Primary intracerebral malignant melanoma with leptomeningeal spread, extradural extension and lung metastasis

A rare primary intracerebral solitary malignant melanoma with extracranial metastasis is reported. The patient was a 66-year-old man who was revealed to have a tumor in the right temporal lobe by MRI. The tumor was totally resected and the histopathological diagnosis was malignant melanoma. Despite postoperative treatment with chemo-radiotherapy, tumor recurred with multiple subarachnoid dissemination. Complete autopsy showed marked leptomeningeal dissemination of tumor in the cerebro-spinal compartment. In the outside of the central nervous system, a microscopic metastatic nodule was found in the right lung. Metastatic tumor in the spinal cord showed the extradural extension which might have led to hematogenous metastasis to the lung.

Diversity of restriction-modification gene homologues in Helicobacter pylori

The complete genome sequences of two Helicobacter pylori strains have recently become available. We have searched them for homologues of restriction-modification genes. One strain (26695) carried 52 such homologues, and the other (J99) carried 53. Their sequence alignments were arranged in the form of a phylogenetic tree and compared with the tree based on rRNA. The trees showed that the homologues are scattered among diverse groups of bacteria. They also revealed high polymorphism within the species--there are 42 pairs with high homology, 10 specific to 26695, and 11 specific to J99. Many of the restriction-modification homologues were characterized by a GC content lower than that of the average gene in the genome. Some of the restriction-modification homologues showed a different codon use bias from the average genes. These observations are interpreted in terms of horizontal transfer of the restriction-modification genes.

Comparison between Pyrococcus horikoshii and Pyrococcus abyssi genome sequences reveals linkage of restriction-modification genes with large genome polymorphisms

Recent work suggests that restriction-modification gene complexes are mobile genetic elements that insert themselves into the genome and cause various genome rearrangements. In the present work, the complete genome sequences of Pyrococcus horikoshii and Pyrococcus abyssi, two species in a genus of hyperthermophilic archaeon (archaebacterium), were compared to detect large genome polymorphisms linked with restriction-modification gene homologs. Sequence alignments, GC content analysis, and codon usage analysis demonstrated the diversity of these homologs and revealed a possible case of relatively recent acquisition (horizontal transfer). In two cases out of the six large polymorphisms identified, there was insertion of a DNA segment with a modification gene homolog, accompanied by target deletion (simple substitution). In two other cases, homologous DNA segments carrying a modification gene homolog were present at different locations in the two genomes (transposition). In both cases, substitution (insertion/deletion) in one of the two loci was accompanied by inversion of adjacent chromosomal segment. In the fifth case, substitution by a DNA segment carrying type I restriction, modification, and specificity gene homologs was likewise accompanied by adjacent inversion. In the last case, two homologous DNA segments, were found at different loci in the two genomes (transposition), but only one of them had insertion of a modification homolog and an unknown ORF. The possible relationship of these polymorphisms to attack by restriction enzymes on the chromosome will be discussed.

Insertion with long target duplication: a mechanism for gene mobility suggested from comparison of two related bacterial genomes

The complete genome sequences of two closely related organisms--two Helicobacter pylori strains--have recently become available. Comparison of these genomes at single base pair level has suggested the presence of a mechanism for bacterial gene mobility--insertion with long target duplications. This mechanism is formally similar to classical transposon insertion, but the duplication is much longer, often in the range of 100bp. Restriction and/or modification enzyme genes are often within or adjacent to the insertion. A similar process may have mediated insertion of the cag(+) pathogenicity island in H. pylori. A similar structure was identified in comparisons between Neisseria meningitidis and Neisseria gonorrhoeae genomes. We hypothesize that this mechanism, as well as two other types of polymorphism linked with restriction-modification genes (insertion accompanied by target deletion and a tripartite structure composed of substitution/inversion/deletion), have resulted from attack by restriction enzymes on the chromosome.

