Alpha- and gamma-interferon (IFN alpha, IFN gamma) but not interleukin-1 (IL-1) modulate synthesis and secretion of beta 2-microglobulin by hepatocytes

CCR7-expressing B16 melanoma cells downregulate interferon-γ-mediated inflammation and increase lymphangiogenesis in the tumor microenvironment

The expression of the CC chemokine receptor-7 (CCR7) by cancers, including melanoma, augments lymph node (LN) metastasis, but little is known about its role in lymphangiogenesis and anti-tumor immunity. We injected control B16 murine melanoma cells (pLNCX2-B16) and CCR7-overexpressing B16 cells (CCR7-B16) in murine footpads and compared resulting tumors at the protein and mRNA level using immunostaining, Affymetrix gene microarray and quantitative reverse-transcriptase PCR. Although control and CCR7-B16 primary tumors were of similar size, LN metastasis was dramatically enhanced in CCR7-B16 tumors. Microarray analysis of leukocyte-depleted pLNCX2-B16 and CCR7-B16 tumor cell suspensions showed that three major groups of genes linked to interferon (IFN)-γ signaling pathways (for example, STAT1, CXCR 9-11, CCL5 and CXCL10, major histocompatibility complex (MHC) I and MHC II) were downregulated in the CCR7-B16 tumor microenvironment, suggesting activation through CCR7 can downregulate pathways critical for host anti-tumor immunity. In addition, mRNA expression of the lymphatic marker podoplanin was upregulated in CCR7-B16 tumors by 3.35-fold versus control tumors. Anti-podoplanin monoclonal antibody staining revealed a three-fold increase in intratumoral CCL21-expressing lymphatic vessels, as well as a two-fold increase in the number of invading tumor cells per lymphatic vessel in CCR7-B16 versus control tumors. Enhanced anti-vascular endothelial growth factor C (VEGF-C) staining was present in CCR7-B16 versus control tumors, suggesting that VEGF-C may have a role in the CCR7-mediated lymphangiogenesis. In summary, CCR7-B16 tumors show a striking decrease in IFN-γ-mediated inflammatory gene expression in contrast to increased expression of VEGF-C, CCL21 and podoplanin by lymphatic vessels. Enhanced lymphangiogenesis may contribute to the dramatic increase in LN metastasis that is observed in the CCR7-expressing tumors.

Cellular Localization and Function of the Antiviral Protein, Ovine Mx1 (oMx1): II. The oMx1 Protein Is a Regulator of Secretion in an Ovine Glandular Epithelial Cell Line

PROBLEM

Embryonic loss is a major contributor to infertility. Understanding factors affecting embryonic loss will help increase fertility.

METHOD OF STUDY

We investigated if ovine Mx1 (oMx1) mediated secretion by ovine glandular epithelial (oGE) cells using small interfering RNA (siRNA). Effects on secretion were examined through the conventional endoplasmic reticulum-Golgi pathway using beta2- microglobulin (beta2MG) as a marker, and interferon-stimulated gene 15 (ISG15) as a marker for unconventional secretion.

RESULTS

Mx1 siRNA reduced oMx1 mRNA levels at 12 and 24 hr after IFN-tau treatment (P < 0.05), without affecting levels of oMx2, ISG15, 2',5'-oligoadenylate synthetas or beta2MG. Mx1 siRNA reduced Mx1 protein levels at 48 and 120 hr after treatment (P < 0.05) and protein levels remained low at 120 hr. Transient oMx1 knock-down reduced secretion of oMx1 (P < 0.01). ISG15 protein in secretions was reduced without affecting intracellular levels (P < 0.05). Levels of beta2MG in secretions were not affected by Mx1 siRNA.

CONCLUSION

We showed that oMx1 protein is secreted by oGE cells and that reduction in oMx1 protein levels by siRNA reduced secretion of ISG15, but not beta2MG. Results support the hypothesis that oMx1 is a regulator of secretion through unconventional secretory pathway(s).

beta(2)-Microglobulin amyloidosis caused spinal cord compression in a long-term haemodialysis patient

STUDY DESIGN

A case report of cervical myelopathy caused by epidural beta (2)-microglobulin (beta2m) amyloid deposits in a 50-year-old woman with haemodialysis treatment.

OBJECTIVE

Long-term haemodialysis in patients with end-stage renal disease leads to several complications based on beta2m deposits, which can affect, in the cervical spine, the intervertebral disk, and in rare cases, they may compress the spinal cord and nerves. The objective of this report is to describe the clinical and radiological follow-up preceding the indispensable surgical excision of an amyloid mass in a 50-year-old woman with haemodialysis treatment. Long-term postoperative cervicalgia owing to subcondylian bone cyst-associated atlanto-occipital instability is also described and discussed.

SETTING

Department of Neurosurgery A, Hop Pellegrin, Bordeaux, France.

