The plasminogen activation system reduces fibrosis in the lung by a hepatocyte growth factor-dependent mechanism

Mice deficient in the plasminogen activator inhibitor-1 gene (PAI-1-/- mice) are relatively protected from developing pulmonary fibrosis from bleomycin administration. We hypothesized that one of the protective mechanisms may be the ability of the plasminogen system to enhance hepatocyte growth factor (HGF) effects, which have been reported to be anti-fibrotic in the lung. HGF is known to be sequestered in tissues by binding to extracellular matrix components. Following bleomycin administration, we found that HGF protein levels were higher in bronchoalveolar lavage fluid from PAI-1-/- mice compared to wild-type (PAI-1+/+) mice. This increase could be suppressed by administering tranexamic acid, which inhibits plasmin activity. Conversely, intratracheal instillation of urokinase into bleomycin-injured PAI-1+/+ mice to activate plasminogen caused a significant increase in HGF within bronchoalveolar lavage and caused less collagen accumulation in the lungs. Administration of an anti-HGF neutralizing antibody markedly increased collagen accumulation in the lungs of bleomycin-injured PAI-1-/- mice. These results support the hypothesis that increasing the availability of HGF, possibly by enhancing its release from extracellular matrix by a plasmin-dependent mechanism, is an important means by which activation of the plasminogen system can limit pulmonary fibrosis.     

Unique properties of fetal lymphoid progenitors identified according to RAG1 gene expression

RAG1/GFP knockin mice were exploited to isolate and characterize fetal lymphoid progenitors. CD11b and IL-7Ralpha are expressed in a developmental stage-dependent fashion, revealing how substantial numbers of early lymphoid progenitors were discarded or neglected in previous studies. The myeloerythroid potential of fetal progenitors in clonal assays declined in synchrony with activation of the RAG1 locus but was not completely extinguished. Lymphoid differentiation corresponded to patterns of gene expression previously found for adult marrow, but no fraction of fetal liver was enriched with respect to B + T progenitors. Also, unlike adults, fetal lymphoid progenitors transiently expressed endothelial cell markers. These findings help to reconcile discrepancies in previous reports and suggest that the fetal immune system arises via unique mechanisms.     

Cloning of a truncated Babesia equi gene encoding an 82-kilodalton protein and its potential use in an enzyme-linked immunosorbent assay

To isolate Babesia equi genes encoding immunodominant proteins, a cDNA expression library prepared from B. equi mRNA was immunoscreened with B. equi-infected horse serum. Eighteen positive cDNA clones were obtained, and the clone that showed the strongest immunoreactivity, designated Be82, was further characterized. The Be82 gene consisted of 1,953 bp and contained a partial open reading frame lacking the 5'-terminal sequence. As shown by Western blot analyses, immune sera from mice intraperitoneally injected with the Be82 gene product recognized the 82- and 52-kDa proteins of B. equi but not those of Babesia caballi. The glutathione S-transferase fusion protein expressed in Escherichia coli that was purified and used as the antigen in the enzyme-linked immunosorbent assay reacted specifically with B. equi-infected horse sera. These results suggest that the Be82 gene product is a potential diagnostic antigen candidate in the detection of B. equi infection in horses that will be useful both in the performance of epidemiological studies and in the granting of quarantine passes.     

PCR for detection and identification of Streptococcus sobrinus

Oligonucleotide primers were designed based upon a comparison of the dextranase gene (dex) sequences from Streptococcus sobrinus and S. mutans. The primers amplified a 1610-bp long DNA fragment on the dex gene by a PCR. The pair of primers was specific to S. sobrinus as the other members of the mutans streptococci - S. mutans, S. downei, S. cricetus, S. rattus, S. macacae and S. ferus - gave no PCR products. Other gram-positive oral bacteria (15 strains of 10 species of cocci and 18 strains of 12 species of rods) and gram-negative oral bacteria (3 strains of 3 species of cocci and 31 strains of 22 species of rods) also gave negative results in the PCR. The PCR procedure was able to detect as little as 100 fg of purified chromosomal DNA or as few as 9 cfu of S. sobrinus NIDR6715. Seven clinical isolates of S. sobrinus were also positive in the dex PCR. This laboratory developed the S. mutans-specific PCR (dexA PCR) method with the primers specific for a portion of the dextranase gene of S. mutans Ingbritt. Primers for the dex and dexA PCR methods detected two species exclusively from the mutans streptococci. Furthermore, these two species were effectively differentiated by the species-specific amplicons with different lengths. The application of the PCR method to human dental plaque showed that the prevalence of S. sobrinus (83%) in oral cavities was higher than currently supposed (0-50%). These results suggest that the described PCR method is suitable for the specific detection and identification of human cariogenic bacteria, S. sobrinus and S. mutans.     

