The mouse/human cross-species heterodimer of leucine-rich repeat kinase 2: possible significance in the transgenic model mouse of Parkinson's disease.

Leucine-rich repeat kinase (LRRK2) is the causal molecule of autosomal dominant Parkinson's disease (PD). We previously reported that intracellular degradation of wild-type (WT) LRRK2 is promoted by formation of heterodimers with the I2020T mutant LRRK2. In the present study, we investigated whether this is also the case for mouse/human cross-species heterodimers, which could be formed in transgenic mice. First, by co-transfection and immunoprecipitation, we identified the cross-species heterodimer of mouse LRRK2 and human LRRK2. Next, we found that the protein level of mouse LRRK2 decreased when co-transfected with human I2020T LRRK2, but not with human WT LRRK2. These results suggested that degradation of mouse LRRK2 was promoted by formation of a cross-species heterodimer with the mutant LRRK2. In I2020T LRRK2-transgenic mice, the lower protein level of brain LRRK2 in comparison with control mice, together with higher expression of the mRNA, suggested that endogenous LRRK2 was degraded by formation of cross-species heterodimers. Our results suggest a new concept of cross-species dimer/oligomer formation in transgenic disease-model mice.

Hydrogen peroxide increases interleukin-12 p40/p70 molecular ratio and induces Th2-predominant responses in mice.

To investigate the influence of oxidative stress on the immune response, mice were injected with H(2)O(2), and peritoneal macrophages were isolated and stimulated in vitro with lipopolysaccharide (LPS). H(2)O(2) significantly augmented both interleukin (IL)-12p40 and IL-12p70 production and increased the p40/p70 molecular ratio. This was confirmed by mRNA analysis, which showed that H(2)O(2) increased LPS-induced mRNA expression of both IL-12p40 and IL-12p35 subunits with an increased p40/p35 ratio. Analysis of anti-ovalbumin (OVA) antibodies revealed that H(2)O(2) injection significantly increased the production of type 2 helper T cell (Th2)-associated antibody classes [immunoglobulin (Ig)E and IgG1] but not a Th1-associated antibody class (IgG2a). To confirm the Th2-predominant immune response, we analyzed the profile of cytokine production by spleen T cells of OVA-immunized and H(2)O(2)-injected mice. H(2)O(2) significantly increased the production of IL-4 but not that of interferon-gamma. Together, these results suggest that H(2)O(2)-induced overproduction of IL-12p40 promotes the Th2-predominant response through increased production of IL-12p40-homodimers, which could serve as an antagonist of the Th1-inducing cytokine IL-12p70.

Contribution of CD4+ and CD8+ T cells and interferon-gamma to the progress of chronic rejection of kidney allografts: the Th1 response mediates both acute and chronic rejection.

T cells mediating chronic rejection (CR) of human kidney allografts were characterized by comparing them with those mediating acute rejection (AR). Two lines of analysis were performed using biopsy specimens (23 CR and 8 AR). First, the extent of infiltration of CD4+ and CD8+ T cells into allografts was assessed from mRNA expression of CD4 and CD8. The group of CR specimens was not significantly different from the group of AR specimens in terms of the extent of CD4+ and CD8+ T cell infiltration, underlining the importance of the immunological contribution to the progress of CR. Second, Th1/Th2 polarization in infiltrating T cells was investigated by measuring mRNA expression of interferon gamma (IFN-gamma; a Th1 cytokine) and interleukin 4 (IL-4; a Th2 cytokine). IFN-gamma expression was detected in most CR specimens, and was not significantly different between the group of CR specimens and the group of AR specimens. On the other hand, IL-4 expression was detected in only two CR specimens and one AR specimen; from its pathological features, the AR in this last case was concomitant with CR. These results suggest that most cases of CR and of AR are mediated by Th1 mechanisms, although some cases of CR show features of both Th1 and Th2.

Clonality analysis of T cells mediating acute and chronic rejection in kidney allografts.

The clonality of T-cell populations mediating acute and chronic rejection (AR and CR, respectively) of kidney allografts was ascertained by investigating the diversity of TCRBV genes expressed by allograft-infiltrating T cells. Both oligoclonality and polyclonality cases were found in biopsy specimens of AR as well as CR. These results indicated that the T-cell clonality in each specimen did not correlate directly with the mode of rejection. When AR and CR specimens were compared, however, the CR specimen group was significantly more polyclonal (or less oligoclonal) than the AR group. This result may reflect the higher chance of epitope spreading in the more slowly progressing CR than in AR.