CASE REPORT

We present a clinical case of a patient with spinal cord compression. The patient was treated by surgical excision of an amyloid mass subsequent to a C2-C3 laminectomy. The patient experienced clinical improvement with a regression of all of her neurological symptoms. Histological findings confirm the diagnosis of beta2m amyloid deposition. However, 5 years after surgery the subcondylian bone cysts were still observed and atlanto-occipital instability required her to wear a minerva.

CONCLUSION

Our case report confirms that surgical excision of beta2m epidural deposits is necessary and relevant when neurological prognosis is discussed, and that pain is still the major symptom of disease evolution. The use of high-flux synthetic membranes could decrease the beta2m blood level and early renal graft is the only method to prevent such complications.

Characterization of the proteins released from activated platelets leads to localization of novel platelet proteins in human atherosclerotic lesions

Proteins secreted by activated platelets can adhere to the vessel wall and promote the development of atherosclerosis and thrombosis. Despite this biologic significance, however, the complement of proteins comprising the platelet releasate is largely unknown. Using a proteomics approach, we have identified more than 300 proteins released by human platelets following thrombin activation. Many of the proteins identified were not previously attributed to platelets, including secretogranin III, a potential monocyte chemoattractant precursor; cyclophilin A, a vascular smooth muscle cell growth factor; calumenin, an inhibitor of the vitamin K epoxide reductase-warfarin interaction, as well as proteins of unknown function that map to expressed sequence tags. Secretogranin III, cyclophilin A, and calumenin were confirmed to localize in platelets and to be released upon activation. Furthermore, while absent in normal vasculature, they were identified in human atherosclerotic lesions. Therefore, these and other proteins released from platelets may contribute to atherosclerosis and to the thrombosis that complicates the disease. Moreover, as soluble extracellular proteins, they may prove suitable as novel therapeutic targets.

Regulation of haptoglobin secretion by recombinant bovine cytokines in primary cultured bovine hepatocytes

We examined the regulation of haptoglobin (Hp) secretion in primary cultured bovine hepatocytes using recombinant bovine (rb) proinflammatory cytokines. The concentrations of Hp in the supernatant of cultured hepatocytes after incubation with rb interleukin (IL)-6, rb tumor necrosis factor (TNF)-alpha, rbIL-1 beta or rbIFN-gamma alone or with combinations of two of these cytokines were measured by ELISA. The rbIL-6, rbTNF-alpha and rbIL-1 beta increased Hp synthesis, but rbIFN-gamma did not, and rbIL-6 was the most effective Hp inducer among these cytokines. The Hp secretion was accelerated synergistically by combined treatment with rbIL-6 and rbTNF-alpha, whereas it remained unchanged with a combination of rbIL-6 and rbIL-1 beta. In contrast, the combination of rbIL-6 and rbIFN-gamma downregulated Hp secretion. In conclusion, IL-6 is the principal cytokine in Hp secretion in bovine hepatocytes in vitro, and its activity may be regulated by other cytokines.

Prenatal evaluation of fetal renal function based on serum beta(2)-microglobulin assessment

The relationship between fetal renal function (FRF) and fetal serum beta(2)-microglobulin (B2MG) was investigated by comparing its value in 112 unaffected fetuses with that of 23 fetuses presenting with urinary tract malformations (UTM). Fetal serum level of B2MG was totally unrelated to gestational age; its value increased in cases of severe impairment of FRF but was similar to controls in all mild uropathies (p<0.05). Evaluating serum B2MG could be beneficial in fetuses with severe renal damage, but is of no use in unilateral UTM since only the global FRF is tested and not the function of each single kidney.

Role of beta(2)-microglobulin in the immune response in renal osteodystrophy

Renal osteodystrophy is the major cause of skeletal morbidity in dialysis patients. It is characterized by beta(2)-microglobulin (beta(2)M) amyloid deposition at the osteoarticular sites and a destructive arthropathy. beta(2)M is present on the surface of all nucleated cells as the small extracellular subunit of the major histocompatibility complex (MHC) class I molecule and actively participates in the immune response. Accumulating evidence suggests that beta(2)M plays a key role in the development of renal osteodystrophy through a T cell-mediated inflammatory immune mechanism.

Control of apolipoprotein E secretion in the human hepatoma cell line KYN-2

Even though it is known that apolipoprotein E (apoE) is deeply involved in major age-related disorders such as atherosclerosis or Alzheimer's disease (AD), the control of cell-specific apoE expression is still poorly understood. We compared the apoE secretion as previously described in astrocytic cell17 to hepatic cell apoE secretion. We used the human hepatoma cell line KYN-2 to better delineate the characteristics of apoE secretion and to validate it with respect to the classical human hepatoma cell line HepG2. Interleukin-1beta (IL-1beta) and interferon-gamma (IFN-gamma) significantly inhibited, while IL-2, IL-6 and tumour necrosis factor-alpha (TNF-alpha) were inactive on apoE secretion by KYN-2 as well as HepG2 cells. Cholesterol and 25-OH cholesterol had no effect, while forskolin exerted a significant inhibitory effect, on apoE secretion in KYN-2 cells. Our results suggest that the KYN-2 cell line represents an appropriate cell model, and in any case an alternative model to the HepG2 cell line, to study the control of apoE secretion. The response of KYN-2 cells to both cytokines and cholesterol differs from that found in astrocytoma cells, suggesting that blood variations of apoE concentrations in AD may not reflect the dysregulations taking place in the brain.

