Dual role of interleukin-17 in pannus growth and osteoclastogenesis in rheumatoid arthritis

Introduction  

In a murine model, interleukin (IL)-17 plays a critical role in the pathogenesis of arthritis. There are controversies, however, regarding whether IL-17 is a proinflammatory mediator in rheumatoid arthritis (RA). We previously established an ex vivo cellular model using synovial tissue (ST)-derived inflammatory cells, which reproduced pannus-like tissue growth and osteoclastic activity in vitro. Using this model, we investigated the effects of IL-17 on pannus growth and osteoclastogenesis in RA.     

Crystallographic studies of V44 mutants of Clostridium pasteurianum rubredoxin: effects of side-chain size on reduction potential

Understanding the structural origins of differences in reduction potentials is crucial to understanding how various electron transfer proteins modulate their reduction potentials and how they evolve for diverse functional roles. Here, the high-resolution structures of several Clostridium pasteurianum rubredoxin (Cp Rd) variants with changes in the vicinity of the redox site are reported in order to increase this understanding. Our crystal structures of [V44L] (at 1.8 A resolution), [V44A] (1.6 A), [V44G] (2.0 A) and [V44A, G45P] (1.5 A) Rd (all in their oxidized states) show that there is a gradual decrease in the distance between Fe and the amide nitrogen of residue 44 upon reduction in the size of the side chain of residue 44; the decrease occurs from leucine to valine, alanine or glycine and is accompanied by a gradual increase in their reduction potentials. Mutation of Cp Rd at position 44 also changes the hydrogen-bond distance between the amide nitrogen of residue 44 and the sulfur of cysteine 42 in a size-dependent manner. Our results suggest that residue 44 is an important determinant of Rd reduction potential in a manner dictated by side-chain size. Along with the electric dipole moment of the 43-44 peptide bond and the 44-42 NH--S type hydrogen bond, a modulation mechanism for solvent accessibility through residue 41 might regulate the redox reaction of the Rds.     

Quantitation using a stable isotope dilution assay (SIDA) and thresholds of taste-active pyroglutamyl decapeptide ethyl esters (PGDPEs) in sake

A stable isotope dilution assay (SIDA) for two taste-active pyroglutamyl decapeptide ethyl esters (PGDPE1; (pGlu)LFGPNVNPWCOOC₂H₅, PGDPE2; (pGlu)LFNPSTNPWCOOC₂H₅) in sake was developed using deuterated isotopes and high-resolution mass spectrometry. Recognition thresholds of PGDPEs in sake were estimated as 3.8 μg/L for PGDPE1 and 8.1 μg/L for PGDPE2, evaluated using 11 student panelists aged in their twenties. Quantitated concentrations in 18 commercial sake samples ranged from 0 to 27 μg/L for PGDPE1 and from 0 to 202 μg/L for PGDPE2. The maximum levels of PGDPE1 and PGDPE2 in the sake samples were approximately 8 and 25 times higher than the estimated recognition thresholds, respectively. The results indicated that PGDPEs may play significant sensory roles in the sake. The level of PGDPEs in unpasteurized sake samples decreased during storage for 50 days at 6 °C, suggesting PGDPEs may be enzymatically decomposed.     

A familial case of visceral toxocariasis due to consumption of raw bovine liver

We present 3 adult cases of visceral toxocariasis from the same family, who each consumed thin slices of raw bovine liver weekly, and developed eosinophilia and multiple small lesions in their livers and lungs. Serological examinations using the larval excretory–secretory product of Toxocara canis strongly indicated infection with Toxocara species larvae. The patients responded well to treatment with albendazole. Ingestion of raw liver from paratenic animals is considered to be a common transmission route of human toxocariasis, especially in adults.     

Notes on some plant-inhabiting fungi collected from the Nansei Islands (3)*

In this paper, four plant-inhabiting fungi newly collected from the Nansei Islands, Japan, are reported. Among them, Phaeodiscula tremae Sawada from Tokunoshima Island was transferred to the genus Capnodiastrum and given a new name C. sawadae, because in the genus Capnodiastrum, the specific epithet tremae has already been used for the different South American species. Nyssopsora formosana on Koelreuteria formosana and Pestalotiopsis fici on Ardisia quinquegona collected in Okinawa Main Island and Pseudocercospora acaciae-confusae on Acacia confusa collected in Okinoerabu Island were newly recorded from Japan.     

Fatigue and tensile properties of radicular dentin substrate

The purpose of this study was to compare the fatigue and tensile strengths of radicular dentin. Forty bovine lower central incisors were used, twenty teeth for the fatigue test and twenty teeth for the tensile test. Bovine teeth were each sectioned into coronal and radicular portions. Dentin slabs of 1mm thickness were prepared along the radicular tooth using a low-speed cutting machine and trimmed into dumbbell-shaped specimens. A dentin slab was harvested from each tooth. Subsequently, fatigue and tensile tests were performed in Hank's balanced saline solution at 37 °C. The staircase method was employed to determine fatigue strength and its standard deviation. Fracture surfaces were observed by scanning electron microscopy. Mean fatigue strength and tensile strength were 44.3±5.0 and 84.4±8.3 MPa, respectively. The fatigue strength of radicular dentin was significantly lower than the tensile strength. The fatigue strength of radicular dentin was only approximately one half of the tensile strength.     

Neutralization of leukotriene C4 and D4 activity by monoclonal and single-chain antibodies

Background

Cysteinyl leukotrienes (LTs) are key mediators in inflammation. To explore the structure of the antigen-recognition site of a monoclonal antibody against LTC₄ (mAbLTC), we previously isolated full-length cDNAs for heavy and light chains of the antibody and prepared a single-chain antibody comprising variable regions of these two chains (scFvLTC).

