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Sporadic inclusion-body myositis (sIBM) is the most common acquired muscle disease in Caucasians over the age of 50 years. Pathologically it is marked by inflammatory, degenerative, and mitochondrial changes that interact in a yet-unknown way to cause progressive muscle degeneration and weakness. The cause of the disease is unknown, but it is thought to involve a complex interplay between environmental factors, genetic susceptibility, and aging. The strongest evidence for genetic susceptibility comes from studies of the major histocompatibility complex (MHC), where different combinations of alleles have been associated with sIBM in different ethnic groups. The rare occurrence of familial cases of inclusion-body myositis (fIBM) adds additional evidence for genetic susceptibility. Other candidate genes such as those encoding some of the proteins accumulating in muscle fibers have been investigated, with negative results. The increased understanding of related disorders, the hereditary inclusion-body myopathies (hIBM), may also provide clues to the underlying pathogenesis of sIBM, but to date there is no indication that the genes responsible for these conditions are involved in sIBM. This review summarizes current understanding of the contribution of genetic susceptibility factors to the development of sIBM.

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Malignant mesothelioma (MM) is a solid tumor largely unresponsive to conventional therapies. Immunological gene therapy shows promise in murine models and human clinical trials; however, the role of surgery in combination with gene therapy has not been widely studied. The aim of this study was to determine if debulking surgery improved the effectiveness of gene therapy in a murine MM model. Mice were subcutaneously inoculated with the MM cell line, AC29, at two different sites, 4 days apart, to allow a surgical and distal site tumor to develop. Once tumors were established, the surgical site tumor was debulked and vaccination of syngeneic tumor transfectants encoding genes for IL-4, IL-2, GM-CSF, B7-1 or allogeneic MHC molecules commenced at a site away from both tumors, and tumor growth was measured. Neither debulking surgery nor gene therapy alone delayed tumor growth. However, there was a clear delay of tumor growth when debulking surgery was combined with vaccination of tumor transfectants expressing B7-1 or high levels of GM-CSF. Combinations of these two transfectants did not lead to a synergistic effect. This study demonstrates that debulking surgery can augment the immunostimulatory effects of immunological gene therapy and can delay tumor growth. This has implications for the future design of human gene therapy trials for solid tumors such as MM.

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The beneficial effects of cyclo-oxygenase (COX) inhibitors in both colon cancer and adenomatous polyps suggest a role for the prostanoid pathway in epithelial malignancy. Although variable prostanoid synthesis in non-small cell lung cancer (NSCLC) has been demonstrated in freshly obtained tissue, COX messenger ribonucleic acid (mRNA) and protein localization in such tumours had not been investigated ex vivo. Thirty-four cases of primary NSCLC were examined for both constitutive (COX-1) and inducible COX (COX-2) by means of in situ hybridization and immunohistochemistry. COX-1 mRNA expression was absent or below the level of detection via in situ hybridization. COX-1 immunohistochemistry demonstrated uniform faint cytoplasmic staining in tumour cells and stromal inflammatory cells. Semiquantitative analysis of COX-2 expression in NSCLC demonstrated the highest levels of both mRNA and protein in adenocarcinoma cells (n=10, p<0.005 compared with large cell and squamous cell carcinoma), intermediate and variable expression in large cell carcinoma (n=11) and low or absent expression in squamous cell tumours (n=13). Levels of COX-2 expression in infiltrating inflammatory cells was the same in all tumour types. In conclusion, tumour cell cyclo-oxygenase-2 rather than cyclo-oxygenase-1 expression may account for the variable prostanoid production seen in non-small cell lung cancer, and primary lung adenocarcinoma expresses the highest levels of cyclooxygenase-2. Assessment of cyclo-oxygenase-2 expression ex vivo should be performed in studies examining the potential therapeutic effects of cyclo-oxygenase inhibitors in non-small cell lung cancer.

