Classification of mutations in the human CD40 ligand, gp39, that are associated with X-linked hyper IgM syndrome

The interaction between the T cell activation antigen gp39 and CD40, its receptor CD40 on B cells, plays a critical role in the regulation of humoral immune responses. Using a detailed three-dimensional model of the gp39 extracellular region, we have analyzed 20 mutations in gp39 that were, with one exception, isolated from patients with X-linked hyper IgM (XHIM) syndrome. On the basis of this analysis, the mutations were classified according to their predicted locations and effects. Twelve mutations are thought to compromise the gp39 structure by affecting interactions in hydrophobic core regions or at monomer interfaces, whereas seven others map closely to gp39 residues important for interaction with CD40. The latter mutations may thus, directly or indirectly, interfere with CD40 binding. One naturally occurring mutant whose carrier displays normal immune responses maps to a solvent-exposed position in a loop region of the molecule.

A patient with TSC1 germline mutation whose clinical phenotype was limited to lymphangioleiomyomatosis

BACKGROUND

Lymphangioleiomyomatosis (LAM) can occur as in isolated form (sporadic LAM) or as a pulmonary manifestation of tuberous sclerosis complex (TSC) (TSC-associated LAM). Recent studies, however, revealed that both forms of LAM are genetically related but that sporadic LAM is a distinct clinical entity caused by somatic mutations of TSC2 (not TSC1) rather than a forme fruste of TSC carrying either of the TSC1 or TSC2 germline mutations.

METHOD

Case presentation and in-depth molecular and histopathological examinations. A 34-year-old Japanese woman was diagnosed as having pulmonary lymphangioleiomyomatosis (LAM) when bilateral pneumothoraces were surgically treated in 1992. Although slowly progressive renal disfunction was observed due to bilateral multiple renal cysts during the past 4 years, she had no other clinical features of TSC and was diagnosed as having sporadic LAM with multiple renal cysts of undetermined aetiology. Her subsequent clinical course was complicated by an endobrochial carcinoid tumour, which eventually resulted in her death in June 1999 due to massive haemoptysis.

RESULTS

Postmortem examination revealed the presence of LAM lesions in the lungs, mediastinal lymph nodes, kidneys and uterus. Diffuse renal LAM lesions are presumed to generate multiple renal cysts by constricting the nephron rather than epithelial hyperplasia obstructing lumina, which is analysis of the TSC genes demonstrated that she did not have TSC2/PKD1 contiguous gene syndrome but had a TSC1 germline mutation (Sato T et al. J Hum Genet 2002; 47: 20-8) that had occured de novo.

CONCLUSION

This patient therefore illustrates that clinical manifestations of TSC are sufficiently diverse as to allow a forme fruste of TSC that mimics sporadic LAM and that TSC1 mutation can cause multiple renal cysts resulting in renal failure.

Longitudinal follow-up study of 11 patients with pulmonary lymphangioleiomyomatosis: diverse clinical courses of LAM allow some patients to be treated without anti-hormone therapy

OBJECTIVE

The purpose of this study is to clarify the existing issues on the clinical diversity, natural history, and mode of disease progression of pulmonary lymphangioleiomyomatosis (LAM).

METHODOLOGY

Eleven patients with LAM were reviewed retrospectively with special reference to serial changes in pulmonary function and radiological findings during the course of their disease, treatment, and outcome. All patients were female with a mean age of 33.8 years at presentation and the observation period ranged from 2.1 to 20.8 years (mean 7.4 years).

RESULTS

Four of six patients, treated with anti-hormone therapy, presented with exertional dyspnoea, marked airflow limitation (forced expiratory volume in 1 s/forced vital capacity, 23-38%), and severely impaired diffusing capacity (%DLCO, 21.4-36% of the predicted). The remaining two patients showed only a decreased diffusing capacity (70.6% and 59.4% of the predicted) which rapidly deteriorated with subsequent development of airflow limitation. Repeated chest computed tomographic (CT) examinations revealed increasing numbers of cysts with simultaneous loss of normal lung parenchyma in these two patients. In contrast, the five patients who received no anti-hormone therapy had no respiratory symptoms aside from pneumothorax at onset. Remarkable differences were noted, with pulmonary function being well maintained and slow progression of cystic changes on CT being observed in the latter group.

CONCLUSIONS

Diverse clinical courses observed in patients with pulmonary LAM can be well delineated and assessed by periodic examinations including pulmonary function tests and chest CT imaging. Anti-hormone therapy is not always necessary for a certain group of LAM patients and they appear to have a stable course and favourable outcomes without anti-hormone treatment.

Cells derived from tuberous sclerosis show a prolonged S phase of the cell cycle and increased apoptosis

Tuberous sclerosis complex (TSC) is a multisystemic disorder characterized by systemic hamartomas. Although the disease-determining genes TSC1 and TSC2 have been isolated, the molecular pathogenesis of the disease is not understood. We examined cell cycle abnormalities in skin specimens and cultured cells derived from specific lesions of TSC patients with confirmed TSC1 or TSC2 mutations. None of the specimens used in this study showed loss of heterozygosity (LOH). We detected more cells positive for PCNA and fewer cells positive for MPP2 in the epidermis of TSC patients than in the epidermis of control patients without TSC. Incorporation of 5-bromo-2-deoxyuridine (BrdU) was similar in fibroblasts derived from TSC lesions and in normal human fibroblasts. These results suggest that the cell cycle of TSC cells shows a prolonged S phase. Flow cytometric analysis confirmed S phase prolongation in TSC cells. Many apoptotic cells were detected by a nick end labeling assay in both skin tissue and cultured fibroblasts derived from specific TSC lesions. Examination of cyclin levels showed increased nuclear cyclin A and cytoplasmic cyclin B and decreased nuclear cdc2 levels. We conclude that suppression of either TSC1 or TSC2 may change cyclin levels, prolong S phase and induce apoptotic cell death.