Dialysis-related spinal canal stenosis: a clinicopathological study on amyloid deposition and its AGE modification

Three cases operated for spinal canal stenosis induced by dialysis-related amyloidosis (DRA) were investigated clinicopathologically. Cases were all-male, and had undergone hemodialysis around 20 years. In two cases, cervical plain X-rays showed only minor spondylotic changes. However, magnetic resonance imaging (MRI), myelography, and computed tomography (CT) showed extradural thickness with compression on the cervical spinal cord and cauda equina. In one case cervical X-rays showed typical destructive spondyloarthropathy (DSA), and MRI showed compression myelopathy. Surgical treatment on both cervical and lumbar spine in two cases and on cervical spine only in one case successfully reduced the symptoms. Extradural thickened tissue and ligament flavum obtained during surgery were studied histopathologically and immunostained by using anti-CD68, anti-beta2-microglobulin (beta2m), and anti-advanced glycation end product (AGE) antibody. Congo red stain showed diffuse or nodular amyloid deposition, and immunostaining with anti-beta2m and anti-AGE antibodies also demonstrated the same distribution pattern. Thus, beta2m-positive amyloid tissue in the extradural thickness (extradural amyloid deposition) was immunohistochemically demonstrated to be modified with AGE. Inflammatory reaction with histiocytic and giant cell infiltration was also shown around the amyloid tissues. There were CD68-positive cells, and some cells were positive for AGE and beta2m. These findings suggest that beta2m accumulation and inflammatory reaction finally promote destruction of connective tissues. MRI, CT and/or myelography are necessary for diagnosing spinal canal stenosis accompanied by DRA. In conclusion, we propose a more comprehensive concept of dialysis-related spinal canal stenosis, which includes both DSA and myeloradiculopathy induced by extradural thickness.

Regulation of beta2-microglobulin expression in different human cell lines by proinflammatory cytokines

BACKGROUND

Proinflammatory monocytic cytokines such as interleukin-1 (IL-1), tumour necrosis factor-alpha (TNF-alpha) and IL-6 have been incriminated in the pathogenesis of elevated beta2-microglobulin (beta2M) serum concentrations in patients undergoing haemodialysis with so-called bioincompatible dialyser membranes. However, neither the source of the elevated serum beta2M nor the precise role of monocytic cytokines in the expression of the beta2M gene have been elucidated conclusively. The aim of the current study was to evaluate whether monocytic cytokines, and in particular IL-6, are regulators of beta2M gene expression in human hepatoma cells, T-lymphocytes and monocytes.

METHODS

HepG2 and HuH7 human hepatoma cells, Jurkat T-cells, monocytic MonoMac6 cells, primary human monocytes and synoviocytes were stimulated with IL-1beta, IL-6, interferon-alpha (IFN-alpha), IFN-gamma or conditioned media from lipopolysaccharide (LPS)-treated monocytes. Expression of beta2M mRNA was analysed by Northern blotting, beta2M protein synthesis was determined by metabolic labelling and immunoprecipitation, and beta2M secretion was measured by an enzyme-linked immunosorbent assay (ELISA).

RESULTS

In all cell types tested, IFN-gamma and, to a lesser extent, IFN-alpha stimulated gene expression of beta2M resulting in an increased synthesis and secretion of beta2M protein. Neither IL-1beta and IL-6 nor supernatants from LPS-treated monocytes were capable of inducing beta2M gene expression, with the exception of a small increase in HuH7 hepatoma cells upon IL-1beta treatment.

CONCLUSIONS

The present study provides evidence that interferons are important regulators of beta2M expression. It also shows that proinflammatory monocytic cytokines do not modulate directly the expression of beta2M in cells of hepatic, monocytic and T-lymphocytic origin. Whether they influence beta2M synthesis and secretion indirectly by modulating interferon synthesis needs to be elucidated.

Synthesis and turnover of beta2-microglobulin in Ad12-transformed cells defective in assembly and transport of class I major histocompatibility complex molecules

In primary embryonal fibroblasts from transgenic mice expressing H-2 genes and a miniature swine class I transgene (PD1), transformation with the highly oncogenic Ad12 results in a reduction in peptide transporter and proteasome-associated (LMP2 and LMP7) gene expression, and suppression in transport and cell surface expression of all class I antigens. The selective suppression in transport of H-2 (but not of PD1) molecules in cells reconstituted for the expression of peptide transporter and LMP genes implied that an additional factor(s) is involved in the assembly of class I complexes. Here we show that the beta2m, H-2Db, and H-2Kb genes are transcribed and translated in Ad12-transformed cells. However, unlike normal and E1Ad5-transformed cells, in which beta2m is either secreted unbound or bound to class I heavy chains, in Ad12-transformed cells significant amounts of beta2m are retained in the cell bound to the membrane, but free of class I heavy chains. This abnormal turnover of beta2m in the Ad12-transformed cells suggests the existence of a novel beta2m-binding molecule(s) that sequesters beta2m, and this process may provide a mechanism by which transformation with Ad12 may subvert class I complex formation.

