receptors interacting with various fragments of this versatile complement protein are expressed on a wide variety of cell types, including lymphocytes, macrophages, dendritic cells, follicular dendritic cells, granulocytes, erythrocytes and consequently, C3-products may influence several biological functions at different sites of the body, where complement activation occurs. Regarding the expression of various C3-receptors on mast cells, mainly rodent serosal type mastocytes have been investigated so far. It has been known for a long time that C3a triggers the release of mediators of immediate type hypersensitivity via binding to serosal-type cells. Complement receptor type 1 (CR1/CD35) and type 2 (CR2/CD21) interacting with the larger activation products, such as C3b and C3d, have so far been shown on serosal type mast cells only. In this study, the expression of CR1/2 on mucosal type mast cells is demonstrated. Using mouse CR1/2 specific single chain antibodies and the natural ligand C3d in cytofluorimetric measurements, we show that the rat mucosal mast cell line RBL-2H3 and mouse bone marrow-derived mast cells (BMMC) express CD21. RT-PCR experiments carried out with mouse CR1 and CR2 specific primers show CD21, but not CD35 specific products in BMMC. It is also demonstrated that, in contrast to serosal type mast cells, mucosal mastocytes do not express CD19. In an attempt to reveal the possible function of CR2 on mucosal type mast cells, the effect of receptor-clustering was tested regarding degranulation, Ca-response and IL-6 production, but no CR2-mediated change was detected in any of these processes.

Surface expression of complement receptor gC1q-R/p33 is increased on the plasma membrane of human spermatozoa after capacitation

Evidence is increasing that complement components might play a role in fertilization. C1q, the first component of the classical complement cascade, has the ability to promote sperm agglutination in a capacitation-dependent manner as well as an effect on sperm-oolemma binding and fusion. We have previously detected gC1qR, the receptor for the globular head portion of C1q, on the surface of capacitated sperm. In this study, we examined the expression of gC1qR in both fresh and capacitated human spermatozoa. We performed immunoprecipitation for gC1qR and analyzed biotinylated sperm membrane by Western blot to illustrate an increase in receptor density after overnight capacitation. These results were confirmed by flow cytometric analysis of spermatozoa using fluorescein isothiocyanate-labeled monoclonal anti-gC1qR antibody. Confocal, indirect immunofluorescence microscopy revealed an increase in receptor expression over the rostral portion of the sperm head after capacitation. In addition, the ability of live spermatozoa to bind to monoclonal anti-gC1qR antibody-coated microtiter wells was also increased after capacitation. These results suggest that gC1qR may play a role in human fertilization.

Sialyl Lewis(x) hybridized complement receptor type 1 moderates acid aspiration injury

The potentially enhanced anti-inflammatory effects of the sialyl Lewis(x) (sLe(x))-decorated version of soluble complement receptor type 1 (sCR1) in moderating acid aspiration injury are examined. HCl was instilled in tracheostomy tubes placed in mice, and extravasation of (125)I-labeled albumin in bronchoalveolar lavage (BAL) fluid was used to calculate the vascular permeability index (PI). Neutrophil counts in BAL fluid and immunohistochemistry were performed. PI was moderated by 82% after treatment with sCR1sLe(x) compared with 54% in sCR1-untreated mice (P < 0.05). Respective reductions in PI in mice treated 0.5 and 1 h after acid aspiration with sCR1sLe(x) of 70 and 57% were greater than the decreases in PI of 45 and 38% observed in respective sCR1-treated groups (P < 0.05). BAL fluid neutrophil counts in sCR1sLe(x)-treated mice were significantly less than those in sCR1-treated animals, which were similar to those in untreated mice. Immunohistochemistry stained for sCR1 only on the pulmonary vascular endothelium of sCR1sLe(x)- but not sCR1-treated mice. In conclusion, sCR1sLe(x) moderates permeability by antagonizing complement activation and neutrophil adhesion. Delayed complement and neutrophil antagonism significantly reduces injury.