Effect of interleukin-18 on viral myocarditis: enhancement of interferon- gamma and natural killer cell activity

Encephalomyocarditis virus causes viral myocarditis with myocyte necrosis and inflammatory cell infiltration in mice. Because previous studies have shown that some cytokines prevent the sequelae of myocarditis, we assessed the effect of a newly identified cytokine, interleukin-18 (IL-18), in preventing the sequelae of myocarditis. Murine IL-18 (10 microg/day/mouse) was given peritoneally for 10 days in C3H mice infected with EMC virus. Mice were divided into group IL-18 (infected-treated), saline group (infected-untreated), group IL-18-2 (treatment started on day 2), group IL-18-5 (treatment started on day 5). Although the 14-day survival rate in saline group was 20%, that in the group IL-18 increased to 80% (P<0.05). Either mice in group IL-18-2 or in group IL-18-5 did not survive longer than saline group. The viral titer of the heart on day 3 was lower in group IL-18 compared to the saline group (1.00+/-0.20 log(10)tissue culture infected dose (TCID)(50)/mg wet weight v 1.42+/-0.12 log(10)TCID(50)/mg, n=3 of each). Mice in group IL-18 had less myocardial necrosis and cellular infiltration than the saline group. The myocardial expression of interferon- gamma (IFN- gamma) mRNA in group IL-18 was significantly (P<0.05) greater than the saline group on days 1 and 3 after viral inoculation. Circulating IFN- gamma was significantly elevated on days 1, 5, and 7, but significantly reduced on day 3. The natural killer cell activities in the spleen on days 1, 3, and 5 were significantly (P<0.05) greater in group IL-18 than in the saline group (41+/-9%v 10+/-6% on day 3, 4 of each). We conclude that IL-18 reduces the severity of EMC viral myocarditis by inducing cardiac expression of IFN- gamma mRNA and increasing splenic natural killer cell activity.

High prevalence of Chlamydia trachomatis, Neisseria gonorrhoeae and Mycoplasma genitalium in female commercial sex workers in Japan

Our objectives were to explore the prevalence of Chlamydia trachomatis, Neisseria gonorrhoeae, and Mycoplasma genitalium in Japanese female commercial sex workers (CSWs), in comparison with pregnant women as controls. A high-risk group of 174 female CSWs and 90 asymptomatic pregnant women were enrolled in this study. Detection of C. trachomatis, N. gonorrhoeae, and M. genitalium on the endocervix of the women was performed mainly by using polymerase chain reaction (PCR)-based assays. The prevalence rates of C. trachomatis, N. gonorrhoeae, and M. genitalium were 19.0%, 32.8%, and 12.6%, respectively, in the CSWs, compared with 5.6%, 0%, and 1.1% respectively, in the pregnant women. These results suggest a high prevalence of C. trachomatis, N. gonorrhoeae, and M. genitalium in Japanese CSWs. We conclude that continued close monitoring of the prevalence of C. trachomatis, N. gonorrhoeae, and M. genitalium infection in CSWs is important for preventing the dissemination of these microorganisms, and that further investigation of M. genitalium as a sexually transmitted pathogen in women is needed.

[Genetic analysis of two patients with adenosine deaminase (ADA)-deficiency: detection of three novel mutations and characterization of two paradoxical carriers]

Genetic basis of two patients (AT, MT) with ADA deficiency was studied. We identified three novel mutations (119 Q-->Stop, 235 R-->Q, one base deletion in Exon 4) from the patients. 119 Q-->Stop was detected in AT and her father. Deletion of one base in Exon 4 which would change the reading frame after codon 105 H, was detected in MT, her father and brother. There was no relation between the two families, however, 235 R-->Q was also detected in both the patients and their mothers. Extremely low ADA activity of PBMCs was revealed in healthy MT's mother and brother just as MT, although their dAXP levels of RBCs showed significantly lower than that of MT. We defined that they shared an additional mutation (310 M-->T) together with the mutation described above, respectively. EBV-transformed B-cell line (EBV-B) were established from the carriers. To our surprise, ADA activity of their lines was 1/10-1/5 of normal. The result of heat treatment studies using the EBV-B showed that the mutant ADA rapidly lose its enzyme activity without degradation of the protein. It suggests that 310 M-->T mutant ADA rapidly lost its enzyme activity due to conformational change of the catalytic site of ADA.