Biological responses to administered interferon in alcoholics

To elucidate the influence of chronic alcohol intake on interferon (IFN) therapy in patients with various diseases, 3 million units of natural IFN (nHuIFN-alpha Ly) was administered once to alcoholics, nonalcoholic chronic hepatitis C (CH-C) patients, and healthy subjects. The serial changes of serum activity of 2'-5' oligoadenylate synthetase, serum levels of beta 2-microglobulin, C-reactive protein (CRP), and body temperature were monitored. The increase in the activity of 2'-5' oligoadenylate synthetase, the response of serum-reactive protein, and body temperature after IFN administration were significantly lower in the alcoholics than those in CH-C group, and healthy subjects (control group). The serum beta 2-microglobulin level was already higher in the alcoholics before IFN administration than those of the control group and the CH-C group. These findings suggest that physiological responses to exogenous IFN in alcoholics are generally decreased. Hence, for the maximum effect of IFN therapy, it is important for patients to abstain from alcohol intake and for doctors to carefully consider the timing of initiation.

Inflammatory effects of peritoneal dialysis: evidence of systemic monocyte activation

We evaluated in peritonitis-free patients undergoing continuous ambulatory peritoneal dialysis (CAPD) the release of both interleukin-6 (IL-6) and beta-2-microglobulin (beta 2m) by cultured peripheral blood mononuclear cells (PBMC), as well as the levels of serum amyloid A (SAA), that is, the main hepatic acute phase protein during inflammation. The same measurements were obtained in hemodialysis (HD) patients, uremic non-dialyzed patients (ESRD) and healthy controls (CON). In CAPD, IL-6 production from PBMC was markedly increased in comparison to the control value (600.7 +/- 104.3 vs. 14.2 +/- 3.6 pg/3 x 10(6) PBMC/24 hr, P < 0.005). Similarly, a striking enhancement of the PBMC release of beta 2m was detected in CAPD with respect to CON (10.1 +/- 2.6 vs. 0.063 +/- 0.013 micrograms/3 x 10(6) PBMC/24 hr, P < 0.001). Also, the SAA levels were significantly greater in CAPD patients (21.3 +/- 8.7 micrograms/dl) than in controls (3.14 +/- 0.17 micrograms/dl, P < 0.05). Analogous increases of both IL-6 and beta 2m cell releases, as well as of SAA levels, were observed in HD patients. No difference concerning the three parameters was detected between CON and ESRD. In conclusion, CAPD induces per se PBMC activation with an enhanced release of both IL-6 and beta 2m; this is associated to higher levels of SAA. These systemic inflammatory effects are comparable to those observed in HD patients indicating that CAPD is similar to HD in terms of biocompatibility of the treatment.

Serum and urine beta-2-microglobulin in hemophagocytic syndrome

BACKGROUND

Previous reports suggesting a correlation between lymphoproliferative disease and serum levels of beta-2-microglobulin (beta-2M) and in vitro data indicating a role of cytokines in the production of beta-2M prompted a study of serum and urine beta-2M concentration in patients with hemophagocytic syndrome (HPS), because no data were previously available for HPS, a pathologic state associated with excessive cytokines secreted from activated reactive/malignant lymphocytes and histiocytes.

METHODS

Serum and urine beta-2M levels were measured in six children with HPS during active and convalescent phase and in other diseases.

RESULTS

Serum and urine beta-2M levels during active phase HPS were significantly high not only in serum (median, 7.5 mg/l; range, 2.3-16.0 mg/l; P < 0.01), but also in urine (median, > 31,650 micrograms/gram Creatinine (gCr); range, 8179-236,333 micrograms/gCr; P < 0.01), compared with levels during convalescent phase HPS (median, 2.0 mg/l; range, 0.9-2.5 mg/l in serum and median, 338 micrograms/gCr; range, 223-585 micrograms/gCr in urine) and in control subjects with diseases such as acute lymphocytic leukemia (median, 2.3 mg/l; range, 1.0-2.8 mg/l in serum and median, 327 micrograms/gCr; range, 48-2684 micrograms/gCr in urine), infectious mononucleosis (median, 2.9 mg/l; range, 2.5-5.5 mg/l in serum and median, 348 micrograms/gCr; range, 80-1325 micrograms/gCr in urine), and Kawasaki disease (median, 2.8 mg/l; range, 1.5-3.3 mg/l in serum and median, 1016 micrograms/gCr; range, 214-4500 micrograms/gCr in urine). Noteworthy was the observation that urine beta-2M levels correlated closely with HPS disease activity.

CONCLUSIONS

Urine beta-2M appears to be a useful marker for assessing disease activity in patients with HPS.

