Extracellular ATP acts on P2Y2 purinergic receptors to facilitate HIV-1 infection

Contact with HIV-1 envelope protein elicits release of ATP through pannexin-1 channels on target cells; by activating purinergic receptors and Pyk2 kinase in target cells, this extracellular ATP boosts HIV-1 infectivity

Purinergic signalling and immune cells

This review article provides a historical perspective on the role of purinergic signalling in the regulation of various subsets of immune cells from early discoveries to current understanding. It is now recognised that adenosine 5'-triphosphate (ATP) and other nucleotides are released from cells following stress or injury. They can act on virtually all subsets of immune cells through a spectrum of P2X ligand-gated ion channels and G protein-coupled P2Y receptors. Furthermore, ATP is rapidly degraded into adenosine by ectonucleotidases such as CD39 and CD73, and adenosine exerts additional regulatory effects through its own receptors. The resulting effect ranges from stimulation to tolerance depending on the amount and time courses of nucleotides released, and the balance between ATP and adenosine. This review identifies the various receptors involved in the different subsets of immune cells and their effects on the function of these cells

Short vs prolonged dual antiplatelet treatment upon endovascular stenting of peripheral arteries

Mariya Kronlage,1 Maximilian Wassmann,1 Britta Vogel,1 Oliver J Müller,1 Erwin Blessing,2 Hugo Katus,1,3 Christian Erbel1 1Department of Cardiology, Angiology and Pneumology, University Hospital Heidelberg, Heidelberg, 2SRH Klinikum Karlsbad Langensteinbach, Karlsbad, 3DZHK German Center for Cardiovascular Research, Partner Site Heidelberg/Mannheim, Mannheim, Germany Introduction: Peripheral artery disease (PAD) is a highly prevalent disorder with a substantial economical burden. Dual antiplatelet treatment (DAPT) upon endovascular stenting to prevent acute thrombotic reocclusions is an universally accepted practice for postinterventional management of PAD patients. However, the optimal period of time for DAPT upon endovascular stenting is not known.Methods: In the current nonrandomized, retrospective monocentric study, we evaluated the duration of DAPT upon endovascular stenting. A total of 261 endovascular SFA and iliac stenting procedures were performed on 214 patients and these patients were subdivided into a short (4–6 weeks) or a prolonged (8–12 weeks) DAPT regime group. More than 65% of the patients included were male, approximately 35% were diabetic, and 61% had a history of smoking. Of all the patients, 90% exhibited a Rutherford stage 2–3, and approximately half of the patients had a moderate-to-severe calcified target lesion with a length of >13 cm. Major safety end points were defined as any bleeding, compartment syndrome, and ischemic events. In addition to this, patency, all-cause mortality, as well as amputation were followed up over a period of 12 months upon intervention.Results: Twelve months after endovascular stenting, primary patency in our cohort was comparable between the groups (83.94% short vs 79.8% long DAPT, P>0.05). Major bleeding occurred in 18 cases without any difference between the groups (P>0.05). In addition, during the 12-month follow-up, 6 (3.4%) patients in the short and 3 (3.5%) in the prolonged DAPT regime suffered a stroke/transient ischemic attack (P>0.05). In addition, there was no difference regarding mortality and amputation rate comparing short vs prolonged DAPT regime in a 12-month follow-up.Conclusion: In the current cohort, prolonged DAPT after endovascular stenting had no beneficial effect on the outcome in a 12-month follow-up. Keywords: peripheral artery disease, stent implantation, dual antiplatelet therapy, primary patency, endovascular therap

A comparative study on endovascular treatment of (sub)acute critical limb ischemia: mechanical thrombectomy vs thrombolysis

Mariya Kronlage,1,2 Ilka Printz,1 Britta Vogel,1 Erwin Blessing,3 Oliver J Müller,1,2 Hugo A Katus,1,2 Christian Erbel1 1Department of Cardiology, Angiology and Pneumology, University Hospital Heidelberg, 2DZHK German Center for Cardiovascular Research, Partner Site Heidelberg/Mannheim, Heidelberg, 3SRH Klinikum Karlsbad Langensteinbach, Karlsbad, Germany Objective: The aim of this study was to compare different interventional methods for treatment of (sub)acute limb ischemia upon thrombotic occlusions of the lower extremity in terms of their safety and efficacy in a tertiary hospital setting.Design: This is a retrospective, single-center study of non-randomized data.Methods: A total of 202 patients, including 26 critically ill patients, underwent rotational thrombectomy (Rotarex®), local thrombolysis (recombinant tissue plasminogen activator), or combination of both at the University Hospital Heidelberg (2006–2015). The different interventional procedures were compared in terms of overall and amputation-free survival, as well as patency in a 1-year follow-up (Kaplan–Meier analysis).Results: The study demonstrated a primary revascularization success of >98% in all groups. One year after revascularization, primary and secondary patency after mechanical thrombectomy alone were significantly better in comparison to local thrombolysis or a combination of Rotarex® and lysis (63% and 85%, P<0.05). Overall survival 12 months after intervention reached up to 96% in noncritically ill patients, and amputation-free survival was 94.3% in all three groups. Mean hospitalization duration and rate of major bleedings were significantly increased after thrombolysis compared to Rotarex® (P<0.05).Conclusion: In patients with (sub)acute limb ischemia, Rotarex® mechanical thrombectomy represents a safe and effective alternative to thrombolysis and is associated with a reduced rate of major bleedings, shorter hospitalization durations, and lower costs. Keywords: acute limb ischemia, thrombolysis, mechanical thrombectomy, Rotarex®, arterial thrombosis and embolism, acute artery occlusio

Diffusion MRI in peripheral nerves: Optimized <em>b</em> values and the role of non-Gaussian diffusion.

