Control of P2X2 Channel Permeability by the Cytosolic Domain

ATP-gated P2X channels are the simplest of the three families of transmitter-gated ion channels. Some P2X channels display a time- and activation-dependent change in permeability as they undergo the transition from the relatively Na+-selective I1 state to the I2 state, which is also permeable to organic cations. We report that the previously reported permeability change of rat P2X2 (rP2X2) channels does not occur at mouse P2X2 (mP2X2) channels expressed in oocytes. Domain swaps, species chimeras, and point mutations were employed to determine that two specific amino acid residues in the cytosolic tail domain govern this difference in behavior between the two orthologous channels. The change in pore diameter was characterized using reversal potential measurements and excluded field theory for several organic ions; both rP2X2 and mP2X2 channels have a pore diameter of ~11 Å in the I1 state, but the transition to the I2 state increases the rP2X2 diameter by at least 3 Å. The I1 to I2 transition occurs with a rate constant of ~0.5 s^-1. The data focus attention on specific residues of P2X2 channel cytoplasmic domains as determinants of permeation in a state-specific manner

Measuring Near Plasma Membrane and Global Intracellular Calcium Dynamics in Astrocytes

The brain contains glial cells. Astrocytes, a type of glial cell, have long been known to provide a passive supportive role to neurons. However, increasing evidence suggests that astrocytes may also actively participate in brain function through functional interactions with neurons. However, many fundamental aspects of astrocyte biology remain controversial, unclear and/or experimentally unexplored. One important issue is the dynamics of intracellular calcium transients in astrocytes. This is relevant because calcium is well established as an important second messenger and because it has been proposed that astrocyte calcium elevations can trigger the release of transmitters from astrocytes. However, there has not been any detailed or satisfying description of near plasma membrane calcium signaling in astrocytes. Total internal reflection fluorescence (TIRF) microscopy is a powerful tool to analyze physiologically relevant signaling events within about 100 nm of the plasma membrane of live cells. Here, we use TIRF microscopy and describe how to monitor near plasma membrane and global intracellular calcium dynamics almost simultaneously. The further refinement and systematic application of this approach has the potential to inform about the precise details of astrocyte calcium signaling. A detailed understanding of astrocyte calcium dynamics may provide a basis to understand if, how, when and why astrocytes and neurons undergo calcium-dependent functional interactions

Lipopolysaccharide induced inflammation in the perivascular space in lungs

<p>Abstract</p> <p>Background</p> <p>Lipopolysaccharide (LPS) contained in tobacco smoke and a variety of environmental and occupational dusts is a toxic agent causing lung inflammation characterized by migration of neutrophils and monocytes into alveoli. Although migration of inflammatory cells into alveoli of LPS-treated rats is well characterized, the dynamics of their accumulation in the perivascular space (PVS) leading to a perivascular inflammation (PVI) of pulmonary arteries is not well described.</p> <p>Methods</p> <p>Therefore, we investigated migration of neutrophils and monocytes into PVS in lungs of male Sprague-Dawley rats treated intratracheally with <it>E. coli </it>LPS and euthanized after 1, 6, 12, 24 and 36 hours. Control rats were treated with endotoxin-free saline. H&E stained slides were made and immunohistochemistry was performed using a monocyte marker and the chemokine Monocyte-Chemoattractant-Protein-1 (MCP-1). Computer-assisted microscopy was performed to count infiltrating cells.</p> <p>Results</p> <p>Surprisingly, the periarterial infiltration was not a constant finding in each animal although LPS-induced alveolitis was present. A clear tendency was observed that neutrophils were appearing in the PVS first within 6 hours after LPS application and were decreasing at later time points. In contrast, mononuclear cell infiltration was observed after 24 hours. In addition, MCP-1 expression was present in perivascular capillaries, arteries and the epithelium.</p> <p>Conclusion</p> <p>PVI might be a certain lung reaction pattern in the defense to infectious attacks.</p

