TY - JOUR A1 - Oehler, Beatrice A1 - Brack, Alexander A1 - Blum, Robert A1 - Rittner, Heike L. T1 - Pain Control by Targeting Oxidized Phospholipids: Functions, Mechanisms, Perspectives JF - Frontiers in Endocrinology N2 - Within the lipidome oxidized phospholipids (OxPL) form a class of chemically highly reactive metabolites. OxPL are acutely produced in inflamed tissue and act as endogenous, proalgesic (pain-inducing) metabolites. They excite sensory, nociceptive neurons by activating transient receptor potential ion channels, specifically TRPA1 and TRPV1. Under inflammatory conditions, OxPL-mediated receptor potentials even potentiate the action potential firing rate of nociceptors. Targeting OxPL with D-4F, an apolipoprotein A-I mimetic peptide or antibodies like E06, specifically binding oxidized headgroups of phospholipids, can be used to control acute, inflammatory pain syndromes, at least in rodents. With a focus on proalgesic specificities of OxPL, this article discusses, how targeting defined substances of the epilipidome can contribute to mechanism-based therapies against primary and secondary chronic inflammatory or possibly also neuropathic pain. KW - oxidized phospholipids KW - TRP channel KW - ion channel KW - analgesia KW - pain therapy KW - nociception KW - therapeutic antibody KW - mimetic peptide Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-223432 SN - 1664-2392 VL - 11 ER - TY - JOUR A1 - Lux, Thomas J. A1 - Hu, Xiawei A1 - Ben-Kraiem, Adel A1 - Blum, Robert A1 - Chen, Jeremy Tsung-Chieh A1 - Rittner, Heike L. T1 - Regional differences in tight junction protein expression in the blood−DRG barrier and their alterations after nerve traumatic injury in rats JF - International Journal of Molecular Sciences N2 - The nervous system is shielded by special barriers. Nerve injury results in blood–nerve barrier breakdown with downregulation of certain tight junction proteins accompanying the painful neuropathic phenotype. The dorsal root ganglion (DRG) consists of a neuron-rich region (NRR, somata of somatosensory and nociceptive neurons) and a fibre-rich region (FRR), and their putative epi-/perineurium (EPN). Here, we analysed blood–DRG barrier (BDB) properties in these physiologically distinct regions in Wistar rats after chronic constriction injury (CCI). Cldn5, Cldn12, and Tjp1 (rats) mRNA were downregulated 1 week after traumatic nerve injury. Claudin-1 immunoreactivity (IR) found in the EPN, claudin-19-IR in the FRR, and ZO-1-IR in FRR-EPN were unaltered after CCI. However, laser-assisted, vessel specific qPCR, and IR studies confirmed a significant loss of claudin-5 in the NRR. The NRR was three-times more permeable compared to the FRR for high and low molecular weight markers. NRR permeability was not further increased 1-week after CCI, but significantly more CD68\(^+\) macrophages had migrated into the NRR. In summary, NRR and FRR are different in naïve rats. Short-term traumatic nerve injury leaves the already highly permeable BDB in the NRR unaltered for small and large molecules. Claudin-5 is downregulated in the NRR. This could facilitate macrophage invasion, and thereby neuronal sensitisation and hyperalgesia. Targeting the stabilisation of claudin-5 in microvessels and the BDB barrier could be a future approach for neuropathic pain therapy. KW - tight junction KW - claudin-5 KW - neuropathic pain KW - nerve injury KW - dorsal root ganglion Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-285029 SN - 1422-0067 VL - 21 IS - 1 ER - TY - JOUR A1 - Oehler, Beatrice A1 - Kistner, Katrin A1 - Martin, Corinna A1 - Schiller, Jürgen A1 - Mayer, Rafaela A1 - Mohammadi, Milad A1 - Sauer, Reine-Solange A1 - Filipovic, Milos R. A1 - Nieto, Francisco R. A1 - Kloka, Jan A1 - Pflücke, Diana A1 - Hill, Kerstin A1 - Schaefer, Michael A1 - Malcangio, Marzia A1 - Reeh, Peter W. A1 - Brack, Alexander A1 - Blum, Robert A1 - Rittner, Heike L. T1 - Inflammatory pain control by blocking oxidized phospholipid-mediated TRP channel activation JF - Scientific Reports N2 - Phospholipids occurring in cell membranes and lipoproteins are converted into oxidized phospholipids (OxPL) by oxidative stress promoting atherosclerotic plaque formation. Here, OxPL were characterized