Dialysis-associated amyloidosis

Dialysis-related arthropathy represents a major complication of uremic patients treated by hemodialysis or other renal replacement therapies. Nearly 10 years ago, this syndrome was shown to be associated with a new type of amyloid, mainly composed of beta-2 microglobulin (beta 2-M). Retention of the beta 2-M protein due to chronic renal failure, although unquestionably a prerequisite for the occurrence of beta 2-M amyloidosis, appears not to be the unique pathogenetic factor involved in this complication. A role has also been attributed to an enhanced local or systemic generation of inflammatory mediators, an increased production of beta 2-M, and an altered metabolism of the molecule including partial proteolysis and glycation. It is possible that factors related to renal replacement therapy such as dialysis membrane biocompatibility also play a role. However, the clarification of the precise underlying mechanism(s) awaits further study. Because dialysis technology has progressed considerably during the last decade, a significant beta 2-M removal can be achieved at present using high-flux dialyzers. Moreover, a marked reduction in bioincompatibility during the dialysis procedure as manifested by activation of complement and stimulation of mononuclear blood cells can now be attained. Future studies will tell whether technical progress in dialysis technique results in a decrease in the incidence of symptomatic dialysis-associated amyloidosis.

Human hepatoma cells synthesize and secrete lysozyme: modulation by cytokines

Plasma lysozyme levels are elevated in several different pathological conditions. In our study we show that well differentiated human hepatoma cells Hep3B and HepG2 are active synthesis sites of lysozyme and that this synthesis can be modulated by acute phase mediators. The production and modulation of lysozyme synthesis was studied by means of Northern-blot analysis, sodium dodecyl sulfate-polyacrylamide gel electrophoresis and a specific bioassay after treatment of the cells with interleukin-1 beta, interleukin-6 and tumor necrosis factor-alpha. Hep3B and HepG2 cells constitutively synthesize high amounts of lysozyme. Lysozyme synthesis and secretion were found to be augmented by interleukin-1 beta and tumor necrosis factor-alpha in both cell lines. Interleukin-6 caused an increase in lysozyme production in Hep3B but a decrease in the HepG2 cells. As expected, the synthesis of albumin was decreased in both cell lines. Furthermore we demonstrated that HepG2 and Hep3B cells produce a biologically active form of the enzyme as measured by a specific bioassay. The results demonstrate that lysozyme is constitutively synthesized by Hep3B and HepG2 hepatoma cell lines and that lysozyme synthesis is modulated by acute-phase mediators. Well differentiated human hepatoma cells may respond differently to different cytokines.

Relationship between the tumour-associated antigen 90K and cytokines in the circulation of persons infected with human immunodeficiency virus

A tumour-associated antigen known as 90K has been found in high concentrations in the serum of patients infected with human immunodeficiency virus (HIV) even in the absence of neoplastic complications. In order to investigate the relationship between the production of 90K and soluble inflammatory mediators, we studied serum concentrations of the antigen, tumour necrosis factor-alpha (TNF-alpha), interleukin-I-alpha (IL-I-alpha), interferon-gamma (IFN-gamma), IFN-alpha, neopterin and beta 2-microglobulin (beta 2-m) in patients with non-neoplastic HIV infection at various stages of disease and in control persons. The antigen was detected in all those studied but its concentration was higher in HIV-infected patients compared with controls (P < 0.001), increasing progressively with advancing stages of disease. There was a negative correlation between concentrations of 90K and IL-I-alpha in patients in U.S.A. Centers for Disease Control groups II and III (P < 0.02) and also between that of 90K and both TNF-alpha (P < 0.01) and IL-I-alpha (P < 0.05) in control persons. The results indicate that 90K is not merely a tumour-associated antigen and that its production may be part of immune and inflammatory responses in the absence of neoplasia. The correlation between the concentrations of 90K and of some cytokines in asymptomatic patients and healthy persons suggests that 90K may be part of a network of immune and inflammatory reactants.

Intercellular adhesion molecule-1 concentration in sera of patients with acute and chronic liver disease: relationship to disease activity and cirrhosis

To study the influence of chronic hepatitis on intercellular adhesion molecule-1 serum concentration, we measured intercellular adhesion molecule-1 in the serum of 84 patients with chronic liver disease (17 chronic persistent hepatitis, 42 chronic active hepatitis and 25 active cirrhosis) caused by hepatitis B virus (n = 46), hepatitis C virus (n = 10) and autoimmunity (n = 28). Furthermore, 20 patients with acute viral hepatitis (16 hepatitis B virus and 4 hepatitis A virus) and 6 patients with acute drug-induced hepatitis were included. Sera from 20 healthy persons were used as control. Follow-up examinations were performed during immunosuppressive therapy in 20 patients with autoimmune chronic liver disease (13 chronic active hepatitis and 7 active cirrhosis). Intercellular adhesion molecule-1 serum concentration was significantly increased in patients with acute viral hepatitis, drug-induced hepatitis, chronic active hepatitis and active cirrhosis compared with healthy controls and with patients with chronic persistent hepatitis. Intercellular adhesion molecule-1 was also significantly increased in severe chronic active hepatitis and active cirrhosis compared with moderate chronic active hepatitis and moderate active cirrhosis. Serum concentration of intercellular adhesion molecule-1 decreased significantly in patients with autoimmune chronic liver disease after 2 mo of immunosuppression when remission was present. A close correlation between aspartate aminotransferase and intercellular adhesion molecule-1 serum levels was found. We conclude the following: (a) in chronic liver disease intercellular adhesion molecule-1 serum concentration may represent, at least in part, hepatocellular damage; and (b) intercellular adhesion molecule-1 serum level does not differentiate between chronic autoimmune and chronic viral hepatitis.

