Interstitial deletion of the Apc locus in β-catenin-overexpressing cells is a signature of radiation-induced intestinal tumors in C3B6F1 ApcMin/+ mice†

Recent studies have identified interstitial deletions in the cancer genome as a radiation-related mutational signature, although most of them do not fall on cancer driver genes. Pioneering studies in the field have indicated the presence of loss of heterozygosity (LOH) spanning Apc in a subset of sporadic and radiation-induced intestinal tumors of ApcMin/+ mice, albeit with a substantial subset in which LOH was not detected; whether copy number losses accompany such LOH has also been unclear. Herein, we analyzed intestinal tumors of C3B6F1 ApcMin/+ mice that were either left untreated or irradiated with 2 Gy of γ-rays. We observed intratumor mosaicism with respect to the nuclear/cytoplasmic accumulation of immunohistochemically detectable β-catenin, which is a hallmark of Apc+ allele loss. An immunoguided laser microdissection approach enabled the detection of LOH involving the Apc+ allele in β-catenin-overexpressing cells; in contrast, the LOH was not observed in the non-overexpressing cells. With this improvement, LOH involving Apc+ was detected in all 22 tumors analyzed, in contrast to what has been reported previously. The use of a formalin-free fixative facilitated the LOH and microarray-based DNA copy number analyses, enabling the classification of the aberrations as nondisjunction/mitotic recombination type or interstitial deletion type. Of note, the latter was observed only in radiation-induced tumors (nonirradiated, 0 of 8; irradiated, 11 of 14). Thus, an analysis considering intratumor heterogeneity identifies interstitial deletion involving the Apc+ allele as a causative radiation-related event in intestinal tumors of ApcMin/+ mice, providing an accurate approach for attributing individual tumors to radiation exposure.

Calorie restriction alters the mechanisms of radiation-induced mouse thymic lymphomagenesis

Calorie restriction (CR) suppresses not only spontaneous but also chemical- and radiation-induced carcinogenesis. Our previous study revealed that the cancer-preventive effect of CR is tissue dependent and that CR does not effectively prevent the development of thymic lymphoma (TL). We investigated the association between CR and the genomic alterations of resulting TLs to clarify the underlying resistance mechanism. TLs were obtained from previous and new experiments, in which B6C3F1 mice were exposed to radiation at 1 week of age and fed with a CR or standard (non-CR) diet from 7 weeks throughout their lifetimes. All available TLs were used for analysis of genomic DNA. In contrast to the TLs of the non-CR group, those of the CR group displayed suppression of copy-neutral loss of heterozygosity (LOH) involving relevant tumor suppressor genes (Cdkn2a, Ikzf1, Trp53, Pten), an event regarded as cell division-associated. However, CR did not affect interstitial deletions of those genes, which were observed in both groups. In addition, CR affected the mechanism of Ikzf1 inactivation in TLs: the non-CR group exhibited copy-neutral LOH with duplicated inactive alleles, whereas the CR group showed expression of dominant-negative isoforms accompanying a point mutation or an intragenic deletion. These results suggest that, even though CR reduces cell division-related genomic rearrangements by suppressing cell proliferation, tumors arise via diverse carcinogenic pathways including inactivation of tumor suppressors via interstitial deletions and other mutations. These findings provide a molecular basis for improved prevention strategies that overcome the CR resistance of lymphomagenesis.

High Relative Biological Effectiveness of 2 MeV Fast Neutrons for Induction of Medulloblastoma in Ptch1+/- Mice with Radiation-specific Deletion on Chromosome 13

Neutron radiation, a high-linear energy transfer radiation, has a high relative biological effectiveness (RBE) for various end points. The age at exposure is an important modifier of the effects of radiation, including carcinogenesis, with infants being generally more radiosensitive. Ptch1+/- mice offer a unique experimental system for assessing radiation carcinogenesis. Spontaneous development of medulloblastoma tumors occurs in nonirradiated animals that lose their Ptch1+ allele, most frequently by a loss of heterozygosity (LOH) of chromosome 13 via recombination or non-disjunction (referred to as S-type tumors). In contrast, tumors occur in irradiated Ptch1+/- mice as a result of chromosome 13 LOH with an interstitial deletion (R-type), making spontaneous and radiation-induced tumors discernible. To elucidate the influence of age on the effect of fast neutrons, we irradiated Ptch1+/- mice with neutrons (mean energy, ∼2 MeV) or γ rays on embryonic day (E)14 and E17 and on postnatal day (P)1, 4 or 10 and classified the resulting medulloblastomas based on chromosome 13 aberrations. Instead of LOH, some tumors harbored mutations in their Ptch1+ gene via a nonirradiation-associated mechanism such as duplication, insertion, base substitution or deletion with microhomology-mediated end joining; thus, these tumors were classified as S-type. The RBE regarding the induction of R-type tumors was 12.9 (8.6, 17.2), 9.6 (6.9, 12.3), 21.5 (17.2, 25.8), and 7.1 (4.7, 9.5) (mean and 95% confidence interval) for mice irradiated on E14, E17, P1 and P4, respectively, with the highest value seen during the most active development of the tissue and P10 being completely resistant. These results indicate that the developmental stage at exposure of the tissue influences the RBE of neutrons.

Interstitial chromosomal deletion of the tuberous sclerosis complex 2 locus is a signature for radiation-associated renal tumors in Eker rats

Ionizing radiation can damage DNA and, therefore, is a risk factor for cancer. Eker rats, which carry a heterozygous germline mutation in the tumor-suppressor gene tuberous sclerosis complex 2 (Tsc2), are susceptible to radiation-induced renal carcinogenesis. However, the molecular mechanisms involved in Tsc2 inactivation are unclear. We subjected Fischer 344 × Eker (Long Evans Tsc2+/- ) F1 hybrid rats to gamma-irradiation (2 Gy) at gestational day 19 (GD19) or postnatal day 5 (PND5) and investigated the patterns of genomic alterations in the Tsc2 allele of renal tumors that developed at 1 year after irradiation (N = 24 tumors for GD19, N = 10 for PND5), in comparison with spontaneously developed tumors (N = 8 tumors). Gamma-irradiation significantly increased the multiplicity of renal tumors. The frequency of LOH at the chromosome 10q12 region, including the Tsc2 locus, was 38%, 29% and 60% in renal carcinomas developed from the nonirradiated, GD19 and PND5 groups, respectively. Array comparative genomic hybridization analysis revealed that the LOH patterns on chromosome 10 in renal carcinomas were classified into chromosomal missegregation, mitotic recombination and chromosomal deletion types. LOH of the interstitial chromosomal deletion type was observed only in radiation-associated carcinomas. Sequence analysis for the wild-type Tsc2 allele in the LOH-negative carcinomas identified deletions (nonirradiated: 26%; GD19: 21%) and base-substitution mutations (GD19: 4%). Reduced expression of Tsc2 was also observed in the majority of the LOH-negative carcinomas. Our results suggest that interstitial chromosomal deletion is a characteristic mutagenic event caused by ionizing radiation, and it may contribute to the assessment of radiation-induced cancer risk.

