The drug efflux pump Pgp1 in pro-inflammatory lymphocytes is a target for novel treatment strategies in COPD

Background

Pro-inflammatory/cytotoxic T cells (IFNγ, TNFα, granzyme B+) are increased in the peripheral circulation in COPD. NKT-like and NK cells are effector lymphocytes that we have also shown to be major sources of pro-inflammatory cytokines and granzymes. P-glycoprotein 1 (Pgp1) is a transmembrane efflux pump well characterised in drug resistant cancer cells. We hypothesized that Pgp1 would be increased in peripheral blood T, NKT-like and NK cells in patients with COPD, and that this would be accompanied by increased expression of IFNγ, TNFα and granzyme B. We further hypothesized that treatment with cyclosporine A, a Pgp1 inhibitor, would render cells more sensitive to treatment with corticosteroids.

Methods

Pgp1, granzyme B, IFNγ and TNFα expression were measured in peripheral blood T, NK and NKT-like cells from COPD patients and control subjects (± cyclosporine A and prednisolone) following in vitro stimulation and results correlated with uptake of efflux dye Calcein-AM using flow cytometry.

Results

There was increased Pgp1 expression by peripheral blood T, NKT-like and NK cells co-expressing IFNγ, TNFα and granzyme B in COPD patients compared with controls (e.g. %IFNγ/Pgp1 T, NKT-like, NK for COPD (Control): 25(6), 54(27), 39(23)). There was an inverse correlation between Pgp1 expression and Calcein-AM uptake. Treatment with 2.5 ng/ml cylosporin A and10^-6 M prednisolone resulted in synergistic inhibition of pro-inflammatory cytokines in Pgp1 + cells (p < 0.05 for all).

Conclusions

Treatment strategies that target Pgp1 in T, NKT-like and NK cells may reduce systemic inflammatory mediators in COPD and improve patient morbidity.     

Infection,inflammation and exercise in cystic fibrosis

Regular exercise is positively associated with health. It has also been suggested to exert anti-inflammatory effects. In healthy subjects, a single exercise session results in immune cell activation, which is characterized by production of immune modulatory peptides (e.g. IL-6, IL-8), a leukocytosis and enhanced immune cell functions. Upon cessation of exercise, immune activation is followed by a tolerizing phase, characterized by a reduced responsiveness of immune cells. Regular exercise of moderate intensity and duration has been shown to exert anti-inflammatory effects and is associated with a reduced disease incidence and viral infection susceptibility. Specific exercise programs may therefore be used to modify the course of chronic inflammatory and infectious diseases such as cystic fibrosis (CF).Patients with CF suffer from severe and chronic pulmonary infections and inflammation, leading to obstructive and restrictive pulmonary disease, exercise intolerance and muscle cachexia. Inflammation is characterized by a hyper-inflammatory phenotype. Patients are encouraged to engage in exercise programs to maintain physical fitness, quality of life, pulmonary function and health.In this review, we present an overview of available literature describing the association between regular exercise, inflammation and infection susceptibility and discuss the implications of these observations for prevention and treatment of inflammation and infection susceptibility in patients with CF.     

Focal DNA Copy Number Changes in Neuroblastoma Target MYCN Regulated Genes

Neuroblastoma is an embryonic tumor arising from immature sympathetic nervous system cells. Recurrent genomic alterations include MYCN and ALK amplification as well as recurrent patterns of gains and losses of whole or large partial chromosome segments. A recent whole genome sequencing effort yielded no frequently recurring mutations in genes other than those affecting ALK. However, the study further stresses the importance of DNA copy number alterations in this disease, in particular for genes implicated in neuritogenesis. Here we provide additional evidence for the importance of focal DNA copy number gains and losses, which are predominantly observed in MYCN amplified tumors. A focal 5 kb gain encompassing the MYCN regulated miR-17∼92 cluster as sole gene was detected in a neuroblastoma cell line and further analyses of the array CGH data set demonstrated enrichment for other MYCN target genes in focal gains and amplifications. Next we applied an integrated genomics analysis to prioritize MYCN down regulated genes mediated by MYCN driven miRNAs within regions of focal heterozygous or homozygous deletion. We identified RGS5, a negative regulator of G-protein signaling implicated in vascular normalization, invasion and metastasis, targeted by a focal homozygous deletion, as a new MYCN target gene, down regulated through MYCN activated miRNAs. In addition, we expand the miR-17∼92 regulatory network controlling TGFß signaling in neuroblastoma with the ring finger protein 11 encoding gene RNF11, which was previously shown to be targeted by the miR-17∼92 member miR-19b. Taken together, our data indicate that focal DNA copy number imbalances in neuroblastoma (1) target genes that are implicated in MYCN signaling, possibly selected to reinforce MYCN oncogene addiction and (2) serve as a resource for identifying new molecular targets for treatment.     

Patterns of Risk of Cancer in Patients with Metal-on-Metal Hip Replacements versus Other Bearing Surface Types: A Record Linkage Study between a Prospective Joint Registry and General Practice Electronic Health Records in England

Background

There are concerns that metal-on-metal hip implants may cause cancer. The objective of this study was to evaluate patterns and timing of risk of cancer in patients with metal-on-metal total hip replacements (THR).

