Acute liver dysfunction complicated with uncontrollable glycemia due to insulin antibody: successful treatment with glucocorticoid and lispro insulin

Here, we report a case of acute liver dysfunction complicated with uncontrollable glycemia due to insulin antibody. The patient was admitted to our hospital due to diabetic ketoacidosis. He was administered insulin immediately, however, his fasting plasma glucose level remained unstable despite the insulin treatment. Blood biochemistry revealed severe liver dysfunction, although no markers including hepatitis virus or autoantibodies associated with autoimmune liver diseases were detected. The 125I-insulin binding rate was high (54%). The characteristics of insulin antibody in this patient were similar to the antibodies of IAS patients, therefore we administered oral glucocorticoid against insulin antibody. The reduction in the 125I-insulin binding rate and the binding capacity of the high affinity site of insulin antibodies were balanced after oral glucocorticoid therapy. In addition, preprandial subcutaneous regular insulin was switched to lispro insulin. Postprandial plasma glucose levels were relatively improved by lispro insulin. The etiology of acute liver dysfunction was unknown, however, we believe that the combination of oral glucocorticoid and lispro insulin was suitable and useful for preventing recurrent liver dysfunction in this patient.

Genetic polymorphisms of toll-like receptor 9 influence the immune response to CpG and contribute to hyper-IgM in primary biliary cirrhosis

The serum hallmark of primary biliary cirrhosis (PBC) is the presence of anti-mitochondrial antibodies (AMA), found in 95% of patients. However, nearly every patient with PBC, including those who are AMA-negative, has an elevation in serum IgM. This hyper-IgM is neither representative of other Ig isoforms, nor is due to the levels of AMA. In fact, we have recently reported that the hyper-IgM is an innate immune response and can be induced with CpG-B with concurrent up-regulation of toll-like receptor 9 (TLR9). Based on these observations, we performed a two-tier study. First, we quantitated TLR9 genotypes in patients with PBC and controls and correlated these data with the B cell response to CpG-B. Second, based on these data, we performed an extensive TLR9 genotyping in a large cohort of patients and controls. We report herein that the 2848 AA TLR9 genotype is associated with enhanced gene expression and higher frequency of intracellular IgM(+) B cells following CpG stimulation. Interestingly, however, despite the functional association, there is no difference in the distribution of TLR9 genotypes between patients and controls. Our data emphasize the importance of dissecting the innate immune response in PBC.

Spontaneous scratching behavior in MRL/lpr mice, a possible model for pruritus in autoimmune diseases, and antipruritic activity of a novel κ-opioid receptor agonist nalfurafine hydrochloride

Pruritus is a common, distressing and difficult to manage complication of many autoimmune diseases. A suitable animal model of autoimmune disease associated pruritus would contribute to a better understanding of the pathophysiology of this symptom and lead to the development of safe and effective antipruritic agents. We noticed spontaneous scratching behavior in aged MRL/lpr mice, a model of autoimmune disease. This scratching behavior was observed in a specific pathogen-free environment and was more frequent in female mice. In contrast to animal models of dermatitis; NC/Nga mice, the serum IgE and IgG1 levels in MRL/lpr mice were not elevated. These features indicate that this scratching behavior is similar to human autoimmune disease associated pruritus. The antipruritic effects of an antihistamine (chlorpheniramine), an opioid receptor antagonist (naltrexone), and a novel kappa-opioid receptor agonist (nalfurafine hydrochloride [TRK-820]) were evaluated. The frequency of scratching was not reduced by oral administration of chlorpheniramine, suggesting that the behavior is antihistamine-resistant. The oral administration of nalfurafine and subcutaneously administered naltrexone inhibited the scratching behavior without causing gross behavioral changes. In conclusion, MRL/lpr mice scratching behavior is a suitable model of pruritus that occurs in autoimmune diseases, and nalfurafine was shown to be efficacious against this behavior suggesting that it may be beneficial in patients with autoimmune disease associated pruritus.