Analysis of alpha-synuclein, parkin, tau, and UCH-L1 in a Japanese family with autosomal dominant parkinsonism.

We examined whether autosomal dominant parkinsonism of a Japanese family, Sagamihara family, was due to the mutations of alpha-synuclein, parkin, tau, and UCH-L1, which have been reported as the causal genes for parkinsonism in other families. Restriction-enzyme digestion of polymerase-chain reaction (PCR) amplified genomic DNA fragments of alpha-synuclein exons 3 and 4 detected no point mutation. PCR-amplification of parkin exons 3, 4, 5, 6 and 7 detected no exon deletion. Direct sequencing of PCR-amplified DNA fragments of tau exons 9, 10, 12, and 13 and intron 10, and of UCH-L1 exon 4 revealed that all these exons and intron were normal including a polymorphic nucleotide substitution. These results indicated that the parkinsonism of the Sagamihara family seems not to be due to previously identified point mutations of alpha-synuclein, tau, or UCH-L1, or to exon deletion of parkin.

Immunohistochemical detection of human gastrointestinal glutathione peroxidase in normal tissues and cultured cells with novel mouse monoclonal antibodies.

This is the first report to describe the successful detection of human gastrointestinal glutathione peroxidase in normal tissues by Western blotting and immunohistochemical staining techniques. Four hybridoma clones producing monoclonal antibodies (MAbs) against the human gastrointestinal glutathione peroxidase were established from mice immunized with a gastrointestinal glutathione peroxidase-derived peptide. The MAbs did not crossreact with other members of the glutathione peroxidase family, be it cellular glutathione peroxidase, phospholipid hydroperoxide glutathione peroxidase, or extracellular glutathione peroxidase. Although the MAbs were found to react with a 24-kD protein in a Western blotting assay using gastric carcinoma cell extracts as antigen, they did not react with a B-lymphoblastoid cell extract. Immunohistochemical staining showed gastrointestinal glutathione peroxidase localized in the cytoplasm and in the nucleus of gastric carcinoma cells. Moreover, gastrointestinal glutathione peroxidase was detected in tissue extracts of human stomach, small intestine, large intestine, liver, and gallbladder by Western blotting, and its localization was immunohistochemically confirmed in the mucosal epithelia of the basal area of gastric pits and intestinal crypts.

Human T-cell receptor BV6 gene polymorphism in relation to expression level and CD4/CD8 skewness.

Using 50 samples of umbilical cord blood lymphocytes from Japanese donors, we analysed two human T-cell receptor beta variable (TCRBV) genes, BV6S4 and BV6S5, for their polymorphism, usage frequencies and CD4/CD8 skewness. They showed contrasting CD4/CD8 skewness, BV6S4 to CD8+ T cells and BV6S5 to CD4+ T cells. Genotyping of the BV6S4 alleles (A1, A2 and A3) revealed two of the six possible BV6S4 genotypes, A1/A2 and A2/A2. Among the two BV6S4 genotypes, no significant difference was detected in usage frequency or CD4/CD8 skewness. On the other hand, genotyping of the BV6S5 alleles (A1 and A2) revealed all three possible BV6S5 genotypes, A1/A1, A1/A2 and A2/A2, and the gene usage frequency was high, in the order A1/A1 > A1/A2 > A2/A2. These results indicate that the amino acid substitutions in BV6S5 (S36R and G70E) are in some way associated with the expression level of this gene. In the analysis of CD4/CD8 skewness, the three BV6S5 genotypes had similar skewness, indicating that A1 alleles are expressed more frequently than A2 alleles in both CD4+ and CD8+ T-cell populations. Although BV6S5 exhibits marked skewness to CD4+ T cells, our results indicate that the higher expression of A1 alleles is not associated with the increased ratio of CD4+ T cells.

Role of iron and superoxide for generation of hydroxyl radical, oxidative DNA lesions, and mutagenesis in Escherichia coli.

