Cumulative Incidence and Predictors of Progression in Corticosteroid-Na?ve Patients with Sarcoidosis

Background

Assessment of the clinical course of sarcoidosis requires long-term observation. However, the appropriate period of follow-up for sarcoidosis remains unclear, especially in patients without indication of corticosteroid therapy at the time of diagnosis.

Objective

This study aimed to clarify the cumulative incidence and identify risk factors for disease progression in corticosteroid-naïve sarcoidosis patients.

Methods

The clinical courses of 150 Japanese patients with sarcoidosis, who were followed for more than 2 years and had no indication for corticosteroid therapy at diagnosis, were retrospectively reviewed. Disease progression was defined as worsening of pulmonary sarcoidosis, development of new organ involvement, or extrapulmonary organ damage. The cumulative incidence of progression was estimated by generating a cumulative incidence curve with the Fine and Gray method.

Results

The median follow-up duration was 7.7 years (interquartile range, 4.7–13.6 years). Thirty-two (21%) patients experienced disease progression. New organ involvement appeared in 16 patients (11%). The 6-month, and 1-, 5-, 10-, and 15-year cumulative incidence of progression was 2%, 5%, 15%, 28%, and 31%, respectively. The number of organs involved at diagnosis was an independent predictor for progression with a multifactorial adjusted hazard ratio of 1.71 (95% confidence interval, 1.11–2.62). The optimal cut-off of the number of organs involved at diagnosis to identify future progression was three.

Conclusions

In corticosteroid-naïve sarcoidosis patients, the risks of disease progression are comparable from 0–5 years and 5–10 years after diagnosis. The number of organs involved at diagnosis is a useful predictor for progression of sarcoidosis.     

Hepatitis E Virus in Cambodia: Prevalence among the General Population and Complete Genome Sequence of Genotype 4

Hepatitis E virus (HEV) is a growing public health problem in many countries. In this study, we investigated HEV seroprevalence among the general population in the Siem Reap province, Cambodia, and performed HEV genetic analysis with the aim to develop an HEV prevention strategy. This seroepidemiological cross-sectional study conducted from 2010 to 2014 included 868 participants from four different locations in Siem Reap province, Cambodia. They answered questionnaires and provided blood samples for the analysis of hepatitis virus infections. Among the participants (360 men and 508 women; age range, 7–90 years), the prevalence of anti-HEV IgG was 18.4% (95% confidence interval: 15.9–21.0); HEV RNA was detected in two participants (0.23%) and was classified as genotype 3 and 4. Full-length genome of the genotype 4 isolate, CVS-Sie10, was sequenced; it contained 7,222 nucleotides and three ORFs and demonstrated high sequence identity with the swine China isolates swGX40 (95.57%), SS19 (94.37%), and swDQ (91.94%). Multivariate logistic regression analysis revealed that men, elderly people, and house workers were risk groups significantly associated with the positivity for anti-HEV IgG. This is the first report on the detection of HEV genotype 4 in humans in Cambodia and on the complete genome sequence of HEV genotype 4 from this country. Our study demonstrates that new HEV infection cases occur frequently among the general population in Cambodia, and effective preventive measures are required.     

Roles of mitochondrial fragmentation and reactive oxygen species in mitochondrial dysfunction and myocardial insulin resistance

Purpose

Evidence suggests an association between aberrant mitochondrial dynamics and cardiac diseases. Because myocardial metabolic deficiency caused by insulin resistance plays a crucial role in heart disease, we investigated the role of dynamin-related protein-1 (DRP1; a mitochondrial fission protein) in the pathogenesis of myocardial insulin resistance.