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Malignant mesothelioma (MM) is a solid tumor of the mesothelium for which there is no curative treatment. MM appears to be sensitive to immunotherapeutic approaches, and one of the most powerful immunomodulatory cytokines with antitumor effects is interleukin (IL)-12. We have previously shown in a murine model of MM that systemic administration of recombinant IL-12 induces a potent anti-MM immune response. The nature and accessibility of MM tumors means that they are suitable candidates for direct cytokine and gene-transfer therapeutic approaches. Therefore, we undertook a study to assess the antitumor effects induced by the local production of IL-12 within MM tumors by transfecting a murine MM line with the genes for IL-12. The IL-12 transfectant (AB1-IL-12) did not produce tumors in normal mice, but did so in athymic nude mice, implicating T cells in the prevention of MM tumor growth. In mixing experiments, paracrine IL-12 production inhibited growth of untransfected MM cells provided that cells producing IL-12 represented more than 50-80% of the inoculum. Furthermore, BALB/c mice previously challenged with AB1-IL-12 were protected against rechallenge with parental AB1 tumor, indicating that the transfectant induced long-term immunity. AB1-IL-12 induced systemic immunity that was effective at reducing the incidence of parental AB1 tumor at a distal site, but its effects were dose-dependent. Though both CD4(+) and CD8(+) cells infiltrated the rejecting tumor, CD8(+) effector cells were essential for protection against development of parental AB1 tumor. This study shows that paracrine secretion of IL-12, generated by gene transfer, can induce immunity against MM that can act locally and also at a distant site. In addition, there was no evidence of toxicity, which has been associated with the systemic administration of IL-12, indicating that this cytokine is a good candidate for experimental gene therapy in MM.

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Cyclo-oxygenase is the rate-limiting enzyme in the prostanoid pathway. Although expression of the inducible isoform of cyclo-oxygenase (COX-2) is associated with cytokine-mediated inflammation, recent evidence suggests a homeostatic role for epithelial COX-2 in the gastrointestinal tract. The aim of this study was to examine the expression and localization of COX-2 in human airway epithelium both in vivo and in vitro. Human airway specimens from patients undergoing lung resection surgery for primary lung tumours (n=10) or nasal mucosal resection for non-inflammatory nasal obstruction (n=5) were examined for COX-2 expression by in situ hybridization and immunohistochemistry. COX-2 expression was also studied in two human airway epithelial cell lines (BEAS-2B and A549) using reverse transcription polymerase chain reaction and Northern and Western blot analysis. COX-2 messenger ribonucleic acid (mRNA) and protein were localized to individual columnar epithelial cells and to airway resident inflammatory cells in 9/10 lower and 5/5 upper airway specimens. Expression of COX-2 did not correlate with evidence of airway inflammation. Focal expression of COX-2 mRNA and protein was observed in bronchus-associated lymphoid tissue. Both COX-2 mRNA and protein were detected in BEAS-2B and A549 cells cultured under standard conditions. In conclusion, expression of COX-2 in human airway epithelium occurs in the upper and lower airways, is widespread in airway epithelial and airway resident inflammatory cells in the absence of overt airway inflammation, and is detectable in cultured human airway epithelial cells in the absence of inflammatory cytokine stimulation. These data suggest a potentially important homeostatic role for COX-2 in the regulation of human airway contractility, inflammation and immune responses.

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Inclusion body myositis (IBM) is a form of idiopathic inflammatory myopathy of unknown aetiology. A strong association with HLA class II (HLA-DR3) suggested a role for genes in the human major histocompatibility complex (MHC) in the predisposition to this disease. In this study, we have taken advantage of the ancestral haplotype (AH) concept and historical recombinations to map for a possible susceptibility gene(s) in the MHC. We performed detailed typing of three MHC-related HSP70 genes and defined allelic combinations in the context of MHC AH. We also modified existing methods to give a simple and accurate method for typing two TNF microsatellites. Using the HSP70 and TNF markers and HLA-DR, -B, and C4 typing of our patients with IBM, we defined a potential site for the MHC-associated susceptibility gene(s) in the region between HLA-DR and C4.