We measured the generation of hydroxyl radical (OH(.)) and oxidative DNA lesions in aerobically grown Escherichia coli cells lacking in both superoxide dismutases (SodA SodB) and repressor of iron uptake (Fur) using electroparamagnetic resonance and gas chromatography-mass spectrometry with a selected-ion monitoring method. A specific signal corresponding to OH(.) generation and an increase in oxidative DNA lesions such as 7,8-dihydro-8-oxoguanine and 1,2-dihydro-2-oxoadenine were detected in the strain deficient in sodA sodB fur. We showed that iron metabolism deregulation in fur mutant produced a 2.5-fold iron overload. The sodA sodB fur strain was about 100-fold higher mutability than the wild-type strain. The mutation spectrum in the strain was found to induce GC --> TA and AT --> CG transversions predominantly. The hypermutability of the strain was suppressed by the tonB mutation which reduces iron transport. Thus, excess iron and excess superoxide were responsible for OH(.) generation, oxidative DNA lesion formation, and hypermutability in E. coli.

Possible mechanisms of immunotherapy for maintaining pregnancy in recurrent spontaneous aborters: analysis of anti-idiotypic antibodies directed against autologous T-cell receptors.

We examined whether immunotherapy for recurrent spontaneous abortion (RSA) using paternal lymphocytes induces anti-T-cell receptor (TCR) idiotypic antibodies in RSA patients. The sera of these patients were assessed for inhibitory activity against mixed lymphocyte reactions (MLR) between maternal responder cells and paternal stimulator cells. Sera of four of the five women who maintained pregnancy successfully after immunotherapy showed significant MLR inhibition, whereas none of the five women who had unsuccessful pregnancies showed significant MLR inhibition. These sera inhibited the MLR of autologous responder T-cells, when stimulated with lymphocytes having the same HLA-DR antigens as the patient's husband, but not when stimulated with lymphocytes having unrelated HLA-DR antigens. This MLR inhibitory activity was absorbed by autologous maternal T-lymphoblasts induced by stimulation with lymphocytes having the paternal HLA-DR type but not by those induced by stimulation with lymphocytes having other HLA-DR types. The maternal serum inhibited the proliferation of autologous T-cells, but not of non-autologous T-cells, stimulated with paternal lymphocytes. These results indicate that anti-TCR idiotypic antibodies were induced in RSA patients by immunotherapy. These antibodies may contribute to maintaining pregnancy by negatively regulating maternal T-cells directed against HLA-DR antigens of the fetus.

T-cell receptor variable gene analysis of renal allograft-infiltrating cells in biopsy specimens using a nonradioisotopic micromethod.

BACKGROUND: A sensitive micromethod for T-cell receptor (TCR) analysis is needed for clonality analysis of renal allograft-infiltrating T cells (RAITs) obtained by needle biopsy. METHODS: TCR cDNA was amplified by the anchored polymerase chain reaction and was hybridized with 28 different TCR beta variable (TCRBV) genes fixed on nylon membranes, and the percentage of each TCRBV gene was measured spectrophotometrically. RESULTS: The specificity and linearity of the hybridization technique and the constancy of the TCRBV percentages over a wide range of sample amounts were demonstrated by control experiments. Analysis of RAITs of biopsy specimens from four patients showed broad or skewed TCRBV usage, indicating the presence of polyclonal and oligoclonal RAIT populations, respectively. In one patient who received OKT3 immunosuppressive treatment, the TCRBV skewness was dramatically reduced after the treatment. CONCLUSION: We have established a powerful method for analyzing RAIT clonality, which is especially useful for monitoring RAIT dynamics after immunosuppression therapy.

Analysis of the T-cell receptors utilized for allogeneic HLA-DR recognition: comparison of different responder-cell donors possessing an identical HLA-DR allele.