Evolution of sequence recognition by restriction-modification enzymes: selective pressure for specificity decrease

Several type II restriction-modification (RM) gene complexes kill host bacterial cells that have lost them, through attack on the chromosomal recognition sites of these cells. Two RM gene complexes recognizing the same sequence cannot simultaneously enjoy such stabilization through postsegregational host killing, because one will defend chromosomal sites from attack by the other. In the present work, we analyzed intrahost competition between two RM gene complexes when the recognition sequence of one was included in that of the other. When the EcoRII gene complex, recognizing 5'-CCWGG (W = A, T), is lost from the host, the SsoII gene complex, which recognizes 5'-CCNGG (N = A, T, G, C), will prevent host death by protecting CCWGG sites on the chromosome. However, when the SsoII (CCNGG) gene complex is lost, the EcoRII (CCWGG) gene complex will be unable to prevent host death through attack by SsoII on 5'-CCSGG (S = C, G) sites. These predictions were verified in our experiments, in which we analyzed plasmid maintenance, cell growth, cell shape, and chromosomal DNA. Our results demonstrate the presence of selective pressure for decrease in the specificity of recognition sequence of RM systems in the absence of invading DNA.

Incidence of human papillomavirus 16 and 18 infection and p53 mutation in patients with oral squamous cell carcinoma in Japan

The purpose of this study was to investigate the prevalence of human papillomaviruses (HPVs) 16 and 18 infection, and p53 mutation in oral squamous cell carcinomas (SCCs) in Japanese patients. Our results showed a higher incidence of HPV16 and 18 infections than previous studies because we combined the findings of a consensus polymerase chain reaction (PCR), restriction fragment length polymorphism by using the restriction enzyme digestion of the PCR products and Southern blot hybridization. Each HPV16 and 18 E6/E7 DNA was detected in 9 (20%) and 25 (54%) of 46 samples. The p53 mutation in the exons from 5 to 8 were detected in 20 out of 46 samples (43%) by a PCR-single strand conformation polymorphism analysis. There was a significant relationship between HPV16 and the p53 mutation (P =0.02) suggesting that HPV16 infection has a mutagenic effect in oral SCC. However, neither HPV infection nor p53 mutation influenced survival.

High-resolution CT findings of macrophage activation syndrome: a case report

Macrophage activation syndrome (MAS) is a rare disorder characterised by benign, reactive, excessive, well-differentiated macrophage proliferation, secondary to an immune dysregulation in response to some triggering agents such as viral infection. We report a 3-year-old girl with MAS and pulmonary involvement. This is the first radiographic description of MAS on high-resolution CT.

[Physiological role of respiratory-related bronchial constriction]

The respiration-related rhythmic constriction of the fifth-generation bronchi was analyzed in 11 tracheostomized dogs. During spontaneous breathing, the bronchial pressure (Pbr) estimated with a balloon-tipped catheter increased almost in parallel with the pleural pressure (Ppl) in the early inspiratory phase, but decreased in the late inspiratory phase. The parallel duration/inspiratory duration was 0.72 +/- 0.19 (mean +/- SD). This finding was more prominent in hypercapnia, but statistical significance was not obtained. When the efferent phrenic nerve fibers were electrically stimulated (pulse train, 0.1 ms, 30 Hz, 5 V, 2 s), Pbr changed almost in parallel with Ppl during the inspiratory phase, and expiration was completed significantly earlier than during spontaneous breathing (time constant 0.17 +/- 0.06 s vs 0.26 +/- 0.07 s). Bronchial constriction in early expiration may increase airway pressure and keep patency of the peripheral bronchi.

Improved dysgammaglobulinaemia in congenital rubella syndrome after immunoglobulin therapy: correlation with CD154 expression

A boy with congenital rubella syndrome developed dysgammaglobulinaemia with elevated serum levels of IgM. CD154 was not induced on his peripheral blood mononuclear cells when rubella virus RNA was detected in his throat swabs and peripheral blood by reverse transcriptase polymerase chain reaction. Following intravenous immunoglobulin therapy, improvement of immunoglobulin abnormalities, disappearance of rubella virus and normalisation of CD154 expression were demonstrated.

CONCLUSION

These findings implicate the efficacy of intravenous immunoglobulin therapy for dysgammaglobulinaemia in congenital rubella syndrome and a role of CD154 for a prolonged virus infection.

