Carboxypeptidase A3 expression in canine mast cell tumors and tissue-resident mast cells

Mast cell tumors (MCTs) are one of the most common cutaneous malignancies in dogs. Previous studies have reported expression of mast cell–specific proteases chymase and tryptase in canine cutaneous MCTs and in connective tissue and mucosal mast cells. In humans and rodents, mast cells express an additional specific protease, carboxypeptidase A3 (CPA3). In this article, we describe CPA3 immunoreactivity in connective tissue, visceral, mucosal, and neoplastic mast cells in dogs. Positive immunolabeling for CPA3 was observed in nonneoplastic mast cells in 20/20 formalin-fixed paraffin-embedded normal tissues (skin, liver, spleen, intestine), and in 63/63 MCTs irrespective of their histological grade. CPA3 protein expression was comparable to that of c-kit in both the nonneoplastic and neoplastic mast cells. Three distinct labeling patterns (membranous, diffuse, and focal cytoplasmic) were observed for CPA3 in MCTs. The focal cytoplasmic labeling pattern was associated with high-grade MCTs staged with the Kiupel 2-tier grading criteria. We propose CPA3 as a novel immunohistochemical marker for canine mast cells in health and disease.

Myeloid cell expressed proprotein convertase FURIN attenuates inflammation

The proprotein convertase enzyme FURIN processes immature pro-proteins into functional end- products. FURIN is upregulated in activated immune cells and it regulates T-cell dependent peripheral tolerance and the Th1/Th2 balance. FURIN also promotes the infectivity of pathogens by activating bacterial toxins and by processing viral proteins. Here, we evaluated the role of FURIN in LysM+ myeloid cells in vivo. Mice with a conditional deletion of FURIN in their myeloid cells (LysMCre-fur^(fl/fl)) were healthy and showed unchanged proportions of neutrophils and macrophages. Instead, LysMCre-fur^(fl/fl) mice had elevated serum IL-1β levels and reduced numbers of splenocytes. An LPS injection resulted in accelerated mortality, elevated serum pro-inflammatory cytokines and upregulated numbers of pro-inflammatory macrophages. A genome-wide gene expression analysis revealed the overexpression of several pro-inflammatory genes in resting FURIN-deficient macrophages. Moreover, FURIN inhibited Nos2 and promoted the expression of Arg1, which implies that FURIN regulates the M1/M2-type macrophage balance. FURIN was required for the normal production of the bioactive TGF-β1 cytokine, but it inhibited the maturation of the inflammation-provoking TACE and Caspase-1 enzymes. In conclusion, FURIN has an anti-inflammatory function in LysM+ myeloid cells in vivo.

Adipokine genes and radiographic hand osteoarthritis in Finnish women: a cross-sectional study

OBJECTIVES

Available evidence suggests that genetic factors and overweight play major roles in the aetiology of osteoarthritis (OA). We analysed the association of 18 single-nucleotide polymorphisms (SNPs) from nine adipokine and adipokine receptor genes (LEP, LEPR, ADIPOQ, RETN, NAMPT, SERPINA12, ITLN1, RARRES2, and APLN) with radiographic hand OA.

METHOD

The study design was cross-sectional. Bilateral hand radiographs of 542 occupationally active Finnish female dentists and teachers aged 45-63 years were examined and classified for the presence of hand OA using reference images. Hand OA was defined as at least three finger joints with radiographic OA of grade 2-4. The genotypes were determined using polymerase chain reaction-based methods. Body mass index (BMI) was calculated based on self-reported height and measured weight. Associations of the individual SNPs and their haplotypes with hand OA were tested using logistic regression analysis.

RESULTS

The minor allele of RETN rs10401670 was associated with a decreased [odds ratio (OR) = 0.73, 95% confidence interval (CI) 0.55-0.97, p = 0.03] and RARRES2 rs4721 with an increased (OR 1.41, 95% CI 1.07-1.87, p = 0.01) prevalence of hand OA. Also, LEPR AC (OR 1.54, 95% CI 1.01-2.35, p = 0.05) and RETN GGTT (OR 0.58, 95% CI 0.37-0.93, p = 0.02) haplotypes were associated with hand OA. These associations were modified by BMI when comparing normal and overweight women. However, the associations lost their statistical significance after adjusting for multiple testing.

CONCLUSION

Our results suggest weak associations between the studied variations in LEPR, RARRES2, and RETN genes and hand OA in Finnish women, and that the associations are modified by BMI. However, these associations could not be verified in the current study.