REACTIVE LYMPHOID HYPERPLASIA OF THE STOMACH

The surgically excised stomachs were re-examined histopathologically, and eighteen cases were placed in the category of reactive lymphoid hyperplasia (RLH). The distribution and the classes of infiltrating immunoglobulin (Ig) bearing cells were examined on lesions of RLH cases together with ten histopathologically determined malignant lymphomas (ML) of the stomach and the control stomachs. It was found that in eleven cases of RLH and one case of ML, many lymphoid cells bearing different classes of Ig were present in those lesions in an intermingled way (polyspecific group). Meanwhile, lymphoid cells in three RLH cases and two ML cases bore only a single mono-specific Ig (monospecific group). In other cases, the number of Ig bearing cells were not sufficient to reach any clear conclusions (undetermined group). It was speculated that regardless of the histopathological diagnosis, the mono-specific group might belong to the category of neoplasm of B cell type and the polyspecific group in the category of true reactive process. The possible histopathological criteria for differentiation of the reactive process and lymphoid neoplasm of the stomach were re-checked, and the importance of immunohistochemical study on these cases were stressed.     

The expression of B7-H1 on keratinocytes in chronic inflammatory mucocutaneous disease and its regulatory role

PD-1 and its ligands, B7-H1/PD-L1 and B7-DC/PD-L2, have been identified recently as CD28-B7 family molecules that are implicated in immune regulation. Lichen planus (LP) is a T cell-mediated chronic inflammatory mucocutaneous disease. We investigated the expression and function of PD-1 and its two ligands in LP. Immunohistochemical examination revealed the abundant expression of PD-1 and B7-H1 in infiltrating T cells and macrophages, and lower-level expression of B7-DC on macrophages in the subepithelium. Interestingly, substantial expression of B7-H1 on keratinocytes (KCs) was found close to the numerous T cell infiltrates in the subepithelium. Unstimulated cultured KCs expressed both B7-H1 and B7-DC, and their expression was upregulated by proinflammatory cytokines, particularly IFN-gamma. The T-cell proliferative responses and IFN-gamma production that were induced by IFN-gamma-treated KCs were augmented preferentially by anti-B7-H1 mAb, but not by anti-B7-DC mAb. These results indicate the regulatory role of B7-H1 on KCs in the interactions with T cells. Our results suggest that the induction of B7-H1 on KCs may play an important role in tolerance induction in the inflamed oral mucosa and skin.     

Detection of local abnormalities in ventricular activation sequence by body surface isochrone mapping in patients with previous myocardial infarction

Body surface isochrone mapping was performed in 36 normal subjects and in 85 patients with previous myocardial infarction. Eighty-seven unipolar electrocardiograms distributed over the anterior chest and the back were recorded simultaneously. For each lead, activation time was measured as the time from the onset of QRS to the peak of the R wave. The lead points where R waves were not observed were designated the "no R wave area" (NR area). Isochrone maps of normal subjects had a consistent pattern, with isochrone lines extending from the right upper anterior chest to the left anterior chest and then to the back. NR area was small and was located only on the right upper chest or the upper back. On the isochrone maps of patients with myocardial infarction, abnormal findings were observed; NR area was found in 26 of 28 patients with anterior infarction on the upper to middle anterior chest, in 13 of 22 patients with inferior infarction on the lower chest, and in 24 of 25 patients with anterior and inferior infarction on the upper to lower anterior chest. Activation time was delayed near the NR area (peri-NR area delay) in 37 patients. In patients with apical infarction, an islandlike zone of delayed activation was typically found on the left precordium. These abnormal patterns are considered to indicate local abnormalities in the activation of infarcted myocardium; the NR area indicates dead unexcitable scar, and the peri-NR area delay and islandlike zone of delayed activation indicate partially infarcted myocardium of slow activation. Patients with NR area had greater degree of left ventricular asynergy and lower ejection fraction than those without.(ABSTRACT TRUNCATED AT 250 WORDS)     

Age-related changes in the response to vasoconstrictor and dilator agents in isolated beagle coronary arteries

Summary Responses to vasoactive agents were compared in helical strips of coronary arteries isolated from beagles of 30 days, 3 months, 2 years and 12 years old. Serotonin contracted the arterial strips dose-dependently, the contraction being greater in the arteries of proximal portion than in the distal arteries. The contraction increases with age from 3 months to 12 years, although EC50 values did not differ. Angiotensin II contracted distal coronary arteries to a greater extent than the proximal ones. Age did not alter the peptide-induced contraction. In prostaglandin F₂-contracted coronary arteries, acetylcholine-induced relaxations, dependent on endothelium, were less in the arteries from senescent beagles than in those from adult beagles (2 years old). Histamine relaxed the infant beagle arteries to a lesser extent than the adult and senescent beagle arteries. Histamine-induced relaxations were attenuated selectively by cimetidine. Relaxations caused by adenosine and prostaglandin I₂ did not differ in coronary arteries from beagles of different ages. It may be concluded that greater responsiveness to serotonin of senescent beagle coronary arteries is due preferentially to increased function of serotonergic receptors rather than impaired function of the arterial endothelium responsible for the release of relaxing factor(s), although some impairment of the function is supposed, on the basis of interferences with acetylcholine-induced relaxation in the aged beagle arteries. Histaminergic H₂ receptor function appears to develop in beagle coronary arteries until 3 months of age. Send offprint requests to N. Toda