We examined whether individuals with an identical HLA-DR type utilized the same T-cell receptors (TCRs) to recognize a given allogeneic HLA-DR molecule. CD4+ T cells from three responder-cell donors possessing the DRB*0901 allele were stimulated with HLA-DRB1*0406 molecules, subjected to the primary mixed lymphocyte reaction (MLR) and the TCRs of the activated CD4+ T cells were analysed using single strand conformation polymorphism (SSCP) and random cDNA clone sequencing. The responder cells of each donor yielded many dominant SSCP bands in several TCRAV and TCRBV segments, but none of these dominant SSCP bands derived from two or three responders. Random cDNA sequence analysis demonstrated that the alloreactive TCRs were diverse, but each of the three responder-cell donors showed some dominant cDNA clones. However, no amino acid sequence identities or similarities among the dominant cDNAs of these donors were detected. These results indicate that certain T-cell clones from each individual's TCR repertoire pool expand preferentially as a result of allogeneic HLA-DR recognition but these clones are not necessarily common to different individuals, even when their responder cells possess identical DR alleles and are stimulated with the same alloantigen.

An improved system for selection of forward mutations in an Escherichia coli supF gene carried by plasmids.

An improved system to examine forward mutations that occurred in the supF gene of Escherichia coli carried on a multicopy plasmid is described. The system was validated by measuring spontaneous mutations of supF plasmids propagated in wild-type, recA- and mutM- mutY- E. coli strains, the mutation frequencies of which were 1.3 x 10(-7), 6.3 x 10(-7) and 1.5 x 10(-6), respectively. Sequence analysis of the supF mutant plasmids revealed that G:C-->T:A and G:C-->C:G transversions dominated. This improved system allows rapid scoring and sequencing forward mutations in the supF gene, thus permitting its use as a genetic target for repair and mutagenesis studies in bacteria and mammalian cells.

Binding properties of human immunodeficiency virus type-2 (HIV-2) RNA corresponding to the packaging signal to its nucleocapsid protein.

The nucleocapsid (NC) protein of human immunodeficiency virus type-1 (HIV-1) contains two zinc finger motifs (ZFMs), and binds specifically to the packaging signal which is located in the 5' leader sequence of the viral genomic RNA between the first splice donor and the gag initiator codon (AUG). In this study, we analyzed the specificity of the binding of the corresponding region of HIV-2 (Region 3) to its NC protein (NCp8), by performing a competitive ultraviolet (UV) cross-linking assay using in vitro-synthesized 32P-labeled and unlabeled RNAs corresponding to a sequence between the primer binding site and the gag AUG (Region 1). Binding of 32P-labeled Region 1 RNA to NCp8 was inhibited specifically by adding unlabeled Region 1 and 3 RNAs and no specific binding was detected using deletion mutant peptides of NCp8. These findings suggest that the region(s) which bind(s) specifically to HIV-2 NCp8 lie(s) between the first splice donor and the gag AUG in the 5' leader sequence and that NCp8 is the minimum binding region responsible for the specific binding of the region downstream of the first splice donor site of HIV-2 RNA.

Allogeneic recognition of HLA-DRB1*0406 by T cells with HLA-DRB1*0403: role of amino acid residue 37 on the beta sheet in T cell recognition.

Five T cell clones reactive with allogeneic HLA-DR molecules were obtained by stimulating CD4+ T cells (DRB1*0403) with DRB1*0406-homozygous KT13 cells whose DR beta chain differed by a single amino acid residue (37) on the beta sheet from the DRB1*0403 product. Except for one T cell clone which had both auto- and alloreactivities, these clones proliferated by stimulation with KT13 but not with autologous cells, indicating that the single substitution at position 37 on the HLA-DR molecule was sufficient to alter the alloantigenicity of the DR molecule and to elicit an allogeneic T cell response. Two clones reacted with some but not all B cell lines with DRB1*0406, suggesting the possible involvement of a certain peptide whose distribution is restricted to some cells which form the alloantigenic structure recognized by these clones. The two remaining clones showed broad but distinct anti-DR specificity in addition to anti-DRB1*0406 reactivity, suggesting that they recognize the DRB1*0406-peptide complex whose antigenic structures also occur in some combinations of other DRB1 alleles with certain peptides bound to these alleles. The T cell clone with both auto- and alloreactivity was found to react with autologous monocytes but not with autologous B or T cells and to express lower TCR alpha beta than other T cell clones which showed no autoreactivity. The possible recognition molecule for this autoreactive T cell clone is discussed.

T-cell receptor diversity expressed by CD4+ T cells activated by primary allogeneic HLA-DR stimulation: estimation of the degree of CDR3 diversity.

