Flagellin Modulates the Function of Invariant NKT Cells From Patients With Asthma via Dendritic Cells

PurposeInvariant natural killer T (iNKT) cells play a critical role in the pathogenesis of asthma. We previously reported the association between circulating Th2-like iNKT cells and lung function in asthma patients and the suppressive effect of Toll-like receptor 5 ligand flagellin B (FlaB) on asthmatic in a mouse model. Thus, we investigated whether FlaB modulates the function of circulating iNKT cells in asthmatic patients.MethodsPeripheral blood mononuclear cells (PBMCs) were treated with FlaB, and the secreted and intracellular cytokines of iNKT cells were evaluated by using ELISA and flow cytometry, respectively, following stimulation with α-galactosylceramide. Foxp3⁺ iNKT cells were also measured. To determine the effect of FlaB-treated dendritic cells (DCs) on iNKT cells, we co-cultured CD14⁺ monocyte-derived DCs and T cells from patients with house dust mite-sensitive asthma and analyzed intracellular cytokines in iNKT cells.ResultsA reduction of IL-4 and IL-17 production by iNKT cells in PBMCs after FlaB treatment was alleviated following blocking of IL-10 signaling. A decrease in the frequencies of IL-4⁺ and IL-17⁺ iNKT cells by FlaB-treated DCs was reversed after blocking of IL-10 signaling. Simultaneously, an increase in Foxp3⁺ iNKT cells induced by FlaB treatment disappeared after blocking of IL-10.ConclusionsFlaB may inhibit Th2- and Th17-like iNKT cells and induce Foxp3⁺ iNKT cells by DCs via an IL-10-dependent mechanism in asthmatic patients. In patients with a specific asthma phenotype associated with iNKT cells, FlaB may be an effective immunomodulator for iNKT cell-targeted immunotherapy.     

Different pattern of viral infections and clinical outcomes in patient with acute exacerbation of chronic obstructive pulmonary disease and chronic obstructive pulmonary disease with pneumonia

Respiratory viruses are well‐known causes of acute exacerbation of chronic obstructive pulmonary disease (AE‐COPD) and also important pathogens for concomitant pneumonia in COPD (CP‐COPD). However, the differences in a viral infection pattern and clinical impacts of respiratory viruses between the two groups have not been well investigated. The clinical and microbiological data from COPD patients admitted with AE‐COPD (n = 281) or CP‐COPD (n = 284) between January 2010 and December 2012 were reviewed. After excluding 88 patients (40 with AE‐COPD and 48 with CP‐COPD) who did not undergo a multiplex RT‐PCR test for respiratory viruses, the demographic characteristics, identified viruses, and clinical outcomes of the AE‐COPD and CP‐COPD groups were compared. Respiratory viruses were identified in 41.9% of AE‐COPD group and 33.5% of the CP‐COPD groups. The most common virus was influenza virus in the AE‐COPD group (33.7%) versus human coronavirus (24.1%) in the CP‐COPD group. Influenza virus was significantly more common in the AE‐ACOPD group than in the CP‐COPD group (P < 0.01). In‐hospital mortality of AE‐COPD and CP‐COPD were 1.2% and 12.3%, respectively (P < 0.01). Among CP‐COPD patients, in‐hospital mortality of patients with only viral infection group, only bacterial infection group, and viral‐bacterial co‐infection were 2.6%, 25.8%, and 17.5%, respectively (P = 0.01). Respiratory viruses were commonly identified in both AE‐COPD and CP‐COPD, influenza virus and human coronavirus were the most common viruses identified in AE‐COPD and CP‐COPD patients, respectively. The mortality rates of only viral infection group was significantly lower than only bacterial infection or viral‐bacterial co‐infection group in CP‐COPD patients. J. Med. Virol. 88:2092–2099, 2016. © 2016 Wiley Periodicals, Inc.

     

Impairment of p38 MAPK-mediated cytosolic phospholipase A2 activation in the kidneys is associated with pathogenicity of Candida albicans

In studying the mechanisms underlying the susceptibility of the kidney to candidal infection, we previously reported that the reduced production of cytokines [i.e. tumour necrosis factor-alpha (TNF-alpha)] via platelet-activating factor (PAF)-induced activation of nuclear factor-kappaB (NF-kappaB) renders the organ susceptible to the fungal burden. In this study, we investigated the possibility that pathogenic Candida albicans may evade clearance and perhaps even multiply by inhibiting elements in the signalling pathway that lead to the production of TNF-alpha. The fungal burden of pathogenic C. albicans in the kidneys was 10(4)-10(5)-fold higher than that of a non-pathogenic strain. PAF-induced early activation of NF-kappaB and TNF-alpha mRNA expression were both observed in the kidneys of mice infected with non-pathogenic strains of C. albicans, but not in mice infected with pathogenic strains. Impairment of PAF-mediated early NF-kappaB activation following infection with pathogenic C. albicans was associated with the prevention of activation of the enzyme cytosolic phospholipase A(2) (cPLA(2)) as well as the upstream pathway of cPLA(2), p38 mitogen-activated protein kinase. Collectively, these findings indicate that C. albicans exerts its pathogenicity through impairing the production of anticandidal cytokines by preventing cPLA(2) activity. This novel mechanism provides insight into understanding pathogenic C. albicans and perhaps identifies a target for its treatment.     