Characterization of endogenous Chinese hamster ovary cell surface molecules that mediate T cell costimulation

Chinese hamster ovary (CHO) cells are commonly used in the generation of transfectants for use in in vitro costimulation assays. However, we have noted that nontransfected CHO cells can themselves provide a low-level B7/CD28 independent costimulatory signal for CD3-mediated murine T cell activation and IL-2 production. This study set out to identify those molecules that contribute to this CHO-dependent costimulatory activity. We describe a CHO subline capable of delivering potent CD28-independent costimulation to murine T cells and the generation of monoclonal antibodies against these CHO cells that inhibited this costimulatory activity. These blocking antibodies do not affect CHO cell-independent costimulation or bind mouse cells, suggesting an effect mediated by their target molecules on the costimulatory competent CHO cells. Immunoprecipitation and expression cloning revealed that these antibodies bound the hamster homologues of Crry (CD21/35), CD44, CD54 (ICAM-1), CD63, CD87, CD147, and an 80- to 90-kDa protein which could not be cloned. Expression of these hamster genes on COS cells demonstrated that hamster CD54 was able to costimulate both CD3-mediated IL-2 secretion and T cell proliferation by naive murine T cells independent of the other molecules identified.

C1qR(P), a myeloid cell receptor in blood, is predominantly expressed on endothelial cells in human tissue

C1qR(P) is a type I cell surface glycoprotein that has been shown to enhance ingestion of suboptimally opsonized targets by phagocytes in vitro. In this study, we developed and characterized polyclonal antibodies to study the tissue distribution of this receptor targeted to either the N- or C-terminal portion of the molecule. C1qR(P) was detected in vascular endothelial cells and in a subset of pyramidal neurons in the brain, as well as neutrophils, but it was absent in most tissue macrophages. Analysis of in vitro differentiation of blood monocytes to dendritic cells demonstrated a down-regulation of the receptor as monocytes differentiate to dendritic cells, providing a possible explanation for the lack of reactivity of these cells in tissue. The predominant presence of C1qR(P) in endothelial cells, while compatible with a phagocytic role in host defense and/or clearance of cellular material, suggests other possible novel roles for this receptor.

Establishment of a swine monocyte cell line

A swine monocyte cell line was established from peripheral blood sample collected from a healthy adult male pig. The cloned cells grow actively in forming monolayers in both glass and plastic cell culture flasks with the growth medium reported previously (Kadoi, 2000) at 36.5 degrees C incubation. The plating efficiency is more than 95%. Densely grown cells in flasks show an epithelioid morphology. The fundamental properties of the cells were examined for cytological definition as monocytes. A positive property detected was guinea pig complement receptor, porcine IgG receptor, non-specific esterase, and acid phosphatase. A significant phagocytic activity proved by the inoculation of Saccharomyces cerevisiae is also one of the characteristics observed in the LPS-activated cells.

Use of complement receptor 1 (CD35) assay in the diagnosis and prognosis of immune complex mediated glomerulopathies

Complement Receptor 1 (CR1) is a polymorphic glycoprotein expressed on erythrocytes, leukocytes and glomerular podocytes and has a major role in immune complex processing. In addition, it regulates the complement cascade activation by preventing formation of classical and alternative pathway convertases and by acting as a cofactor for Factor I mediated cleavage of C3. In this study, we have examined the expression of erythrocyte CR1 (E-CR1) and glomerular CR1 (G-CR1) in different kinds of nephropathies using ELISA and immunofluorescence microscopy to understand their role in immune complex (IC) mediated renal diseases. E-CR1 was significantly reduced in all categories of lupus nephritis in comparison to normal subjects and non-IC renal diseases. However, other IC mediated diseases like IgA nephropathy and membranoproliferative glomerulonephritis had normal E-CR1 levels. G-CR1 showed distinct differences between IC and non-IC mediated diseases. G-CR1 was virtually absent in lupus kidneys. In other IC mediated diseases, there was a correlation of G-CR1 expression to the IC and complement fragment deposition. G-CR1 serves as a useful diagnostic marker for IC mediated diseases while E-CR1 is useful as a prognostic marker to monitor the course of disease after the treatment has initiated.