Differences of Hepatocellular Carcinoma Patients with Hepatitis B Virus Genotypes of Ba, Bj or C in Japan

Hepatitis B virus (HBV) genotypes B (HBV/B) and C (HBV/C) are prevalent in Asia. Recently HBV/B has been classified into two subtypes, HBV/Ba which is ubiquitously found in Asia, and HBV/Bj which is specific in Japan. In addition, the frequency of positive HBeAg has been reported to be higher in patients with HBV/Ba than those with HBV/Bj. However, little is known about the differences between patients with various genotypes who developed hepatocellular carcinoma (HCC). In 296 serum samples of HCC patients collected from all over Japan, HBV genotypes were determined with the restriction fragment length polymorphism. HBV/A was detected in 1.0%, HBV/Ba in 4.4%, HBV/Bj in 7.4%, and HBV/C in 86.5%. In the Tohoku district and Okinawa, HBV/Ba, HBV/Bj and HBV/C were found in 6.7, 40.0 and 48.9%, compared to 4.0, 1.6 and 93.2% in the other districts in Japan. HBV/Bj patients were more frequently found in the group older than 65 years while HBV/Ba patients were found in all age groups. The frequency of positive HBeAg in HBV/Bj patients was significantly low compared to that in the other patients. More than 60% of the patients with HCC had cirrhosis as the underlying liver diseases. However, in HBV/Ba patients aged 50 years or younger, 80% of them had chronic hepatitis, while 87.5% of those aged older than 50 years had cirrhosis. These data suggest that great differences exist among patients with HCC infected with different genotypes.

Antibodies against cytokeratin 8/18 in a patient with de novo autoimmune hepatitis after living-donor liver transplantation

Graft dysfunction mimicking autoimmune hepatitis rarely develops after liver transplantation for nonautoimmune disease. The mechanism(s) and causes of de novo autoimmune hepatitis are unknown. We examined autoantibodies serially in a patient with de novo autoimmune hepatitis and in patients without de novo autoimmune hepatitis after liver transplantation. Anticytokeratin 8/18 antibodies were detected in the first patient's sera after the onset of de novo autoimmune hepatitis, whereas other patients without de novo autoimmune hepatitis were seronegative throughout the follow-up period even with acute cellular rejection or other cause of liver dysfunction. In conclusion, the changes in cytokeratin 8/18 in hepatocytes might be one of the sources of pathogenesis of de novo autoimmune hepatitis after liver transplantation.

Appearance of human plasma cells following differentiation of human B cells in NOD/SCID mouse spleen

Relatively little is known for the differentiation and maturation process of human B cells to plasma cells. This is particularly important in reconstitution work involving transfer of autoantibodies. To address this issue, we transplanted human peripheral blood mononuclear cells (PBMC) directly into the spleen of irradiated NOD/SCID mice depleted of natural killer cell activity. Within 6 weeks, naive B cells differentiated into memory B cells and, importantly, the numbers of human CD138+ plasma cells in spleen increased by 100 fold after transplantation. Plasma cell numbers correlated with the detection of human IgM and IgG in serum, indicating that human B cells had differentiated into mature plasma cells in the murine spleen. In addition to CD19+ plasma cells, a distinct CD19- plasma cell population was detected, suggesting that downregulation of CD19 associated with maturation of plasma cells occurred. When purified human B cells were transplanted, those findings were not observed. Our results indicate that differentiation and maturation of human B cells and plasma cells can be investigated by transplantation of human PBMC into the spleen of NOD/SCID mice. The model will be useful for studying the differentiation of human B cells and generation of plasma cells.

Bacterial CpG induces hyper-IgM production in CD27(+) memory B cells in primary biliary cirrhosis

BACKGROUND AND AIMS

Sera from patients with primary biliary cirrhosis (PBC) are characterized by the presence of antimitochondrial antibodies and elevated levels of immunoglobulin (Ig) M. We hypothesized that the increase in serum IgM is the result of chronic B-cell activation induced via the Toll-like receptor (TLR) signaling pathway.