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The frequency of clinical and biochemical relapses was determined in a group of 50 patients with polymyositis (PM), dermatomyositis (DM), or overlap syndromes who were followed for periods of up to 13 years. Relapses occurred in 30 of the 50 patients (60%) during the period of follow-up. The annual relapse rate was not significantly different in the three groups of patients. Subclinical relapses occurred in each group but were less frequent in the DM than in the PM and overlap groups. Relapses could occur at any time but were more frequent during periods of stable maintenance therapy. There was no correlation between relapses and initial disease severity, delay to diagnosis and commencement of treatment, or any class I or II histocompatibility locus antigen.

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Malignant mesothelioma (MM) is a fatal solid tumor of the mesothelium for which there is currently no ameliorating treatment. Using our murine model of this malignancy, which closely resembles the human disease, we have shown that immunotherapy may be of value in the treatment of MM. Because recombinant interleukin-12 (rIL-12) has strong immunomodulatory effects in vivo, we studied the effects of rIL-12 on murine antitumor immune responses, using a nonimmunogenic murine MM tumor cell line (AB1) in vivo. Systemic administration of rIL-12 at the time of tumor inoculation prevented AB1 tumor growth in up to 70% of treated mice, 50% of which were still resistant to AB1 upon rechallenge, indicating that long-term immunologic antitumor effects had been established. This rIL-12-induced effect was dependent on the involvement of both CD4(+) and CD8(+) but not natural killer (NK) cells. Importantly, treatment of established tumors with intralesional injections of rIL-12 resulted in temporary tumor regression or growth inhibition. This effect was dependent on the continuous presence of rIL-12 and correlated with increased numbers of CD4(+) and CD8(+) cells infiltrating the remaining tumor mass. Effective inhibition of tumor growth also occurred when IL-12 was released within MM tumors by coadministration of MM cells that had been stably transfected with the gene for IL-12. These data indicate that IL-12 has potential in the immunotherapy of MM, through gene transfer or local cytokine administration, provided that significant intratumor levels of IL-12 can be achieved for prolonged periods.

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BACKGROUND: The pathogenesis of nasal polyp disease is poorly understood. Recent evidence has suggested that nitric oxide (NO), an endogenous soluble gas vasodilator and inflammatory mediator, may be synthesised within the nasal cavity. Three nitric oxide synthase isoforms have been identified in humans, with the inducible isoform (iNOS) generally expressed in the setting of inflammation. OBJECTIVE: The aim of this study was to detect and localize iNOS expression in nasal polyp tissue, and compare these findings with normal nasal turbinate tissue. METHODS: We examined the expression and localisation of inducible nitric oxide synthase (iNOS) in human nasal airway specimens from patients undergoing elective nasal turbinectomy (n = 5) or nasal polypectomy (n = 5). iNOS mRNA expression was determined by semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) followed by Southern blot analysis and localised by in situ hybridization. Densitometric data were analysed using Student's unpaired t-test. Adjacent sections were also examined for iNOS protein expression by immunohistochemistry. RESULTS: Semi-quantitative RT-PCR/Southern analysis of RNA obtained from the 10 surgical specimens demonstrated that iNOS mRNA expression was significantly increased in the five nasal polyps (P < 0.05). In situ hybridization studies revealed strong iNOS mRNA signal localized to the respiratory epithelium of nasal polyps, but not nasal turbinates. This pattern was confirmed by immunohistochemistry. Localization to inflammatory cells or other subepithelial structures was not seen. CONCLUSIONS: We conclude that iNOS expression is upregulated in nasal polyp disease, and is localized to the polyp epithelial layer. These data reinforce the concept that the epithelial layer may be important in the pathogenesis of nasal disease, and suggest a potential role for NO in the formation of nasal polyps.