Upregulation of the p75 low-affinity neurotrophin receptor by phagocytically active perivascular active cells in the rat neural lobe

Expression of the p75 low-affinity neurotrophin receptor (p75NTR) was investigated immunocytochemically at the light and ultrastructural level during the axonal degeneration that follows partial denervation of the rat neural lobe (NL) and following systemic administration of lipopolysaccharide (LPS). A significant increase in the intensity and extent of p75NTR immunoreactivity in the NL of partially denervated animals compared with age-matched, sham-operated controls was observed at 5-10 days postdenervation, with immunoreactivity returning to control values by 35 days. Dual-label confocal comparison of p75NTR localization with that of the C3bi complement receptor, a microglial marker, and S100, an astrocyte-specific Ca2+-binding protein, revealed no colocalization. Immunoelectron-microscopic examination demonstrated that the p75NTR immunoreactivity is present in a subpopulation of cells located within the extensive perivascular space of the NL. No examples of p75NTR-immunoreactive pituicytes or endothelia were observed at the light or ultrastructural level. Dense p75NTR immunoreactivity was frequently observed surrounding endocytotic omega profiles of plasmalemma engulfing extracellular debris as well as lining vacuoles within the cytoplasm of perivascular cells. The association of p75NTR with phagocytosis was confirmed by confocal microscopy, showing the presence of p75NTR in all cells expressing the ED-1 antigen, which is restricted to the lysosomal membrane of phagocytes (Damoiseaux et al. 1994). Likewise, a marked increase in p75NTR and ED-1 immunoreactivity was observed in the NL following systemic administration of LPS. These results suggest a strong correlation between modulation of p75NTR immunoreactivity and conditions that induce high levels of phagocytic activity by perivascular cells in the NL of the rat. Implications for understanding the mechanisms by which phagocytes may support compensatory responses to neuronal injury are discussed.

Characterization and molecular cloning of rat C1qRp, a receptor on NK cells

Here we report the generation of monoclonal antibodies (mAb) LOV3 and LOV8 to a 110-130-kDa membrane glycoprotein expressed by rat NK cells. This NK surface molecule was identified by eucaryotic expression cloning as the structural orthologue of the phagocytosis-stimulating receptor for complement factor C1q and mannose-binding lectin on human macrophages, C1qRp. Rat C1qRp is a monomeric type I integral membrane protein consisting of 643 amino acids with an N-terminal lectin-like domain, five epidermal growth factor-like domains, a transmembrane domain and a 45-residue cytoplasmic domain. It is encoded by a single gene on rat chromosome 3q41-q42 and is 67% and 87.5% identical at the amino acid level to human and mouse C1qRp, respectively. Rat C1qRp is expressed by resting and by activated NK cells, on subpopulations of NKR-P1(+) T cells (NK/T cells), dendritic cells, macrophages and granulocytes, but not by B cells or NKR-P1(-) T cells. Expression of this innate immune receptor is therefore not restricted to hematopoietic cells of the myeloid lineage, but is also expressed on subsets of cells of lymphoid origin. The mAb did not affect the cytotoxic function of NK cells, and C1qRp on NK cells may have functions not related to NK killing.

[Evaluation of FcR and CR receptor expression in granulocytes and immune complex level in patients with tick-borne encephalitis (TBE)]

The aim of this study was to estimate expression of FcR and CR membrane receptors of PMN and circulating immune complexes level in serum from infected patients before and after treatment. Before treatment we observed significant decrease of PMN percentage with FcR and CR receptors in comparison to control. After treatment there was increase of PMN percentage with receptors in comparison to values before treatment but it did not reach values of controls. Immune complexes level before treatment was significant higher than controls before treatment and it decreased after treatment but did not reach control level. Depression of phagocytic activity of PMN may be one of the main reasons for spreading viral infection.