METHODS

We analyzed peripheral blood mononuclear cells (PBMCs) from patients with PBC and controls following incubation with CpG, a natural ligand for TLR9, and determined the basal and stimulated levels of intracellular IgM, the density of TLR9, and the contribution of specific B-cell subpopulations.

RESULTS

Our data demonstrate uniquely that in vitro incubation of PBMCs from PBC with CpG-B, but not CpG-A, led to a markedly high frequency of intracellular IgM-positive B cells, associated with high levels of synthesized IgM and identified to be a function of CD27(+) memory B cells. This memory B-cell subset also expressed higher densities of TLR9 as compared with naive B cells. These results were not due to increased proliferation, as defined by 5-carboxyfluoresein diacetate succinimidyl ester labeling, or an increase in the life span of B cells, as defined by Bcl-2 expression.

CONCLUSIONS

These findings for the first time identify a major role for innate immune mechanisms in the induction and persistence of abnormal humoral immune responses in PBC.

Direct evidence for mutual interactions between perineuronal astrocytes and interneurons in the CA1 region of the rat hippocampus

Recent studies have demonstrated that astrocytes express a variety of ion channels and neurotransmitter receptors and can modulate the activity of neurons. Since a single astrocyte makes tight contacts with many neighboring neuronal cells, they can provide efficient and wide modulation of neuronal networks. Here, we provide direct evidence for mutual interactions between perineuronal astrocytes and interneurons in the stratum radiatum of the rat hippocampus. Direct depolarization of a perineuronal astrocyte suppressed the excitatory postsynaptic currents in an adjacent interneuron and increased the paired-pulse ratio, indicating that perineuronal astrocytes have a suppressive effect on presynaptic elements. Moreover, perineuronal astrocyte activation modulated the directly induced firing pattern of the interneuron, with initial facilitation and subsequent suppression. Conversely, direct firing of the interneuron depolarized the membrane potential and reduced the input resistance of the perineuronal astrocyte. These results directly demonstrate the existence of bidirectional interactions between neurons and perineuronal astrocytes.

Serial analysis of antimitochondrial antibody in patients with primary biliary cirrhosis

Antimitochondrial antibodies (AMAs) are the classic serologic marker in primary biliary cirrhosis (PBC). However, there have been only limited attempts to study changes in titer or isotype analysis of such AMAs in patients followed for long periods of time

We took advantage of stored sera from well-characterized patients with PBC followed for a period of 7-28 years (mean duration of 13.5 years). Immunoblot and enzyme-linked immunosorbant assays were performed against PDC-E2, BCOADC-E2 and OGDC-E2 as well as isotype analysis of antigen-specific IgG, IgA and IgM antibodies against each of these mitochondrial autoantigens. Sera were analyzed for total IgG, IgA and IgM by radial immunodiffusion. The sera titer of AMAs was significantly higher in younger patients with PBC. Indeed, age of onset of clinical PBC was a significant predictor for the highest values of sera AMAs. In contrast, the AMA titer did not significantly change over time in this prolonged longitudinal study. The total sera levels of the individual immunoglobulins did not show a time-dependent change, when based on age of onset of the disease. Higher titers of AMAs were noted in the younger patients. Furthermore, despite this long follow-up, there was no evidence for a significant change in AMA levels; also, levels were not influenced by drug therapy used during the period of observation.

PBC-AIH overlap syndrome with concomitant ITP and Hashimoto's disease with positivity for anti-centromere antibody