[Evaluation of spontaneous pneumothorax in patients with pulmonary lymphangioleiomyomatosis]

We retrospectively evaluated the development of spontaneous pneumothorax in patients with pulmonary lymphangioleiomyomatosis (LAM). Fifteen patients with LAM, whose diagnosis was confirmed histopathologically, were enrolled. All were women, and had a mean age at diagnosis of 31.6 +/- 7.3 years. They were divided into two groups according to the presence or absence of pneumothorax at the time of onset, Group A consisting of nine patients with pneumothorax, and Group B, of six without pneumothorax. Spontaneous pneumothorax developed in 15 out of a total of 18 hemithoraces in Group A patients in whom 13 hemithoraces were surgically treated for pneumothorax (eight open thoracotomies and five video-assisted thoracoscopic surgeries). Bullectomy with either parietal pleurectomy, pleural abrasion, or instillation of chemical irritants to prevent the recurrence of pneumothorax offered better outcomes than bullectomy alone in terms of the postoperative recurrence rate of pneumothorax (p < 0.05). On the other hand, three of the five Group B cases developed pneumothorax during the course of LAM, but none was operated because of severely impaired lung function. The other patient in Group B was not only free of pneumothorax at onset, but also did not develop pneumothorax or suffer from impaired lung function. There were no deaths due to pneumothorax recorded among Group A patients, but two patients in group B died. A better survival rate was noted in Group A than in Group B by Kaplan-Meier analysis, suggesting that these two groups may represent the broad clinical spectrum of LAM.

Multifocal micronodular pneumocyte hyperplasia and lymphangioleiomyomatosis in tuberous sclerosis with a TSC2 gene

A 45-year-old woman with a long-standing diagnosis of tuberous sclerosis (TSC) is presented. She has multifocal micronodular pneumocyte hyperplasia (MMPH) and lymphangioleiomyomatosis (LAM) of the lung, together with the detection of TSC2 gene mutation. During surgery for spontaneous pneumothorax, an open-lung biopsy was performed. Micronodules were well defined, measuring approximately 4 mm in diameter. These MMPHs were histologically composed of papillary proliferation of Type II pneumocytes, with positive immunoreactivity of keratin and surfactant apoprotein. The cystlike spaces, with dilatation and destruction of air spaces, were diffusely formed, and the walls were composed of the spindle cells. Such LAM showed positive immunoreactivity for HMB-45 (a monoclonal antibody specific for human melanoma) and tuberin (the gene product of TSC2). On germline mutation analysis using leukocytes of the present patient, a TSC2 gene mutation was confirmed as a deletion of G (or g) on Exon 9 by polymerase chain reaction-single-strand conformational polymorphism. However, no mutation was detected in her son. With microdissection analysis using paraffin-embedding lung tissues, LOH of the TSC2 gene preliminarily was detected in a LAM lesion but not in MMPH. It is suggested that MMPH, in addition to LAM, could be another pulmonary lesion in TSC patients and that the detection of TSC2 and/or TSC1 gene could essentially be useful for the pathogenesis of MMPH and LAM in TSC patients.

Compound heterozygosity for alpha-1-antitrypsin (S(iiyama) and QO(clayton)) in an Oriental patient

Alpha-1-antitrypsin (alpha1AT) deficiency is extremely rare among Orientals. We treated a 37-year-old man with severe pulmonary emphysema associated with a low serum concentration of alpha1AT. Mutation analysis of the alpha1AT gene was performed using a reverse transcription-polymerase chain reaction followed by sequencing. The patient proved to be a compound heterozygote carrying a S(iiyama) deficient allele and a QO(clayton) null allele. This is the first Japanese case of alpha1AT deficiency to arise from such compound heterozygosity in a family with no apparent consanguineous marriage, suggesting that the gene frequency for deficient alleles might be somewhat higher than previously estimated.

Unrelated umbilical cord stem cell transplantation for X-linked immunodeficiencies

Banked unrelated umbilical cord blood matched at 5 of 6 human leukocyte antigen loci was used to reconstitute the immune system in 2 brothers with X-linked lymphoproliferative syndrome and 1 boy with X-linked hyperimmunoglobulin-M syndrome. Pretransplant cytoreduction and posttransplant graft-versus-host prophylaxis were given. Hematopoietic engraftment and correction of the genetic defects were documented by molecular techniques. Two years after transplantation, all 3 patients have normal immune systems. These reports support the wider use of banked partially matched cord blood for transplantation in primary immunodeficiencies.

Immunologic reconstitution following bone marrow transplantation for X-linked hyper IgM syndrome

X-linked hyper IgM syndrome (XHIM), caused by mutations of the CD40 ligand (CD40L) gene, is characterized by recurrent bacterial and opportunistic infections, an increased incidence of autoimmunity and malignancies, and immunodeficiency due to abnormal T/B cell interaction. Because of poor long-term prognosis, bone marrow transplantation (BMT) has been proposed as an alternative treatment. An 8-month-old boy with XHIM and a splice site mutation of CD40L underwent BMT using a fully matched sibling donor. Markers of engraftment and immunologic reconstitution were measured serially. After BMT, activated T cells expressed functional CD40L, and genomic DNA obtained from circulating white cells contained predominantly wild-type CD40L sequences. Serum immunoglobulin levels including IgE and antibody responses to recall antigens normalized, and immunization with the T-cell-dependent neoantigen, bacteriophage &phi;X174, demonstrated amplification of the response and isotope switching. BMT provides a permanent cure for XHIM if a fully matched sibling donor is available and the procedure is performed before complications have occurred.