Methods and Results

DRP1-expressing H9c2 myocytes, which had fragmented mitochondria with mitochondrial membrane potential (ΔΨ_m) depolarization, exhibited attenuated insulin signaling and 2-deoxy-d-glucose (2-DG) uptake, indicating insulin resistance. Treatment of the DRP1-expressing myocytes with Mn(III)tetrakis(1-methyl-4-pyridyl)porphyrin pentachloride (TMPyP) significantly improved insulin resistance and mitochondrial dysfunction. When myocytes were exposed to hydrogen peroxide (H₂O₂), they increased DRP1 expression and mitochondrial fragmentation, resulting in ΔΨ_m depolarization and insulin resistance. When DRP1 was suppressed by siRNA, H₂O₂-induced mitochondrial dysfunction and insulin resistance were restored. Our results suggest that a mutual enhancement between DRP1 and reactive oxygen species could induce mitochondrial dysfunction and myocardial insulin resistance. In palmitate-induced insulin-resistant myocytes, neither DRP1-suppression nor TMPyP restored the ΔΨ_m depolarization and impaired 2-DG uptake, however they improved insulin signaling.

Conclusions

A mutual enhancement between DRP1 and ROS could promote mitochondrial dysfunction and inhibition of insulin signal transduction. However, other mechanisms, including lipid metabolite-induced mitochondrial dysfunction, may be involved in palmitate-induced insulin resistance.     

Role of lactose on the production of d-arabitol by Kluyveromyces lactis grown on lactose

There are remarkably few reports on d-arabitol production from lactose. Previous studies in our laboratory have shown that the osmophilic yeast Kluyveromyces lactis NBRC 1903 convert lactose to extracellular d-arabitol. The present study was undertaken to determine the participation of osmotic stress caused by lactose on d-arabitol production by K. lactis NBRC 1903 and to provide the information on the kinetics of d-arabitol production from lactose by K. lactis NBRC 1903. It was confirmed that d-arabitol production was triggered when an initial lactose concentration was above 278 mmol L⁻¹. d-Arabitol yield increased with an increase in initial lactose concentration. The highest d-arabitol concentration of 79.5 mmol L⁻¹ was achieved in the cultivation of K. lactis NBRC 1903 in a medium containing 555 mmol L⁻¹ lactose and 40 g L⁻¹ yeast extract. Lactose was found to play two important roles in d-arabitol production by K. lactis NBRC 1903 grown on lactose. First, lactose was assimilated as the substrate both for cell growth and d-arabitol production. Second, a high lactose concentration induced cellular response to high osmotic stress and up-regulated the flow from d-glucose-6-phosphate to d-arabitol. The arrest of cell growth triggered d-arabitol production.     

Fine-mapping of qRL6.1, a major QTL for root length of rice seedlings grown under a wide range of NH4 + concentrations in hydroponic conditions

Root system development is an important target for improving yield in cereal crops. Active root systems that can take up nutrients more efficiently are essential for enhancing grain yield. In this study, we attempted to identify quantitative trait loci (QTL) involved in root system development by measuring root length of rice seedlings grown in hydroponic culture. Reliable growth conditions for estimating the root length were first established to renew nutrient solutions daily and supply NH₄ ⁺ as a single nitrogen source. Thirty-eight chromosome segment substitution lines derived from a cross between ‘Koshihikari’, a japonica variety, and ‘Kasalath’, an indica variety, were used to detect QTL for seminal root length of seedlings grown in 5 or 500 μM NH₄ ⁺. Eight chromosomal regions were found to be involved in root elongation. Among them, the most effective QTL was detected on a ‘Kasalath’ segment of SL-218, which was localized to the long-arm of chromosome 6. The ‘Kasalath’ allele at this QTL, qRL6.1, greatly promoted root elongation under all NH₄ ⁺ concentrations tested. The genetic effect of this QTL was confirmed by analysis of the near-isogenic line (NIL) qRL6.1. The seminal root length of the NIL was 13.5–21.1% longer than that of ‘Koshihikari’ under different NH₄ ⁺ concentrations. Toward our goal of applying qRL6.1 in a molecular breeding program to enhance rice yield, a candidate genomic region of qRL6.1 was delimited within a 337 kb region in the ‘Nipponbare’ genome by means of progeny testing of F₂ plants/F₃ lines derived from a cross between SL-218 and ‘Koshihikari’.     