Methods

We examined whether mAbLTC and scFvLTC neutralized the biological activities of LTC₄ and LTD₄ by competing their binding to their receptors.

Results

mAbLTC and scFvLTC inhibited their binding of LTC₄ or LTD₄ to CysLT₁ receptor (CysLT₁R) and CysLT₂ receptor (CysLT₂R) overexpressed in Chinese hamster ovary cells. The induction by LTD₄ of monocyte chemoattractant protein-1 and interleukin-8 mRNAs in human monocytic leukemia THP-1 cells expressing CysLT₁R was dose-dependently suppressed not only by mAbLTC but also by scFvLTC. LTC₄- and LTD₄-induced aggregation of mouse platelets expressing CysLT₂R was dose-dependently suppressed by either mAbLTC or scFvLTC. Administration of mAbLTC reduced pulmonary eosinophil infiltration and goblet cell hyperplasia observed in a murine model of asthma. Furthermore, mAbLTC bound to CysLT₂R antagonists but not to CysLT₁R antagonists.

Conclusions

These results indicate that mAbLTC and scFvLTC neutralize the biological activities of LTs by competing their binding to CysLT₁R and CysLT₂R. Furthermore, the binding of cysteinyl LT receptor antagonists to mAbLTC suggests the structural resemblance of the LT-recognition site of the antibody to that of these receptors.

General significance

mAbLTC can be used in the treatment of inflammatory diseases such as asthma.     

Oral adsorbent AST-120 decreases serum levels of AGEs in patients with chronic renal failure

Advanced glycation end products (AGEs) are senescent macroprotein derivatives that are formed at an accelerated rate in patients with chronic renal failure (CRF). AGE formation and accumulation in plasma and vascular tissues contribute to accelerated atherosclerosis in this devastating disorder. AST-120 is an oral adsorbent that attenuates the progression of CRF by removing uremic toxins. Recently, AST-120 has been reported to reduce the progression of atherosclerosis as well. However, whether AST-120 decreases serum levels of AGEs and subsequently exerts atheroprotective properties remains to be elucidated. Ten nondiabetic CRF patients were enrolled in this study. All patients were kept on regular therapeutic diet and medications throughout the study. Serum AGE levels before and after AST-120 treatments were measured using enzyme-linked immunosorbent assay. Effects of patient-derived serum on atherosclerosis-related gene expression in cultured human umbilical vein endothelial cells (HUVECs) were analyzed by semiquantitative RT-PCR. Administration of AST-120 (6 g/day) for 3 months significantly decreased serum levels of AGEs in nondiabetic CRF patients, whereas AGE levels remained unchanged in age- and renal function-matched CRF patients without AST-120 treatment (n = 6). Patient serum after AST-120 treatment significantly reduced mRNA levels of receptor for AGEs, monocyte chemoattractant protein-1, and vascular adhesion molecule-1 in HUVECs compared with serum before treatment. Moreover, in vitro, AST-120 was found to adsorb carboxymethyllysine (CML), one of the well-characterized, digested food-derived AGEs. This study suggests that atheroprotective properties of AST-120 can be ascribed, at least in part, to its AGE-lowering ability via absorption of CML.     

Starch Gelatinization at Different Temperatures as Measured by Enzymic Digestion Method

The gelatinization process of potato starch was isothermally investigated at 52.5∽65.3°C. The degree of gelatinization was measured by an enzymic digestion method using glucoamylase. When the starch–water suspension was incubated at a definite temperature the gelatinization reached a limit at each temperature after 30∽60 min incubation. So, it can be supposed that starch gelatinization reached an equilibrium state. It was found that gelatinization of potato starch occurred even at 52.5°C, a temperature which is lower than the so-called gelatinization temperature generally reported. Starch gelatinization was found to follow first order kinetics, and from the temperature dependence of the rate constants obtained, the activation energy was calculated to be 22±5 kcal/mol. The relationship between the degree of gelatinization of the starch whose gelatinization reached an equilibrium state at a definite temperature and the incubation temperature gave a transition curve expressed, by the fraction of gelatinized potato starch granules as a function of temperature, and the half-transition temperature was found to be 59.1°C. From the transition curve.the van’t Hoff enthalpy for gelatinization was determined to be +130±3 kcal/mol.     

The unique hydrogen bonded water in the reduced form of<Emphasis Type="Italic"> Clostridium pasteurianum</Emphasis> rubredoxin and its possible role in electron transfer

Rubredoxin is a small iron-sulfur (FeS₄) protein involved in oxidation–reduction reactions. The side chain of Leu41 near the iron-sulfur center has two conformations, which we suggested previously serve as a gate for a water molecule during the electron transfer process. To establish the role of residue 41 in electron transfer, an [L41A] mutant of Clostridium pasteurianum rubredoxin was constructed and crystallized in both oxidation states. Despite the lack of the gating side chain in this protein, the structure of the reduced [L41A] rubredoxin reveals a specific water molecule in the same position as observed in the reduced wild-type rubredoxin. In contrast, both the wild-type and [L41A] rubredoxins in the oxidized state do not have water molecules in this location. The reduction potential of the [L41A] variant was ~50 mV more positive than wild-type. Based on these observations, it is proposed that the site around the S of Cys9 serves as a port for an electron acceptor. Lastly, the Fe–S distances of the reduced rubredoxin are expanded, while the hydrogen bonds between S of the cysteines and the backbone amide nitrogens are shortened compared to its oxidized counterpart. This small structural perturbation in the Fe(II)/Fe(III) transition is closely related to the small energy difference which is important in an effective electron transfer agent.