Lentiviral and murine retroviral transduction of T cells for expression of human CD40 ligand

Efficient transduction of primary human T cells is an important goal toward treating a number of genetic defects. Patient T cells could be harvested by leukapheresis, transduced, and returned to the donor. A wide range of secreted or cell surface therapeutic proteins may be delivered in this way. The ability to produce antibodies is the consequence of interactions between T cells and B cells and lack of expression of CD40 ligand (CD40L) on T cells causes X-linked hyper-IgM syndrome (XHIM). We are investigating delivery of a normal CD40 ligand to treat this disorder. We tested promoters driving the expression of either reporter genes such as enhanced green fluorescent protein (eGFP) or human CDC40L. Using murine retroviruses, the best able to drive gene expression in T cells was the cytomegalovirus (CMV) promoter enhancer element; however, transduction efficiency was low. To achieve efficient, high-level gene expression we tested lentiviral gene delivery vectors. At a low multiplicity of infection (MOI) (0.5-2) a large fraction of target cells was transduced by lentiviral vectors (40-93%), and the strength of gene expression was high, as determined by flow cytometric analysis. We monitored the expression of eGFP or human CD40L on T cell lines and untransformed primary human T cells from normal and CD40L-deficient patients. We achieved efficient gene expression without an extended exposure to virus, and without the need for selection. These results are encouraging for efficient lentivirus-mediated transduction of refractory human cells to achieve therapeutic gene delivery.

Analysis of all exons of TSC1 and TSC2 genes for germline mutations in Japanese patients with tuberous sclerosis: report of 10 mutations

Twenty-seven Japanese patients with the tuberous sclerosis complex (TSC), consisting of 23 sporadic and 4 familial cases, were tested for mutations in the TSC1 and TSC2 genes, using single-strand conformational polymorphism analysis and direct sequencing. Four possible pathogenic mutations were found in the TSC1 gene, including three frame shifts and a nonsense mutation in a familial case. All mutations were expected to result in a truncated hamartin gene product. The TSC2 gene analysis identified six possible pathogenic mutations only in the sporadic cases, including two frame shifts, one in-frame deletion, and three missense mutations. Two of the TSC2 mutations were expected to result in a truncated tuberin gene product. These results of the Japanese TSC patients were compatible with the reports from Europe and the United States, i.e., (1) TSC1 mutations are rarer in sporadic cases than in familial cases, (2) substantial numbers of sporadic cases arise from mutations in the TSC2 gene, and (3) mutations of the TSC1 gene may cause premature truncation of hamartin.

Massive pulmonary hemorrhage due to cytomegalovirus infection in a Japanese patient with alpha-1-antitrypsin-deficient emphysema

Although alpha(1)-antitrypsin (AAT) deficiency is one of the most common hereditary diseases and a recognized cause of emphysema in Caucasians, variants of this deficiency are extremely rare among Orientals. We present here a Japanese emphysema patient with the AAT deficiency variant originally identified as S(iiyama). After an 8-year follow-up period, the patient suffered from repeated pulmonary Pseudomonas aeruginosa infection for 4 years. He died suddenly of massive pulmonary hemorrhage. The pathologic examination revealed a necrotic hematoma in the right S10 lobe, which exhibited pneumonia due to cytomegalovirus (CMV) infection. Pulmonary hemorrhage due to CMV can occur and be fatal in patients with emphysema and AAT deficiency.

Enteroviral meningoencephalitis as a complication of X-linked hyper IgM syndrome

We describe 5 children from 2 families with mutations in the CD40 ligand (CD40L) gene leading to absent expression of CD40L on activated CD4 cells. All subjects presented with interstitial pneumonia with low serum IgG and normal serum IgM. One child had normal and one child had elevated serum IgA. Four had confirmed Pneumocystis carinii pneumonia. In spite of intravenous immunoglobulin treatment yielding therapeutic serum immunoglobulin levels, 3 children had enteroviral encephalitis. When assessed by flow cytometry, the 3 surviving affected male children had absent CD40L expression on activated CD4(+) T cells. The affected children from both families were shown to have the same single nucleotide insertion (codon 131) resulting in frameshift and early termination within exon 4 (extracellular domain). This observation demonstrates that persistent enteroviral infection is not only observed in X-linked agammaglobulinemia but may also occur in patients with X-linked hyper IgM syndrome.

CD40 ligand mutants responsible for X-linked hyper-IgM syndrome associate with wild type CD40 ligand

CD40 ligand (CD40L) is a 33-kDa type II membrane glycoprotein mainly expressed on activated CD4(+) T cells in trimeric form. When it is mutated, the clinical consequences are X-linked hyper-IgM syndrome (XHIM), a primary immunodeficiency disorder characterized by low levels of IgG, IgA, and elevated or normal levels of IgM. Mutated CD40L can no longer bind CD40 nor provide signals for B cells to proliferate and to switch from IgM to other immunoglobulin isotypes. When considering gene therapy for XHIM, it is important to address the possibility that the mutated CD40L associates with transduced wild type CD40L, and as a consequence, immune reconstitution is not attained. In this study, we demonstrate that the various mutated CD40L species we have identified in patients with XHIM, including both full-length and truncated mutants, associate with wild type CD40L on the cell surface of co-transfected COS cells. The association between wild type and mutated CD40L was also observed in CD4(+) T cell lines established from XHIM patients with leaky splice site mutations. The clinical phenotype of these patients suggests that this association between wild type and mutated CD40L species may result in less efficient cross-linking of CD40.