IL-7Rα Expression Regulates Murine Dendritic Cell Sensitivity to Thymic Stromal Lymphopoietin

Thymic stromal lymphopoietin (TSLP) and IL-7 are related cytokines that mediate growth and differentiation events in the immune system. They signal through IL-7Rα-containing receptors. Target cells of TSLP in Th2 responses include CD4 T cells and dendritic cells (DCs). Although it has been reported that expression of TSLP receptor (TSLPR) on CD4 T cells is required for OVA-induced lung inflammation, DCs have also been shown to be target cells of TSLP. In this study, we show that murine ex vivo splenic DCs are unresponsive to TSLP, as they fail to phosphorylate STAT5, but in vitro overnight culture, especially in presence of IL-4, renders DCs responsive to both TSLP and IL-7. This induced responsiveness is accompanied by dramatic upregulation of IL-7Rα on DCs with little change in expression of TSLPR or of γ_c In splenic DCs, the induction of IL-7Rα occurs mainly in CD8^- DCs. In vivo, we found that IL-4 has a differential regulatory role on expression of IL-7Rα depending on the cell type; IL-4 decreases IL-7Rα expression on CD4 T cells whereas it upregulates the expression on DCs. Our results indicate that the induction of IL-7Rα expression on DCs is critical for TSLP responsiveness and that IL-4 can upregulate IL-7Rα on DCs.

The Plasma Level of Proprotein Convertase FURIN in Patients with Suspected Infection in the Emergency Room: A Prospective Cohort Study

There is an increasing need for novel biomarkers that enable better diagnostic and prognostic stratification of patients with suspected infection. A proprotein convertase enzyme FURIN is upregulated upon immune cell activation, and it promotes infectivity by cleaving and activating pathogens. In this study, we determined FURIN levels in plasma using ELISA from 537 patients that were admitted to emergency room with suspected infection. Patients were sorted to high- and low-level FURIN groups with a cut-off level of 370 pg/ml. The study cohort included five diagnostic groups: Group 1, no systemic inflammatory response syndrome (SIRS, n = 59 patients); Group 2, bacterial infection without SIRS (n = 67); Group 3, SIRS, but no bacterial infection (n = 308); Group 4, sepsis without organ failure (n = 308); and Group 5, severe sepsis (n = 49). Statistically significant associations were not found between the plasma level of FURIN and the prevalence of sepsis (P = 0.957), diagnostic group of a patient (P = 0.737) or the bacteria in blood culture (P = 0.499). Additionally, the concentration of FURIN did not predict the severity or case fatality of the infectious disease. However, statistically significant associations were found between high plasma level of FURIN and diagnosed rheumatic disease (P < 0.001) as well as with the prevalence of non-smokers (P = 0.034). Thus, albeit the plasma level of FURIN does not predict the severity of infectious disease, it may be of use in the diagnostics of autoimmune diseases.

Relapsing sepsis episodes of Escherichia coli with CTX-M ESBL or derepressed ampC genes in a patient with chronic autoimmune pancreatitis complicated by IgG4 hypergammaglobulinaemia

Bloodstream recurrent infections have been reported for a variety of opportunistic bacteria. These are often either catheter related or are caused by indwelling devices. A case of relapsing sepsis with two Escherichia coli strains carrying extended-spectrum β-lactamase and derepressed ampC genes is reported. The patient had seven episodes of bloodstream infections within 1 year and was diagnosed with chronic autoimmune pancreatitis and IgG4 hypergammaglobulinaemia. Abscesses were found in his spleen and pancreas cauda, which was finally resected. Relapses of bacteraemia with resistant enterobacteria should be considered during perioperative protection. Surgical removal of the infective focus could be curative.

Proprotein convertase FURIN constrains Th2 differentiation and is critical for host resistance against Toxoplasma gondii

The proprotein convertase subtilisin/kexin enzymes proteolytically convert immature proproteins into bioactive molecules, and thereby they serve as key regulators of cellular homeostasis. The archetype proprotein convertase subtilisin/kexin, FURIN, is a direct target gene of the IL-12/STAT4 pathway and it is upregulated in Th1 cells. We have previously demonstrated that FURIN expression in T cells critically regulates the maintenance of peripheral immune tolerance and the functional maturation of pro-TGF-β1 in vivo, but FURIN's role in cell-mediated immunity and Th polarization has remained elusive. In this article, we show that T cell-expressed FURIN is essential for host resistance against a prototypic Th1 pathogen, Toxoplasma gondii, and for the generation of pathogen-specific Th1 lymphocytes, including Th1-IL-10 cells. FURIN-deficient Th cells instead show elevated expression of IL-4R subunit α on cell surface, sensitized IL-4/STAT6 signaling, and a propensity to polarize toward the Th2 phenotype. By exploring FURIN-interacting proteins in Jurkat T cells with Strep-Tag purification and mass spectrometry, we further identify an association with a cytoskeleton modifying Ras-related C3 botulinum toxin substrate/dedicator of cytokinesis 2 protein complex and unravel that FURIN promotes F-actin polymerization, which has previously been shown to downregulate IL-4R subunit α cell surface expression and promote Th1 responses. In conclusion, our results demonstrate that in addition to peripheral immune tolerance, T cell-expressed FURIN is also a central regulator of cell-mediated immunity and Th1/2 cell balance.