Mutational landscape of T-cell lymphoma in mice lacking the DNA mismatch repair gene Mlh1: no synergism with ionizing radiation

Biallelic germline mutations in the DNA mismatch repair gene MLH1 lead to constitutional mismatch repair-deficiency syndrome and an increased risk for childhood hematopoietic malignancies, including lymphoma and leukemia. To examine how Mlh1 dysfunction promotes lymphoma as well as the influence of ionizing radiation (IR) exposure, we used an Mlh1-/- mouse model and whole-exome sequencing to assess genomic alterations in 23 T-cell lymphomas, including 8 spontaneous and 15 IR-associated lymphomas. Exposure to IR accelerated T-cell lymphoma induction in the Mlh1-/- mice, and whole-exome sequencing revealed that IR exposure neither increased the number of mutations nor altered the mutation spectrum of the lymphomas. Frequent mutations were evident in genes encoding transcription factors (e.g. Ikzf1, Trp53, Bcl11b), epigenetic regulators (e.g. Suv420h1, Ep300, Kmt2d), transporters (e.g. Rangap1, Kcnj16), extracellular matrix (e.g. Megf6, Lrig1), cell motility (e.g. Argef19, Dnah17), protein kinase cascade (e.g. Ptpro, Marcks) and in genes involved in NOTCH (e.g. Notch1), and PI3K/AKT (e.g. Pten, Akt2) signaling pathways in both spontaneous and IR-associated lymphomas. Frameshift mutations in mononucleotide repeat sequences within the genes Trp53, Ep300, Kmt2d, Notch1, Pten and Marcks were newly identified in the lymphomas. The lymphomas also exhibited a few chromosomal abnormalities. The results establish a landscape of genomic alterations in spontaneous and IR-associated lymphomas that occur in the context of mismatch repair dysfunction and suggest potential targets for cancer treatment.

The effect of age at exposure on the inactivating mechanisms and relative contributions of key tumor suppressor genes in radiation-induced mouse T-cell lymphomas

Children are considered more sensitive to radiation-induced cancer than adults, yet any differences in genomic alterations associated with age-at-exposure and their underlying mechanisms remain unclear. We assessed genome-wide DNA copy number and mutation of key tumor suppressor genes in T-cell lymphomas arising after weekly irradiation of female B6C3F1 mice with 1.2Gy X-rays for 4 consecutive weeks starting during infancy (1 week old), adolescence (4 weeks old) or as young adults (8 weeks old). Although T-cell lymphoma incidence was similar, loss of heterozygosity at Cdkn2a on chromosome 4 and at Ikaros on chromosome 11 was more frequent in the two older groups, while loss at the Pten locus on chromosome 19 was more frequent in the infant-irradiated group. Cdkn2a and Ikaros mutation/loss was a common feature of the young adult-irradiation group, with Ikaros frequently (50%) incurring multiple independent hits (including deletions and mutations) or suffering a single hit predicted to result in a dominant negative protein (such as those lacking exon 4, an isoform we have designated Ik12, which lacks two DNA binding zinc-finger domains). Conversely, Pten mutations were more frequent after early irradiation (60%) than after young adult-irradiation (30%). Homozygous Pten mutations occurred without DNA copy number change after irradiation starting in infancy, suggesting duplication of the mutated allele by chromosome mis-segregation or mitotic recombination. Our findings demonstrate that while deletions on chromosomes 4 and 11 affecting Cdkn2a and Ikaros are a prominent feature of young adult irradiation-induced T-cell lymphoma, tumors arising after irradiation from infancy suffer a second hit in Pten by mis-segregation or recombination. This is the first report showing an influence of age-at-exposure on genomic alterations of tumor suppressor genes and their relative involvement in radiation-induced T-cell lymphoma. These data are important for considering the risks associated with childhood exposure to radiation.

Genetic Analysis of T Cell Lymphomas in Carbon Ion-Irradiated Mice Reveals Frequent Interstitial Chromosome Deletions: Implications for Second Cancer Induction in Normal Tissues during Carbon Ion Radiotherapy

Monitoring mice exposed to carbon ion radiotherapy provides an indirect method to evaluate the potential for second cancer induction in normal tissues outside the radiotherapy target volume, since such estimates are not yet possible from historical patient data. Here, male and female B6C3F1 mice were given single or fractionated whole-body exposure(s) to a monoenergetic carbon ion radiotherapy beam at the Heavy Ion Medical Accelerator in Chiba, Japan, matching the radiation quality delivered to the normal tissue ahead of the tumour volume (average linear energy transfer = 13 keV.μm^-1) during patient radiotherapy protocols. The mice were monitored for the remainder of their lifespan, and a large number of T cell lymphomas that arose in these mice were analysed alongside those arising following an equivalent dose of ¹³⁷Cs gamma ray-irradiation. Using genome-wide DNA copy number analysis to identify genomic loci involved in radiation-induced lymphomagenesis and subsequent detailed analysis of Notch1, Ikzf1, Pten, Trp53 and Bcl11b genes, we compared the genetic profile of the carbon ion- and gamma ray-induced tumours. The canonical set of genes previously associated with radiation-induced T cell lymphoma was identified in both radiation groups. While the pattern of disruption of the various pathways was somewhat different between the radiation types, most notably Pten mutation frequency and loss of heterozygosity flanking Bcl11b, the most striking finding was the observation of large interstitial deletions at various sites across the genome in carbon ion-induced tumours, which were only seen infrequently in the gamma ray-induced tumours analysed. If such large interstitial chromosomal deletions are a characteristic lesion of carbon ion irradiation, even when using the low linear energy transfer radiation to which normal tissues are exposed in radiotherapy patients, understanding the dose-response and tissue specificity of such DNA damage could prove key to assessing second cancer risk in carbon ion radiotherapy patients.

Ikaros is a critical target during simultaneous exposure to X-rays and N-ethyl-N-nitrosourea in mouse T-cell lymphomagenesis

Cancer risk associated with radiation exposure is considered the result of concurrent exposure to other natural and manmade carcinogens. Available data on the molecular characteristics of cancer after simultaneous exposure to radiation and chemicals are insufficient. In our study, we used a mouse thymic lymphoma (TL) model that was synergistically induced by simultaneous exposure to X-rays and N-ethyl-N-nitrosourea (ENU) at subcarcinogenic doses and analyzed the mutation frequency and spectrum of the TL-associated genes Ikaros, Notch1, p53 and Kras. We found that the point mutation frequency in Ikaros was significantly increased to 47% for simultaneous exposure compared to 13 and 0% for X-ray and ENU exposure alone, respectively. These mutations were mostly G:C > A:T at non-CpG sites and T:A > C:G, both of which are characteristic of ENU mutagenesis. About half of the point mutations were accompanied by loss of heterozygosity (LOH), typical of X-irradiation. The remaining half did not include LOH, which suggests that they were dominant-negative mutations. In Notch1, the frequency of abnormalities was high (>58%) regardless of the treatment, suggesting that Notch1 aberration may be important for T-cell lymphomagenesis. The p53 and Kras mutation frequencies were low for all treatments (<23%). Importantly, the frequency of TLs containing mutations in multiple genes, especially both Ikaros and Notch1, increased after simultaneous exposure. Thus, after simultaneous exposure, Ikaros is a critical target and is inactivated by ENU-induced point mutations and/or X-ray-induced LOH in T-cell lymphomagenesis. Furthermore, concomitant alterations of multiple tumor-associated genes may contribute to enhanced lymphomagenesis after simultaneous exposure.