A NEVER-ENDING STORY OF RHEUMATOID ARTHRITIS

There are distinct Rheumatic disorders, still Rheumatoid arthritis (RA) is believed to be very prevailing. RA is an empathic disorder described over integral redness, constant inflammation, and the existence of auto-antibodies. In RA, inflammation in joints, loss of motion of joint stiffness, joint tenderness are most common in patients. Deformity of joints can be prevented by early diagnosis and treatment. The extremity of the disease can be reduced by combining the drugs and improved weight more profiled than single medication. Treat-to-target progress results in a superior-conclusion in RA, and the ACR, EULAR, and other specialized systems have supported treat-to-target as a basic curative strategy for RA. The novel methods used in RA have upgraded the development of the disorder and maximum people helpful in cancellation of clinical manifestations if the identification of disorder takes place before time. This review article is written after studying most of the journal’s articles, which were published between 1997-2019

Multiple exposures to swine barn air induce lung inflammation and airway hyper-responsiveness

BACKGROUND: Swine farmers repeatedly exposed to the barn air suffer from respiratory diseases. However the mechanisms of lung dysfunction following repeated exposures to the barn air are still largely unknown. Therefore, we tested a hypothesis in a rat model that multiple interrupted exposures to the barn air will cause chronic lung inflammation and decline in lung function. METHODS: Rats were exposed either to swine barn (8 hours/day for either one or five or 20 days) or ambient air. After the exposure periods, airway hyper-responsiveness (AHR) to methacholine (Mch) was measured and rats were euthanized to collect bronchoalveolar lavage fluid (BALF), blood and lung tissues. Barn air was sampled to determine endotoxin levels and microbial load. RESULTS: The air in the barn used in this study had a very high concentration of endotoxin (15361.75 ± 7712.16 EU/m(3)). Rats exposed to barn air for one and five days showed increase in AHR compared to the 20-day exposed and controls. Lungs from the exposed groups were inflamed as indicated by recruitment of neutrophils in all three exposed groups and eosinophils and an increase in numbers of airway epithelial goblet cells in 5- and 20-day exposure groups. Rats exposed to the barn air for one day or 20 days had more total leukocytes in the BALF and 20-day exposed rats had more airway epithelial goblet cells compared to the controls and those subjected to 1 and 5 exposures (P < 0.05). Bronchus-associated lymphoid tissue (BALT) in the lungs of rats exposed for 20 days contained germinal centers and mitotic cells suggesting activation. There were no differences in the airway smooth muscle cell volume or septal macrophage recruitment among the groups. CONCLUSION: We conclude that multiple exposures to endotoxin-containing swine barn air induce AHR, increase in mucus-containing airway epithelial cells and lung inflammation. The data also show that prolonged multiple exposures may also induce adaptation in AHR response in the exposed subjects

Expression and activity of N-myristoyltransferase in lung inflammation of cattle and its role in neutrophil apoptosis

N-myristoyltransferase (NMT) attaches a 14 carbon fatty acid, myristic acid, to the N-terminal glycine residue of proteins. NMT exists in two isoforms NMT1 and NMT2. Myristoylated proteins play critical roles in protein–protein interactions, cell signaling and oncogenesis. Although elevated expression of NMT1 has been described in colorectal carcinoma, its expression and roles in normal and inflamed lungs of the cattle are unknown. Therefore, we investigated the expression and activity of NMT in a bovine model of lung inflammation induced with Mannheimia hemolytica and in vitro in neutrophils and macrophages. Western blots revealed increased expression of NMT1 in lungs from infected animals compared to control animals. Total NMT activity was reduced in inflamed lungs compared to control animals (p < 0.05) along with increased expression of enolase, a putative inhibitor of NMT. NMT1 staining was observed in the septum, vascular endothelium and the epithelium in the lungs from control as well as infected calves. NMT1 expression was intense in neutrophils in the necrotic areas in the inflamed lungs. Immuno-electron microscopy localized NMT1 in cytoplasm and nuclei of endothelium, pulmonary intravascular macrophages and airway epithelium. Total NMT activity and NMT1 expression were increased in neutrophils and macrophages exposed to Escherichia coli LPS in vitro. NMT knockdown increased apoptosis in activated neutrophils. This is the first report demonstrating expression of NMT in normal and inflamed lungs and a novel role for NMT in regulation of neutrophil lifespan