Coxsackievirus B1 reveals strain specific differences in plasmacytoid dendritic cell mediated immunogenicity

Enterovirus infections are usually mild but can also cause severe illnesses and play a role in chronic diseases, such as cardiomyopathies and type 1 diabetes. Host response to the invading virus can markedly modulate the course of the infection, and this response varies between individuals due to the polymorphism of immune response genes. However, it is currently not known if virus strains also differ in their ability to stimulate the host immune system. Coxsackievirus B1 (CBV1) causes severe epidemics in young infants and it has recently been connected with type 1 diabetes in seroepidemiological studies. This study evaluated the ability of different field isolates of CBV1 to induce innate immune responses in PBMCs. CBV1 strains differed markedly in their capacity to induce innate immune responses. Out of the 18 tested CBV1 strains two induced exceptionally strong alpha interferon (IFN-α) response in PBMC cultures. The responding cell type was found to be the plasmacytoid dendritic cell. Such a strong innate immune response was accompanied by an up-regulation of several other immune response genes and secretion of cytokines, which modulate inflammation, and adaptive immune responses. These results suggest that enterovirus-induced immune activation depends on the virus strain. It is possible that the immunotype of the virus modulates the course of the infection and plays a role in the pathogenesis of chronic immune-mediated enterovirus diseases.

Genetic susceptibility to asbestos-related fibrotic pleuropulmonary changes

The objective of this study was to determine whether genetic polymorphisms in enzymes that metabolise oxidative agents modify the individual susceptibility to developing asbestos and smoking-related pleuropulmonary changes. Nine polymorphisms of six genes (EPHX1, GSTM1, GSTM3, GSTP1, GSTT1 and NAT2) were genotyped from 1,008 Finnish asbestos-exposed workers. The genotype data were compared to signs of lung fibrosis and pleural thickenings, as well as with total lung capacity, single-breath diffusing capacity of the lung for carbon monoxide (D(L,CO)) and specific diffusing capacity (expressed as D(L,CO) per unit of alveolar volume (V(A))). The GSTT1 deletion polymorphism was associated with fibrotic changes (p=0.003), and decreased D(L,CO) (p=0.02) and D(L,CO)/V(A) (p=0.002), and the GSTM1 deletion polymorphism was associated with the greatest thickness of pleural plaques (p=0.009). On further analysis, the GSTT1 null genotype was found to pose over a three-fold risk for severe fibrotic changes (OR 3.12, 95% CI 1.51-6.43), and around two-fold risks for decreased D(L,CO) (OR 1.77, 95% CI 1.06-2.95) and D(L,CO)/V(A) (OR 2.37, 95% CI 1.33-4.23). In addition, the GSTM1 null genotype showed an elevated risk (OR 1.36, 95% CI 1.03-1.80) for thicker pleural plaques. Our data suggest that inherited detoxification capacity may affect the development and severity of asbestos and smoking-related nonmalignant pulmonary changes.

Glutamine: fructose-6-phosphate amidotransferase activity and gene expression are regulated in a tissue-specific fashion in pregnant rats

We examined whether regulation of glutamine: fructose-6-phosphate amidotransferase (GFA), the rate-limiting enzyme of the hexosamine pathway, is tissue specific and if so whether such regulation occurs at the level of gene expression. We compared GFA activity and expression and levels of UDP-hexosamines and UDP-hexoses between insulin-sensitive (liver and muscle) tissues and a glucose-sensitive (placenta) tissue from 19 day pregnant streptozotocin diabetic and non-diabetic rats. In pregnant non-diabetic rats GFA activities averaged (1521+/-75 pmol/mg protein x min) in the placenta, 895+/-74 in the liver and 81+/-11 in muscle (p<0.001 between each tissue). In the diabetic rats, GFA activities were approximately 50% decreased both in the liver (340+/-42 pmol/mg protein x min, p<0.05 vs control rats) and in skeletal muscle (46+/-3, p<0.05) compared to control rats. In the placenta, GFA activities were identical between diabetic (1519+/-112 pmol/mg protein x min) and non-diabetic (1521+/-75) animals. In the liver, the reduction in GFA activity could be attributed to a significant decrease in GFA mRNA concentrations, while GFA mRNA concentrations were similar in the placenta between diabetic and non-diabetic animals. UDP-N-acetylglucosamine (UDP-GlcNAc), the end product of the hexosamine pathway, was significantly reduced in the liver and in skeletal muscle but similar in the placenta between diabetic and non-diabetic rats. In summary, GFA activity and expression and the concentration of UDP-GlcNAc are decreased in the liver but unaltered in the placenta, although GFA activity is almost 2-fold higher in this tissue than in the liver. These data provide the first evidence for tissue specific regulation of GFA and for its regulation at the level of gene expression.