Mutations of the CD40 ligand gene and its effect on CD40 ligand expression in patients with X-linked hyper IgM syndrome

X-linked hyper IgM syndrome (XHIM) is a primary immunodeficiency disorder caused by mutations of the gene encoding CD40 ligand (CD40L). We correlated mutations of the CD40L gene, CD40L expression, and the clinical manifestations observed in XHIM patients from 30 families. The 28 unique mutations identified included 9 missense, 5 nonsense, 9 splice site mutations, and 5 deletions/insertions. In 4 of 9 splice site mutations, normally spliced and mutated mRNA transcripts were simultaneously expressed. RNase protection assay demonstrated that 5 of 17 mutations tested resulted in decreased levels of transcript. The effect of the mutations on CD40L expression by activated peripheral blood mononuclear cells (PBMC) and T-cell lines or clones was assessed using one polyclonal and four monoclonal antibodies and a CD40-Ig fusion protein. In most patients, the binding of at least one antibody but not of CD40-Ig was observed, suggesting nonfunctional CD40L. However, activated PBMC from three patients and activated T-cell lines from two additional patients, each with different genotype, bound CD40-Ig at low intensity, suggesting functional CD40L. Thus, failure of activated PBMC to bind CD40-Ig is not an absolute diagnostic hallmark of XHIM and molecular analysis of the CD40L gene may be required for the correct diagnosis. Patients with genotypes resulting in diminished expression of wild-type CD40L or mutant CD40L that can still bind CD40-Ig appear to have milder clinical consequences.

Parvovirus B19-induced anemia as the presenting manifestation of X-linked hyper-IgM syndrome

Parvovirus B19 (B19) can cause chronic anemia due to persistent infection in immunocompromised hosts who cannot produce neutralizing antibody necessary for clearing B19. Three patients with X-linked hyper-IgM syndrome (XHIM), who were all asymptomatic until they developed B19-induced chronic anemia at the ages of 8, 14, and 17 years, respectively, were found to have mutations of the CD40L gene, including a missense mutation (T254M), a nonsense mutation resulting in a new initiation codon and loss of the intracellular domain (R11X), and a splice site mutation (nt 309+2t-->a). Antibody responses to the T cell-dependent antigen, bacteriophage phiX174, were impaired, but neutralizing antibody titers were higher than in XHIM patients with classic phenotype. All 3 patients responded to intravenous immune globulin (IVIG) treatment. Certain mutations of the CD40L gene result in a mild XHIM phenotype that may become apparent following B19 infection in patients not on IVIG therapy and therefore not protected from B19 infection.

Progressive interstitial pneumonia associated with myelodysplastic syndrome: implication of superoxide hyperproduction by neutrophils

Interstitial pneumonia and aseptic neutrophilic infiltration in the lung are rare pulmonary manifestations of myelodysplastic syndrome (MDS). We report a patient with progressive interstitial pneumonia associated with MDS. Histological examination of the lung revealed infiltration of atypical haematopoietic cells associated with MDS and diffuse alveolitis with honeycombing. Neutrophils obtained from the patient showed superoxide hyperproduction after stimulation with phagocytosis and phorbol myristate acetate, which might be attributed to the pathogenesis of interstitial pneumonia.

Defective antigen-induced lymphocyte proliferation in the X-linked hyper-IgM syndrome

We examined T-cell proliferation in five patients with X-linked hyper-IgM syndrome (XHIM), using a panel of antigens and lectins. All patients had impaired antigen-induced proliferation, whereas their lectin responses were normal. Thus, in addition to severely depressed antibody responses, patients with XHIM have a defect in antigen-specific T-cell proliferation, which may explain their susceptibility to pathogens such as Pneumocystis carinii.

Mutations of the CD40 ligand gene in 13 Japanese patients with X-linked hyper-IgM syndrome

X-linked hyper-IgM syndrome (XHIM) is a rare primary immunodeficiency caused by a defective CD40 ligand. We identified mutations of the CD40 ligand gene in 13 unrelated Japanese XHIM patients. Of the four patients with missense mutations, one had a mutation within the transmembrane domain, and the three others had mutations affecting the TNF homology region of the extracellular domain. Two of the missense mutations resulted in the substitution of amino acids that are highly conserved in TNF family proteins. Three patients had nonsense mutations, all of which resulted in the truncation of the TNF homology domain of the CD40 ligand. Three patients had genomic DNA deletions of 2, 3 or 4 nucleotides, respectively. All of the deletions were flanked by direct repeat sequences, suggesting that these deletions were caused by slipped mispairing. Three patients had mutations within introns resulting in altered splicing, and multiple splicing products were found in one patient. Thus, each of the 13 Japanese patients had different mutations, 9 of them being novel mutations. These results indicate that mutations in XHIM are highly heterogeneous, although codon 140 seems to be a hot spot of the CD40 ligand gene since two additional point mutations were located at Trp 140, bringing the total numbers of mutations affecting codon 140 to six. In one XHIM family with a missense mutation, prenatal diagnosis was performed by single-strand conformation polymorphism analysis of genomic DNA of a male fetus.