We report a case of primary biliary cirrhosis (PBC)-autoimmune hepatitis (AIH) overlap syndrome with concurrent idiopathic thrombocytopenic purpura (ITP) and Hashimoto's disease with positivity for anticentromere antibody. The patient was a 64-year-old woman with symptoms of jaundice and general fatigue. About 30 years earlier, she had been diagnosed as having ITP and had undergone splenectomy. As part of her present history, she had exhibited liver dysfunction in 1995, during the follow-up of Hashimoto's disease, and a liver biopsy led to the diagnosis of PBC. In March 2000, she was admitted to hospital because of general fatigue and jaundice. Blood tests revealed: total protein (TP), 6.6 g/dl; gamma-globulin (glb), 35.9%; total bilirubin (T-bil), 9.41 mg/dl; direct bilirubin (D-bil), 7.52 mg/dl; aspartate aminotransferase (AST), 957 U/l; alanine aminotransferase (ALT), 651 U/l; alkaline phosphatase (ALP), 595 U/l; gamma-guanosine triphosphate (GTP), 129 U/l; IgG, 2620 mg/dl; IgM, 223 mg/dl; hepatitis B surface antigen (HBsAg), negative; anti-hepatitis C virus (HCV), negative; antinuclear antibody, positive; antimitchondrial antibody (AMA), negative (by the immunofluorescence [IF] method); and anti-pyruvate dehydrogenase complex (PDC)-E2 antibody, positive (by Western blotting). Anticentromere antibody (ACA), which is an alternative diagnostic marker for PBC, was detected in this patient. Prednisolone was administered after admission and liver function test results improved markedly. The liver biopsy in 1995 had revealed infiltration of lymphocytes and plasma cells in the portal areas with fibrous expansion and periportal necrosis. Destructive cholangitis was observed, as well as scattered epitheloid cell granulomas in some portal areas. Liver biopsy after the steroid treatment revealed alleviated necrotic inflammatory responses of hepatocytes, while the destructive cholangitis persisted. This is a very rare case of PBC-AIH overlap syndrome accompanied by ITP and Hashimoto's disease which provides a possible insight into the mechanisms and interplay of autoimmune diseases.

Prevalence of antimitochondrial antibody in Japanese corporate workers in Kanagawa prefecture

BACKGROUND

The prevalence of antimitochondrial antibody (AMA) in humans and its relationship to the development of primary biliary cirrhosis (PBC) are not well known. We have estimated the frequency of AMA in the general population, and studied its association with PBC.

METHODS

We studies 1714 corporate workers (median age, 48 years; range, 30 to 59 years) who had an annual health check from 1998 to 1999 at Kawasaki Social Insurance Hospital in Japan. We used an indirect immunofluorescence method for screening serum AMA. We applied the prevalence of AMA-positive people in the study group to the general population in Japan. Then the inferred AMA-positive population was compared to the actual number of patients with PBC in statistics published by the Japanese Government.

RESULTS

AMA was detected in 11 of 1714 people (0.64%; 95% confidence interval, 0.26% to 1.02%). All these 11 sera reacted with 2-oxoacid-dehydrogenase complex by immunoblotting. Of these 11 individuals, none had subjective symptoms, all had normal serum bilirubin levels, and 6 had abnormal liver function test results. Using published statistics for the Japanese population, we inferred that there were approximately 336,472 AMA-positive people in Japan from age 30 to 59 years. The number of patients with symptomatic PBC recorded by the nationwide epidemiological survey of the Japanese Government was 2459. Thus, we inferred the rate of symptomatic PBC among AMA-positive persons to be about 0.73% (2459/336,472).

CONCLUSIONS

AMA is not a rare antibody in the general population, but few people develop recognizable PBC even if they have AMA.

Autoantibodies from primary biliary cirrhosis patients with anti-p95c antibodies bind to recombinant p97/VCP and inhibit in vitro nuclear envelope assembly

We have reported previously that p95c, a novel 95-kDa cytosolic protein, was the target of autoantibodies in sera of patients with autoimmune hepatic diseases. We studied 30 sera that were shown previously to immunoprecipitate a 95 kDa protein from [(35)S]-methionine-labelled HeLa lysates and had a specific precipitin band in immunodiffusion. Thirteen sera were available to test the ability of p95c antibodies to inhibit nuclear envelope assembly in an in vitro assay in which confocal fluorescence microscopy was also used to identify the stages at which nuclear assembly was inhibited. The percentage inhibition of nuclear envelope assembly of the 13 sera ranged from 7% to 99% and nuclear envelope assembly and the swelling of nucleus was inhibited at several stages. The percentage inhibition of nuclear assembly was correlated with the titre of anti-p95c as determined by immunodiffusion. To confirm the identity of this autoantigen, we used a full-length cDNA of the p97/valosin-containing protein (VCP) to produce a radiolabelled recombinant protein that was then used in an immunoprecipitation (IP) assay. Our study demonstrated that 12 of the 13 (93%) human sera with antibodies to p95c immunoprecipitated recombinant p97/VCP. Because p95c and p97 have similar molecular masses and cell localization, and because the majority of sera bind recombinant p97/VCP and anti-p95c antibodies inhibit nuclear assembly, this is compelling evidence that p95c and p97/VCP are identical.