Analysis of the tissue distribution of the rat C5a receptor and inhibition of C5a-mediated effects through the use of two MoAbs

The C5-anaphylatoxin C5a is a protein of 74 (human) or 77 (rat) amino-acid residues, respectively, the generation of which may be induced by either the classical and/or the alternative pathways. C5a binds specifically to its receptor (C5aR/CD88) which belongs to the superfamily of G-protein-coupled receptors with seven transmembrane segments. In this study we describe the tissue distribution of the rat C5aR (rC5aR) and the blocking of its ligand by the application of two monoclonal antibodies (MoAbs). The first antibody (MoAb R63) which is directed against the amino-terminal domain Ex1 of the rat C5aR was generated in mice immunized with RBL-2H3 cells which had been stably transfected with the rat C5a receptor gene. Checking the rC5aR expression in various tissues bronchial epithelial cells stained positive only in tissue samples from animals with a mycoplasm infection indicating that the receptor may be induced in this cell type as a consequence of an inflammatory process. Using immunohistochemistry there was no evidence for nonmyeloid expression in the large or small intestine, heart, lung, kidney or liver of the normal rat. The MoAb R63 was found to be a reliable tool for the investigation of the expression of the receptor by FACS analyses or immunohistochemistry. Despite numerous attempts neutralizing antibodies could not be generated against the receptor. Therefore a C5a-ligand neutralizing MoAb was generated against the synthesized carboxyterminal 20mer peptide. This antibody (6-9F) recognized the carboxy terminus of C5a/C5a-FLUOS and prevented its binding at a three-fold molar excess as evidenced by FACS-analyses. It also blocked the C5a-mediated signal transduction as demonstrated by the inhibition of intracellular Ca2+-release (at a 16-fold molar excess) and the release of N-Acetyl-beta-D-glucosaminidase (at a 25-fold molar excess).

Intracerebral complement C5a receptor (CD88) expression is regulated by TNF and lymphotoxin-alpha following closed head injury in mice

The anaphylatoxin C5a is a potent mediator of inflammation in the CNS. We analyzed the intracerebral expression of the C5a receptor (C5aR) in a model of closed head injury (CHI) in mice. Up-regulation of C5aR mRNA and protein expression was observed mainly on neurons in sham-operated and head-injured wild-type mice at 24 h. In contrast, in TNF/lymphotoxin-alpha knockout mice, the intracerebral C5aR expression remained at low constitutive levels after sham operation, whereas it strongly increased in response to trauma between 24 and 72 h. Interestingly, by 7 days after CHI, the intrathecal C5aR expression was clearly attenuated in the knockout animals. These data show that the posttraumatic neuronal expression of the C5aR is, at least in part, regulated by TNF and lymphotoxin-alpha at 7 days after trauma.

Localization of P32 protein (gC1q-R) in mitochondria and at specific extramitochondrial locations in normal tissues

P32 protein, also known as the gC1q receptor for complement component C1q, is a binding protein for nuclear pre-mRNA splicing factor SF2/ASF and numerous other nuclear and cell surface proteins, yet is targeted to the mitochondrial matrix compartment where these proteins are not present. In the present study, we use immunogold electron microscopy to evaluate the subcellular distribution of P32 protein (gC1q-R) in cultured cell lines and in rat tissues embedded in the acrylic resin LR Gold. Immunogold labeling of Raji lymphoma, CHO, human fibroblasts, HeLa and B-SC-1 cells shows reactivity primarily within mitochondria. Highly specific labeling of mitochondria is also obtained in rat tissues, including adrenal gland, cerebellum, cerebral cortex, heart, kidney, liver, pituitary, pancreas, skeletal muscle, spleen, testes and thyroid. However, strong P32 (gClq-R) reactivity is also present in (i) zymogen granules, condensing vacuoles, endoplasmic reticulum, and on the cell surface of pancreatic acinar cells, (ii) on the cell surface of microvascular endothelial cells in pancreas and kidney, (iii) on the cell surface and in nuclei of splenic lymphocytes, and (iv) in the acrosome of developing spermatids in testes. Western immunoblots show that the polyclonal antibody to P32 (gC1q-R) used in this study reacts specifically with a 32-kDa protein in both purified pancreatic zymogen granules and in mitochondria, and no other proteins are reactive. These results provide evidence that P32 (gC1q-R) is a mitochondrial protein that also localizes outside mitochondria in certain cells and tissues under normal physiological conditions.

