BackgroundAdenosine levels rise during inflammation and modulate inflammatory responses by engaging with four different G protein-coupled receptors. It is suggested that adenosine exhibits pro-inflammatory effects through its A1 receptor (A1R), and anti-inflammatory effects through A2A receptor (A2AR). Therefore, understanding of the mechanisms that govern adenosine receptor regulation may advance treatment of various inflammatory disorders. We previously reported that peak A1R expression during leukocyte recruitment, is followed by a peak in A2AR during inflammation resolution.Principal FindingsHere, we examined whether A1R activation sequentially induces A2AR expression and by this reverses inflammation. The effect of adenosine on A1R mediated A2AR expression was examined in peritoneal macrophages (PMΦ) and primary peritoneal mesothelial cells (PMC) in vitro. Induction of A2AR was inhibited by pertussis toxin (PTX) and partly dependent on A2AR stimulation. Administration of A1R agonists to healthy mice reduced A1R expression and induced A2AR production in PMC. Mice that were preconditioned with A1R agonists 24 hours before E. coli inoculation exhibited decreased TNFα and IL-6 sera levels and reduced leukocytes recruitment. Preconditioning was blocked by pretreatment with A1R antagonist, as well as, or by late treatment with A2AR antagonist, and was absent in A2AR−/− mice.ConclusionsOur data suggest that preconditioning by an A1R-agonist promotes the resolution of inflammation by inducing the production of A2AR. Future implications may include early treatment during inflammatory disorders or pretreatment before anticipated high risk inflammatory events, such as invasive surgery and organ transplantation.

Loss of function of the peritoneal membrane is associated with peritonitis. Adenosine levels in sites of inflammation were shown to increase and exhibit immunoregulatory effects. Our aim was to elucidate the regulatory role of adenosine during peritonitis and to test the involvement of peritoneal mesothelial cells (PMC) in adenosine regulation. In a mice model of Escherichia coli peritonitis, the adenosine A(2A) receptor (A(2A)R) agonist (CGS21680) prevented leukocyte recruitment and reduced tumor necrosis factor alpha (TNF-alpha) and interleukin-6 (IL-6) levels. Peritonitis induced the elevation of adenosine with a peak at 24 h. Analysis of adenosine receptor levels on peritoneum showed that A(1) receptor (A(1)R) protein levels peak at 12 h after inoculation and then return to baseline at 24 h, whereas high affinity A(2A)R protein levels peak at 24 h concomitantly with the peak of adenosine concentration. Low affinity A(2B) receptor (A(2B)R) levels elevated slowly, remaining elevated up to 48 h. In human PMC (HPMC), the early cytokines, IL-1-alpha, and TNF-alpha upregulated the A(2B) and A(2A) receptors. However, interferon-gamma (IFN-gamma) upregulated the A(2B)R and decreased A(2A)R levels. Treatment with the A(2A)R agonist reduced IL-1-dependent IL-6 secretion from HPMC. In conclusion, the kinetics of adenosine receptors suggest that at early stage of peritonitis, the A(1)R dominates, and later its dominance is replaced by the G stimulatory (Gs) protein-coupled A(2A)R that suppresses inflammation. Early proinflammatory cytokines are an inducer of the A(2A)R and this receptor reduces their production and leukocyte recruitment. Future treatment with adenosine agonists should be considered for attenuating the damage to mesothelium during the course of acute peritonitis.

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Death-associated protein kinase (DAPk) is a tumor suppressor thought to inhibit cancer by promoting apoptosis and autophagy. Because cancer progression is linked to inflammation, we investigated the in vivo functions of DAPk in lung responses to various acute and chronic inflammatory stimuli. Lungs of DAPk knockout (KO) mice secreted higher concentrations of IL-6 and keratinocyte chemoattractant (or chemokine [C-X-C motif] ligand 1) in response to transient intranasal administrations of the Toll-like receptor-4 (TLR4) agonist LPS. In addition, DAPk-null macrophages and neutrophils were hyperresponsive to ex vivo stimulation with LPS. DAPk-null neutrophils were also hyperresponsive to activation via Fc receptor and Toll-like receptor-3, indicating that the suppressive functions of this kinase are not restricted to TLR4 pathways. Even after the reconstitution of DAPk-null lungs with DAPk-expressing leukocytes by transplanting wild-type (WT) bone marrow into lethally irradiated DAPk KO mice, the chimeric mice remained hypersensitive to both acute and chronic LPS challenges, as well as to tobacco smoke exposure. DAPk-null lungs reconstituted with WT leukocytes exhibited elevated neutrophil content and augmented cytokine secretion in the bronchoalveolar space, as well as enhanced epithelial cell injury in response to both acute and chronic inflammatory conditions. These results suggest that DAPk attenuates a variety of inflammatory responses, both in lung leukocytes and in lung epithelial cells. The DAPk-mediated suppression of lung inflammation and airway injury may contribute to the tumor-suppressor functions of this kinase in epithelial carcinogenesis.