Antimicrobial activity of gemifloxacin (SB-265805), a newer fluoroquinolone, against clinical isolates of Neisseria gonorrhoeae, including fluoroquinolone-resistant isolates

Antimicrobial activity of gemifloxacin (SB-265805), a newly developed fluoroquinolone, to Japanese isolates of Neisseria gonorrhoeae was compared with those of various fluoroquinolones, including norfloxacin, ciprofloxacin, tosufloxacin, levofloxacin, sparfloxacin, and trovafloxacin. Among the fluoroquinolones tested, gemifloxacin was most active against N. gonorrhoeae isolates. The MIC90 values of gemifloxacin for 94 N. gonorrhoeae isolated from 1992 through 1993 and 100 isolated from 1996 through 1997 were 0.03 and 0.125 microg/ml, respectively. On the other hand, MIC90 values of the other fluoroquinolone for the 1992-1993 isolates and the 1996-1997 isolates ranged from 0.125 to 2 microg/ml and from 0.5 to 8 microg/ml, respectively. Gemifloxacin was also the most potent fluoroquinolone against 31 ciprofloxacin-resistant isolates with the ciprofloxacin MIC of 1 to 16 microg/ml, for which the gemifloxacin MIC50 and MIC90 values were 0.25 and 2 microg/ml, respectively. Moreover, the activity of gemifloxacin against fluoroquinolone-resistant gonococcal isolates containing multiple amino acid substitutions in both GyrA and ParC proteins was superior to those of the other compounds.

Circulating interleukin-6 and interleukin-6 receptors in patients with acute and recent myocardial infarction

Interleukin-6 (IL-6), a proinflammatory cytokine, plays a key role in the pathogenesis of coronary artery disease (CAD). We investigated circulating IL-6 and its receptors in patients with CAD. We evaluated 39 Japanese patients with CAD (30 males and 9 females aged 36-79 years), measuring their plasma levels of IL-6 and IL-6 receptors alpha and beta (IL-6R alpha, IL-6R beta). Circulating levels of IL-6, IL-6R alpha and IL-6R beta were measured by an enzyme-linked immunosorbent assay. Blood was sampled immediately after admission and again after 1, 2, 3, 6 and 9 h, then every 12 h for 5 days. Atrial natriuretic peptide (ANP) and B-type natriuretic peptide (BNP) were measured on day 3 after symptom onset. Plasma levels of IL-6 and IL-6Rs were significantly increased in 28 patients with acute myocardial infarction (AMI) compared with 15 normal controls. However, neither IL-6 nor IL-6Rs showed an increase in 6 patients with angina pectoris. We observed two peaks for circulating IL-6 in AMI, the first of which showed a significant correlation with ANP as well as BNP. These results may help to explain why the amount of IL-6 produced is closely related to the severity of myocardial dysfunction in patients with CAD.

[The proposal for young people who wish to become clinical laboratory physicians]

Based on my personal experiences for past 10 years, I would like to propose my plans for young physicians concerned with clinical laboratory medicine as follows: 1. Training periods (several years after graduated from medical school): Pursue your courses in the various fields of medicine including clinical activities. 2. Periods of fellowship(approximately about 35 years-old): During this period, it is recommended to go abroad for young scientist to add to your stock of knowledges and experiences. 3. Periods of devoting yourself to the work in the clinical laboratory medicine(approximately about 40 years-old): You are recommended to be self-reliant in the routine works and academic studies in the fields of laboratory medicine.