Frequency and significance of anti-glutathione S-transferase autoantibody (anti-GST A1-1) in autoimmune hepatitis

Several phase I and phase II multi-drug metabolizing enzymes, such as CYP2D6, 3A4, and UGTA1, were reported to act as immunotargets in a subset of autoimmune hepatitis and hepatic autoimmunity. However, it is uncertain whether glutathione S-transferase (GST) A1-1, one of the phase II multi-drug metabolizing enzymes, is also an immunotarget in autoimmune hepatitis. So, in the present study, we investigated the frequency and significance of anti-GST A1-1 in sera from patients with autoimmune hepatitis. A total of 74 serum samples from patients with autoimmune hepatitis were examined in the present study. As controls, 20 serum samples from patients with primary biliary cirrhosis, 10 serum samples from patients with primary sclerosing cholangitis, 40 serum samples from patients with liver cirrhosis type B and C, 32 serum samples from patients with systemic lupus erythematosus, and 20 serum samples from normal controls were used. Anti-GST A1-1 antibody was determined by immunoblotting using the recombinant full-length GST A1-1 protein as the antigen. The immunofluorescent staining pattern of anti-GST A1-1 was investigated using rat liver and kidney sections. We compared clinicopathologic findings between anti-GST A1-1-positive and -negative autoimmune hepatitis patients. Anti-GST A1-1 was detected in 12 (16%) of 74 patients with autoimmune hepatitis, however, it was not detected in any control serum samples except for two patients with primary biliary cirrhosis. The immunofluorescence staining pattern of anti-GST A1-1 was found to be unique and different from those of anti-mitochondrial antibody or anti-liver-kidney microsome type 1 antibody. Anti-GST A1-1 coexisted with other autoantibodies such as anti-nuclear or anti-smooth muscle antibodies, but did not coexist with anti-soluble liver antigen/liver pancreas. Anti-GST A1-1-positive autoimmune hepatitis patients had severe clinical features and a poor prognosis compared with anti-GST A1-1-negative patients. These findings suggested that despite the low frequency, anti-GST A1-1 might be the marker of an early progression in autoimmune hepatitis.

Olprinone improves diaphragmatic contractility and fatigability during abdominal sepsis in a rat model

BACKGROUND

Respiratory failure with diaphragmatic fatigability is common in patients suffering sepsis or septic shock. However, the development and progress of diaphragmatic fatigability remains poorly understood, and no method has been established to treat fatigability. In this study, we hypothesize that neutrophil activation contributes to the development of diaphragmatic fatigability. We also sought to investigate whether a phosphodiesterase inhibitor, olprinone, improves diaphragmatic fatigability associated with abdominal sepsis and inhibits an increase in myeloperoxidase activity in diaphragmatic muscle.

METHODS

Male Wistar rats were randomly assigned to a sham group, coecal legation perforation group (CLP), and a phosphodiesterase inhibitor (PDE) pretreated group. At 16 h after surgical procedure, the left hemidiaphragm was removed for the measurement of diaphragmatic contractility and fatigability. In addition, for the measurement of serial changes in myeloperoxidase activity, the right hemidiaphragm was also removed at 4, 8 or 16 h after the surgical procedure in each group.

RESULTS

In a septic model involving rats, we observed that diaphragmatic muscles were fatigable and myeloperoxidase activity increased. We also demonstrated that intraperitoneal administration of olprinone improves diaphragmatic fatigability and inhibits an increase in myeloperoxidase activity induced by abdominal sepsis.