Immunogenicity of rat hepatocytes in vivo: effect of cholestasis-induced changes in major histocompatibility complex expression

Hepatocytes normally express few major histocompatibility complex (MHC) class I and no MHC class II molecules, a phenomenon which could explain their low immunogenicity. However, in pathological situations, such as allograft rejection and cholestasis, hepatocytes strongly express MHC class I molecules and their immunogenicity could be different. The aim of this study was to assess the role of MHC expression on the immunogenicity of hepatocytes in vivo. Hepatocytes were obtained from normal and cholestatic DA rats by whole-liver perfusion with EDTA. Cholestasis was induced by ligation-section of the common bile duct. MHC expression on hepatocytes was assessed by cytofluorimetry after labelling with monoclonal antibodies against MHC class I and class II antigens. The percentage of hepatocytes expressing MHC class I was 9.8 +/- 2.2% in normal rats and 77.2 +/- 3.3% in cholestatic rats (P = 2 x 10(-4)); MHC class II expression was present on 1 +/- 0.5% of normal hepatocytes and 0.4% +/- 0.1% of cholestatic hepatocytes (P > 0.05). Lewis rats received a DA or Wistar-Furth heart allograft 7 days after intravenous injection of 2 x 10(7) hepatocytes from normal or cholestatic DA rats. The DA heart allograft was rejected in 6.3 +/- 0.4 days in Lewis controls, 8.8 +/- 1.1 days (N.S.) in Lewis recipients that received normal DA hepatocytes and 17.6 +/- 3.0 days (P = 2 x 10(-4)) in Lewis recipients that received hepatocytes from cholestatic DA rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Variability in the expression of a beta 2-microglobulin epitope on hepatocytes in chronic type C hepatitis on treatment with interferon

Cytotoxic CD8+ T lymphocytes recognize viral antigens in the context of human leukocyte antigen class I molecule coexpression by target cells. Analysis of beta 2-microglobulin reactivity is useful in evaluating changes in human leukocyte antigen class I antigen distribution. In this study we analyzed liver biopsy specimens obtained from 15 patients with chronic active hepatitis type C who underwent a clinical trial with recombinant interferon-alpha 2b. We comparatively studied by immunohistochemical analysis the expression of human leukocyte antigen class I antigens in frozen liver samples obtained before entry in the protocol and in specimens taken 8 mo after initiation of treatment. Six normal liver samples were used as controls. For immunohistochemical analysis, a panel of several human leukocyte antigen class I monoclonal antibodies, specific for beta 2-microglobulin or different heavy-chain determinants, was used. In addition, we included a novel monoclonal antibody (HP-1H8), characterized in this report, which is specific for a distinct beta 2-microglobulin epitope. On entry, mean serum ALT was 240 +/- 89 IU/L and mean Knodell's index was 9.9 +/- 2.4, whereas at the time of the second biopsy mean values had diminished to 45 +/- 22 IU/L and 4.7 +/- 3.0, respectively. Liver sections from controls and patients expressed human leukocyte antigen class I light- and heavy-chain determinants in hepatocytes, biliary duct epithelium, sinusoidal lining cells and lymphocytes. Remarkably, the beta 2-microglobulin epitope recognized by the HP-1H8 monoclonal antibody was undetectable on hepatocytes from normal livers but clearly evident on hepatocytes from patients with chronic active hepatitis C before interferon treatment. Positive staining was more intense in areas of piecemeal and lobular necrosis. Double immunostaining with a CD2 monoclonal antibody demonstrated that labeling with HP-1H8 was predominantly associated with T-cell infiltration. Interestingly, the reactivity of HP-1H8 with hepatocytes was diminished or disappeared in specimens obtained during interferon treatment; the pattern of reactivity then resembled that of samples from normal controls. Our data indirectly suggest that, in addition to the increased expression of human leukocyte antigen class I molecules on hepatocytes in viral infections, conformational changes may take place in these antigens. These changes can be revealed by immunostaining with the HP-1H8 monoclonal antibody. Interferon therapy could down-regulate this expression through its effect in reducing the histological activity resulting from the lysis of virus-infected hepatocytes by cytotoxic T cells.