Circulating interleukin-6 significantly correlates to thyroid hormone in acute myocardial infarction but not in chronic heart failure

To investigate relationships between thyroid states and the cardiac endocrine system, we analyzed thyrotropin (TSH), thyroid hormone, plasma levels of interleukin-6 (IL-6) and brain natriuretic peptide (BNP) in 50 patients with chronic heart failure (CHF), in 30 patients with heart failure from acute myocardial infarction (AMI), and in 15 controls. Plasma levels of IL-6 and BNP in both CHF and AMI were significantly elevated, while free triiodothyronine (FT3) was significantly decreased compared to controls. FT3/free thyroxine (FT4) ratio was significantly decreased in CHF but not in AMI compared to controls. In CHF, diuretic treatment diminished circulating BNP but not IL-6, while diuretic treatment increased FT3/FT4 ratio. In AMI, FT3/FT4 ratio was significantly decreased 72 h compared to 12 h after the onset of AMI, while BNP and IL-6 were significantly increased 72 h compared to 12 h after the onset of AMI. In both CHF and AMI, BNP significantly correlated with FT4. On the other hand, significant correlations between IL-6 and FT3, and between IL-6 and FT3/FT4 ratio were detected in AMI but not in CHF. This preliminary study suggests that IL-6, BNP and thyroid hormone reflect ventricular dysfunction in both acute and chronic heart failure, and that IL-6 significantly relates to circulating thyroid hormone in AMI but not in CHF.

Moderate-intensity regular exercise decreases serum tumor necrosis factor-alpha and HbA1c levels in healthy women

OBJECTIVE

To evaluate the effects of moderate-intensity regular exercise on serum levels of tumor necrosis factor-alpha (TNF-alpha) and glucose and lipid metabolism parameters.

DESIGN

Longitudinal intervention study of a 5 month exercise training program (30-45 min/day, 4-5 days/week).

SUBJECTS

Forty-one healthy Japanese women aged 41-69 y at baseline; 27 participants in the exercise program.

MEASUREMENTS

Body mass index (BMI), waist-to-hip ratio (WHR), percentage body fat, and fasting levels for serum TNF-alpha, serum soluble TNF receptor p55 (TNF-RI) and TNF receptor p75 (TNF-RII), serum lipids, HbA1c, and serum insulin before and after exercise.

RESULTS

In overweight to obese subjects, serum levels of TNF-alpha, TNF-RI and TNF-RII were significantly higher than those in lean subjects. There were significant correlations between log serum TNF-alpha and BMI, percentage body fat, WHR, HbA1c and log insulin. TNF-RI was significantly correlated with BMI, percentage body fat, WHR and HbA1c. TNF-RII was also associated with BMI, percentage body fat and WHR. However, the correlation between TNF-RII and HbA1c did not reach statistical significance. Neither TNF-RI nor TNF-RII was correlated with log insulin. In contrast, TNF-alpha, TNF-RI and TNF-RII were negatively correlated with HDL cholesterol. Regular exercise decreased BMI, percentage body fat, HbA1c, serum TNF-alpha, TNF-RI and TNF-RII and increased HDL cholesterol levels. In addition, exercise-induced change in serum TNF-alpha was independently correlated with changes in HbA1c and serum insulin, after being adjusted for the change in fat-free mass.

CONCLUSION

Changes in serum TNF-alpha that occur with exercise may play an important role in improving glucose metabolism parameters.

A defect in harmonin, a PDZ domain-containing protein expressed in the inner ear sensory hair cells, underlies Usher syndrome type 1C

Usher syndrome type 1 (USH1) is an autosomal recessive sensory defect involving congenital profound sensorineural deafness, vestibular dysfunction and blindness (due to progressive retinitis pigmentosa)1. Six different USH1 loci have been reported. So far, only MYO7A (USH1B), encoding myosin VIIA, has been identified as a gene whose mutation causes the disease. Here, we report a gene underlying USH1C (MIM 276904), a USH1 subtype described in a population of Acadian descendants from Louisiana and in a Lebanese family. We identified this gene (USH1C), encoding a PDZ-domain-containing protein, harmonin, in a subtracted mouse cDNA library derived from inner ear sensory areas. In patients we found a splice-site mutation, a frameshift mutation and the expansion of an intronic variable number of tandem repeat (VNTR). We showed that, in the mouse inner ear, only the sensory hair cells express harmonin. The inner ear Ush1c transcripts predicted several harmonin isoforms, some containing an additional coiled-coil domain and a proline- and serine-rich region. As several of these transcripts were absent from the eye, we propose that USH1C also underlies the DFNB18 form of isolated deafness.