Combined exposure to X-irradiation followed by N-ethyl-N-nitrosourea treatment alters the frequency and spectrum of Ikaros point mutations in murine T-cell lymphoma

Ionizing radiation is a well-known carcinogen, but its potency may be influenced by other environmental carcinogens, which is of practical importance in the assessment of risk. Data are scarce, however, on the combined effect of radiation with other environmental carcinogens and the underlying mechanisms involved. We studied the mode and mechanism of the carcinogenic effect of radiation in combination with N-ethyl-N-nitrosourea (ENU) using doses approximately equal to the corresponding thresholds. B6C3F1 mice exposed to fractionated X-irradiation (Kaplan's method) followed by ENU developed T-cell lymphomas in a dose-dependent manner. Radiation doses above an apparent threshold acted synergistically with ENU to promote lymphoma development, whereas radiation doses below that threshold antagonized lymphoma development. Ikaros, which regulates the commitment and differentiation of lymphoid lineage cells, is a critical tumor suppressor gene frequently altered in both human and mouse lymphomas and shows distinct mutation spectra between X-ray- and ENU-induced lymphomas. In the synergistically induced lymphomas, we observed a low frequency of LOH and an inordinate increase of Ikaros base substitutions characteristic of ENU-induced point mutations, G:C to A:T at non-CpG, A:T to G:C, G:C to T:A and A:T to T:A. This suggests that radiation doses above an apparent threshold activate the ENU mutagenic pathway. This is the first report on the carcinogenic mechanism elicited by combined exposure to carcinogens below and above threshold doses based on the mutation spectrum of the causative gene. These findings constitute a basis for assessing human cancer risk following exposure to multiple carcinogens.

Genomic and gene expression signatures of radiation in medulloblastomas after low-dose irradiation in Ptch1 heterozygous mice

Accurate cancer risk assessment of low-dose radiation poses many challenges that are partly due to the inability to distinguish radiation-induced tumors from spontaneous ones. To elucidate characteristic features of radiation-induced tumors, we analyzed 163 medulloblastomas that developed either spontaneously or after X-ray irradiation at doses of 0.05-3 Gy in Ptch1 heterozygous mice. All spontaneous tumors showed loss of heterozygosity in broad regions on chromosome 13, with losses at all consecutive markers distal to Ptch1 locus (S-type). In contrast, all tumors that developed after 3 Gy irradiation exhibited interstitial losses around Ptch1 with distal markers retained (R-type). There was a clear dose-dependent increase in the proportion of R-type tumors within the intermediate dose range, indicating that the R-type change is a reliable radiation signature. Importantly, the incidence of R-type tumors increased significantly (P = 0.007) at a dose as low as 50 mGy. Integrated array-comparative genomic hybridization and expression microarray analyses demonstrated that expression levels of many genes around the Ptch1 locus faithfully reflected the signature-associated reduction in genomic copy number. Furthermore, 573 genes on other chromosomes were also expressed differently between S-type and R-type tumors. They include genes whose expression changes during early cerebellar development such as Plagl1 and Tgfb2, suggesting a recapitulation of gene subsets functioning at distinct developmental stages. These findings provide, for the first time, solid experimental evidence for a significant increase in cancer risk by low-dose radiation at diagnostic levels and imply that radiation-induced carcinogenesis accompanies both genomic and gene expression signatures.

Complicated biallelic inactivation of Pten in radiation-induced mouse thymic lymphomas

Inactivation of the phosphatase and tensin homolog gene (Pten) occurs via multiple tissue-dependent mechanisms including epigenetic silencing, point mutations, insertions, and deletions. Although frequent loss of heterozygosity around the Pten locus and plausible involvement of epigenetic silencing have been reported in radiation-induced thymic lymphomas, the proportion of lymphomas with inactivated Pten and the spectrum of causal aberrations have not been extensively characterized. Here, we assessed the mode of Pten inactivation by comprehensive analysis of the expression and alteration of Pten in 23 radiation-induced thymic lymphomas developed in B6C3F1 mice. We found no evidence for methylation-associated silencing of Pten; rather, complex structural abnormalities comprised of missense and nonsense mutations, 1- and 3-bp insertions, and focal deletions were identified in 8 of 23 lymphomas (35%). Sequencing of deletion breakpoints suggested that aberrant V(D)J recombination and microhomology-mediated rearrangement were responsible for the focal deletions. Seven of the 8 lymphomas had biallelic alterations, and 4 of them did not express Pten protein. These Pten aberrations coincided with downstream Akt phosphorylation. In conclusion, we demonstrate that Pten inactivation is frequently biallelic and is caused by a variety of structural abnormalities (rather than by epigenetic silencing) and is involved in radiation-induced lymphomagenesis.

Low-dose radiation attenuates chemical mutagenesis in vivo

The biological effects of low-dose radiation are not only of social concern but also of scientific interest. The radioadaptive response, which is defined as an increased radioresistance by prior exposure to low-dose radiation, has been extensively studied both in vitro and in vivo. Here we briefly review the radioadaptive response with respect to mutagenesis, survival rate, and carcinogenesis in vivo, and introduce our recent findings of cross adaptation in mouse thymic cells, that is, the suppressive effect of repeated low-dose radiation on mutation induction by the alkylating agent N-ethyl-N-nitrosourea.

Aberrant activation of interleukin-9 receptor and downstream Stat3/5 in primary T-cell lymphomas in vivo in susceptible B6 and resistant C3H mice

BACKGROUND

Interleukin (IL)-2 family cytokine-mediated signal transduction plays important roles not only in normal development but also in the malignant transformation of lymphoid cells. However, little is known about the status of receptor activation and downstream signal transduction in primary lymphomas in vivo.

MATERIALS AND METHODS

Primary T-cell lymphomas (TL) of mice were induced by X-ray irradiation. Expression and activation of IL-2 family cytokine receptors and downstream Janus kinase (Jak)-signal transducers and activators of transcription (Stat) pathway were determined.

RESULTS

IL-9Ra was exceptionally highly expressed and phosphorylated in primary TL. IL-9Ralpha proteins in TL were heterogeneous due to different glycosylation. Downstream Stat3 and 5, but not Stat1, were also phosphorylated. There was a clear strain difference between susceptible C57BL/6 and resistant C3H mice in Stat3 and 5 activation and expression of Cyclin D1.

CONCLUSION

Aberrant expression, modification and activation of IL-9Ralpha and Stat proteins contribute to in vivo growth of TL in a manner linking to the genetic susceptibility to TL induction.