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Polymyositis is regarded as an autoimmune inflammatory muscle disease. A major subgroup of patients have autoantibodies to cellular histidyl-transfer RNA synthetase (HRS). We have analyzed the role of the autoantigen HRS in the induction of murine myositis in a comparative study of inoculation of BALB/c mice with recombinant HRS protein versus naked DNA coding for HRS. Adult BALB/c mice produced antibodies to human HRS following inoculation with HRS protein and adjuvant, but myositis was not observed. Alternatively, expression plasmid DNA constructs encoding full-length and truncated human HRS were inoculated intramuscularly in gene transfer studies. DNA-inoculated mice produced relatively low anti-HRS antibody titers. However, in contrast to recombinant HRS protein-inoculated mice, HRS gene transfer induced pathology with evidence of cellular infiltration of perivascular and endomysial regions of the inoculated muscle. Multiple inoculations of a plasmid construct encoding a hybrid molecule consisting of HRS and the transferrin receptor cytoplasmic tail induced the highest levels of antibodies and persisting cellular infiltration. Unlike HRS, expression of influenza virus hemagglutinin (HA) following inoculation of an HA plasmid did not induce myositis. Transfer of naked DNA constructs expressing HRS is likely to provide valuable information on the autoimmune response to this protein and its role in the development of myositis.

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Stable IL-2 transfectant clones have been derived from two non-immunogenic murine malignant mesothelioma (MM) cell lines to investigate the induction of protective antitumor immunity to MM. AC29-IL-2 transfectant clones grew at a slower rate in vivo than the parental cell line or a transfectant control clone but all inoculated mice developed tumours despite the continued ability of the tumour cells to express IL-2. Tumour development after inoculation of AB1-IL-2 transfectants varied, the degree of in vivo inhibition (40-100%) being directly related to the rate of IL-2 secretion of the transfectants. When mice which had rejected the AB1-IL-2 transfectants were challenged with parental AB1 cells, a proportion (16-70%) of mice from each group remained tumour free at least 45 days after challenge (naive mice developed tumours within 26 days). The inhibition of growth of the initial inoculum of AB1-IL-2 transfectants was independent of CD4+ and CD8+ cells, consistent with the demonstration of non-specific cytotoxic activity by splenocytes from mice inoculated with the IL-2 transfectants. These data suggest that IL-2 expression by MM cells is capable of generating in vivo immunity to the tumour. This immunity may be relatively weak or may be subject to down-regulation so that consistent rejection of unmodified tumour cells is not achieved. Genetic modification with combinations of genes, including IL-2 and B7-1, will be necessary for reliable generation of protective immunity to MM.