Reversible inhibition of albumin production by rat hepatocytes maintained on a laminin-rich gel (Engelbreth-Holm-Swarm) in response to secretory products of Kupffer cells and cytokines

Decreased albumin synthesis by hepatocytes in liver injury is thought to occur in response to Kupffer cell-derived acute-phase cytokines. In this study we used hepatocytes maintained in a differentiated phenotype, by culture on a laminin-rich gel substratum (Engelbreth-Holm-Swarm matrix), to investigate the effects of Kupffer cell-conditioned medium and purified cytokines (interleukin-1, interleukin-6 and tumor necrosis factor-alpha) on albumin synthesis. Kupffer cell-conditioned medium caused a reversible decrease in albumin synthesis to 64.7% of control (p less than 0.01, Wilcoxon's rank sum test, n = 11) on day 2. Repeated doses caused further dose-dependent reversible responses. The same result was obtained when protease inhibitors (alpha 1-antitrypsin and alpha 2-macroglobulin) were added to Kupffer cell-conditioned medium (n = 3), thus eliminating the potential effect of matrix degradation. Pure interleukin-1, interleukin-6 and tumor necrosis factor-alpha also inhibited albumin synthesis (p less than 0.05, Wilcoxon's rank sum test, n = 5), interleukin-6 having the greatest effect. After exposure to interleukin-1 (30 U.ml-1) and tumor necrosis factor-alpha (300 U.ml-1), decreased albumin synthesis was followed by a rebound increase (n = 3). Our results support the hypothesis that reduced albumin synthesis in the acute-phase response is modulated by cytokines released from Kupffer cells. Moreover, our results suggest that hepatocytes may exhibit a compensatory increase in albumin synthesis after cytokine withdrawal. These findings may be of physiological importance in the recovery from injury and the acute-phase response in vivo.

IL-1 beta and prostaglandins regulate integrin mRNA expression

The purpose of this study was to examine the effects of IL-1 beta on integrin expression in MG-63 human osteosarcoma cells. Human recombinant IL-1 beta (rIL-1 beta) produced significant increases in both alpha 2- and alpha 5-subunit mRNA levels, as well as a smaller increase in alpha v-subunit mRNA. In contrast, IL-1 beta decreased alpha 4-subunit mRNA levels by approximately 30% relative to untreated controls. These findings suggest that human IL-1 beta differentially regulates expression of integrins. When cultures were treated with both IL-1 beta and the cyclooxygenase inhibitor, indomethacin, the expression of alpha 2-, alpha 5-, and alpha v-subunit mRNA levels were dramatically increased relative to untreated controls; co-treatment with 0.5 mM prostaglandin E2 (PGE2) partially reversed this effect. Indomethacin alone did not affect integrin mRNA levels. Treatment with IL-1 beta or IL-1 beta + indomethacin also induced significant changes in MG-63 morphology (i.e., increased cell elongation) and increased the ability of cells to contract collagen gels. PGE2 reversed the above effects on cell morphology and gel contraction. These findings indicate that (a) IL-1 beta differentially regulates the expression of integrins and (b) that PGE2, which is induced by IL-1 beta, may provide a negative feedback loop which counteracts the stimulatory effect of IL-1 beta on integrin gene expression. It is suggested that products of inflammation may affect cell behavior by differentially regulating the expression of various integrins.

Can the nephrologist prevent dialysis-related amyloidosis?

The pathogenesis of dialysis-related amyloidosis is still poorly understood. Therefore, preventive measures can be proposed at present only on the basis of retrospective studies and hypothetical considerations. Two main solutions may be recommended, namely an effective dialytic removal of beta 2-microglobulin (beta 2-M), which is the protein precursor of dialysis amyloid, and the avoidance of bioincompatibility-associated phenomena such as those induced by dialysis membranes and endotoxins. Promising new imaging techniques such as computed tomography (CT) scan, nuclear magnetic resonance (NMR), and scintigraphy with specific tracers for amyloid may be helpful to evaluate the long-term results of different treatment schedules, including various strategies of renal replacement therapy.

Immunoreactivity and proliferative actions of beta 2 microglobulin on human bone-derived cells in vitro

Recent studies have demonstrated homology between bone-derived growth factor and beta 2 microglobulin. We have shown that beta 2 microglobulin has proliferative actions on human bone-derived cells in vitro and that these cells also show immunogenicity for beta 2 microglobulin. beta 2 microglobulin stimulated the incorporation of 3H-thymidine into DNA of human bone cells in a dose-dependent manner. In contrast to this stimulatory action, beta 2 microglobulin had no detectable activity with the same concentration on the production of osteocalcin, alkaline phosphatase activity or prostaglandin E2 synthesis. The possibility that the human bone-derived cells could also produce beta 2 microglobulin was examined. Under basal conditions these cells exhibit immunoreactivity for beta 2 microglobulin, the expression of which could be enhanced following treatment with interferon gamma in a dose-dependent manner. The co-localization of staining for beta 2 microglobulin and alkaline phosphatase, a marker of the osteoblast phenotype, indicate that human osteoblast-like cells represent a source of activity of this factor. The production of beta 2 microglobulin by human osteoblast-like cells and the subsequent action of this factor on cells within the bone microenvironment may indicate a role for beta 2 microglobulin as a local regulator of bone metabolism.