[Alpha 1-antitrypsin deficiency in Japan]

Alpha 1-antitrypsin (alpha 1-AT) deficiency is very rare in Japan although it is one of the most common hereditary disorders in Caucasians. Only 12 cases of alpha 1-AT deficiency have been reported in Japan. Their genetic abnormalities have already elucidated in 10 cases: Mnichinan, a heterozyge of Mmalton, 7 unrelated cases of Siiyama, and a case of 14q-syndrome. The Siiyama is the first prevalent deficient variant in the race other than the Caucasian race. The Siiyama mutation occurred on the normal alpha 1-AT variant M1 (Val213) which seems to be evolutionally newer than M1 (Ala213) on which the Z type mutation occurred. The result that alanine residue was not detected at 213 amino acid position in alpha 1-AT genes of 193 Japanese volunteers may be the reason why genetically proved Z deficient variant have not been reported yet in Japan.

Genomic structure and PCR-SSCP analysis of the human CD40 ligand gene: its application to prenatal screening for X-linked hyper-IgM syndrome

To develop a general method for analysis of the mutation and prenatal diagnosis of X-linked hyper-IgM syndrome (XHM), the human CD40 ligand (hCD40L) gene was cloned and sequenced with special reference to the 5' and 3' flanking regions and exon/intron boundaries. The hCD40L gene consists of five exons and four introns, as already reported by others. Two major transcription initiation sites were identified at 67 bp and 64 bp upstream from the ATG initiation codon. The hCD40L mRNA transcripts terminated at 321 bp, 327 bp and 987 bp downstream from the TGA stop codon. Based on the intronic sequences, oligonucleotide primers were designed for amplifying the coding region of each exon separately. Polymerase chain reaction--single-strand conformational polymorphism (PCR-SSCP) analysis was successfully applied to screening for the defective hCD40L gene in a family with XHM. The nonsense mutation, Trp140 (TGG)-->stop (TAG) in exon 5, was found in the mother and an affected child. We also performed prenatal diagnosis by PCR-SSCP during the first trimester of pregnancy in this family.

Localization of platelet-derived growth factor and insulin-like growth factor I in the fibrotic lung

To better understand the mechanisms responsible for the increase in numbers of fibroblasts and increased collagen synthesis in fibrotic intestitial lung diseases, platelet-derived growth factor (PDGF)-A and PDGF-B, PDGF receptor-alpha and -beta, insulin-like growth factor I (IGF-I), and IGF-I receptor were evaluated immunohistochemically. Additionally, the messenger ribonucleic acids (mRNAs) for PDGF-A and PDGF-B, PDGF receptor-alpha and -beta, and IGF-I were investigated by in situ hybridization in alveolar macrophages and lung tissues from patients with interstitial lung disease. In specimens of bronchoalveolar lavage fluid (BALF), PDGF-A, PDGF-B, and IGF-I were local in alveolar macrophages in patients with idiopathic pulmonary fibrosis (IPF), patients with sarcoidosis (Sar), and normal individuals. Although there were no differences between IPF and Sar in terms of the staining intensity or number of positive cells, the number of such cells was smaller in the normal controls. In lung tissues with early-stage IPF, PDGF and IGF-I proteins were localized exclusively in alveolar macrophages, mononuclear phagocytes, fibroblasts, alveolar Type II cells, vascular endothelial cells, and vascular smooth-muscle cells. In lung tissues with late-stage IPF and those from normal controls, only alveolar macrophages contained PDGF and IGF-I proteins. Interestingly, the cellular localizations of PDGF receptor-alpha and -beta, and of IGF-I receptor were the same as those of the PDGF and IGF-I proteins in early-stage IPF, whereas these cells were not positive for any of these substances in late-stage IPF or normal controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Alpha 1-antitrypsin-deficient variant Siiyama (Ser53[TCC] to Phe53[TTC]) is prevalent in Japan. Status of alpha 1-antitrypsin deficiency in Japan

In contrast to the fact that alpha 1-antitrypsin (alpha 1-AT) deficiency is one of the most common hereditary disorders of Caucasians, deficient variants among Orientals have been recognized to be extremely rare. Only 12 cases of alpha 1-AT deficiency have been reported in Japan, including five cases in which the genetic defects have already been elucidated: Mnichinan (delta Phe52[TTC] and Gly148[GGG]-->Arg148[AGG]), two unrelated cases of Siiyama (Ser53[TCC]-->Phe53[TTC]), a heterozygote of Mmalton (delta Phe52[TTC]), and one additional case of 14q- syndrome (sporadic deletion of the neighboring region of the alpha 1-AT gene locus). alpha 1-AT Siiyama is a deficient variant originally identified in a 38-yr-old patient with pulmonary emphysema in Japan. The amino acid substitution in this variant occurs in a highly conserved residue of the serpin (serine protease inhibitor) backbone (Seyama K, et al. 1991. J. Biol. Chem. 266:12627-12632). We attempted to determine whether alpha 1-AT deficiency in Japan was caused by independent genetic defects or whether it shared some common mutations in the alpha 1-AT gene. We examined five of seven available families for which the genetic defects causing alpha 1-AT deficiency have not yet been explored. When the allele-specific polymerase chain reaction (PCR) was performed with a pair of oligonucleotide primers having the mutated base sequence of the alpha 1-AT Siiyama allele at the 3' end, all eight cases of alpha 1-AT deficiency among five unrelated families turned out to be homozygous carriers of the alpha 1-AT Siiyama mutation.(ABSTRACT TRUNCATED AT 250 WORDS)

[Cardiac sarcoidosis with myopathy and advanced A-V nodal block in a woman with a previous diagnosis of sarcoidosis]