The C5a receptor is expressed by human renal proximal tubular epithelial cells

The C5a receptor is expressed by a variety of cell types. These studies demonstrate by immunohistochemistry that the receptor is present on the surface of proximal and distal tubular epithelial cells from normal kidney. In addition, the receptor was detected on transitional epithelial cells of the ureter and bladder. Primary proximal tubular cultures and a proximal tubular cell line both also expressed the C5a receptor, as demonstrated by immunofluorescence and by FACS analysis. The presence of mRNA encoding the receptor was confirmed by reverse transcriptase-polymerase chain reaction analysis. As opposed to its effect on glomerular mesangial cells, the receptor did not mediate a proliferative response by the proximal tubular cells. C5a also did not enhance the synthesis/secretion of transforming growth factor-beta 1, monocyte chemoattractant protein-1, platelet-derived growth factor-AB or tumour necrosis factor-alpha by cultured proximal tubular cells. Therefore, although the C5a receptor clearly is expressed by proximal tubular cells, clarification of its functional relevance on this cell type awaits further studies.

Expression of complement regulatory proteins in diffuse proliferative glomerulonephritis

This study assessed the expression of complement receptor 1 (CR1), decay accelerating factor (DAF) and membrane inhibitor of reactive lysis (CD59) on the erythrocytes and glomerulus of diffuse proliferative glomerulonephritis (DPGN) of systemic lupus erythematosus (SLE) patients using flow cytometry and immunofluorescence techniques to elucidate their role in the pathogenesis of DPGN. Expression of CR1 on the erythrocytes and glomerulus of DPGN patients was reduced compared with expression in normal subjects. However, expression of DAF and CD59 was increased on both erythrocytes and glomerulus of DPGN patients, suggesting the generation of a protective response against complement-mediated injury.

The absence of reactive astrocytosis is indicative of a unique inflammatory process in Parkinson's disease

Virtually any neurological disorder leads to activation of resident microglia and invasion of blood-borne macrophages, which are accompanied by an increase in number and change in phenotype of astrocytes, a phenomenon generally termed reactive astrocytosis. One of the functions attributed to activation of astrocytes is thought to involve restoration of tissue damage. Hitherto, the role of astrocytes in the inflammatory reaction occurring in Parkinson's disease has not received much attention. In the present study, we examined the inflammatory events in autopsies of the substantia nigra and putamen from Parkinson's disease patients using age-matched autopsies from normal patients as controls. In the substantia nigra, activation of microglia was consistently observed in all Parkinson's disease autopsies as verified from immunohistochemical detection of CR3/43 and ferritin. Activation of resident microglia was not observed in the putamen. No differences were observed between controls and Parkinson's disease autopsies from the substantia nigra and putamen, in terms of distribution, cellular density or cellular morphology of astrocytes stained for glial fibrillary acidic protein or metallothioneins I and II, the latter sharing high affinity for metal ions and known to be induced in reactive astrocytes, possibly to exert anti-oxidative effects. Together, these findings indicate that the inflammatory process in Parkinson's disease is characterized by activation of resident microglia without reactive astrocytosis, suggesting that the progressive loss of dopaminergic neurons in Parkinson's disease is an ongoing neurodegenerative process with a minimum of involvement of the surrounding nervous tissue. The absence of reactive astrocytosis in Parkinson's disease contrasts what follows in virtually any other neurological disorder and may indicate that the inflammatory process in Parkinson's disease is a unique phenomenon.

