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Abstract Background New onset or worsening of a headache disorder substantially contributes to the disease burden of post-COVID-19. Its management poses a suitable means to enhance patients’ participation in professional, social, and personal activities. Unfortunately, the pathophysiology of post-COVID-19 headaches is poorly understood. This study aims to investigate the role of (neuro-) inflammatory mechanisms in order to guide the development of anti-inflammatory treatment strategies. Methods We included patients from the interdisciplinary post-COVID-19 Rehabilitation Study (PoCoRe, n = 184 patients) run at a tertiary care university hospital, comprising patients with PCR-confirmed SARS-CoV-2 infection ≥ 6 weeks prior to their initial consultation. Patients reporting any headache since their infection were considered for this study (n = 93). These were interviewed and classified according to the International Classification of Headache Disorders, Third Edition (ICHD-3) by headache specialists. Patient sera were additionally analysed for levels of VILIP-1, MCP-1 (CCL2), sTREM-2, BDNF, TGF-ß1, VEGF, IL-6, sTREM-1, ß-NGF, IL-18, TNF-alpha, sRAGE, and CX3CL1 (Fractalkine). Markers of inflammation were compared between four groups of patients (none, unchanged, worsened, or new headache disorder). Results Patients reported experiencing more severe headaches (n = 17), new onset headaches (n = 46), unchanged headaches (n = 18), and surprisingly, some patients denied having any headaches (n = 12) despite self-reports. Serum levels of CX3CL1 were increased in the worsened (2145 [811–4866] pg/ml) and new onset (1668 [0-7357] pg/ml) headache group as compared to patients with no (1129 [0-5379] pg/ml) or unchanged (1478 [346–4332] pg/ml) headaches. Other markers also differed between groups, but most significantly between patients with worsened (TGF-ß1: 60 [0-310] pg/ml, VEGF: 328 [86–842] pg/ml, ß-NGF: 6 [3–38] pg/ml) as compared to unchanged headaches (TGF-ß1: 29 [0–77] pg/ml, VEGF: 183 [72–380] pg/ml, ß-NGF: 3 [2–89] pg/ml). The results did not differ between headache phenotypes. Discussion This study provides evidence that worsened or new headaches following COVID-19 are associated with pro-(neuro-)inflammatory profiles. This supports the use of anti-inflammatory treatment options in this population, especially in the subacute phase.

Abstract Background To date, migraine is diagnosed exclusively based on clinical criteria, but fluid biomarkers are desirable to gain insight into pathophysiological processes and inform clinical management. We investigated the state-dependent profile of fluid biomarkers for neuroaxonal damage and microglial activation as two potentially relevant aspects in human migraine pathophysiology. Methods This exploratory study included serum and cerebrospinal fluid (CSF) samples of patients with migraine during the headache phase (ictally) (n = 23), between attacks (interictally) (n = 16), and age/sex-matched controls (n = 19). Total Tau (t-Tau) protein, glial fibrillary acidic protein (GFAP), ubiquitin carboxy-terminal hydrolase L1 (UCH-L1), and neurofilament light chain (NfL) were measured with the Neurology 4-plex kit on a Single Molecule Array SR-X Analyzer (Simoa® SR-X, Quanterix Corp., Lexington, MA). Markers of microglial activation, C-X3-C motif chemokine ligand 1 (CX3CL1) and soluble triggering receptor expressed on myeloid cells 2 (sTREM2), were assessed using an immunoassay. Results Concentrations of CX3CL1 but not sTREM2 were significantly increased both ictally and interictally in CSF but not in serum in comparison to the control cohort (p = 0.039). ROC curve analysis provided an AUC of 0.699 (95% CI 0.563 to 0.813, p = 0.007). T-Tau in serum but not in CSF was significantly increased in samples from patients taken during the headache phase, but not interictally (effect size: η2 = 0.121, p = 0.038). ROC analysis of t-Tau protein in serum between ictal and interictal collected samples provided an AUC of 0.729 (95% CI 0.558 to 0.861, p = 0.006). The other determined biomarkers for axonal damage were not significantly different between the cohorts in either serum or CSF. Discussion CX3CL1 in CSF is a novel potential fluid biomarker of migraine that is unrelated to the headache status. Serum t-Tau is linked to the headache phase but not interictal migraine. These data need to be confirmed in a larger hypothesis-driven prospective study.