In 1992, a 49-year-old woman was admitted to the hospital because of exertional dyspnea. Three years earlier sarcoidosis had been diagnosed, and the patient was found to have bilateral hilar lymphadenopathy. The eye, skin, and knee joint were also involved. During the second hospital stay, atrial flutter with advanced A-V nodal block, scattered defects on a 201T1 scintigram, and marked cardiomegaly on chest roentgenogram led to the diagnosis of cardiac sarcoidosis. Signs and symptoms of cardiac failure subsided after placement of an artificial cardiac pacemaker, but the patient still complained of mild muscle weakness in the lower extremities on exertion. 67Ga scintigraphy revealed marked accumulation in the lower extremities, and muscle biopsy of the left gastrocnemius revealed numerous epithelioid cell granulomas with muscle fiber degeneration. Oral corticosteroid therapy was effective. A review of the 24 cases of sarcoid myopathy reported in Japan indicated that the male-to-female ratio is 1:3.8. As compared to patients in whom myopathy led to the diagnosis of sarcoidosis, those in whom myopathy developed after sarcoidosis was diagnosed were (1) relatively older, (2) more likely to have multiple organ involvement, and (3) more likely to have cardiac sarcoidosis. Corticosteroids were beneficial in about three quarters of these 16 cases, who received corticosteroid therapy.

Amylase mRNA transcripts in normal tissues and neoplasms: the implication of different expressions of amylase isogenes

To understand the cellular origin and mechanism of gene expression in amylase-producing cancers, the phenotyping of amylase isogenes by the polymerase chain reaction and restriction-fragment-length polymorphism using restriction endonucleases TaqI, DdeI, HinfI, and AfaI were performed for 3 amylase-producing lung adenocarcinomas, 16 lung cancers without hyperamylasemia, other human malignant neoplasms, cultured cell lines, and normal tissues. In addition, amylase mRNA transcripts were semi-quantified by the limited polymerase chain reaction. Amylase mRNA transcripts were detected in all of the tissues examined. The AMY1 gene (salivary type) was exclusively and highly expressed in the salivary glands and the amylase-producing lung adenocarcinomas. Coexpression of the AMY1 gene and AMY2 gene (pancreatic type) was observed in most of the lung cancers without hyperamylasemia, lung tissue, and cells scraped from the tracheal epithelium, thyroid, and female genital tract (ovary, fallopian tube, and uterus cervix), while minimal levels of mRNA transcripts of the AMY2 gene were detected in other malignant neoplasms, various normal tissues, and the cultured cell lines. All mRNA transcripts identified as being those of the AMY2 gene were further identified as being from the AMY2B gene except for the transcripts from the pancreas, in which the AMY2A gene and AMY2B gene were coexpressed. On the basis of these results, the clinical occurrence of amylase-producing cancer likely relates to the tissues expressing the AMY1 gene, while the AMY2B gene, which evolutionarily is the oldest gene among human amylase isogenes, is constitutively expressed in various tissues.

Alpha 1-antitrypsin Siiyama (Ser53-->Phe). Further evidence for intracellular loop-sheet polymerization

Antitrypsin Siiyama is a rare example of the deficiency variants of antitrypsin that accumulate in the endoplasmic reticulum of the hepatocyte. The common example is Z antitrypsin, which has a mutation (Glu342-->Lys) at the junction of the head of the fifth strand of the A sheet and the base of the reactive center loop. It was previously shown that Z antitrypsin spontaneously polymerizes due to the insertion of the reactive center loop of one molecule into the A sheet of a second. The mutation in antitrypsin Siiyama (Ser53-->Phe) affects a residue that provides a ridge for the sliding movement that opens the A sheet, and it had been predicted that this would result in the same type of loop-sheet polymerization observed with the Z variant. We confirm this here and show that virtually all the plasma antitrypsin in a homozygote for the Siiyama variant was polymerized due to non-covalent bonding with a loss of accessibility of the reactive center loop. The common basis of the polymerization of Z and Siiyama antitrypsin is supported by identical findings on electron microscopy. Taken together these results confirm that loop-sheet polymerization is a general mechanism and as such is likely to be responsible for the intracellular inclusions associated with liver pathology.

[Graphic evaluation of the significance band for hypercapnia in pulmonary disorders]

Alveolar hypoventilation due to the chronic obstruction of the airway such as pulmonary emphysema, or severe restrictive dysfunction due to sequela of pulmonary tuberculosis causes chronic hypercapnia (chronic respiratory acidosis). Ninety-five percentile of significance band of chronic and acute hypercapnia of both experimental and clinical setting is introduced in the graphic display of the acid-base balance. On acute exacerbation of these disorders, examination of arterial blood gas in series are usually plotted along the significance band of hypercapnia. With clinical improvement, the plot will gradually drop down to the chronic stable area of the band. Although cases with metabolic disorders complicate the interpretation, evaluation of the acid-base status using the graphic display will be of help at bedside assessment.

[The fate of patients with intermittent claudication-comparison of surgical and non-surgical treatment]

The purpose of this study was to determine the operative indication for patients with intermittent claudication because of arteriosclerosis obliterans, and to compare the late result of the surgical treatment group (182 cases, 250 limbs) with that of the non-surgical treatment group (35 cases, 43 limbs). There were 3 operative deaths and 34 late deaths in the surgical group, and 14 late deaths in the non-surgical group. The number one cause of death was heart failure, including ischemic heart disease, in both groups. The 4-year cumulative patency rates were 91% in the aorto-iliac, 71% in the femoro-distal and 79% in the aorto-femoro-distal arterial reconstructions. Long term symptom free rates of the surgical group and the non-surgical group, except fatal case, were 83% and 44% in the aorto-iliac, 79% and 27% in the femoro-distal, 87% and 33% in the aorto-femoro-distal arterial regions, respectively. Late result of intermittent claudication in the surgical group was better than that in the non-surgical group. We concluded that intermittent claudication should be considered to be the indication for surgery, except for the cases with high risk diseases or malignant diseases.