Incorporation of [3-3H]glucose and 2-[1-14C]deoxyglucose into glycogen in heart and skeletal muscle in vivo: implications for the quantitation of tissue glucose uptake

2-deoxyglucose has been widely used to quantitate tissue glucose uptake in vivo, assuming that 2-deoxyglucose is transported and phosphorylated but not further metabolized. We examined the validity of this assumption by infusing [3-3H]glucose and 2-[1-14C]deoxyglucose in a similar primed continuous fashion to chronically catheterized, freely moving rats during normoglycemic hyperinsulinemic conditions. The rates of 2-deoxyglucose uptake were determined from the accumulation of 2-[1-14C]deoxyglucose-6-phosphate and 2-[1-14C]deoxyglucose-6-phosphate combined with the rate of the incorporation of 2-[1-14C]deoxyglucose into glycogen in rectus abdominis muscle and the heart. When the rates of glycogen synthesis during the 2-h hyperinsulinemic period from the two tracers were compared in rectus abdominis muscle, the rate of glycogen synthesis was twofold higher when measured with [3-3H]glucose (337 +/- 14 micromol x kg(-1) x min(-1)) than when measured with 2-[1-14C]deoxyglucose (166 +/- 10 micromol x kg(-1) x min(-1), P < 0.001). In the heart, the rate of glycogen synthesis was twofold higher when measured with 2-[1-14C]deoxyglucose (141 +/- 20 micromol x kg(-1) x min(-1)) than when measured with [3-3H]glucose (72 +/- 15 micromol x kg(-1) x min(-1), P < 0.001). The rate of 2-deoxyglucose uptake was 29% underestimated in rectus abdominis muscle, when counts found in glycogen were not included in glucose uptake calculations (398 +/- 25 vs. 564 +/- 25 micromol x kg(-1) x min(-1), P < 0.001). In the heart, glucose uptake was underestimated by 7% if glycogen counts were not taken into account (1,786 +/- 278 vs. 1,926 +/- 291 micromol x kg(-1) dry x min(-1), P < 0.05). The fraction of [3-3H]glucose incorporated into glycogen of total glucose metabolism (calculated from 2-deoxyglucose conversion to 2-deoxyglucose-6-phosphate and glycogen) was 0.6 (337/564) in rectus abdominis muscle and 0.037 (72/1,926) in the heart. We conclude that 2-deoxyglucose is incorporated into glycogen in the heart and in skeletal muscle in vivo under normoglycemic hyperinsulinemic conditions in the rat. Failure to consider the incorporation of 2-deoxyglucose into glycogen will underestimate the rate of tissue glucose uptake. To avoid such problems, the amount of 2-deoxyglucose incorporated into glycogen should be quantitated in subsequent studies.

Activation of the hexosamine pathway by glucosamine in vivo induces insulin resistance in multiple insulin sensitive tissues

We determined the effect of infusion of glucosamine (GlcN), which bypasses the rate limiting reaction in the hexosamine pathway, on insulin-stimulated rates of glucose uptake and glycogen synthesis in vivo in rat tissues varying with respect to their glutamine:fructose-6-phosphate amidotransferase (GFA) activity. Three groups of conscious fasted rats received 6-h infusions of either saline (BAS), insulin (18 mU/kg x min) and saline (INS), or insulin and GlcN (30 micromol/ kg x min, GLCN). [3-(3)H]glucose was infused to trace whole body glucose kinetics and glycogen synthesis, and rates of tissue glucose uptake were determined using a bolus injection of [1-(14)C]2-deoxyglucose at 315 min. GlcN decreased insulin-stimulated glucose uptake (315-360 min) by 49% (P < 0.001) at the level of the whole body, and by 31-53% (P < 0.05 or less) in the heart, epididymal fat, submandibular gland and in soleus, abdominis and gastrocnemius muscles. GlcN completely abolished glycogen synthesis in the liver. GlcN decreased insulin-stimulated glucose uptake similarly in the submandibular gland (1.3 +/- 0.2 vs. 2.0 +/- 0.3 nmol/mg protein x min, GLCN vs. INS, P < 0.05) and gastrocnemius muscle (1.4 +/- 0.3 vs. 3.1 +/- 0.5 nmol/mg protein x min), although the activity of the hexosamine pathway, as judged from basal GFA activity, was 10-fold higher in the submandibular gland (286 +/- 35 pmol/mg protein x min) than in gastrocnemius muscle (27 +/- 3 pmol/mg protein x min, P < 0.001). These data raise the possibility that overactivity of the hexosamine pathway may contribute to glucose toxicity not only in skeletal muscle but also in other insulin sensitive tissues. They also imply that the magnitude of insulin resistance induced between tissues is determined by factors other than GFA.