CXCL13 in Cerebrospinal Fluid: Clinical Value in a Large Cross-Sectional Study

Cerebrospinal Fluid Cytology in Lyme Neuroborreliosis Revisited-Role of Neutrophilic Granulocytes: A Retrospective Single-Center Study

Background/Objectives: diagnosis of Lyme neuroborreliosis (LNB) relies on medical history, clinical findings, and detection of pathogen-specific antibodies in the blood and cerebrospinal fluid (CSF). The chemoattractant CXCL13 serves as an additional marker for LNB acuity. During the diagnostic workup, cytomorphological examination of immune cells in CSF provides early insights. Lympho-monocytic pleocytosis with plasma cells and activated lymphocytes is usually described as a typical feature of LNB. In contrast we frequently observe a cytological cell picture featuring neutrophilic granulocytes as well as activated mononuclear cells and plasma cells in patients with LNB, which we refer to as a mixed cell picture. We, hence, investigated the presence of granulocytes to determine their role as typical findings associated with LNB. Methods: we conducted a retrospective analysis of CSF cytology in patients diagnosed with definite LNB at the Department of Neurology, Christian Doppler Medical Centre, Salzburg between 2015 and 2021. CSF results of patients with more than 10 erythrocytes/µL were excluded to avoid the presence of granulocytes due to artificial blood contamination. Additionally, CXCL13 levels were recorded, where available. Results: a total of 75 patients (42 female; 56%) met the diagnostic criteria of definite LNB. Cytology revealed the presence of granulocytes in the CSF of 91% of the patients (68/75). CXCL13 elevation was found to be significantly associated with the presence of granulocytes in CSF (p = 0.0025, or 1.009 (95% CI: 1.003-1.016). Conclusions: we confirm a mixed cell picture with granulocytes, activated mononuclear cells and plasma cells being a typical finding in the CSF cytology of LNB. The association between granulocytes and elevated CXCL13 suggests that their presence is a specific feature of the acute, untreated phase of LNB.

CXCL13 as a Biomarker: Background and Utility in Multiple Sclerosis

CXCL13 is a chemokine which is upregulated within the CNS in multiple sclerosis, Lyme neuroborreliosis, and other inflammatory diseases and is increasingly clinically useful as a biomarker. This review provides background for understanding its function in the immune system and its relationship to ectopic lymphoid follicles. Also reviewed are its utility in multiple sclerosis and Lyme neuroborreliosis and potential problems in its measurement. CXCL13 has the potential to be an exceptionally useful biomarker in a range of inflammatory diseases.

CXCL13: a common target for immune-mediated inflammatory diseases

CXCL13 is a chemokine that plays an important role in the regulation and development of secondary lymphoid organs. CXCL13 is also involved in the regulation of pathological processes, particularly inflammatory responses, of many diseases. The function of CXCL13 varies depending on the condition of the host. In a healthy condition, CXCL13 is mainly secreted by mouse stromal cells or human follicular helper T cells, whereas in diseases conditions, they are produced by human peripheral helper T cells and macrophages in non-lymphoid tissues; this is termed ectopic expression of CXCL13. Ectopic CXCL13 expression is involved in the pathogenesis of various immune-mediated inflammatory diseases as it regulates the migration of B lymphocytes, T lymphocytes, and other immune cells in inflammatory sites as well as influences the expression of inflammatory factors. Additionally, ectopic expression of CXCL13 plays a key role in ectopic lymphoid organ formation. In this review, we focused on the sources of CXCL13 in different conditions and its regulatory mechanisms in immune-mediated inflammatory diseases, providing novel ideas for further research on targeting CXCL13 for the treatment of immune-mediated inflammatory diseases.

Body fluid markers for multiple sclerosis and differential diagnosis from atypical demyelinating disorders

INTRODUCTION

Body fluid markers could be helpful to predict the conversion into clinically definite multiple sclerosis (MS) in people with a first demyelinating event of the central nervous system (CNS). Consequently, biomarkers such as oligoclonal bands, which are integrated in the current MS diagnostic criteria, could assist early MS diagnosis.

AREAS COVERED

This review examines existing knowledge on a broad spectrum of body fluid markers in people with a first CNS demyelinating event, explores their potential to predict conversion to MS, to assess MS disease activity, as well as their utility to differentiate MS from atypical demyelinating disorders such as neuromyelitis optica spectrum disorder and myelin oligodendrocyte glycoprotein associated disease.

EXPERT OPINION

This field of research has shown a dramatic increase of evidence, especially in the last decade. Some biomarkers are already established in clinical routine (e.g. oligoclonal bands) while others are currently implemented (e.g. kappa free light chains) or considered as breakthroughs (e.g. neurofilament light). Determination of biomarkers poses challenges for continuous monitoring, especially if exclusively detectable in cerebrospinal fluid. A handful of biomarkers are measurable in blood which holds a significant potential.

Proinflammatory Chemokine Levels in Cerebrospinal Fluid of Patients with Neuroinvasive Flavivirus Infections

Tick-borne encephalitis virus (TBEV) and West Nile virus (WNV) are the most important neuroinvasive arboviruses detected in Europe. In this study, we analyzed cerebrospinal fluid (CSF) concentrations of 12 proinflammatory chemokines (CCL2, CCL3, CCL4, CCL11, CCL17, CCL20, CXCL1, CXCL5, CXCL8, CXCL9, CXCL10, and CXCL11) in 77 patients with neuroinvasive diseases (NIDs). Flavivirus infection was confirmed in 62 patients (TBEV and WNV in 31 patients each), while in 15 patients the etiology of NID was not determined (NDE). Similar patterns of high-level expression of chemokines regulating monocyte/macrophage responses (CCL2), neutrophil recruitment (CXCL1 and CXCL8), and interferon-inducible chemoattractants for leukocytes (CXCL10 and CXCL11) have been observed in WNV and TBEV groups. None of the tested chemokines significantly differed between patients with TBEV or WNV. Concentrations of CCL17, CCL20, CXCL5, CXCL10, and CXCL11 were significantly lower in both WNV and TBEV groups compared to NID NDE patients. The logistic regression model showed that CSF concentrations of CXCL11, CXCL5, and CXCL10 could potentially be used for the classification of patients into the WNV or TBEV group versus groups with other NIDs. This study identified, for the first time, similar patterns of CSF chemokine expression in WNV and TBEV infections, suggesting common immunopathogenic mechanisms in neuroinvasive flavivirus infections that should be further evaluated.