Antipituitary antibodies as pathogenetic factors in patients with pituitary disorders

Our previous reports showed detection of antipituitary antibodies (APA) by immunoblot analysis and enzyme linked immunosorbent assay (ELISA) by using rat pituitary tissue as antigen in patients with certain endocrine disorders. In the present report, we evaluated APA by using our immunoblot and ELISA technique in 76 patients with various pituitary disorders. The prevalence of a 22 kDa band of APA detected by immunoblot was found to be significantly higher (P<0.01) in patients with pituitary disorders (20 of 76, 26%) than in the controls (3 of 209, 1%). APA levels detected by ELISA were significantly higher in patients with GH deficiency, isolated ACTH deficiency, acromegaly, and idiopathic panhypopituitarism compared with control (mean +/- SD; 2.40+/-2.66, 2.36+/-1.87, 2.09+/-1.87, 3.10+/-1.96 versus 1.42+/-0.64 (C.I.) P<0.05, respectively). APA levels detected by ELISA in 7 patients with GH deficiency showed a statistically significant decrease (p<0.05) after administration of GH replacement therapy. APA detection by immunoblot is useful in examining as pathogenesis, while ELISA may be useful as an objective index of pathological state in patients with autoimmune-related pituitary disorders.

A case of sensory neuropathy associated with childhood Sjögren syndrome

Complications observed in adulthood Sjögren syndrome also occur in the childhood disease and suggest that Sjögren syndrome should be considered as a cause of neuropathy in children. Treatment with corticosteroid is a choice for such cases.

[Antibacterial activities of piperacillin in several fresh clinical isolates]

We investigated activity of piperacillin (PIPC) in comparison with 8 antibacterial reference drugs against several fresh clinical strains isolated from patients with infectious diseases in the respiratory tract and after surgical interventions in 1999. The following results were obtained: 1. PIPC had its MIC90 of 0.12-6 micrograms/ml in Gram-positive bacteria (Methicillin susceptible Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pyogenes, Streptococcus agalactiae, Streptococcus pneumoniae, Enterococcus faecalis) and showed its MIC of 1 microgram/ml or higher in 9 possible PRSP strains out of 38 isolates of S. pneumoniae but there were no possible isolates with evident resistance in other species of bacteria. 2. PIPC showed favorable antibacterial activities as its MIC90 were 2-8 micrograms/ml in Gram-negative bacteria (Escherichia coli, Klebsiella pneumoniae, Serratia marcescens, Citrobacter freundii, Pseudomonas aeruginosa, Moraxella (Branhamella) catarrhalis, Haemophilus influenzae), except for P. mirabilis in which its MIC90 was as high as 64 micrograms/ml. 11 out of 39 isolates of P. mirabilis were resistant to other drugs such as PIPC, ABPC, CTM and CZOP. 3. PIPC had its MIC90 of > 128 micrograms/ml in Bacteroides fragilis. From these results, PIPC was considered highly effective in several infections in view of maintaining its favorable antibacterial activities in several causative bacteria even today when 20 years had passed since its first application to clinical practice.

Involvement of circulating interleukin-6 and its receptor in the development of euthyroid sick syndrome in patients with acute myocardial infarction

OBJECTIVE

In patients with acute myocardial infarction (AMI), low triiodothyronine (T(3)) levels with normal or subnormal levels of thyrotropin (TSH), the euthyroid sick syndrome (ESS), have been reported, however, the mechanism of altered thyroid hormone metabolism is unknown. Recent reports have shown that interleukin-6 (IL-6) plays a key role in the pathogenesis of AMI and ESS. This preliminary study investigates the relationship between thyroid states and plasma levels of IL-6, the soluble IL-6 receptor (sIL-6R), and the soluble transducing 130kDa glycoprotein (sgp130) in AMI.

DESIGN AND METHODS

We measured the concentration of TSH, free T(3) (FT(3)), free thyroxine (FT(4)), IL-6, sIL-6R and sgp130 in plasma from 24 patients with AMI and 20 normal controls.

RESULTS

All 24 AMI patients showed significantly lower concentrations of FT(3) with normal or subnormal levels of TSH, and higher concentrations of IL-6 and sIL-6R than controls. IL-6 level was correlated with creatine phosphokinase (CPK) and FT(3) levels but not with FT(4 )or TSH levels in patients with AMI. The time course of IL-6 and FT(3 )concentration seemed to be closely linked. sIL-6R level was correlated with CPK and sgp130 levels, but not with FT(3), FT(4) or TSH levels. FT(4 )level was correlated with sgp130 level.