Ikaros is a mutational target for lymphomagenesis in Mlh1-deficient mice

Deficiencies in DNA mismatch repair (MMR) result in replication errors within key tumor suppressor genes or oncogenes, and cause hereditary nonpolyposis colorectal cancer (HNPCC). Hematological malignancy with microsatellite instability is also associated with defective MMR, but little is known about the target genes for MMR. Here we identified Ikaros, a master transcription factor of lymphoid lineage commitment and differentiation, as a mutational target in spontaneous and radiation-induced T-cell lymphomas in Mlh1-deficient mice. Three quarters of lymphomas lacked Ikaros protein expression, which resulted from a frameshift mutation that created a stop codon. Mononucleotide repeat sequences at 1029-1034(C)6 and 1567-1572(G)6 in Ikaros were mutational hot spots with a one-base deletion occurring with a frequency of 45 and 50%, respectively. Point mutations and splicing alterations were also observed. In total, 85% of the lymphomas showed aberrations in Ikaros. The characteristic of Mlh1-deficient lymphomas is harboring of multiple mutations simultaneously in the same tumor, displaying a combination of two frameshift mutations at different repeats, frameshift and point mutations, and/or deletion mutations. This is the first report of Ikaros mutations coupled with Mlh1 deficiency in lymphomagenesis.

Up regulated expression of tumour necrosis factor {alpha} converting enzyme in peripheral monocytes of patients with early systemic sclerosis

BACKGROUND

Systemic sclerosis (SSc) is accompanied by abnormalities in humoral and cellular immune systems.

OBJECTIVE

To determine the genes specifically expressed in the immune system in SSc by analysis of the gene expression profile of peripheral blood mononuclear cells (PBMC) from patients with SSc, including those treated with haematopoietic stem cell transplantation (HSCT). Additionally, to investigate the clinical significance of the up regulation of tumour necrosis factor alpha (TNFalpha) converting enzyme (TACE).

METHODS

PBMC from patients with SSc (n = 23) and other autoimmune diseases (systemic lupus erythematosus (SLE, n = 16), rheumatoid arthritis (RA, n = 29)), and from disease-free controls (n = 36) were examined. Complementary DNA arrays were used to evaluate gene expression of PBMC, in combination with real time quantitative polymerase chain reactions. TACE protein expression in PBMC was examined by fluorescence activated cell sorter (FACS).

RESULTS

In patients with SSc 118 genes were down regulated after HSCT. Subsequent comparative analysis of SSc without HSCT and healthy controls indicated SSc-specific up regulation for three genes: monocyte chemoattractant protein-3 (p = 0.0015), macrophage inflammatory protein 3alpha (p = 0.0339), and TACE (p = 0.0251). In the FACS analysis, TACE protein was mainly expressed on CD14(+) monocytes both in patients with SSc and controls. TACE expression on CD14(+) cells was significantly increased in patients with early SSc (p = 0.0096), but not in those with chronic SSc, SLE, or RA. TACE protein levels in SSc monocytes correlated with the intracellular CD68 levels (p = 0.0016).

CONCLUSIONS

Up regulation of TACE expression was a unique profile in early SSc, and may affect the function of TNFalpha and other immunoregulatory molecules.

Frequent retention of heterozygosity for point mutations in p53 and Ikaros in N-ethyl-N-nitrosourea-induced mouse thymic lymphomas

In agreement with Knudson's two-hit theory, recent findings indicate that the inactivation of tumor suppressor genes is not only mediated by the loss of function but also by the dominant-negative or gain-of-function activity. The former generally accompanies loss of a wild-type allele whereas in the latter a wild-type allele is retained. N-Ethyl-N-nitrosourea (ENU), which efficiently induces point mutations, reportedly leads to the development of tumors by activating ras oncogenes. Little is known about how ENU affects tumor suppressor genes and, therefore, we examined ENU-induced mutations of p53 and Ikaros in thymic lymphomas and compared these with mutations of Kras. In addition, loss of heterozygosity was examined for chromosome 11 to which both p53 and Ikaros were mapped. The frequency of point mutations in p53 and Ikaros was 30% (8/27) and 19% (5/27), respectively, comparable to that observed in Kras (33%: 9/27). In total, 14 of the 27 thymic lymphomas examined (52%) harbored mutations in at least one of these genes. One Ikaros mutation was located at the splice donor site, generating a novel splice isoform lacking zinc finger 3, Ik (F3del). Interestingly, 90% (10/11) of the tumors with point mutations retained wild-type alleles of p53 and Ikaros. Sequence analysis revealed that the most common nucleic acid substitutions were T>A (4/8) in p53, T>C (4/5) in Ikaros and G>A/T (8/9) in Kras, suggesting that the spectrum of mutations was gene dependent. These results suggest that point mutations in tumor suppressor genes without loss of the wild-type allele play an important role in ENU-induced lymphomagenesis.

Effect of carbon ions on life span shortening and tumorigenesis in mice

One of the important concerns for astronauts in space is cancer risk associated with cosmic radiation, including heavy particle ions. But little information on cancer risk is available. We investigated the effect of carbon ions on life span shortening and tumor induction in B6C3F1 mice. The mice were exposed weekly to 0.4 and 2.0 Gy whole-body carbon-ion- or X-ray-irradiation for 4 consecutive weeks. The spectrum of induced tumors varied depending on the dose. The cause of death was thymic lymphomas and liver tumors at high and low dose, respectively. The life span shortening by X-rays was proportional to dose, while carbon ions produced a convex upward relationship. The relative biological effectiveness for the 50% life span shortening was about 1.4. The large effect of carbon ions encourages the study on tumor induction at low doses in the space.

Loss of heterozygosity in heavy-ion-induced murine T-cell lymphomas

One of the important concerns for astronauts in space environment is cancer risk associated with cosmic radiation, including heavy particle carbon-ions. But little information on cancer risk is available. In the present study, we investigated the induction of and cellular and molecular characteristics of T-cell lymphomas of B6C3F1 mice induced by carbon-ions and X-rays. The incidence, the latent period and the surface expression of T-cell differentiation antigens were similar between carbon-ion- and X-ray-induced lymphomas. The size of T-cell lymphomas induced by carbon-ions was significantly smaller than that by X-rays. Molecular analysis indicated that high frequency of loss of heterozygosity (LOH) was found on chromosomes 4, 11, 12 and 19 in both lymphomas. Interestingly, the frequency of LOH on chromosome 11 was much higher, but that on chromosome 12 was lower in carbon-ion-induced T-cell lymphomas than in X-ray-induced ones. These results indicate that mechanistic differences may exist between carbon-ion- and X-ray-induced lymphomagenesis.

Cerebral imaging by magnetic resonance imaging and single photon emission computed tomography in systemic lupus erythematosus with central nervous system involvement

OBJECTIVE

To assess the significance of magnetic resonance imaging (MRI) and single photon emission computed tomography (SPECT) abnormalities in patients with systemic lupus erythematosus (SLE).

METHODS

Forty-four patients with SLE were retrospectively analysed. Patients were classified into three groups [1 and 2: patients with central nervous system (CNS) manifestations before and after starting high-dose steroid therapy, respectively; 3: patients without CNS manifestations. MRI was performed in all 44 patients and SPECT in 31.