[Alpha 1-antitrypsin genes in patients with alpha 1AT deficiency in Japan: mutational analysis and allelic background]

Deficiency of alpha 1-antitrypsin (alpha 1AT), a plasma serine protease inhibitor, increases the risk of precocious pulmonary emphysema. Patients with alpha 1AT deficiency in Japan are extremely rare and no Z type alpha 1AT deficiency, which is one of the most frequent genetic disorders among Caucasians, are reported in Japan at the level of gene analysis. It is not yet clear why Z type alpha 1AT is rare among Japanese. When Ala213(GCG)-Val213(GTG) mutation in the alpha 1AT gene was examined by restriction endonuclease BstPI, all of 156 Japanese samples were Val213(GTG) in contrast to the finding that 30% of U.S. Caucasians are Ala213(GCG), indicating that alpha 1AT genes among Japanese were diverted from M1(Val213) variant and are different from M1(Ala213) variant, from which Z variant was likely diverted. This may explain why Z type alpha 1AT deficiency is not found among Japanese. A new alpha 1AT deficient variant, Siiyama (Ser53(TCC)-Phe53(TTC)), was found in a 39-year-old male with pulmonary emphysema (Seyama K, et al, J Biol Chem, 266, 12627, 1991). Interestingly, 6 out of 10 families with alpha 1AT deficiency in Japan shared the identical substitution as Siiyama. This indicates that although Caucasian type Z alpha 1AT deficiency is not found, Siiyama variant may be relatively common in Japan and even in other oriental countries because of the historical migration of people.

A new variant of alpha-1-antitrypsin deficiency (Siiyama) associated with pulmonary emphysema

A 38-year-old male with pulmonary emphysema due to severely reduced serum alpha-1-antitrypsin (AAT) level (14.5 mg/dl) was found to have an inherited new AAT deficient variant Siiyama. Chest roentgenogram and CT scanning revealed advanced emphysema, and severe obstructive ventilatory impairment was observed. During the 4-year follow-up period, the annual rate of decline of FEV 1.0 showed approximately 10-fold greater than the normal decline in FEV 1.0 (-380 ml/yr). Treatment with tamoxifen in order to raise the serum AAT level only resulted in an insufficient increase. Augmentation therapy of human AAT should be considered in the future.

Siiyama (serine 53 (TCC) to phenylalanine 53 (TTC)). A new alpha 1-antitrypsin-deficient variant with mutation on a predicted conserved residue of the serpin backbone

alpha 1-antitrypsin (alpha 1AT), a plasma serine protease inhibitor, increases the risk of precocious pulmonary emphysema in individuals when deficient. Although more than 25 years have passed since a deficiency in the serum level of alpha 1AT was reported, it is only recently that the consequence of the amino acid replacement which leads to the deficient state has been discussed in terms of the crystallographic structure of alpha 1AT and the amino acid residues conserved in the superfamily to which it belongs. Our case involved a 38-year-old Japanese male with alpha 1AT deficiency which was analyzed and identified as a new deficient variant. The serum alpha 1AT of the proband migrated to the S position of the reference serum which is more cathodal than M1, the predominant normal variant, when isoelectric focusing (pH 4.2-4.9) is performed by a combination of Western blotting and crossed immunoelectrophoresis. The new deficient variant is designated as Siiyama after his birthplace. Although liver biopsy specimen showed no apparent pathological findings, PAS-positive with diastase-resistant inclusion bodies and immunoreactive aggregates were detected in several hepatocytes. In addition, similar alpha 1AT mRNA transcript levels were observed in peripheral blood leukocytes from the proband and healthy subjects by Northern analysis. All the coding exons (exon Ic, II, III, IV, and V) of the alpha 1AT gene of the proband and his family were amplified by polymerase chain reaction and followed by direct sequencing. A single missense mutation, Ser53 (TCC) to Phe53 (TTC was identified in exon II of the proband's alpha 1AT gene. All his family examined were heterozygous at this base. Ser53 is one of the most conserved residues as predicted by Huber and Carrell (Huber, R., and Carrell, R. W. (1989) Biochemistry 28, 8951-8966) and is thought to contribute to the organization of the internal core element of the alpha 1AT molecule. The mutational matrix number of Ser to Phe substitution is -3, indicating that this change is evolutionally rare. In this regard, a possible explanation for the deficient state in alpha 1AT Siiyama is that the change from an uncharged polar to a nonpolar amino acid imposed on the conserved serpin backbone exerts severe effects on the integrity of the molecule, and hence alters the intracellular processing of alpha 1AT.

Mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes with special reference to the mechanism of cerebral manifestations

A 29-year-old man with mitochondrial encephalomyopathy caused by partial deficiency of mitochondrial NADH-ubiquinone oxidoreductase (Complex I) is described. Clinical manifestations were characterized by generalized convulsion, dementia and stroke-like episodes consisting of hemianopsia, Gerstmann's syndrome and visual hallucination. Blood and cerebrospinal fluid lactate and pyruvate levels were elevated. Biochemical studies on a muscle biopsy specimen revealed partial deficiency of Complex I activity, and decreases in the 75-kDa and the 20-kDa subunits of Complex I by immunoblotting analysis. Serial brain CT scans revealed multiple low-density areas with fluctuating densities. Single photon emission tomographic study revealed preservation of blood circulation where CT scans showed diminished density in acute stage, suggesting the presence of abnormal cellular metabolism rather than vascular occlusion as the basic mechanism of his stroke-like episodes. Pathogenesis of neurological manifestations in MELAS is discussed with reference to the possible involvement of free radicals in inducing brain damage.