The C5a receptor is expressed in normal renal proximal tubular but not in normal pulmonary or hepatic epithelial cells

C5a, a 74 amino acid peptide cleaved from the complement protein C5, is an extremely potent anaphylatoxin. Expression of the receptor for the anaphylatoxin C5a (C5aR) has been thought to be restricted to cells of myeloid origin. However, recent evidence suggests that the C5aR is also expressed in hepatocytes as well as in pulmonary epithelial, endothelial and smooth muscle cells. In the present study, we investigated the tissue distribution of C5aR by immunohistochemistry in normal human lung, liver, intestine and kidney using well-defined monoclonal antibodies (mAbs) directed against the extracellular N-terminus of the receptor. In all tissues examined, macrophages displayed an abundant expression of C5aR protein. However, in the normal human lung, C5aR expression was not detectable in bronchial and alveolar epithelial cells or in vascular smooth muscle or endothelial cells. In the normal human liver, no C5aR protein was detected in hepatocytes, whereas Kupffer cells strongly expressed the C5aR. In normal human kidney, the C5aR was detectable only in proximal tubular cells. C5aR gene transcription in Kupffer cells and proximal tubular cells was confirmed by in situ hybridization. Thus, our results point to an as yet unknown role of the C5aR in normal renal physiology. In the normal lung and liver, however, previous evidence for the ubiquitous expression of C5aR in epithelial, endothelial and smooth muscle cells in situ should be re-evaluated.

Production and functional analysis of rat CD59 and chimeric CD59-Crry as active soluble proteins in Pichia pastoris

Crry (CR1-related gene/protein) is a rodent complement regulator that inhibits C3 convertases. CD59 is a conserved protein inhibitor active towards C8 and C9. We have previously produced rat Crry as a recombinant soluble (rs) protein in Pichia pastoris. In this study we produced functionally active rat rsCD59 and a chimeric rsCD59-Crry protein in P. pastoris. The GPI anchor addition site of rat CD59 (Asn-79) was replaced either by a stop codon to produce rsCD59, or with the sequence of the first five short consensus repeats of Crry to produce rsCD59-Crry. Proteins were generated by fermentation and purified by affinity chromatography on an anti-CD59 column. In a standard classical pathway haemolysis assay, all three rs proteins had inhibitory activity, with 50% inhibition at 0.5 microM (rsCrry and rsCD59-Crry) and 4.4 microM (rsCD59). In an assay examining inhibition of C5b-9, in which C5b-7 was first formed, followed by purified C8 and C9, rsCD59 and rsCD59-Crry were active with 50% inhibition at 0.8 microM (rsCD59-Crry) and 1.3 microM (rsCD59). The degree of inhibition was independent of whether the C8 and C9 were of rat or human origin. Therefore, we have produced rsCD59 and rsCD59-Crry in P. pastoris. The rsCD59 retains its inhibitory activity towards C5b-9, while rsCD59-Crry appears to have the combined activities of Crry and CD59. In a haemolytic assay, the inclusion of CD59 to Crry is of no additional benefit to Crry, which may illustrate the overall importance of the C3 convertase step. Yet, inclusion of Crry to CD59 increases the potency of CD59 towards C5b-9.

Expression of receptors for complement anaphylatoxins C3a and C5a following permanent focal cerebral ischemia in the mouse

In the present study, we have examined the expression of anaphylatoxin C3a and C5a receptors (C3aR and C5aR) at the mRNA and protein levels in ischemic brain tissues following permanent middle cerebral artery (MCA) occlusion in the mouse. C3aR and C5aR mRNAs were both detected by semiquantitative reverse transcription and polymerase chain reaction (RT-PCR) and the cellular distribution of each receptor was analyzed by immunohistochemistry. Significant increases in the expression of C3aR and C5aR mRNAs in the ischemic cortex were observed; the expression of both reached a peak at 2 days after MCA occlusion (4.3- and 3.4-fold increases, respectively, compared with nonoperated control cortical samples; P < 0.00625 with Bonferroni's correction, n = 3). C3aR and C5aR stainings were found constitutively on neurons and astrocytes. In ischemic tissues, we observed that C3aR and C5aR were expressed de novo on endothelial cells of blood vessels, at 6 h and 2 days after MCA occlusion, respectively. C3aR and C5aR immunostaining was increased in macrophage-like cells and reactive astrocytes 7 days postocclusion. C3a and C5a may play an important role in promoting inflammatory and/or repair processes in the ischemic brain by regulating glial cell activation and chemotaxis.

Crry, a complement regulatory protein, modulates renal interstitial disease induced by proteinuria

Crry, a complement regulatory protein, modulates renal interstitial disease induced by proteinuria.

