A gain-of-function mutation in the PDGFR-beta alters the kinetics of injury response in liver and skin

Platelet-derived growth factor (PDGF) isoforms stimulate cell proliferation, migration and survival. We recently generated mice carrying a gain-of-function mutation within the activation loop of PDGF beta-receptor (PDGFR-beta D849N). Embryonic fibroblasts derived from these mice show elevated basal phosphorylation and altered kinetics for ligand-induced activation of PDGFR-beta, as well as enhanced proliferation and migration. To investigate the effect of this mutation in vivo, we used carbon tetrachloride-induced liver injury as a model system. We observed a higher basal activation of mutant PDGFR-beta in unchallenged livers; however, the difference in activation upon carbon tetrachloride stimulation was lower than expected, an effect that might be explained by a delayed response of the mutated receptor toward reactive oxygen species. Mutant mice showed enhanced proliferation of nonparenchymal liver cells and activation of hepatic stellate cells, leading to a small increase in early fibrosis formation. Another mouse strain lacking the binding site for phosphatidylinositol-3' kinase in PDGFR-beta showed the reverse phenotype. These results suggest an important role for PDGFR-beta signaling in the early injury-response. We confirmed this hypothesis with a second injury model, cutaneous wound healing, where we observed earlier proliferation and formation of granulation tissue in D849N-mutant mice.     

Bone marrow transplantation in a Hunter patient with P266H mutation.

Mucopolysaccharidosis type II (MPS II, Hunter syndrome) is a lysosomal disease caused by the deficiency of the enzyme iduronate-2-sulfatase (IDS, EC 3.1.6.13). Affected patients show a wide spectrum of clinical phenotypes, from severe to mild. Mutational analysis on this disease resulted in the identification of more than 200 alterations. Bone marrow transplantation (BMT) is considered, at present, an appropriate therapy for MPS II subjects without severe neuropsychological impairment, however molecular analysis in BMT treated patients has been poorly studied. We describe here a patient subjected to BMT in 1995 whose IDS gene alteration, mutation P266H, was identified thereafter. The 4-year follow-up included clinical, biochemical and molecular parameters. DNA analysis showed, after BMT, coexisting host mutant and donor normal alleles, ensuring the effectiveness of the therapy and providing a fast and accurate tool to monitor the colonization of donor cells after treatment.     

Host immunological response and factors associated with clinical outcome in patients with the novel influenza A H7N9 infection

In March 2013, an influenza outbreak caused by the novel avian-origin H7N9 influenza A virus emerged in eastern China and had caused 43 fatalities by 31 July 2013, although the basis for disease pathogenesis still remains unclear. To assess the immunological and viral factors associated with disease severity, viral RNA and inflammatory cytokines were quantified for 18 H7N9 patients in Shanghai, China. Detailed clinical information was collected and clinical laboratory investigations were performed for all patients. H7N9 infection is characterized by high pharyngeal virus load and frequent detection of viral RNA in blood. High pharyngeal virus load persisted through the first 10 days of antiviral therapy in fatal cases. Genetic characterization of the H7N9 virus revealed an Arg292Lys mutation in the neuraminidase gene associated with oseltamivir-resistance. Pronounced lymphopenia and high chemokine and cytokine levels were observed in H7N9-infected patients, particularly in those where disease was fatal. Serum levels of interleukin-6 (IL-6), IL-8 and macrophage inflammatory protein-1β in our subjects also correlated positively with pharyngeal virus load. Lymphocyte counts <0.5 × 10⁹ cells/L, and serum IL-6 >97 pg/mL, IL-8 >40 pg/mL and C-reactive protein >90 mg/L were identified as being connected with adverse clinical outcome through univariate logistic analysis. Significant survival differences were also observed between patients with serum C-reactive protein <90 mg/L or creatinine <90 µmol/L and those with higher levels. Our data demonstrated that high viral load, and the resulting intense inflammatory responses, played an important role in H7N9 pathogenesis. Though immunomodulatory treatment has potential benefits, the focus of clinical management should be on preventing the intense cytokine response by early diagnosis and effective antiviral treatment.     

Emergent 2009 influenza A(H1N1) viruses containing HA D222N mutation associated with severe clinical outcomes in the Americas

Background

During the 2010-2011 influenza season, a small sub-group of 2009 influenza A(H1N1) viruses (hereafter referred to as 2009 A(H1N1)) emerged that was associated with more severe clinical outcomes in Ecuador and North America. Genetically, the haemagglutinin (HA) of this sub-clade was distinct from HAs found in viruses associated with severe outbreaks in 2010 from the United Kingdom and from other global specimens isolated earlier in the season.

Objective

We report the emergence of a novel 2009 A(H1N1) variant possessing a re-emergent HA D222N mutation obtained from patients with severe respiratory illnesses and phylogenetically characterise these D222N mutants with other severe disease-causing variants clustering within a common emerging sub-clade.

Case reports

In early 2011, three cases of 2009 A(H1N1) infection, two from Quito, Ecuador, and one from Washington, DC, USA, were complicated by severe pneumonia requiring mechanical ventilation, resulting in one fatality. These cases were selected due to the reported nature of the acute respiratory distress (ARD) that were captured in Department of Defence (DoD)-sponsored global influenza surveillance nets.

Results

Genetically, the 2009 A(H1N1) strains isolated from two of the three severe cases carried a prominent amino acid change at position 222 (D222N) within the primary HA receptor binding site. Furthermore, these cases represent an emerging sub-clade of viruses defined by amino acid changes within HA: N31D, S162N, A186T and V272I. Phylogenetically, these viruses share a high degree of homology with strains associated with recent fatal cases in Chihuahua, Mexico.