RESULTS

Abnormal findings in MRI were found in 19 patients. MRI abnormalities were significantly more frequent in patients with CNS manifestations than in those without [71 vs 17%, odds ratio (OR) 11.9, confidence interval (CI) 2.8-49.9, P=0.0003]. After the initiation of steroid therapy, patients with CNS manifestations also had an increased frequency of abnormal MRI. No correlation was found between SPECT findings and CNS manifestations. However, patients with CNS manifestations after starting steroids showed a markedly increased frequency of abnormal MRI and SPECT compared with those without CNS manifestations (80 vs 7%; OR 56, CI 4.4-719, P=0.0003). The positive predictive value of abnormality in both techniques in developing CNS manifestations after starting steroids was 89%.

CONCLUSION

MRI findings correlated with CNS manifestations in SLE. Where there is a high suspicion of CNS involvement, the combination of MRI and SPECT may be useful in predicting CNS manifestations after starting steroid therapy.

Significance of magnetic resonance imaging in the diagnosis of nodular regenerative hyperplasia of the liver complicated with systemic lupus erythematosus: a case report and review of the literature

Nodular regenerative hyperplasia of the liver (NRH), characterized by multiple hepatic nodules in the absence of fibrosis, is a rare but important complication of systemic lupus erythematosus (SLE) associated with non-cirrhotic portal hypertension. The diagnosis of NRH is based on the pathological examination, and radiological findings of NRH are poorly documented. We report a case of a 40-year-old woman with SLE complicated with NRH. Sixteen years after diagnosis of SLE, esophageal varices were incidentally found and diagnosis of portal hypertension due to NRH was made by magnetic resonance imaging (MRI) and confirmed by needle liver biopsy. Although MRI showed the lesions as significant nodules, neither computed tomography nor ultrasonography could demonstrate the nodules. However, serial MRI showed significant enlargement of the nodules for 2 years Because NRH may lead to portal hypertension with life-threatening variceral haemorrhage in patients with SLE, MRI is a useful, non-invasive examination to screen the patients for its presence and follow-up. We reviewed the literature regarding NRH in SLE and discuss the management of the affected patients.

Correlation between fatty liver and coronary risk factors: a population study of elderly men and women in Nagasaki, Japan

The relation between fatty liver, detected by ultrasonography as a marker of visceral fat accumulation, and coronary risk factors was studied in 810 elderly men and 1,273 elderly women in Nagasaki, Japan from 1990 to 1992. The prevalence of fatty liver was 3.3% in the male and 3.8% in the female non-obese participants (BMI, body mass index < 26.0 kg/m2) and 21.6% in the male and 18.8% in the female obese participants (26.0 kg/m2 < or = BMI). Fatty liver was significantly (p < 0.01) related to hypercholesterolemia and hypertriglyceridemia in the men and to hypertension, hypercholesterolemia, low-HDL cholesterol, hypertriglyceridemia and diabetes mellitus or impaired glucose tolerance (DM+IGT) in the women independent of age, obesity, smoking and drinking. Non-obesity with fatty liver, rather than obesity with or without fatty liver, had the highest odds ratio for hypertension and low-HDL cholesterol in the men and for hypercholesterolemia, low-HDL cholesterol, hypertriglyceridemia and DM+IGT in the women. The prevalence of fatty liver is the same in elderly men and women, and fatty liver is an independent correlate of coronary risk factors in the elderly.

Stem cell factor protects c-kit+ human primary erythroid cells from apoptosis

OBJECTIVE

It has been reported that stem cell factor (SCF) promotes cell survival in primary cultured human erythroid colony-forming cells (ECFC). Given the heterogeneous nature of ECFC, which may affect interpretation of the data, we purified c-kit+ ECFC and investigated the specificity and mechanisms of the anti-apoptotic effects of SCF on these cells.

MATERIALS AND METHODS

Glycophorin A+ (GPA+) c-kit+ cells were purified from primary cultured ECFC derived from purified human CD34+ cells. The GPA+c-kit- and nonerythroid cells were generated from the same CD34+ cells. Apoptosis of ECFC was investigated in the absence or presence of SCF and erythropoietin (EPO) in serum-free medium. DNA fragmentation was measured with enzyme linked immunosorbent assay for oligonucleosome-sized DNA, gel electrophoresis, and annexin V labeling. Characterization of expanded cells and enriched cells was performed using multiparameter flow cytometry. For Akt assay, cells were lysed and the cleared lysates subjected to SDS-PAGE followed by Western blotting.

RESULTS

In GPA+c-kit+ cells, deprivation of cytokine caused rapid DNA fragmentation within 4 hours that reached a maximum at 6 hours. This was partially but clearly prevented by SCF or EPO. In contrast, no significant DNA fragmentation was seen in GPA+c-kit- and nonerythroid cells within 24 hours. PP2, a specific Src family kinase inhibitor, but not its inactive analogue PP3, reversed the anti-apoptotic effects of SCF. PP2 also inhibited SCF-induced phosphorylation of Akt.

CONCLUSION

These data indicate that SCF protects purified human GPA+c-kit+ cells from apoptosis and suggest that kit-mediated Src kinase activation is involved in Akt activation and cell survival.

Regulation of nuclear factor of activated T-cell family transcription factors during T-cell development in the thymus

BACKGROUND

T lymphocytes undergo a series of developmental events in the thymus, and signaling through the T-cell antigen receptor is crucial in this differential program. The nuclear factor of activated T cells (NFATs) may be involved in transcriptional induction of cytokine genes and other immunoregulatory genes in T cells.

OBJECTIVES

We have examined the distribution of 3 NFAT family members (NFAT1, NFATc, and NFATx) in human fetal thymocytes, by using semiquantitative RT-PCR and electrophoretic mobility shift assay.

RESULTS

The messenger RNA of NFATx was expressed in all T-lymphocyte subsets tested, and expression was highest in CD4(+)CD8(+) thymocytes. Conversely, mRNA of NFAT1 was preferentially expressed in mature CD4(+) single-positive cells. NFATc mRNA was present at low levels in all subsets but was strongly induced by treatment with phorbol ester plus calcium ionophore. Using electrophoretic mobility shift assay, we observed stimulation-dependent NFAT-DNA binding in CD4(+)CD8(+) thymocytes, which was largely dependent on NFATx protein. This DNA-binding activity was inhibited by cyclosporin A, which indicated that NFATx nuclear translocation in CD4(+)CD8(+) thymocytes was regulated by calcineurin phosphatase. In contrast, NFAT1 and NFATc (and to some extent NFATx) were responsible for NFAT DNA binding in the CD4(+) cells.

CONCLUSIONS

Expression of NFAT family members is differentially regulated during T-cell development, and NFATx may be involved in T-cell antigen receptor/calcineurin-dependent signaling in CD4(+)CD8(+) thymocytes.