CONCLUSION

Patients with AMI develop ESS through activation of IL-6 and its receptor system.

Interleukin 12 induces crescentic glomerular lesions in a high IgA strain of ddY mice, independently of changes in IgA deposition

BACKGROUND

Our recently established high immunoglobulin (Ig)A inbred strain (HIGA) of ddY mice showed constantly high serum IgA levels, progressive mesangial sclerosis accompanied by IgA deposits, and elevated renal expression of transforming growth factor (TGF)-beta, mimicking IgA nephropathy. In the present study, we assessed the role of the immune system, especially of T cells, in this strain.

METHODS

The in vitro production of interferon (IFN)-gamma, interleukin (IL)-4 and TGF-beta1 by splenic CD4+ T cells was assessed in HIGA mice at 14 and 28 weeks of age by comparison with age-matched C57BL/6 and BALB/c mice, T-helper (Th) 1, and Th2 prone controls respectively. Moreover, recombinant murine IL-12 was administered intraperitoneally to HIGA mice and serum IgA and renal lesions were analysed.

RESULTS

The production of IFN-gamma by splenic CD4+ T cells was markedly upregulated in HIGA mice at both ages as compared with age-matched C57BL/6 and BALB/c mice. Although splenic CD4+ T cells from HIGA mice produced less IL-4 than those from BALB/c mice at both ages, the former produced significantly more IL-4 with age, which contrasted with the age-associated decrease in the latter. Moreover, TGF-beta1 production of these cells in HIGA mice was equal to or greater than that in the two groups of control mice at both ages. Daily intraperitoneal administration of IL-12 for 1 week significantly enhanced crescent formation with glomerular macrophage accumulation and interstitial cell infiltration, whereas it reduced the serum IgA level.

CONCLUSIONS

In HIGA mice, Th1 is markedly upregulated from a young age and there is an age-associated Th2 increase with TGF-beta1 upregulation in helper T cells. The former may be related to the exacerbation of inflammatory renal lesions on IL-12 administration, while the latter may contribute to increased IgA production, leading to glomerular IgA deposition and progressive glomerulosclerosis in HIGA mice. The pathogenic role of T cell function and fluctuation of these subsets, especially the Th1/Th2 balance, is crucial to the immunopathological phenotype of the renal lesions in HIGA mice.

Increased frequency of surface IgA-positive plasma cells in the intestinal lamina propria and decreased IgA excretion in hyper IgA (HIGA) mice, a murine model of IgA nephropathy with hyperserum IgA

Because abnormalities of mucosal immunity have been suggested in human IgA nephropathy, we examined the involvement of mucosal immunity in IgA deposition to the kidney in hyper IgA (HIGA) mice, which was established as a mouse model for human IgA nephropathy with hyperserum IgA. The number of surface IgA+B220- lymphocytes in the intestinal lamina propria (LP) of HIGA mice increased 2.7-fold at 30 wk of age as compared with those at 10 wk of age, whereas normal mice did not show such increase. The surface IgA+B220- LP lymphocytes spontaneously secreted IgA in culture. Morphological studies showed that the surface IgA+B220- lymphocytes of murine intestinal LP are identical with plasma cells (PCs). About 20% of IgA+B220- PC in LP expressed both Mac-1 and CD19, suggesting that they may derive from peritoneal B-1 cells. Cell cycle study on intestinal IgA-PCs using bromodeoxyuridine revealed no difference between HIGA mice and normal mice, suggesting that the high frequency of IgA-producing PCs in HIGA mice is not due to enhanced proliferation or prolonged survival of IgA-producing PCs in LP. In addition, IgA secretion into the gut lumen of HIGA mice decreased drastically (to one forth) with aging. These data suggest that the increased number of intestinal IgA-producing PCs and the down-regulation of IgA excretion into the intestinal lumen might synergistically contribute to the hyperserum IgA in HIGA mice and resultant IgA deposition to the kidney.