Background Diffusion-weighted imaging (DWI) provides specific in vivo information about tissue microstructure, which is increasingly recognized for various applications outside the central nervous system. However, standard sequence parameters are commonly adopted from optimized central nervous system protocols, thus potentially neglecting differences in tissue-specific diffusional behavior. Purpose To characterize the optimal tissue-specific diffusion imaging weighting scheme over the b domain in peripheral nerves under physiologic and pathologic conditions. Materials and Methods In this prospective cross-sectional study, 3-T MR neurography of the sciatic nerve was performed in healthy volunteers (n = 16) and participants with type 2 diabetes (n = 12). For DWI, 16 b values in the range of 0-1500 sec/mm2 were acquired in axial and radial diffusion directions of the nerve. With a region of interest-based approach, diffusion-weighted signal behavior as a function of b was estimated using standard monoexponential, biexponential, and kurtosis fitting. Goodness of fit was assessed to determine the optimal b value for two-point DWI/diffusion tensor imaging (DTI). Results Non-Gaussian diffusional behavior was observed beyond b values of 600 sec/mm2 in the axial and 800 sec/mm2 in the radial diffusion direction in both participants with diabetes and healthy volunteers. Accordingly, the biexponential and kurtosis models achieved a better curve fit compared with the standard monoexponential model (Akaike information criterion &gt;99.9% in all models), but the kurtosis model was preferred in the majority of cases. Significant differences between healthy volunteers and participants with diabetes were found in the kurtosis-derived parameters Dk and K. The results suggest an upper bound b value of approximately 700 sec/mm2 for optimal standard DWI/DTI in peripheral nerve applications. Conclusion In MR neurography, an ideal standard diffusion-weighted imaging/diffusion tensor imaging protocol with b = 700 sec/mm2 is suggested. This is substantially lower than in the central nervous system due to early-occurring non-Gaussian diffusion behavior and emphasizes the need for tissue-specific b value optimization. Including higher b values, kurtosis-derived parameters may represent promising novel imaging markers of peripheral nerve disease. ©RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Jang and Du in this issue

Transient P2X7 receptor activation triggers macrophage death independent of Toll-like receptors 2 and 4, caspase-1, and pannexin-1 proteins.

The function of P2X(7) receptors (ATP-gated ion channels) in innate immune cells is unclear. In the setting of Toll-like receptor (TLR) stimulation, secondary activation of P2X(7) ion channels has been linked to pro-caspase-1 cleavage and cell death. Here we show that cell death is a surprisingly early triggered event. We show using live-cell imaging that transient (1-4 min) stimulation of mouse macrophages with high extracellular ATP ([ATP]e) triggers delayed (hours) cell death, indexed as DEVDase (caspase-3 and caspase-7) activity. Continuous or transient high [ATP]e did not induce cell death in P2X(7)-deficient (P2X(7)(-/-)) macrophages or neutrophils (in which P2X(7) could not be detected). Blocking sustained Ca(2+) influx, a signature of P2X(7) ligation, was highly protective, whereas no protection was conferred in macrophages lacking caspase-1 or TLR2 and TLR4. Furthermore, pannexin-1 (Panx1) deficiency had no effect on transient ATP-induced delayed cell death or ATP-induced Yo-Pro-1 uptake (an index of large pore pathway formation). Thus, "transient" P2X(7) receptor activation and Ca(2+) overload act as a death trigger for native mouse macrophages independent of Panx1 and pro-inflammatory caspase-1 and TLR signaling

Muscle fatigue revisited - Insights from optically pumped magnetometers.

So far, surface electromyography (sEMG) has been the method of choice to detect and evaluate muscle fatigue. However, recent advancements in non-cryogenic quantum sensors, such as optically pumped magnetometers (OPMs), enable interesting possibilities to flexibly record biomagnetic signals. Yet, a magnetomyographic investigation of muscular fatigue is still missing. Here, we simultaneously used sEMG (4 surface electrode) and OPM-based magnetomyography (OPM-MMG, 4 sensors) to detect muscle fatigue during a 3 × 1-min isometric contractions of the left rectus femoris muscle in 7 healthy participants. Both signals exhibited the characteristic spectral compression distinctive for muscle fatigue. OPM-MMG and sEMG slope values, used to quantify the spectral compression of the signals, were positively correlated, displaying similarity between the techniques. Additionally, the analysis of the different components of the magnetic field vector enabled speculations regarding the propagation of the muscle action potentials (MAPs). Altogether these results show the feasibility of the magnetomyographic approach with OPMs and propose a potential alternative to sEMG for the study of muscle fatigue