CONCLUSION

Olprinone represents a potential therapy for cases of respiratory failure with diaphragmatic fatigability resulting from inhibition of neutrophil activation.

Primary hyperparathyroidism associatiated with aldosterone-producing adrenocortical adenoma and breast cancer: relation to MEN1 gene

A rare case of primary hyperparathyroidism associated with primary aldosteronism and breast cancer is reported. A 44-year-old woman was admitted to our hospital to undergo surgical removal of breast cancer. She had hypertension with low serum potassium, and slightly but significantly elevated serum calcium levels. Further studies demonstrated an enlarged left superior parathyroid gland and a left aldosterone-producing adrenocortical adenoma. Blood pressure was controlled with spironolactone and nifedipine, and left mastectomy was done for breast cancer. The pathological diagnosis was scirrhous breast carcinoma. Although the postoperative course was uneventful, her serum calcium gradually and progressively rose to higher levels. Left superior parathyroidectomy and left adrenalectomy were then performed simultaneously. The pathological diagnoses of the resected parathyroid gland and adrenal gland were parathyroid chief cell adenoma and adrenocortical adenoma with hyperplasia of zona glomerulosa, respectively. To clarify if the occurence of these tumors may be related to MEN1 gene mutations, we analyzed MEN1 gene in this patient, and found a loss of heterozygosity of the MEN1 locus in the parathyroid adenoma and breast cancer. Thus, we conclude that an alteration of the MEN1 gene and/or another tumor suppressor gene located at the MEN1 locus on chromosome 11q13 may be responsible for the development of parathyroid adenoma and breast cancer in our patient suggesting that the clinical spectrum of MEN1 might include breast cancer. In addition, serum calcium should be interpreted with caution in primary aldosteronism, because hypercalcemia may be masked in the presence of aldosterone excess.

Interaction of Porphyromonas gingivalis with low-density lipoproteins: implications for a role for periodontitis in atherosclerosis

OBJECTIVE

The association of periodontitis with atherosclerosis has been suggested from epidemiological studies. Recently, we have reported that macrophages stimulated by Porphyromonas gingivalis formed foam cells in the presence of low-density lipoproteins (LDL). In this study, we examined the direct interactions between LDL and P. gingivalis.

METHODS

We investigated the aggregation of LDL with P. gingivalis and its outer membrane vesicles (OMVs), degradation of the apo B-100 protein of LDL by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and western blot analyses, as well as the effects of protease inhibitors or activators on the mobility of LDL by agarose gel shift assays. The binding of P. gingivalis or its OMVs with LDL was demonstrated by western blot analysis. We also examined whether or not the aggregated LDL induced foam cell formation from murine macrophages.

RESULTS

LDL was aggregated in a dose-dependent manner with P. gingivalis and its OMVs. Moreover, degradation of the apo B-100 protein of LDL was directly demonstrated in the presence of P. gingivalis or its OMVs. Furthermore, the gel shift assays indicated that the mobility of LDL was increased in the presence of P. gingivalis. This alteration was attenuated in the presence of the protease inhibitors TLCK and leupeptin and increased in the presence of reducing agents. Moreover, LDL was bound to specific proteins of P. gingivalis suggesting that these proteins may also play a role in aggregation. Finally, the aggregated LDL induced murine macrophages to form foam cells.

CONCLUSIONS

These results suggest that P. gingivalis may stimulate foam cell formation, in part, by aggregating LDL by proteolysis of apo B-100.

Design approaches to power-over-optical local-area-network systems

This paper discusses fiber optic power and signal transmission systems considering the application of dc powering to information tools such as personal computers. We discuss system requirements and technical issues for the system components, including high-power laser diodes and photovoltaic cells. It is clarified that the conversion efficiencies of photovoltaic cells are kept constant with heat radiation and improve with extremely small series resistance. The transmittable optical powers through the optical fiber limited by a nonlinear optical effect are estimated. We also discuss the system designs for the use of single- and multi-mode optical fibers.