Successive expression and activation of NFAT family members during thymocyte differentiation

Differentiation of immature CD4(+)CD8(+) thymocytes to mature CD4(+) or CD8(+) T cells is induced by positive selection and appears to involve calcineurin-dependent activation of NFAT, a family of transcription factors. NFATx is predominantly expressed in CD4(+)CD8(+) thymocytes, whereas NFATp and NFATc are expressed at much lower levels in the thymus than in mature T cells. However, how or when each NFAT member is involved in the differentiation pathway is unclear. Using an in vitro model system where isolated CD4(+)CD8(+) thymocytes can survive and differentiate into semi-mature CD4-lineage T cells, we suggest that low calcineurin activity sustained for approximately 20 h is required for cell survival and differentiation. Accordingly, the DNA binding activity of NFAT slowly increased during the stimulation of 20 h to induce the differentiation. NFATx significantly contributed to the early rise, but the late increase was mostly due to NFATc activation. Meanwhile, the expression of NFATx mRNA decreased and that of NFATc mRNA increased. The DNA-binding activity of NFATp was detectable but low throughout the stimulation. NFATp became dominantly active after the semi-mature T cells differentiated into mature and activated CD4 T cells. These findings suggest that NFATx and NFATc successively play roles in T cell development.

Signalling into the T-cell nucleus: NFAT regulation

The nuclear factor of activated T cells (NFAT) plays an important role in T-cell biology. Activation of T cells results in the rapid calcineurin-dependent translocation of NFAT transcription factors from the cytoplasm to the nucleus. This translocation process coupled to the subsequent active maintenance of NFAT in the nucleus compartment is critical for the induction of expression of several genes encoding cytokines and membrane proteins that modulate immune responses. The molecular cloning of the NFAT family of transcription factors has facilitated rapid progress in the understanding of the signalling mechanisms that control the activity of NFAT.

Distinct NFAT family proteins are involved in the nuclear NFAT-DNA binding complexes from human thymocyte subsets

The nuclear factor of activated T cells (NFAT) is involved in the transcriptional induction of cytokine and other immunoregulatory genes during an immune response. Among four distinct NFAT family members identified to date, mRNAs of NFAT1, NFATc, and NFATx are expressed in the thymus. Here, we report the distribution of these three NFAT family members in human fetal thymocyte subsets and in peripheral mature T cells. We show that NFATx mRNA was expressed in all T lymphocyte subsets tested and was highest in CD4+CD8+ double positive (DP) thymocytes. Conversely, NFAT1 mRNA was preferentially expressed in the mature CD4+ single positive (SP) populations. NFATc mRNA was present at low levels in all subsets but strongly induced upon treatment with phorbol ester and calcium ionophore. Interestingly, we detected NFAT-DNA binding complexes in DP thymocytes, albeit at lower levels than in CD4 SP cells. Corresponding to the mRNA expression, we observed that NFATx was responsible for the NFAT-DNA binding in DP thymocytes. Moreover, this DNA binding was inhibited by cyclosporin A, indicating that NFATx nuclear translocation was regulated by the calcineurin phosphatase in DP thymocytes. For the CD4 SP populations, NFAT1 and NFATc, and to some extent NFATx, were responsible for the NFAT-DNA binding complexes. These results indicate that NFAT family members are differentially regulated during the development of T cells, and that NFATx may play a distinct role in calcineurin-dependent signaling in DP thymocytes.

Molecular cloning and functional characterization of murine cDNA encoding transcription factor NFATc

Transcription factors of the NFAT (nuclear factor of activated T cells) family play important roles in immune and inflammatory responses by regulating the expression of genes encoding cytokines and immunoregulatory proteins. Here we describe cloning and characterization of full-length cDNA encoding murine (m) NFATc which predicts that the protein has all the conserved structural motifs of NFAT family members, including the rel homology domain, the NFAT homology domain and the nuclear translocation signals. mNFATc complexed with AP-1 bound specifically to the murine IL-2 NFAT recognition sequence and activated transcription from the co-transfected IL-2 promoter in COS-7 cells. Northern blot analysis showed that the cDNA probe hybridized with a 4.5 kb transcript which is highly inducible in murine T cells. By Northern and in situ hybridization, mNFATc transcript was detected from the early stage of development. In the mouse embryo, mNFATc transcript was strongly expressed in thymus, lung and submandibular gland and weakly in skeletal muscle and heart suggesting that mNFATc may have a role both in embryogenesis and in mature T cells.

[Cytokine gene expression in Th1 and Th2: its molecular mechanism and clinical implication]

Activation of helper T-cells mediated by the T-cell receptor induces a series of biochemical events. Among them, both the activation of PKC/Ras- and CaM/CN-mediated pathways play a central role in the signal transduction of cytokine gene induction. Cytokines produced by non-transformed Th1 and Th2 clones were classified into three groups, based on their signal requirement patterns for their expression. Closer examination using various stimulation conditions suggested that the balance between the activities of the two signaling pathways contributes to cytokine expression. Th1 and Th2 effector functions and their development are attributable to their coordinated and differential expression of cytokines. Clarification of the mechanisms of Th1/Th2 differentiation should lead to rational strategies for manipulating pathological immune responses.

Calcineurin-dependent nuclear translocation of a murine transcription factor NFATx: molecular cloning and functional characterization

Members of the nuclear factor of activated T cells (NFAT) are involved in the induction of a number of cytokine genes. We report here cDNA cloning and chromosomal localization of a murine homologue of human NFATx, designated as mNFATx1, and its splicing variants mNFATx2 and m delta NFATx. Northern blot analysis showed mNFATx1 to be predominantly expressed in the thymus. mNFATx1, but not m delta NFATx, produced in COS-7 cells, bound to all NFAT-binding sites of the interleukin (IL)-2 and IL-4 promoters tested. Immunofluorescence assay showed that both mNFATx1 and m delta NFATx introduced into COS-7 cells localized predominantly to the cytoplasm, but did translocate to the nucleus, either by cotransfection with an active form of calcineurin or wild-type calcineurin followed by stimulation with calcium ionophore. Translocation of mNFATx1 correlated well with activation of the murine IL-2 promoter; mNFATx1 translocated under conditions described above, in combination with phorbol 12-myristate 13-acetate, activated the transiently transfected murine IL-2 promoter. Thus, nuclear-translocated mNFATx1 is involved in activation of the IL-2 promoter. These results provide the first evidence for the requirement of calcineurin in the control of mNFATx imported from the cytoplasm to the nucleus and implies that mNFATx may possibly be a substrate of calcineurin in vivo.

Serum levels of soluble Fas/APO-1 (CD95) and its molecular structure in patients with systemic lupus erythematosus (SLE) and other autoimmune diseases

There are two major forms of the Fas molecule, membranous Fas and soluble Fas (sFas). To clarify the clinical significance of sFas in autoimmune diseases, we designed a sandwich ELISA to determine serum concentrations of sFas and its molecular structure, and we then analysed the correlation between levels of sFas and laboratory findings in patients with SLE and other autoimmune diseases. The levels of serum sFas were significantly higher in SLE patients than in subjects with other autoimmune diseases and in healthy donors, and the frequency of a positive serum sFas was much greater in SLE patients with high SLE disease activity index scores than in those with low scores. In addition, sFas-positive SLE patients showed a significant difference in various laboratory parameters from sFas-negative SLE patients. Serial measurements of serum sFas levels in SLE patients with active disease revealed that the elevated level of sFas dramatically decreased with improvement in clinical and laboratory findings, following corticosteroid therapy. We propose that the serum level of sFas can serve as an appropriate marker for evaluating SLE disease activity. Serum sFas is heterogeneous with respect to molecular structure, thus several mechanisms are involved in the generation of sFas.