Abstract Introduction Immunological alterations associated with increased susceptibility to infection are an essential aspect of stroke pathophysiology. Several immunological functions of adipose tissue are altered by obesity and are accompanied by chronic immune activation. The purpose of this study was to examine immune function (monocytes, granulocytes, cytokines) as a function of body mass index (BMI: 1st group: 25; 2nd group: 25 BMI 30; 3rd group: 30) and changes in body weight post stroke. Method Fat status was assessed using standardized weight measurements on days 1, 2, 3, 4, 5, and 7 after ischemic stroke in a cohort of 40 stroke patients and 16 control patients. Liver fat and visceral fat were assessed by MRI on day 1 or 2 [I] and on day 5 or 7 [II]. Leukocyte subpopulations in peripheral blood, cytokines, chemokines, and adipokine concentrations in sera were quantified. In a second cohort (stroke and control group, n = 17), multiple regression analysis was used to identify correlations between BMI and monocyte and granulocyte subpopulations. Results Weight and fat loss occurred from the day of admission to day 1 after stroke without further reduction in the postischemic course. No significant changes in liver or visceral fat were observed between MRI I and MRI II. BMI was inversely associated with IL-6 levels, while proinflammatory cytokines such as eotaxin, IFN-β, IFN -γ and TNF-α were upregulated when BMI increased. The numbers of anti-inflammatory CD14+CD16+ monocytes and CD16+CD62L− granulocytes were reduced in patients with higher BMI values, while that of proinflammatory CD16dimCD62L+ granulocytes was increased. Conclusion A small weight loss in stroke patients was detectable. The data demonstrate a positive correlation between BMI and a proinflammatory poststroke immune response. This provides a potential link to how obesity may affect the clinical outcome of stroke patients.

Abstract Background Stroke induces immune alterations such as impaired oxidative burst and reduced release of neutrophil extracellular traps (NETs). We hypothesised that key enzymes of these defence mechanisms may be altered in ischaemic stroke. Therefore, we analysed the intra- and extracellular amounts of myeloperoxidase (MPO) and neutrophil elastase (NE) in patient sera and granulocytes and monocytes. Because the autonomous nervous system is thought to mediate stroke-induced immune alterations, we also studied the influence of stress hormones and acetylcholine on MPO and NE. Rapid recanalization by recombinant tissue plasminogen activator (r-tPA) is the only available treatment for ischaemic stroke besides thrombectomy, and its influence on antibacterial defence mechanisms of granulocytes and monocytes were addressed here. Methods Ex vivo: Intracellular and serum MPO and NE were measured on days 0, 1, 3 and 5 post-stroke by either flow cytometry or enzyme-linked immunosorbent assay (ELISA) and compared to controls. In vitro: Blood from healthy donors was incubated with catecholamines, dexamethasone and acetylcholine, and the percentage of NET-producing cells and the area covered by NETs were quantified immunohistochemically. Intra- and extracellular MPO and NE were quantified by flow cytometry or ELISA. Blood samples from healthy donors were incubated with r-tPA, and oxidative burst, phagocytosis, NETosis, cytokine release, MPO and NE were quantified by flow cytometry, ELISA and microscopy. Results MPO was reduced in granulocytes but increased in sera obtained from stroke patients compared to controls. NE was not altered intracellularly but was elevated in patient sera. The percentage of NET-producing neutrophils was decreased by stress hormones and increased by acetylcholine. Neither intracellular MPO nor NE was altered by hormone treatment; however, adrenaline and acetylcholine induced NE release. r-tPA led to reduced phagocytosis and oxidative burst in granulocytes and monocytes in vitro. NETosis, MPO release and cytokines were not altered, whereas NE release was enhanced by r-tPA. Conclusions Intracellular reduction of MPO might be responsible for reduced NETosis in stroke patients. The impact of enhanced MPO and NE serum levels in stroke patients should be addressed in future studies. r-tPA impaired antibacterial defence function in vitro. Therefore, patients who undergo unsuccessful recanalization therapy might be at higher risk for infection, which should be analysed in future investigations. Immune alterations due to r-tPA effects in stroke patients should also be investigated.