as novel targets in acute and chronic inflammatory pain. Oxidized 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphocholine (OxPAPC) and its derivatives were identified in inflamed tissue by mass spectrometry and binding assays. They elicited calcium influx, hyperalgesia and induced pro-nociceptive peptide release. Genetic, pharmacological and mass spectrometric evidence in vivo as well as in vitro confirmed the role of transient receptor potential channels (TRPA1 and TRPV1) as OxPAPC targets. Treatment with the monoclonal antibody E06 or with apolipoprotein A-I mimetic peptide D-4F, capturing OxPAPC in atherosclerosis, prevented inflammatory hyperalgesia, and in vitro TRPA1 activation. Administration of D-4F or E06 to rats profoundly ameliorated mechanical hyperalgesia and inflammation in collagen-induced arthritis. These data reveal a clinically relevant role for OxPAPC in inflammation offering therapy for acute and chronic inflammatory pain treatment by scavenging OxPAPC. KW - chronic pain KW - ion channels in the nervous system KW - molecular medicine KW - pain Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-158536 VL - 7 IS - 5447 ER - TY - JOUR A1 - Schulte, Annemarie A1 - Blum, Robert T1 - Shaped by leaky ER: Homeostatic Ca\(^{2+}\) fluxes JF - Frontiers in Physiology N2 - At any moment in time, cells coordinate and balance their calcium ion (Ca\(^{2+}\)) fluxes. The term ‘Ca\(^{2+}\) homeostasis’ suggests that balancing resting Ca2+ levels is a rather static process. However, direct ER Ca\(^{2+}\) imaging shows that resting Ca\(^{2+}\) levels are maintained by surprisingly dynamic Ca\(^{2+}\) fluxes between the ER Ca\(^{2+}\) store, the cytosol, and the extracellular space. The data show that the ER Ca\(^{2+}\) leak, continuously fed by the high-energy consuming SERCA, is a fundamental driver of resting Ca\(^{2+}\) dynamics. Based on simplistic Ca\(^{2+}\) toolkit models, we discuss how the ER Ca\(^{2+}\) leak could contribute to evolutionarily conserved Ca\(^{2+}\) phenomena such as Ca\(^{2+}\) entry, ER Ca\(^{2+}\) release, and Ca\(^{2+}\) oscillations. KW - Ca2+ homeostasis KW - Ca2+ ion analysis KW - ER Ca2+ store KW - ER Ca2+ imaging KW - SERCA KW - store-operated Ca2+ entry KW - Ca2+ leak KW - Ca2+ oscillation Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-287102 SN - 1664-042X VL - 13 ER - TY - JOUR A1 - Ben-Kraiem, Adel A1 - Sauer, Reine-Solange A1 - Norwig, Carla A1 - Popp, Maria A1 - Bettenhausen, Anna-Lena A1 - Atalla, Mariam Sobhy A1 - Brack, Alexander A1 - Blum, Robert A1 - Doppler, Kathrin A1 - Rittner, Heike Lydia T1 - Selective blood-nerve barrier leakiness with claudin-1 and vessel-associated macrophage loss in diabetic polyneuropathy JF - Journal of Molecular Medicine N2 - Diabetic polyneuropathy (DPN) is the most common complication in diabetes and can be painful in up to 26% of all diabetic patients. Peripheral nerves are shielded by the blood-nerve barrier (BNB) consisting of the perineurium and endoneurial vessels. So far, there are conflicting results regarding the role and function of the BNB in the pathophysiology of DPN. In this study, we analyzed the spatiotemporal tight junction protein profile, barrier permeability, and vessel-associated macrophages in Wistar rats with streptozotocin-induced DPN. In these rats, mechanical hypersensitivity developed after 2 weeks and loss of motor function after 8 weeks, while the BNB and the blood-DRG barrier were leakier for small, but not for large molecules after 8 weeks only. The blood-spinal cord barrier remained sealed throughout the observation period. No gross changes in tight junction protein or cytokine expression were observed in all barriers to blood. However, expression of Cldn1 mRNA in perineurium was specifically downregulated in conjunction with weaker vessel-associated macrophage shielding of the BNB. Our results underline the role of specific tight junction proteins and BNB breakdown in DPN maintenance and differentiate DPN from traumatic nerve injury. Targeting claudins and sealing the BNB could stabilize pain and prevent further nerve damage. KW - macrophages KW - neuropathy KW - barrier KW - pain Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-265237 VL - 99 IS - 9 ER -