Characterization of a broadly reactive monoclonal antibody against norovirus genogroups I and II: recognition of a novel conformational epitope

Norovirus, which belongs to the family Caliciviridae, is one of the major causes of nonbacterial acute gastroenteritis in the world. The main human noroviruses are of genogroup I (GI) and genogroup II (GII), which were subdivided further into at least 15 and 18 genotypes (GI/1 to GI/15 and GII/1 to GII/18), respectively. The development of immunological diagnosis for norovirus had been hindered by the antigen specificity of the polyclonal antibody. Therefore, several laboratories have produced broadly reactive monoclonal antibodies, which recognize the linear GI and GII cross-reactive epitopes or the conformational GI-specific epitope. In this study, we characterized the novel monoclonal antibody 14-1 (MAb14-1) for further development of the rapid immunochromatography test. Our results demonstrated that MAb14-1 could recognize 15 recombinant virus-like particles (GI/1, 4, 8, and 11 and GII/1 to 7 and 12 to 15) and showed weak affinity to the virus-like particle of GI/3. This recognition range is the broadest of the existing monoclonal antibodies. The epitope for MAb14-1 was identified by fragment, sequence, structural, and mutational analyses. Both terminal antigenic regions (amino acid positions 418 to 426 and 526 to 534) on the C-terminal P1 domain formed the conformational epitope and were in the proximity of the insertion region (positions 427 to 525). These regions contained six amino acids responsible for antigenicity that were conserved among genogroup(s), genus, and Caliciviridae. This epitope mapping explained the broad reactivity and different titers among GI and GII. To our knowledge, we are the first group to identify the GI and GII cross-reactive monoclonal antibody, which recognizes the novel conformational epitope. From these data, MAb14-1 could be used further to develop immunochromatography.     

Latent TGF-beta-binding protein 2 binds to DANCE/fibulin-5 and regulates elastic fiber assembly

Elastic fibers play the principal roles in providing elasticity and integrity to various types of human organs, such as the arteries, lung, and skin. However, the molecular mechanism of elastic fiber assembly that leads to deposition and crosslinking of elastin along microfibrils remains largely unknown. We have previously shown that developing arteries and neural crest EGF-like protein (DANCE) (also designated fibulin-5) is essential for elastogenesis by studying DANCE-deficient mice. Here, we report the identification of latent transforming growth factor-beta-binding protein 2 (LTBP-2), an elastic fiber-associating protein whose function in elastogenesis is not clear, as a DANCE-binding protein. Elastogenesis assays using human skin fibroblasts reveal that fibrillar deposition of DANCE and elastin is largely dependent on fibrillin-1 microfibrils. However, downregulation of LTBP-2 induces fibrillin-1-independent fibrillar deposition of DANCE and elastin. Moreover, recombinant LTBP-2 promotes deposition of DANCE onto fibrillin-1 microfibrils. These results suggest a novel regulatory mechanism of elastic fiber assembly in which LTBP-2 regulates targeting of DANCE on suitable microfibrils to form elastic fibers.     

Meiotic association between Spo11 regulated by Rec102, Rec104 and Rec114

Meiotic recombination is initiated by DNA double-stranded break (DSB) formation catalyzed by Spo11, a type-II topoisomerase-like transesterificase, presumably via a dimerization-mediated mechanism. We demonstrate the existence of in vivo interactions between Spo11 proteins carrying distinct tags, and the chromatin-binding and DSB activity of tagged Spo11at innate and targeted DSB sites upon fusion to the Gal4 DNA-binding domain. First we identified the interaction between Spo11-3FLAG and Gal4BD-Spo11 proteins, and established that this interaction specifically occurs at the time of DSB formation. We then observed that presence of the Gal4BD-spo11Y135F (nuclease-deficient) protein allows Spo11-3FLAG recruitment at the GAL2 locus, indicative of the formation of a hetero-complex near the GAL2 UAS sites, but no formation of double- or single-strand breaks. Spo11 self-interaction around the GAL2 DSB site depends on other proteins for DSB formation, in particular Rec102, Rec104 and Rec114. Together, these results suggest that in vivo self-association of Spo11 during meiosis is genetically regulated. The results are discussed in relation to possible roles of Spo11 self-interaction in the control of the cleavage activity.