Discussion

Previously, enhanced virulence associated with the change, D222G, has been clinically linked to severe morbidity and mortality. Initial observations of the prevalence of a novel sub-clade of strains in the Americas suggest that viruses with a re-emergent D222N mutation may too correlate with severe clinical manifestations. These findings warrant heightened vigilance for emerging sub-clades of 2009 A(H1N1) and presumptive clinical implications.     

A recurrent CHEK2 p.H371Y mutation is associated with breast cancer risk in Chinese women

The association between the CHEK2 and breast cancer risk in Chinese women is unknown. Here, we screened the full CHEK2 coding sequence in 118 Chinese familial breast cancer cases who are negative for mutations in BRCA1 and BRCA2, one recurrent mutation, CHEK2 c.1111C>T (p.H371Y), was identified in five index cases in this cohort. Functional analysis suggested that CHEK2 p.H371Y was a pathogenic mutation that resulted in decreased kinase activity. We further screened the CHEK2 p.H371Y mutation in 909 unselected breast cancer cases and 1,228 healthy individuals. The frequencies of the CHEK2 p.H371Y in familial and unselected breast cancer cases and controls were 4.24% (5/118), 1.76% (16/909), and 0.73% (9/1228), respectively. The p.H371Y mutation was significantly associated with increased breast cancer risk in unselected breast cancer (odds ratio [OR] 2.43, 95% confidence interval [CI] 1.07–5.52, P = 0.034). Our results indicate that the recurrent mutation, p.H371Y, confers a moderate risk of breast cancer in Chinese women. Hum Mutat 32:1–4, 2011. © 2011 Wiley‐Liss, Inc.     

Direct isolation of H1N2 recombinant virus from a throat swab of a patient simultaneously infected with H1N1 and H3N2 influenza A viruses

Two H1N2 recombinant viruses were isolated by a plaquing method from a throat swab of a patient who was simultaneously infected with H1N1 and H3N2 influenza viruses during the Tokyo epidemic of 1981. This is the first direct evidence that recombination of influenza viruses occurred in the human body.     

A cystic fibrosis patient homozygous for the new frameshift mutation 936delTA: description and clinical data.

We report the identification of a new frameshift mutation (936delTA) in exon 6b of the CFTR gene. In the screening of 486 unrelated Spanish CF patients we found a patient homozygous for 936delTA (with consanguineous parents) and a patient heterozygous for delta F508 and 936delTA. Genotype-phenotype correlation studies showed that 936delTA is associated with pancreatic insufficiency and chronic pulmonary colonisation.     

A new missense mutation of fibrillin in a patient with Marfan syndrome.

A patient with Marfan syndrome was shown to be heterozygous for a G to A transition at nucleotide 3952 of the FBNI gene. This would result in a cysteine to tyrosine substitution at amino acid 1223 in the fibrillin protein.     

Gastrointestinal stromal tumours and their response to treatment with the tyrosine kinase inhibitor imatinib

Gastrointestinal stromal tumours (GISTs), the most common mesenchymal tumours of the digestive tract, are largely resistant to chemo- and radiotherapy. They are currently defined by their overexpression of the KIT receptor tyrosine kinase (CD117), a member of the family of receptor tyrosine kinases (RTKs), and exhibit KIT mutations in more than 85% of cases. Additionally, in more than one-third of KIT wild-type GISTs, mutations of platelet-derived growth factor receptor (PDGF-R), which also belongs to the family of RTKs, were recently found. Since these data indicate that uncontrolled RTK signalling may be implicated in the pathogenesis of GISTs, RTKs and the activated downstream signalling cascades are attractive targets in the therapy of these tumours. Imatinib is a small-molecule inhibitor that selectively blocks the activity of the PDGF-R, ABL and KIT receptor tyrosine kinases by competitive binding to the adenosine triphosphate binding site of their catalytic domains. We herein review the molecular pathological, preclinical and clinical data that identify imatinib as a valuable new agent in the treatment of GISTs.Dedicated to Professor Dr. Dr. h.c. H.F. Otto on the occasion of his 65th birthday.     

A response to P.H. Duesberg with reference to an idiotypic network model of AIDS immunopathogenesis

Professors in British Columbia, Canada have devised an autoimmunity model of AIDS (MIAMI model) based on an atypical network theory of regulation of the immune system. It presents different stimuli as cofactors for AIDS: allogenic stimuli in some risk groups and MHC mimicking antigenic stimuli in other risk groups. V regions are on helper T cells that are somewhat anti-self class II MCH. Helper T cell idiotypes interact with both class II MHC and particular suppressor T cell idiotypes, therefore both may be similar. In fact, foreign lymphocytes also can induce an immune response similar to that of MHC image (MI). Hence the MI response is against the anti-self MHC, i.e., foreign idiotypes identify self, particularly self MHC. Further, the HIV envelope protein (gp120) binds to CD4 at a site that overlaps the site where CD4 interacts with class II MHC. Thus recombinant gp120 well as antibodies that recognize the gp120 undying site of CD4 can prevent the interaction of CD4 with class II MHC. Some mutations of CD4 effect the gp120 binding site but not the class II binding site and vice versa and others effect both. This similarity and others HIV can be considered an image of class II MHC, and the anti HIV immune response may be anti MHC image (AMI). MI and AMI responses are against each other and against idiotypic determinants expressed on helper and suppressor T cells respectively. A dual attack on the idiotypes of helper and suppressor T cells accompany these responses thereby causing an imminent collapse of the entire immune system. The model's significant predictive power thereby suggests that we may be able to prevent HIV from causing AIDS by inducing immunological tolerance to HIV components that resemble MHC molecules. This model rejects the 11 paradoxes identified by Duesberg who surmises that HIV is not a cofactor or cause of AIDS.