[A case of melorheostosis with linear sclerodermatous skin changes]

A 69-years old Japanese woman complained of pain in the left elbow joint and thickened skin over the left upper limb. The pain had been present for 20 years, and the thickened area of the skin gradually enlarged during this period. Her left elbow joint showed some limitation of motion. There was no record of any similar condition in her family history. Radiographs of the left limb showed cortical hyperostosis extending from the middle of the left humerus to the distal end of the radius. Radiographs of the other limbs were normal. A technetium 99m-methylene diphosphonate bone scintigraphy revealed increased uptake in the areas of radiographic hyperostosis. The diagnosis of melorheostosis was made. Skin biopsy of thickened area was performed. The epidermis was normal, and proliferation of normal-appearing collagen fibers into the subcutaneous fat was noted. No inflammatory changes were found. The cause of sclerodermatous skin changes was thought to be not by linear scleroderma but by melorheostosis. In cases of linear sclerodermatous changes, melorheostosis as its origin should be considered.

[A case of mixed connective tissue disease with acute interstitial pneumonitis]

A 43-years-old woman was admitted to the Hokkaido University Hospital because of high fever, muscle weakness and dyspnea in May 1993. She had has muscle weakness of upper extremities since December 1992. She had developed swollen hand, polyarthralgia and Raynaud's phenomenon. High fever and severe dyspnea developed in May 1993. Chest roentogenogram was normal in April 1993. Physical examination showed Velcro rales in both lower lung fields. Her laboratory data showed increased muscle enzymes, high titers of anti-nuclear-antibody (1: 1280) and anti-RNP-antibody (index 199.4 (normal < 7)). Anti-DNA, anti-Sm and anti-Jo-1-antibodies were all negative. Blood gas analysis showed severe hypoxemia. Chest roentogenogram revealed diffuse bilateral interstitial infiltrates prominent in the bases. Diagnosis of mixed connective tissue disease with acute interstitial pneumonitis was made. She was treated with steroid pulse therapy (methylprednisolone 1 g x 3 days) followed by high dose oral prednisolone (60 mg/day), and diffuse interstitial infiltrates disappeared within one week. Prednisolone could be tapered to 17.5 mg/day without relapse. Acute interstitial pneumonitis is a rare complication of mixed connective tissue disease, but may be life threatening. In such cases, high dose steroid therapy should be started without delay.

[The association of the disease activity of rheumatoid factor positive vasculitis and the level of rheumatoid factor]

Rheumatoid factor (RF), an autoantibody against the Fc portion of denatured IgG, has long been recognized as an important biologic marker not only for rheumatoid arthritis but also for other auto-immune diseases. In this study, we measured the level of serum RF in four patients with RF positive systemic vasculitis using laser nephelometry. Three patients were diagnosed as polyarteritis nodosa and the other patient was diagnosed as systemic vasculitis without the finding of typical necrotizing vasculitis from biopsies. In the result, we found that the level of RF paralleled the disease activity in these cases. When active phase of the disease, the level of RF showed very high, and after the treatment combined with plasmapheresis, corticosteroid and immunosuppressive agent, the level of RF decreased in accordance with CRP, ESR and clinical features. These suggested that RF was the disease specific marker for RF positive vasculitis and beneficial informations for proper diagnosis and better treatment could be provided by measurement of the level of RF in patients with RF positive systemic vasculitis.

Severe hepatic involvement without inflammatory changes in systemic lupus erythematosus: report of two cases and review of the literature

Hepatic diseases in systemic lupus erythematosus (SLE) are not rare, but liver biopsies of those cases are usually reported as chronic hepatitis or steroid-induced steatosis. We describe two unusual patients with active SLE who displayed liver dysfunction without inflammatory changes or associated with drug administration. A liver biopsy in case 1 showed massive hepatic cell damage resulting in acute hepatic failure. In case 2, the liver specimen revealed diffuse fatty degeneration without symptoms specific to liver dysfunction. No inflammatory cell infiltrate was observed in the liver tissue of either patient. After steroid pulse therapy (case 1) and the administration of 60 mg/day of prednisolone (case 2), liver function improved in parallel with the stabilization of the other manifestations of SLE. No other causes for liver damage except for SLE were observed in either case. Therefore it is supposed that the liver impairments in these cases were one manifestation of SLE.

Up-regulated expression of Fas antigen (CD95) by peripheral naive and memory T cell subsets in patients with systemic lupus erythematosus (SLE): a possible mechanism for lymphopenia

Fas antigen (CD95) is a membrane-associated molecule that mediates apoptotic cell death and may play a role in the induction and maintenance of T cell tolerance. To elucidate the involvement of Fas antigen in human autoimmune diseases, we analysed Fas antigen expression by peripheral T cells from patients with SLE and rheumatoid arthritis (RA), using three-colour flow cytometry. Both CD4+ and CD8+ T cells from SLE patients expressed Fas antigen in a higher density than did these cells from healthy donors and from RA patients. Enhancement of Fas antigen density was noted in Fas+CD45RO+ memory T cells from SLE patients. More remarkably, a significant expression of Fas antigen was observed in CD45RO- naive T cells from SLE patients. CD4+CD45RO- T cells from SLE patients co-expressed Fas antigen and early to intermediate activation antigens such as CD25 and CD71, and late activation antigen HLA-DR in only FashiCD4+ naive T cells. Such up-regulation of Fas antigen expression in SLE patients seems to be clinically meaningful, because mean fluorescence intensity (MFI) of Fas antigen on CD4+ T cell subsets inversely correlates with the absolute size of CD4+ T cell subsets in peripheral blood of SLE patients. These results suggest that T cells with increased Fas antigen expression may be highly susceptible to apoptotic cell death, in vivo. A putative mechanism for lymphopenia in SLE patients is discussed.

3 cases of anti-Scl-70 (topoisomerase I) antibody associated with central nervous system lupus without renal disorder

We describe 3 cases of systemic lupus erythematosus (SLE) associated with anti-Scl-70 antibody. Common symptoms were central nervous system disorder, discoid rash, lymphadenopathy, and no renal disorder. Two of 3 cases showed some symptoms of scleroderma but could not be diagnosed as such. Although further followup is required to determine if scleroderma develops, these unique symptoms might be a subtype of SLE or a lupus-like syndrome characterized by symptoms and anti-Scl-70 antibody.

Parkinson-like symptoms as a manifestation of systemic lupus erythematosus

A 42-year-old Japanese woman with systemic lupus erythematosus (SLE) developed Parkinsonian-like movements. Steroid pulse therapy was most effective and additional anti-Parkinsonian drugs were not required. Although psychosis, seizures and meningitis are common central nervous system (CNS) manifestations in SLE patients, Parkinsonian-like symptoms are extremely rare. The putative genesis and treatment of CNS lupus are discussed.