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1. In airway epithelium, nitric oxide (NO) is synthesized in the setting of inflammation by inducible nitric oxide synthase (iNOS). Although the role of epithelial derived NO in the regulation of human airways is unknown, prostaglandin E2 (PGE2) is recognised as an important inhibitory mediator in human airways. Cyclo-oxygenase (COX) is the rate limiting enzyme in the production of prostanoids and since inflammatory pathways enhance the expression of an inducible COX (COX-2), both COX-2 and iNOS may be co-expressed in response to an inflammatory stimulus. Although regulation of the COX-2 pathway by NO has been demonstrated in animal models, its potential importance in human airway epithelium has not been investigated. 2. The effect of endogenous and exogenous NO on the COX-2 pathway was investigated in the A549 human airway epithelial cell culture model. Activity of the COX-2 pathway was assessed by PGE2 EIA, and iNOS pathway activity by nitrite assay. A combination cytokine stimulus of interferon gamma (IFNgamma) 100 u ml(-1), interleukin-1beta (IL-1beta) 1 u ml(-1) and lipopolysaccharide (LPS) 10 microg ml(-1) induced nitrite formation which could be inhibited by the competitive NOS inhibitor N(G)-nitro-L-arginine-methyl-ester (L-NAME). IL-1beta alone (1-50 u ml(-1) induced PGE2 formation without significant nitrite formation, a response which was inhibited by the COX-2 specific inhibitor nimesulide. Submaximal stimuli used for further experiments were IFNgamma 100 u ml(-1), IL-1beta 1 u ml(-1) and LPS 10 microg ml(-1) to induce both the iNOS and COX-2 pathways, and IL-1beta 3 u ml(-1) to induce COX-2 without iNOS activity. 3. Cells treated with IFNgamma 100 u ml(-1), IL-1beta I u ml(-1) and LPS 10 microg ml(-1) for 48 h either alone, or with the addition of L-NAME (0 to 10(-2) M), demonstrated inhibition by L-NAME of PGE2 (3.61 +/- 0.55 to 0.51 +/- 0.04 pg/l0(4) cells; P<0.001) and nitrite (34.33 +/- 8.07 to 0 pmol/10(4) cells; P<0.001) production. Restoration of the PGE2 response (0.187 +/- 0.053 to 15.46 +/- 2.59 pg/10(4) cells; P<0.001) was observed after treating cells with the same cytokine stimulus and L-NAME 10(-6) M, but with the addition of the NOS substrate L-arginine (0 to 10(-5) M). 4. Cells incubated with IL-1beta 3 u ml(-1) for 6 h, either alone or with addition of the NO donor S-nitroso-acetyl-penicillamine (SNAP) (0 to 10(-4) M), demonstrated increased PGE2 formation (1.23 +/- 0.03 to 2.92 +/- 0.19 pg/10(4) cells; P< 0.05). No increase in PGE2 formation was seen when the experiment was repeated in the presence of the guanylate cyclase inhibitor methylene blue (50 microM). Cells treated with SNAP alone did not demonstrate an increased PGE2 formation. Cells incubated with IL-1beta 3 u ml(-1) for 6 h in the presence of dibutyryl cyclic guanylate monophosphate (0 to 10(-3) M) also demonstrated an increased PGE2 response (2.56 +/- 0.21 to 4.53 +/- 0.64 pg/10(4) cells; P<0.05). 5. These data demonstrate that in a human airway epithelial cell culture system, both exogenous and endogenous NO increase the activity of the COX-2 pathway in the setting of inflammatory cytokine stimulation, and that this effect is likely to be mediated by guanylate cyclase. This suggests a role for NO in the regulation of human airway inflammation.

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Nitric oxide (NO) synthesized by airway epithelium may be important in the regulation of airway inflammation and reactivity. As such, the expression and localization of nitric oxide synthase (NOS) isoforms was assessed in human airway tissue obtained following thoracotomy, and in cultured human airway epithelial (BEAS-2B) cells. NOS expression was determined by reverse transcription-polymerase chain reaction (RT-PCR)/Southern blot analysis, and localized by in situ hybridization and immunohistochemistry. No synthesis by cell cultures was detected by nitrite assay. Endothelial and neuronal constitutive NOS mRNAs were not detected in airways or cell cultures. Inducible NOS (iNOS) mRNA was detected in 5 of 6 airway specimens, and in situ hybridization demonstrated iNOS mRNA expression in columnar epithelial cells. This was confirmed by immunohistochemistry using an iNOS specific antibody. BEAS-2B cell cultures were stimulated with (I) combinations of tumor necrosis factor alpha (TNF alpha) (50-2,000 U/ml)/interferon gamma (IFN gamma) (20-500 U/ml)/lipopolysaccharide (LPS) (10 micrograms/ml) or (2) histamine (10(-3) M-10(-5) M). Cell cultures treated with TNF alpha/IFN gamma/LPS in combination expressed iNOS mRNA, and this was associated with increases in supernatant nitrite concentrations over 24 h; however, this response diminished with successive passage of cells. Histamine treatment did not result in iNOS mRNA expression or detectable NO synthesis. We conclude that iNOS in human airway tissue is localized to the airway epithelium. Cytokine/ LPS stimulation, but not histamine, results in iNOS mRNA expression and NO synthesis in BEAS-2B cells. BEAS-2B cells may not be a suitable model for the study of NO biology in airway epithelium.