Biochemical characterization of acetyl-CoA:1-alkyl-2-lyso-sn-glycero-3-phosphocholine acetyltransferase in rat spleen microsomes

Acetyl-CoA:1-alkyl-2-lyso-sn-glycero-3-phosphocholine (lyso-PAF) ultrasonic disruption in the presence of 25% glycerol from rat spleen microsomes. About 26% of the enzymatic activity was recovered in the 225,000 X g supernatant by this treatment, although the specific activity was slightly decreased compared with the original microsomes. The solubilized enzyme was remarkably susceptible to various kinds of metal ions. Sulfhydryl reagents such as p-chloromercuribenzoate and N-ethyl-maleimide significantly inhibited the enzyme reaction, suggesting that the enzyme is an SH enzyme. Based on the sedimentation pattern in sucrose density centrifugation, the isoelectric point, the kinetic characteristics and the sensitivity to tryptic digestion of microsomes, it appears that acetyl-CoA:lyso-PAF acetyltransferase does not differ from the acetyltransferase responsible for the transfer of acetate from acetyl-CoA to 1-acyl-2-lyso-sn-glycero-3-phosphocholine.

[Studies on acetyl-CoA:lyso platelet activating factor acetyltransferase of rat spleen microsomes--solubilization and substrate specificity]

Acetyl-CoA: lyso platelet activating factor (1-O-alkyl-2-lyso-sn-glycero-3-phosphorylcholine) acetyltransferase was solubilized from rat spleen microsomes with ultrasonic irradiation in the presence of 25% glycerol and partially purified by Sepharose 6B column chromatography. The overall yield of this procedures was approximately 26% and its specific activity was 1.7 times compared with that of original microsomes. The solubilized enzyme was extremely labile, but did not lose the activity for several weeks at -70 degrees C. The solubilized enzyme was remarkably susceptible to various kinds of metal ions. Furthermore, sulfhydryl reagents such as N-ethylmaleimide and p-chloromercuribenzoate profoundly inhibited the enzyme reaction, suggesting that the enzyme was -SH enzyme. The acetyltransferase activity was remarkably decreased by tryptic digestion of spleen microsomes, which indicated that the enzyme was located in the cytoplasmic surface of microsomal membranes. On the substrate specificity, the enzyme preferentially acetylated 1-O-hexadecyl-2-lyso-sn-glycero-3-phosphorylcholine and 1-O-octadecenyl-2-lyso-sn-glycero-3-phosphorylcholine as compared with other chain length at sn-1 position of lyso platelet activating factor, which may suggest that biologically potent molecular species of PAF are selectively synthesized. On the other hand, the enzyme also acetylated an acyl analog of lyso platelet activating factor. Some experimental results have shown that these two acetylation reaction presumably would be performed by the same enzyme.

Metabolism of platelet-activating factor in primary cultured adult rat hepatocytes by a new pathway involving phospholipase C and alkyl monooxygenase

The metabolic fate of 1-O-[3H]alkyl-2-acetyl-sn-glycero-3-phosphocholine (PAF-acether) upon interaction with primary cultured adult rat hepatocytes was investigated. [3H]PAF-acether was transformed time-dependently into [3H]lyso-PAF-acether, 1-O-[3H]alkylglycerol and finally converted to 3H-labeled fatty aldehyde. 1-O-[3H]Alkyl-2-acyl-sn-glycero-3-phosphocholine (alkylacyl-GPC) was formed after a long incubation time and with a smaller amount compared with that formed in platelets and neutrophils. When lipids from cells, cell surfaces and incubation medium were analyzed separately, most of the transformed products of [3H]PAF-acether remained in the cells. When 1-O-[3H]alkyl-2-lyso-sn-glycero-3-phosphocholine was incubated with hepatocytes, it was mainly converted into 1-O-[3H]alkylglycerol. 3H-labeled fatty aldehyde and [3H]alkylacyl-GPC were also found. Hepatocytes metabolized slowly from 1-O-[1-14C]hexadecylglycerol to 3H-labeled fatty aldehyde and 3H-labeled phospholipid. These findings suggest that cultured hepatocytes mainly catabolize exogeneous PAF-acether by removing the acetyl residue and the polar head group and, finally, by cleaving an ether bond. The deacetylation-reacylation step, which is important in platelets and neutrophils, was not shown to be a main metabolic pathway of PAF-acether in cultured hepatocytes.

Phospholipid requirement of alkylglycerol monooxygenase from rat liver microsomes

The alkylglycerol monooxygenase catalyzing the cleavage of the ether bond in alkylglycerol resides in rat liver microsomes. The enzyme preparation was freed of phospholipids by sodium deoxycholate treatment followed by gel filtration in the presence of deoxycholate. The removal of phospholipids markedly decreased the alkylglycerol monooxygenase activity. The activity of the delipidated enzyme, however, could be completely restored by the addition of phospholipid vesicles without detergent. When individual phospholipids were added, anionic phospholipids such as phosphatidylglycerol and diphosphatidylglycerol were the most effective. These findings, along with our previous observation of a similar effect of liposomes on the purified enzyme, indicate that the amphipathic nature of the protein is responsible for the lipid dependence of enzymatic activity.