Methods

In a linkage study between the English National Joint Registry (NJR) and the Clinical Practice Research Datalink (CPRD), we selected all THR surgeries (NJR) between 2003 and 2010 (n = 11,540). THR patients were stratified by type of bearing surface. Patients were followed up for cancer and Poisson regression was used to derive adjusted relative rates (RR).

Results

The risk of cancer was similar in patients with hip resurfacing (RR 0.69; 95% Confidence Interval [CI] 0.39–1.22) or other types of bearing surfaces (RR 0.96; 95% CI 0.64–1.43) compared to individuals with stemmed metal-on-metal THR. The pattern of cancer risk over time did not support a detrimental effect of metal hip implants. There was substantial confounding: patients with metal-on-metal THRs used fewer drugs and had less comorbidity.

Conclusions

Metal-on-metal THRs were not associated with an increased risk of cancer. There were substantial baseline differences between the different hip implants, indicating possibility of confounding in the comparisons between different types of THR implants.     

Linear fusigen as the major hydroxamate siderophore of the ectomycorrhizal Basidiomycota Laccaria laccata and Laccaria bicolor

A screening for siderophores produced by the ectomycorrhizal fungi Laccaria laccata and Laccaria bicolor in synthetic low iron medium revealed the release of several different hydroxamate siderophores of which four major siderophores could be identified by high resolution mass spectrometry. While ferricrocin, coprogen and triacetylfusarinine C were assigned as well as other known fungal siderophores, a major peak of the siderophore mixture revealed an average molecular mass of 797 for the iron-loaded compound. High resolution mass spectrometry indicated an absolute mass of m/z = 798.30973 ([M + H]⁺). With a relative error of Δ = 0.56 ppm this corresponds to linear fusigen (C₃₃H₅₂N₆O₁₃Fe; MW = 797.3). The production of large amounts of linear fusigen by these basidiomycetous mycorrhizal fungi may possibly explain the observed suppression of plant pathogenic Fusarium species. For comparative purposes Fusarium roseum was included in this study as a well known producer of cyclic and linear fusigen.     

Fungal siderophore biosynthesis is partially localized in peroxisomes

Siderophores play a central role in iron metabolism and virulence of most fungi. Both Aspergillus fumigatus and Aspergillus nidulans excrete the siderophore triacetylfusarinine C (TAFC) for iron acquisition. In A. fumigatus, green fluorescence protein‐tagging revealed peroxisomal localization of the TAFC biosynthetic enzymes SidI (mevalonyl‐CoA ligase), SidH (mevalonyl‐CoA hydratase) and SidF (anhydromevalonyl‐CoA transferase), while elimination of the peroxisomal targeting signal (PTS) impaired both, peroxisomal SidH‐targeting and TAFC biosynthesis. The analysis of A. nidulans mutants deficient in peroxisomal biogenesis, ATP import or protein import revealed that cytosolic mislocalization of one or two but, interestingly, not all three enzymes impairs TAFC production during iron starvation. The PTS motifs are conserved in fungal orthologues of SidF, SidH and SidI. In agreement with the evolutionary conservation of the partial peroxisomal compartmentalization of fungal siderophore biosynthesis, the SidI orthologue of coprogen‐type siderophore‐producing Neurospora crassa was confirmed to be peroxisomal. Taken together, this study identified and characterized a novel, evolutionary conserved metabolic function of peroxisomes.     

No Fabry Disease in Patients Presenting with Isolated Small Fiber Neuropathy

Objective

Screening for Fabry disease in patients with small fiber neuropathy has been suggested, especially since Fabry disease is potentially treatable. However, the diagnostic yield of testing for Fabry disease in isolated small fiber neuropathy patients has never been systematically investigated. Our aim is to determine the presence of Fabry disease in patients with small fiber neuropathy.

Methods

Patients referred to our institute, who met the criteria for isolated small fiber neuropathy were tested for Fabry disease by measurement of alpha-Galactosidase A activity in blood, lysosomal globotriaosylsphingosine in urine and analysis on possible GLA gene mutations.

Results

725 patients diagnosed with small fiber neuropathy were screened for Fabry disease. No skin abnormalities were seen except for redness of the hands or feet in 30.9% of the patients. Alfa-Galactosidase A activity was tested in all 725 patients and showed diminished activity in eight patients. Lysosomal globotriaosylsphingosine was examined in 509 patients and was normal in all tested individuals. Screening of GLA for mutations was performed for 440 patients, including those with diminished α-Galactosidase A activity. Thirteen patients showed a GLA gene variant. One likely pathogenic variant was found in a female patient. The diagnosis Fabry disease could not be confirmed over time in this patient. Eventually none of the patients were diagnosed with Fabry disease.

Conclusions

In patients with isolated small fiber neuropathy, and no other signs compatible with Fabry disease, the diagnostic yield of testing for Fabry disease is extremely low. Testing for Fabry disease should be considered only in cases with additional characteristics, such as childhood onset, cardiovascular disease, renal failure, or typical skin lesions.