[A case of systemic lupus erythematosus (SLE) developing pan-dysautonomia]

A 43-year-old woman who had been diagnosed as primary Sjögren's syndrome since 1986 developed severe constipation, urinary retention, dizziness at standing and polyarthralgia in February, 1990. Laboratory tests revealed proteinuria, hypocomplementemia and high titer of anti-DNA antibody. Diagnosis of SLE was made and she was admitted to our hospital on April 2, 1990. Physical examination on admission showed that she also had asymmetric pupils, impairment of sweating, orthostatic hypotension, neurogenic bladder, gastro-intestinal dysmotility and the diminution of R-R interval variability during deep breathing on the electrocardiogram. These findings suggested that she had pan-dysautonomia but there were no signs of motor and sensory disturbance. Because other diseases such as diabetes mellitus and amyloidosis which induced dysautonomia could be ruled out, her pan-dysautonomia seemed to be due to SLE. After the treatment with steroid pulse therapy, most of her dysautonomia improved rapidly. However, some of the disturbance had persisted for a long time. Pan-dysautonomia has been rarely reported as a complication of SLE, and high dose of steroid therapy at the early stage should be considered.

[Systemic lupus erythematosus associated with benign intracranial hypertension: a case report]

A case of systemic lupus erythematosus (SLE) with benign intracranial hypertension (BIH) is reported. A 41-year-old male with a history of SLE starting in 1982 was admitted to our hospital in December 1989 because of headache and vertigo. Laboratory examinations on admission showed proteinuria, mild anemia, and positive antinuclear and anti-Sm antibodies. No abnormal findings except high pressure of 350 mmH2O were observed in his cerebrospinal fluid (CSF). Fundoscopic examinations showed marked bilateral papilledema and retinal bleeding. Brain CT, MRI and angiography revealed diffuse brain edema without space occupying lesion and cerebrovascular diseases. Because there were no diseases such as endocrinological disorders, severe anemia, and no history of the administration of drugs which might cause intracranial hypertension, the diagnosis of BIH was made. Subsequently, he was treated with intravenous methylprednisolone therapy and osmotic diuretics and his clinical symptoms and pressure of CSF gradually improved. The decrease of CSF adsorption was observed with RI cisternography in our case. Psychosis, seizures and meningitis are common CNS manifestations in SLE patients. But BIH is very rare and its cause is unclear. Only 17 cases of SLE with BIH have been reported. The pathogenesis and treatment of BIH in SLE patients were discussed in this paper.

[A case of rheumatoid arthritis developing pemphigus-like skin lesion during treatment with bucillamine]

Bucillamine is a useful medication for treatment of rheumatoid arthritis (RA) but some patients develop side effects from it. Here, we report a patient with RA developing a pemphigus-like skin lesion during treatment with bucillamine. A 55 year old woman with RA (stage III, class II) had been treated with bucillamine in our hospital since September 1988. Her symptoms of RA had gradually improved after administration of bucillamine but the generalized skin rash with itching developed in June 1989. Skin biopsy revealed spongiosis, the infiltration of lymphocytes in the epidermis and inter-cellular deposition of IgG. These findings were consistent with the histological change of pemphigus. Since symptoms of the skin disappeared two months later after the discontinuation of bucillamine. We considered that her pemphigus-like lesion was induced by this drug. D-penicillamine is one of the drugs which induce pemphigus. Though the mechanisms of this side effect have not been clear, it is thought that autoantibody induced by D-penicillamine could be one of the cause of pemphigus. Because the chemical structure of bucillamine is similar to that of D-penicillamine, the autoimmune mechanisms may also play a role in the onset of the pemphigus-like lesion in this case.

[Pneumoperitoneum without perforation of the gastrointestinal tract in a patient with systemic lupus erythematosus]

Pneumoperitoneum often occurs after the perforation of the gastrointestinal tract. However, pneumoperitoneum without the perforation has been reported as one of the complications of collagen diseases, the cause of which is usually the rupture of pneumatosis cystoides intestinalis (PCI). PCI is sometimes observed in the patients with scleroderma and mixed connective tissue disease but rarely in the patients with systemic lupus erythematosus. We reported here a case of systemic lupus erythematosus developed the pneumoperitoneum without the perforation of gastrointestinal tract. A 51-year-old female who had been diagnosed as systemic lupus erythematosus and taken steroid for 12 years, visited our hospital because of general malaise. She had no abdominal symptoms but the roentgenographic examinations revealed the pneumoperitoneum. The laparotomy was performed and there were no findings of the perforation of the gastrointestinal tract. Because PCI is hardly recognized macroscopically after the rupture and the pneumoperitoneum due to PCI is often asymptomatic, we considered the cause of the pneumoperitoneum in this case was the rupture of PCI. The mechanisms of the formation of PCI in patients with collagen diseases were also discussed in this paper.

[Neuro-psychiatric symptom associated with primary Sjögren's syndrome]

Neuro-psychiatric complications of primary Sjögren's syndrome (SjS) were studied on their frequency and characteristics of clinical signs in 150 patients of our clinic. Clinical symptoms and laboratory examinations were compared in the patients group complicated with neuro-psychiatric symptoms and the non-complicated group. Neuro-psychiatric symptoms (neuro SjS) were complicated with 63 patients (42.0%). Central nervous system (CNS) involvement were occurred in 47 patients (31.3%). In this group (CNS SjS), psychiatric complications were observed in 43 patients (28.7%), consisted with 29 cases of neurosis, 7 cases of depression, 6 cases of presenile dementia, and others. Nine patients (6.0%) in this group had neurologic involvement that were 3 cases of aseptic meningitis, 3 cases of neurogenic bladder, and each case of multiple infarction, multiple sclerosis, and others. These 9 patients showed more frequently positive results for rheumatoid factor, anti-SSA antibody, leucopenia, and lymphopenia, so this subgroup might be consisted of a small group which was resemble to systemic lupus erythematosus. Cranial nerve involvement, mainly injured in trigeminal nerve, and peripheral nerve involvement were complicated with 5 patients (3.3%) and 24 patients (16.0%), respectively. In neuro-psychiatric complicated group, mean age was older and dry mouth were more frequent (p less than 0.05) than non-complicated group. In psychiatric complicated group, mean age was older (p less than 0.01) and dry mouth were more frequent (p less than 0.05). In any groups of neuro-psychiatric complications, the frequency of any autoantibodies was not statistically different from non-complicated group. But, in the group of cranial nerve involvement, anti-RNP antibody was 60.0% positive (in non-complicated group, 17.2%: p less than 0.05). In CNS SjS group, magnetic resonance imaging (MRI) abnormalities were occurred in 8 of 13 patients. High intensity lesions in white matter on the T2-weighted examinations was characteristic, which showed lacnar infarctions or demyelinated lesions in MRI abnormalities. In CNS SjS, corticosteroid or immunosuppressant was not always necessary, because this complication was self-limited or enough controlled by minor-tranquilizer or anti-depressant. The character of onset in neuro SjS was chronic and neuro SjS was insidiously developing disease. And more studies including treatment on neuro SjS were needed.