The expression of a previously untranslated carboxylterminal sequence is associated with the ancestral lutropin (LH) ␤ to the ␤-subunit gene evolution of choriogonadotropins (CG). The peptide extension (denoted as CTP) is rich in mucin-type O-glycans and confers new hormonal properties on CG relative to the LH. Although the LH␤ gene is conserved among mammals and only a few frameshift mutations account for the extension, it is merely seen in primates and equids. Bioinformatics identified a CTP-like sequence that is encrypted in the LH␤ gene of several mammalian species but not in birds, amphibians, or fish. We then examined whether or not decoding of the cryptic CTP in the bovine LH␤ gene (boCTP) would be sufficient to generate the LH␤ species of a ruminant with properties typical to the CG␤ subunit. The mutated bovine LH␤-boCTP subunit was expressed and N-glycosylated in transfected Chinese hamster ovary cells. However, unlike human (h) CG␤ CTP, the cryptic boCTP was devoid of mucin O-glycans. This deficiency was further confirmed when the boCTP domain was substituted for the natural CTP in the human CG␤ subunit. Moreover, when expressed in polarized Madin-Darby canine kidney cells, this hCG␤-boCTP chimera was secreted basolaterally rather than from the apical compartment, which is the route of the wild type hCG␤ subunit, a sorting function attributed to the Oglycans attached to the CTP. This result shows that the cryptic peptide does not orientate CG to the apical face of the placenta, to the maternal circulation as seen in primates. The absence of this function, which distinguishes CG from LH, provides an explanation as to why the LH␤ to CG␤ evolution did not occur in ruminants. We propose that in primates and equids, further natural mutations in the progenitor LH␤ gene resulted in the efficient O-glycosylation of the CTP, thus favoring the retention of an elongated reading frame.The family of glycoprotein hormones includes lutropin (LH), 1 follitropin, and thyrotropin, as expressed by the pituitary, and chorionic gonadotropin (CG), which is produced by the placenta of primates and equids (1). Each hormone is a noncovalent heterodimer composed of a common ␣-subunit and a unique ␤-subunit that confers receptor specificity. The ␤-subunits have substantial sequence similarities, including conserved location of cysteine residues that suggests an origin from a common ancestral gene (2). The human (h) CG␤ genes have evolved from an ancestral LH␤ gene by frameshift mutations that resulted in a readthrough into a previously untranslated region and the extension of the reading frame (3, 4) (Fig. 1A). As a result, a short carboxyl-terminal sequence of hLH␤ is replaced by a longer carboxyl-terminal peptide (CTP) in hCG␤ (3-6). In the equine (e), both the placental CG␤ and pituitary LH␤ subunits are products of the same gene (eLH/CG␤) and contain a CTP that is presumed to have evolved by a distinct mechanism (7) (for further explanations see "Results"). Except for primates and equids, no other identified animal species b...

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Our data suggest that adenosine through its A(2A)R promotes peritoneal fibrosis and therefore should be considered as a target for pharmacological intervention.

Introduction: Patients treated with direct Xa inhibitors may require urgent surgery. Administration of prothrombin complex concentrate (PCC) in this setting is common; however, it is based on limited experience in healthy volunteers. Objective: To characterize the population receiving PCC for apixaban/rivaroxaban reversal prior to an urgent surgery and evaluate its efficacy and safety. Methods: This was a retrospective study in 2 tertiary hospitals. Bleeding was evaluated based on surgical reports, hemoglobin drop, and the use of blood products or additional PCC during 48 h. Safety measures were thrombotic complications and 30-day mortality. Results: Sixty-two patients aged 80.7 ± 9 years, treated with apixaban (39.63%) or rivaroxaban (23.37%), received PCC before an urgent surgery/procedure. Most underwent abdominal operation (61%), orthopedic surgery (13%), or transhepatic cholecystostomy insertion (10%). Bleeding during surgery was reported in 3 patients (5%), no patient required additional PCC, and 16 patients (26%) received packed cells (median: 1 unit, range: 1–5). The 30-day mortality and thrombosis rates were 21% (n = 13) and 3% (n = 2), respectively. The cause of death was related to the primary disease, most commonly sepsis. No patient died due to bleeding/thrombosis. Conclusions: Our results support the use of PCC to achieve hemostasis in patients treated with Xa inhibitors prior to an urgent surgery.