BACKGROUND

Recent studies have suggested a role for urinary complement components in mediating tubulointerstitial damage, which is known to have a good correlation with progression of chronic renal diseases. Although accumulating evidence suggests that complement regulatory proteins play an important protective role in glomeruli, their role in renal tubules remains unclear. In order to establish the role of a complement regulatory protein, Crry, in renal tubular injury, we employed a molecular biological approach to block the expression of Crry in tubules of animals with proteinuria induced with puromycin aminonucleoside nephritis (PAN). Methods and Results. Two different antisense oligodeoxynucleotides (ODNs) against Crry were designed and applied to cultured rat mesangial cells in vitro in order to establish their efficacy. Antisense ODN treatment resulted in decreased expression of Crry protein associated with increased sensitivity to complement attack in cell lysis assays compared with control ODN treatment or no treatment (44.7, 1.50, and 1.34%, respectively). Antisense ODNs did not affect the expression of Thy1 as a control, confirming the specificity of our ODNs. In vivo, we performed selective right renal artery perfusion to administer antisense ODNs to the kidney and showed prominent uptake of ODNs by proximal tubular cells. Reduced expression of Crry protein was demonstrated in proximal tubular cells in antisense ODNs-treated kidneys. Normal rats treated with the antisense ODNs did not show any pathological changes. However, in PAN, rats with massive proteinuria showed increased deposition of C3 and C5b-9 in tubules in antisense-treated kidneys, and histological assessment revealed more severe tubulointerstitial injury in antisense-treated animals compared with controls.

CONCLUSION

These results establish a pathogenic role for complement in leading to tubulointerstitial injury during proteinuria and, to our knowledge for the first time, show a protective role of a complement regulatory protein, Crry, in renal interstitial disease.

Expression and distribution of various antigens of developing microglial cells in the rat telencephalon

The distribution of microglia during the early stages of postnatal development in the rat was studied on rat brain from day of birth to postnatal day 90 (P90), using immunohistochemical methods with a panel of monoclonal antibodies that recognized the complement type 3 receptor (OX-42), macrophage antigen of unknown function (ED1), and the major histocompatibility complex (MHC) class I (OX-18) or class II (OX-6) antigens. Starting from the day of birth, ameboid microglia can be differentiated with positive immunoreactivity to OX-42, OX-18, and ED1. Labeled cells were localized mainly in the developing white matter. After P21, only positive reaction to OX-42 was present, and those cells had the typical morphology of the resting microglial cells that were located either in the white or grey matter. The changes in the appearance of different antigens are correlated with the morphological differentiation and transformation of ameboid microglial cells that are to become ramified microglia, present in the adult animals.

C1q-containing immune complexes purified from sera of juvenile rheumatoid arthritis patients mediate IL-8 production by human synoviocytes: role of C1q receptors

Immune complexes that vary in size and composition are present in the sera and synovial fluid of juvenile rheumatoid arthritis (JRA) patients. They are believed to be potent inducers of the ongoing inflammatory process in JRA. However, the precise composition and role of these complexes in the pathophysiology of JRA remain unclear. We hypothesized that circulating ICs have the potential to interact with resident joint synovial fibroblasts (synoviocytes) and induce the expression of inflammatory cytokines. To test this hypothesis, cultures of synoviocytes from healthy individuals were treated with ICs isolated from the sera of JRA patients. Studies reported in this work demonstrate that IgM affinity-purified ICs from the sera of JRA patients contain IgM, C1q, IgG, and C3 to a variable extent. These ICs induce IL-8 mRNA and protein production in normal synoviocytes. Our data indicate that C1q in these ICs mediates, in part, IL-8 induction in synoviocytes. This is based on our findings of C1q-binding proteins for collagen stalks (cC1qR) and globular heads (gC1q-binding protein) of C1q in synoviocytes. In addition, collagen stalk and to some extent globular head fragments of C1q inhibit IC-mediated IL-8 induction in synoviocytes. Together, these findings provide evidence for a novel mechanism of IL-8 production by synoviocytes, which could play a key role in inflammation by recruiting leukocytes to synovial tissue and fluid-and subsequently contributing to joint disease.