Lymphocytes from hepatic inflammatory infiltrate kill rat hepatocytes in primary culture. Comparison with peripheral blood lymphocytes

In the last few years it has become possible in the liver to isolate lymphocytes from inflammatory infiltrates and to culture them in vitro. Most of the lymphocyte clones obtained are CD 8+ cytotoxic cells, but interactions between these lymphocytes and hepatocytes in primary culture have not been analysed previously. In this study, cloned human T lymphocytes from liver biopsies and from the peripheral blood of patients with chronic hepatitis B or primary biliary cirrhosis, after phenotypical and functional characterization into CD 8+ or CD 4+ cytotoxic lymphocytes, were activated in an antigen-independent fashion by adding either anti CD 3 or anti CD 2/R-3 monoclonal antibodies to the cell suspension. The activated cells were then coincubated with rat hepatocytes in primary culture. The killing capacity of the activated lymphocytes was monitored by light and electron microscopy and by measurement of lactic dehydrogenase (LDH)-release into the culture medium. It was found that cytotoxic CD 8+, but not CD 4+ helper lymphocytes very effectively killed hepatocytes. The killing effect was dependent on the time of cocultivation and on effector-target (E/T) ratio. Total breakdown of the hepatocyte monolayer was achieved after 10-20 h coculture and at an E/T ratio of 10 to 1. As LDH-release in the culture medium reached about 80% of the total LDH-content, most of the hepatocytes were lysed by activated lymphocytes. Cytotoxic activity of clones obtained from different biopsies was comparable with that of clones from peripheral blood. Hepatocytes in primary culture seem to be very sensitive to the killing capacity of activated cytotoxic lymphocytes.

Beta 2-microglobulin amyloidosis in hemodialysis patients. An autopsy study of intervertebral disks and posterior longitudinal ligaments

Ninety-five autopsy cases of chronic renal failure, which had or had not been treated by hemodialysis, were examined histologically and immunohistochemically for evidence of amyloid deposition in the intervertebral disks and posterior longitudinal ligaments of the spine. beta 2-Microglobulin (beta 2M) amyloid was not present in non-dialyzed patients with chronic renal failure. In cases showing beta 2M amyloid deposition, the shortest term of hemodialysis was 2 years and 5 months. The incidence of beta 2M amyloidosis tended to increase as the dialysis period was prolonged. An inverse correlation was present between dialysis period and age in 22 cases showing beta 2M amyloid deposition (correlation coefficient: -0.43, p less than 0.05), and beta 2M amyloidosis tended to occur earlier in elderly patients than in younger patients. This suggests that elderly patients are more susceptible to beta 2M amyloidosis. beta 2M amyloid was absent in all of 8 cases of systemic lupus erythematosus which were treated by dialysis for periods ranging from 2 days to 12 years. In these patients, beta 2M amyloidosis may have been prevented by steroids, which had been administered for long periods in all cases. Another amyloid of unknown composition was also frequently present in the intervertebral disks and posterior longitudinal ligaments not only in patients with chronic renal failure but also control patients without chronic renal failure. This amyloid was immunohistologically negative for beta 2M, amyloid A protein, light chain kappa or lambda, prealbumin, and apolipoprotein A-II.

The role of interferons in the control of HIV replication in macrophages

Interferons can suppress the replication of certain retroviruses, including oncogenic murine retroviruses. In recent studies of the Lentivirinae subfamily of Retroviridae, an endogenous, immunologically induced interferon was found to restrict the replication of visna in macrophages. Several studies have shown that the replication of a human lentivirus, the human immunodeficiency virus (HIV), is also susceptible to interferon control. Here we review the evidence that interferons can protect macrophages from HIV in vitro. Macrophages treated with interferons or bacterial lipopolysaccharide (LPS) become essentially nonpermissive for HIV replication. Using the polymerase chain reaction to amplify HIV proviral DNA, we now report that interferon and LPS act to restrict the formation of proviral DNA. Effects on any several steps in the HIV life cycle may explain this data, and single-cycle infection studies are needed to define the precise roles of these agents. Taken together, these findings may explain the restricted replication of HIV in macrophages in vivo and suggest an antiviral role for endogenously produced interferon in the maintenance of the prolonged asymptomatic period which typically follows HIV infection. Interferons are currently undergoing clinical trials to determine if they have antiviral effects in HIV-infected patients.

Inflammatory cytokines induce synthesis and secretion of gro protein and a neutrophil chemotactic factor but not beta 2-microglobulin in human synovial cells and fibroblasts

Exposure of human synovial cells and fibroblasts in monolayer culture to interleukin 1 results in prominent secretion of proteins with Mr values of 6000 and 7000. By N-terminal sequence analysis, the Mr-6000 protein is identified as the protein encoded by a recently described gro mRNA. The Mr-7000 protein is identical to a neutrophil chemotactic factor released from monocytes. Stimulation of normal human fibroblasts with tumour necrosis factor alpha also results in expression and secretion of these two proteins. In addition to these cytokine-induced proteins, we have identified beta 2-microglobulin as an Mr-8000 protein constitutively secreted by synovial cells.