In order to analyse the diversity of T-cell receptors (TCRs) expressed by the T-cell population activated by allogeneic HLA-DR stimulation, TCR beta cDNA was synthesized from mRNA of human CD4+ T cells that had been stimulated in a primary mixed lymphocyte reaction (MLR). The TCR beta cDNA was amplified by the polymerase chain reaction (PCR), subjected to bacterial cloning, and sequenced from V beta through J beta. Twenty-six different V beta and 10 different J beta segments were detected among 56 randomly selected cDNA clones. Occurrences of V beta 17.1 and J beta 1.5 were higher than those found in the CD4+ T-cell population activated with a CD3-specific antibody. A total of 53 different CDR3 sequences, two of them occurring more than once, were detected among the 56 cDNA clones. In order to estimate the degree of CDR3 diversity, amino acid similarity in the CDR3 region of the cDNA was calculated and compared with those of the anti-CD3-activated T-cell sequences as well as those of various published T-cell clone sequences, each directed to either alloantigens or single antigenic peptides. It was found that the similarity score among CDR3 sequences obtained from the MLR (56.4 +/- 10.3) was comparable to those of anti-CD3-activated T cells (55.7 +/- 10.7) and those of T-cell clones directed toward alloantigens (range, 48.4 +/- 12.4-59.4 +/- 13.1), but significantly smaller than those of T-cell clones directed toward single antigenic peptides such as those derived from myelin basic protein (75.6 +/- 17.9) and cytochrome c (76.9 +/- 20.5). These results provide quantitative proof that TCRs of T cells activated by primary allogeneic HLA-DR stimulation have a larger diversity than those recognizing single antigenic peptides.

Dual recognition of a human cytotoxic T-cell clone for melanoma antigens.

It is well known that tumor-specific CTLs have a crucial role in the elimination of tumors and that different CTL populations recognize tumor antigens in MHC-restricted and MHC-unrestricted manners. We have established two alpha beta CTL clones that recognize melanoma antigens in both human lymphocyte antigen (HLA)-A2-restricted and HLA-unrestricted manners. Flow cytometry analysis showed that these CTL clones carry CD3, CD8, and alpha beta T-cell receptor (TCR) and express low levels of CD56. In contrast, these CTL clones do not express CD16, indicating that they do not contain natural killer cells. TCR analysis of these CTL clones using an anchored PCR method revealed that each clone carries a single alpha beta TCR. Both CTL clones contained the same Valpha and Vbeta gene segments although they carried different Jalpha and Jbeta gene segments. Taken together, these results confirm that CTL clones that carry a single alpha beta TCR recognize melanoma antigens in both HLA-A2-restricted and HLA-unrestricted manners. It is strongly suggested that the dual recognition of these CTL clones for the melanoma antigens is mediated by TCRs. The novel mechanism for antitumor immunity by these CTLs may be important in the effective elimination of tumors in vivo.

Genetic analysis of hydatidiform moles utilizing the oligonucleotide-DNA typing of the HLA-DRB gene.

The genetic origin of hydatidiform moles was analysed utilizing HLA-DNA typing. Using HLA-DR type-specific oligonucleotide probes, the DRB types of seven moles were determined and compared with the parental DRB types to determine the paternal and/or maternal origin of the moles. In four cases, the molar tissues showed single DRB types of paternal origin, although in one, the molar DRB type was also possessed by the mother. These four moles were, therefore, considered to be androgenetic in origin. Chromosomal karyotyping was carried out for three of these cases and confirmed the DR-DNA typing results. Two moles demonstrated a DRB-type triplet, which strongly suggested triploidy. Although one mole showed a heterozygous DRB type, karyotyping indicated triploidy (69, XXX) and suggested that this mole was caused by dispermy-fertilization, in which both of the sperms had the same DRB type. Although the majority (about 80%) of partial hydatidiform moles have been reported to be triploid as a result of dispermy, four of the moles analysed in this study (cases 1, 2, 3 and 4), diagnosed as partial macroscopically and/or histopathologically, were found to be androgenetic in origin using karyotyping and DR-DNA typing. Therefore, HLA-DR DNA typing, combined in some cases with karyotyping, provides an accurate method for diagnosing androgenesis and triploidy in complete and partial hydatidiform moles.