Expression of the beta-chain of the complement regulator C4b-binding protein in human ovary

Human C4b-binding protein (C4BP) is an important regulator of the complement system that also binds and inactivates the anticoagulant vitamin K-dependent protein S. These two activities are performed by two distinct polypeptides of 70 kDa and 45 kDa known as alpha and beta chains, respectively. C4BP is present in plasma in various isoforms with different alpha/beta composition. We report here that C4BPbeta, but not C4BPalpha, is expressed in adult human ovary. Expression of C4BPbeta was detected in all ovarian biopsies analyzed (n = 15), independently of age and phase of the menstrual cycle. In situ hybridization and immunostaining analyses on cryostat sections demonstrated expression of C4BPbeta in both regressing corpus luteum and corpus albicans, but not in the follicles, the corpus luteum, the ovary stroma or the vascular cells. In addition, we noted that the expression pattern of the C4BPbeta mRNA resembles that described for the connective tissue that invades the degenerating corpus luteum and causes a progressive fibrosis that gradually converts it into a scar, the corpus albicans. RT-PCR and immunostaining analyses of primary cultures derived from human ovaries demonstrated the presence of fibroblast-like cells that express C4BPbeta. As a whole, these data suggest a role for the C4BPbeta in human ovary during the healing and scar resorption processes that leads to the formation of the corpus albicans and its replacement by ovarian stroma.

Assessment of certain neutrophil receptors, opsonophagocytosis and soluble intercellular adhesion molecule-1 (ICAM-1) following thermal injury

Polymorphonuclear leukocytes (PMLs) play a key role in host defense, and phagocyte dysfunction has been associated with increased susceptibility to infections in patients with thermal injury. Intercellular adhesion molecule-1 (ICAM-1) plays a role in leukocyte accumulation and extravasation. Therefore, the aim of the present study was to assess the PMLs expression of opsonin receptors: Fc gamma RIII, CR1 and CR3; opsonophagocytosis of PMLs and plasma soluble ICAM-1. Flow cytometric analysis (FCM) was used to study PMLs expression of IgG Fc-receptor III (Fc gamma RIII) as well as the complement receptors CR1 (receptor for C3b) and CR3 (receptor for C3bi) in 23 patients with large burns. Analysis of PML complement- and immunoglobulin-mediated phagocytosis of Candida albicans were performed in parallel using the phagocytic index. Plasma sICAM-1 was determined using ELISA. This study revealed a significant increase, with variable degrees, in CR1 and CR3-dependent fluorescence, complement-mediated phagocytosis of C. albicans and plasma sIGAM-1 that started at day 2 and remained for about 20 days before normalization. In contrast, Fc gamma RIII-dependent fluorescence and Ig-mediated phagocytosis were significantly decreased versus the control values. These results demonstrate significant changes of PMLs opsonin receptors expression and opsonophagocytosis documenting systemic activator of PMLs after large burns. In addition, elevation of plasma sICAM-1 may enhance the harmful effect of neutrophil activation through leukocyte accumulation and extravasation through endothelial damage in skin and in lung.

Comparison of C1q-receptors on rat microglia and peritoneal macrophages

A comparison of the expression and ligand specificity of the C1q (first complement component) receptor on rat microglia and peritoneal macrophages was made. This revealed that radiolabelled C1q was competed from the peritoneal macrophages with intact C1q, and additively displaced by calf-skin collagen and purified C1q globular heads, suggesting the presence of at least two receptors. This was in contrast to microglia, where radiolabelled C1q was displaced with intact C1q and to a modest degree with collagen, but not with globular heads. Taken together, this implies that under these conditions, peritoneal macrophages and microglia both express a C1q receptor which binds to the collagen-like region, and that peritoneal macrophages additionally express a molecule which binds to the globular head of C1q. Analysis of the ligand bound by these cells reflected the differences observed in the competitive binding experiments, with the novel identification of naturally-occurring peptides from the globular head of C1q bound to the peritoneal macrophages, but not the microglia.