Pyruvate slows disease progression in a G93A SOD1 mutant transgenic mouse model

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease caused by selective motor neuron death, and currently no effective treatment is available for ALS. In this study, we investigated the neuroprotective effects of pyruvate, which acts as an anti-oxidant and as an energy source. We treated G93A SOD1 transgenic mice with pyruvate (from 70 days of age, i.p., at 1000 mg/kg/week), and found that it prolonged average lifespan by 12.3 days (10.5%), slowed disease progression, and improved motor performance, but did not delay disease onset. Pyruvate treatment was also associated with reduced nitrotyrosine immunoreactivity, gliosis, and increased Bcl-2 expression in the spinal cords of G93A SOD1 transgenic mice. These results suggest that pyruvate treatment may be a potential therapeutic strategy in ALS.     

Visceral hyperalgesia induced by neonatal maternal separation is associated with nerve growth factor-mediated central neuronal plasticity in rat spinal cord

Neonatal maternal separation (NMS) has been shown to trigger alterations in neuroendocrine, neurochemical and sensory response to nociceptive stimuli along the brain-gut axis. These alterations may be the result of a cascade of events that are regulated by neurotrophic factors. Nerve growth factor (NGF), a member of the neurotrophin family, is essential for the development and maintenance of sensory neurons and for the formation of central pain circuitry. The present study aimed to investigate whether NMS causes changes in neuronal plasticity and the relationship of these changes in plasticity with the expression of NGF and its high affinity tyrosine kinase receptor A (TrkA) in the lumbosacral spinal cord in adult rats. Male Wistar rat pups were either subjected to 180 min daily of NMS or not handled (NH) for 13 consecutive days. The expression of NGF and TrkA was examined in NH and NMS rats with or without colorectal distention (CRD) as determined by Western blot analysis and immunohistochemistry. The present results of Western blot analysis indicated NMS and CRD have a significant effect on NGF protein level in the lumbosacral spinal cord of rats. Assessments of optical densities revealed that NMS enhanced TrkA-ir fiber densities in laminae I-III and laminae V-VI of rats in both conditions with or without CRD. Double immunofluorescence revealed that TrkA co-expressed with calcitonin gene-related peptide (CGRP) in afferent fibers, while no significant difference in terms of the intensity of TrkA-ir in these fibers was found among groups. Quantitative analysis of TrkA-ir neurons indicated a significant interactive effect of NMS and CRD on the mean number of TrkA-ir neurons in laminae V-VI of rats, in which significant difference was found between NMS+CRD and NH+CRD. Double immunofluorescence of TrkA and Fos showed that CRD has a significant effect on TrkA expression in Fos-positive neurons in laminae V-VI and lamina X of rats, while no significant difference was found between NMS+CRD and NH+CRD. These results demonstrate that NMS induced alterations in NGF protein level and TrkA expression in adult rat spinal cord and indicate that NGF is a crucial mediator for the changes in neuronal plasticity that occur in NMS-induced visceral hyperalgesia.     

Spatial and functional relationship between poly(ADP-ribose) polymerase-1 and poly(ADP-ribose) glycohydrolase in the brain

Poly(ADP-ribose) polymerases (PARPs) are members of a family of enzymes that utilize nicotinamide adenine dinucleotide (NAD(+)) as substrate to form large ADP-ribose polymers (PAR) in the nucleus. PAR has a very short half-life due to its rapid degradation by poly(ADP-ribose) glycohydrolase (PARG). PARP-1 mediates acute neuronal cell death induced by a variety of insults including cerebral ischemia, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced Parkinsonism, and CNS trauma. While PARP-1 is localized to the nucleus, PARG resides in both the nucleus and cytoplasm. Surprisingly, there appears to be only one gene encoding PARG activity, which has been characterized in vitro to generate different splice variants, in contrast to the growing family of PARPs. Little is known regarding the spatial and functional relationships of PARG and PARP-1. Here we evaluate PARG expression in the brain and its cellular and subcellular distribution in relation to PARP-1. Anti-PARG (alpha-PARG) antibodies raised in rabbits using a purified 30 kDa C-terminal fragment of murine PARG recognize a single band at 111 kDa in the brain. Western blot analysis also shows that PARG and PARP-1 are evenly distributed throughout the brain. Immunohistochemical studies using alpha-PARG antibodies reveal punctate cytosolic staining, whereas anti-PARP-1 (alpha-PARP-1) antibodies demonstrate nuclear staining. PARG is enriched in the mitochondrial fraction together with manganese superoxide dismutase (MnSOD) and cytochrome C (Cyt C) following whole brain subcellular fractionation and Western blot analysis. Confocal microscopy confirms the co-localization of PARG and Cyt C. Finally, PARG translocation to the nucleus is triggered by NMDA-induced PARP-1 activation. Therefore, the subcellular segregation of PARG in the mitochondria and PARP-1 in the nucleus suggests that PARG translocation is necessary for their functional interaction. This translocation is PARP-1 dependent, further demonstrating a functional interaction of PARP-1 and PARG in the brain.