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Transfection of the genes encoding the co-stimulatory molecules B7-1 and B7-2 has enhanced the development of immunity to a variety of experimental tumors, although most of these were inherently immunogenic. We have determined the effect of expression of these genes on the induction of immunity to 2 non-immunogenic murine malignant mesothelioma (MM) cell lines (AC29 and AB1). We had previously shown that B7-1 transfection into AC29 delayed but did not prevent tumor development by certain of the transfectant clones. Here we demonstrate that over-expression of B7-1 can inhibit tumor development by certain AB1-B7-1 clones, that inhibition of transfectant growth is dependent on CD4+ and CD8+ T cells and that mice that reject some of these transfectant clones are capable of rejecting subsequent inocula of the parental cell line, AB1. The transfectant clones can generate tumor-specific cytotoxic T cells. By contrast, expression of B7-2 in several clones derived from either AB1 or AC29 had no significant effect on the development of tumors in vivo. Our data are consistent with data from other systems that show differences in the effect of modification by B7-1 or B7-2 on the modulation of anti-tumor immune responses. They demonstrate that such modifications can induce protective immunity against an MM cell line but confirm the intra- and inter-tumoral heterogeneity in the effect of genetic modification on the induction of immunity. Our observations are relevant to human MM because these cell lines have been derived from asbestos-induced tumors and share many properties with human cell lines of the same histological type.

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Genetic predisposition to development of the idiopathic inflammatory myopathies is probably multifactorial. Major histocompatibility complex associations with these diseases provide the strongest evidence for a genetic component. In Caucasoids, haplotypes marked by B8/DR3 are associated with each of the clinical subgroups, except mixed connective tissue disease (DR4). The strongest associations are with inclusion body myositis, polymyositis in the presence of anti-Jo-1, and with antibodies to PM-Scl in overlap syndromes. The underlying mechanisms of these associations are probably different. Unique major histocompatibility complex associations are seen with other myositis-associated autoantibodies. The association can vary between racial groups as can the type of autoantibody produced within a disease subgroup, perhaps reflecting different T cell receptor repertoires or different inducing agents. The mapping of a gene for one form of hereditary inclusion body myositis to chromosome 9p1-q1 provides a lead for the investigation of sporadic inclusion body myositis, as does the expanding knowledge of genetic factors in Alzheimer's disease. The demonstration of deletions of mitochondrial DNA in the muscle of patients with inclusion body myositis raises the question of their role in the pathogenesis of the disease.

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The murine histidyl-tRNA synthetase-encoding gene (MMHRS) coding region has been cloned and sequenced. The 1527-bp transcript shows a strikingly similar structural organization to that of its human counterpart, particularly within the three class II aminoacyl-tRNA synthetase structural motifs and the two histidyl-tRNA synthetase signature regions. It is predicted, as in humans, to have a coiled-coil alpha-helical structure that is characteristic of many autoantigens. MMHRS shows some degree of polymorphism at both the DNA and amino-acid levels, although its sequence is well conserved amongst the commonly used laboratory mouse strains.

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The genetic predisposition to inclusion body myositis (IBM) is probably multifactorial. The deposition of the beta-amyloid protein is a characteristic histological feature of both IBM and Alzheimer's disease (AD). The epsilon 4 allele of apolipoprotein E (APO E) has been strongly associated with familial and late-onset AD. We therefore compared the APO E allele frequencies in a group of 14 patients with IBM with those in a group of patients with other inflammatory muscle diseases and in the general population. The frequency of the epsilon 4 allele in IBM was increased (0.29) compared with that in patients with other inflammatory muscle diseases (0.15) and the general population (0.13) (p < 0.05). These data suggest that APO E genotype may be one of the factors involved in determining the predisposition to the development of IBM.

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