[Bisphosphonate as an adjuvant therapy for the pain of bone metastases, 3 cases]

Pain from bone metastases limits mobility and may cause pathological fractures that can seriously impair the patient's quality of life. Conservative treatments such as orthopedic fixation, radiotherapy, and opioids sometimes fail to give satisfactory pain relief. Bisphosphonates have been reported to reduce the severity of pain from bone metastasis due to breast cancer, prostate cancer, and multiple myeloma. Recent clinical reports demonstrated the effectiveness of bisphosphonates in reducing pain from bone metastases in various malignancies. This study presents 3 cases of refractory pain from bone metastases due to thyroid, colorectal and hepatocellular carcinoma. Primary treatment included orthopedic fixation, radiotherapy, and/or parenteral opioids that failed to reduce bone pain. Bisphosphonate therapy was considered at the start of pain control treatment using opioids. All 3 cases showed gradual reduction in pain after i.v. pamidronate administration and allowed physicians to control further pain with opioids. In 1 case, the patient was successfully withdrawn from opioids. The role of bisphosphonates in painful bone metastases remains unclear. However, recent encouraging reports have indicated that bisphosphonate may become one of the adjuvant treatments available to control refractory bone pain from various malignancies.

Porphyromonas gingivalis induces murine macrophage foam cell formation

Atherosclerosis is a complex pathologic process initialed by the formation of cholesterol-rich plaque. Macrophages play a central role in the development of atherosclerosis, specifically in the initial accumulation of cholesterol in the arterial wall. It has been suggested that infection and chronic inflammatory conditions such as periodontitis may influence the atherosclerosis process. Porphyromonas gingivalis, one of the major pathogens involved in periodontitis, has been detected in human atheromas, suggesting that P. gingivalis infection may be associated with atherosclerosis. However, a causal relationship between this pathogen and the disease process has not yet been established. The purpose of the present investigation was to determine whether P. gingivalis could induce macrophages to form foam cells using the murine macrophage cell line (J774) as a model system. For inocula smaller than one bacterium per ten cells, P. gingivalis 381, as well as its lipopolysaccharide (LPS), induced foam cell formation of macrophages when cultured in the presence of human low-density lipoprotein (LDL). Infection of macrophages with increasing doses of P. gingivalis resulted in higher levels of foam cell formation. More than 70% of the cultured macrophages form cholesterol ester droplet-rich cells in the presence of 100 mug/ml of LDL when the inocula was more than 10 bacteria per cell. Low concentrations of P. gingivalis outer membrane vesicles also induced foam cell formation in the presence of LDL. In addition, it was demonstrated that P. gingivalis LPS alone was able to induce macrophage foam cell formation. P. gingivalis and its vesicles not only promoted LDL binding to macrophages but also induced macrophages to modify native LDL, which plays an important role in foam cell formation and the pathogenesis of atherosclerosis. Therefore, P. gingivalis cells or its vesicles released from periodontal lesions into the circulation may deliver virulence factor(s) such as LPS to the arterial wall to initiate or promote foam cell formation in macrophages and contribute to atheroma development.

Relationship between gene polymorphisms of mannose-binding lectin (MBL) and two molecular forms of MBL

Mannose-binding lectin (MBL) activates complement through MBL-associated serine proteases (MASP). A deficiency in MBL due to mutations at exon 1 of the human MBL gene is reported to cause vulnerability to infection. We examined sera of known MBL genotype by gel filtration and assessed their elution patterns using an ELISA for MBL and identified two MBL forms, a high-molecular-mass form and a lower-molecular-mass form. By the identification of either or both forms in individual sera, three types of patterns emerged: type 1 consisted of a high-molecular form; type 2, of a low-molecular form; and type 3, of both forms. Types 1, 2 and 3 corresponded, respectively, to a wild type (A/A), a homozygous mutation at codon 54 (B/B) and their heterozygote (A/B). One exception was a heterozygous LXPA/LYPB phenotype that exhibited the type-2 pattern. Binding to mannan and MASP-1/3 occurred exclusively with the high-molecular form. An apparent MBL deficiency does not in fact representa deficiency in MBL molecules but rather the presence of circulating oligomeric mutant MBL with impaired function.