Intrathecal immune response in neuroborreliosis: importance of cross-reactive antibodies

The potential for CXCL13 in CSF as a differential diagnostic tool in central nervous system infection

Introduction: Central nervous system (CNS) infections can be life-threatening and are often associated with disabling sequelae. One important factor in most CNS infections is a timely pathogen-specific treatment. The diagnostic methods available, however, do not always reach a satisfying sensitivity and specificity. In these cases, there is need for additional diagnostic biomarkers. Chemokines represent potential candidates as biomarkers, since they are an important pillar of the host immune response. The aim of this review is to discuss the diagnostic potential of cerebrospinal fluid (CSF) CXCL13 in patients with CNS infections. Areas covered: Data were obtained from a literature search in PubMed up to October 2019. This review focusses on articles on the potential of CXCL13 as a diagnostic tool. The majority of identified studies aimed to characterize its role in two diseases, namely Lyme neuroborreliosis and neurosyphilis. Expert opinion: CSF CXCL13 has a significant potential as a diagnostic and monitoring add-on marker in Lyme neuroborreliosis. Differences in study design, control groups and clinical parameters between studies, however, affect sensitivity, specificity and cutoff values, underlining the need of further studies to address these issues and pave the way for a generalized clinical practice.

CSF B--lymphocyte chemoattractant (CXCL13) in the early diagnosis of acute Lyme neuroborreliosis

Recent studies have suggested a diagnostic role of the B-lymphocyte attracting chemokine (CXCL13) in the cerebrospinal fluid (CSF) in Lyme neuroborreliosis (LNB). Our aim was to evaluate diagnostic accuracy of CSF CXCL13 in a cohort of 59 consecutive patients referred to hospital for suspected LNB. Thirty-seven patients were classified as definite LNB and used as the reference standard. Seven were classified as probable, and seven as possible LNB. Eight patients did not fulfil case definitions and were used as controls. At presentation, CSF CXCL13 was elevated in all patients with definite LNB, as compared to a positive CSF B. burgdorferi (Bb) antibody index (AI) in 33 of 37. Pre-treatment sensitivity of elevated CSF [corrected] Bb Al [corrected] was 100 % (95 % CI = 91-100) and 89 % [corrected] (95 % CI = 75-96) respectively (p = 0.053). Among the eight control patients, CSF CXCL13 was normal in five and only slightly elevated in three, and Bb AI was negative in five. Specificity of CSF CXCL13 and Bb AI was similar 63 % (95 % CI = 31-86) (p = 1.0).CSF CXCL13 was elevated in 6/7 patients with probable LNB and 3/7 patients with possible LNB. Bb AI was negative in all these 14 patients. An additional control group consisted of 31 patients with multiple sclerosis (MS), 11 with non-inflammatory neurological diseases, and ten with verified non-Lyme meningitis and high CSF cell count. CSF CXCL13 was slightly elevated in 15 MS patients, and in nine meningitis patients. Mean CSF CXCL13 was higher in definite LNB (3524 ng/g CSF protein) than in MS (27 ng/g) and non-Lyme meningitis (23 ng/g) (p < 0.001). Four months post-treatment CSF CXCL13 was normalized in 82 % of patients with definite LNB, as compared to a negative Bb AI in 10 % (p < 0.001).CSF CXCL13 may be a useful supplement in early diagnosis of acute LNB.

Qualitative evidence of Ri specific IgG-synthesis in the cerebrospinal fluid from patients with paraneoplastic neurological syndromes

The presence of Ri-specific oligoclonal IgG bands in the CSF was investigated in five patients with paraneoplastic anti-Ri associated neurological syndromes (PNS) and six controls. In 4/5 CSF samples reactivity of IgG bands with recombinant Ri antigen was found using isoelectrofocusing combined with affinity blotting; in one patient with absence of oligoclonal bands of total IgG in CSF Ri-specific oligoclonal bands were detected with the same sample, indicating a higher sensitivity of Ri-specific affinity blotting as compared to affinity blotting with anti-human IgG antibodies. Our results confirm previous studies demonstrating IgG synthesis against onconeuronal antigens by intrathecal B-cell clones in PNS and extend this observation to patients with anti-Ri syndrome. The pathogenic relevance of these antibodies, however, is further challenged by the finding that specific intrathecal IgG synthesis might not be a prerequisite of CNS involvement, because it was missed in one of our patients.

Antigen-specific oligoclonal bands in cerebrospinal fluid and serum from patients with anti-amphiphysin- and anti-CV2/CRMP5 associated paraneoplastic neurological syndromes

Using isoelectric focusing and affinity blotting employing paraneoplastic recombinant antigens, we investigated cerebrospinal fluid (CSF) and sera from three patients with positive anti-CV2/CRMP5- and one patient with positive anti-amphiphysin serology. CSF and sera were previously adjusted to total IgG concentrations of 20 mg/l. All patients suffered from paraneoplastic neurological syndromes (PNS) with predominant involvement of the central nervous system (CNS). Using affinity blot preloaded with paraneoplastic antigen, we detected in three of four patients more or stronger specific oligoclonal bands (OCB) in the CSF than in the corresponding serum, providing qualitative evidence of antigen specific intrathecal antibody synthesis. These results are in line with previous studies demonstrating specific OCB predominantly in CSF from patients with anti-Hu-, anti-Yo- and anti-Ri-associated PNS, supporting the hypothesis of autoimmunity in the pathogenesis of PNS. One patient harboured extensive anti-amphiphysin specific OCB, although OCB of total IgG could not be detected, indicating a higher sensitivity for detection of intrathecal antibody synthesis of the affinity blot preloaded with the paraneoplastic antigen, compared with investigation of total IgG OCB. These results could have implications concerning pathophysiological autoimmune aspects in other inflammatory diseases of CNS associated with total IgG OCB, provided that the target antigen is known.

Severe tick-borne encephalitis in Slovenia in the years 2001–2005: Time for a mass vaccination campaign?

The aim of this retrospective study was to assess some clinical, epidemiological and laboratory parameters of severe tick-borne encephalitis in Slovenia in the last five years, to compare them with published data, and to estimate need for providing a policy of active immunization. Thirty-three adult patients with a severe course of the disease, admitted to the intensive care unit of the Department of Infectious Diseases, University Medical Centre Ljubljana, Slovenia during a five year period, participated. All the patients had specific serum IgM antibodies against tick-borne encephalitis virus at admissions and IgG antibodies were present in 29 out of 33 patients. Twenty-two patients were admitted because of severe consciousness disturbances, nine suffered from spinal nerve paralysis, in two patients cranial nerve paralysis was observed, and one suffered from generalized tonic-clonic seizures. Ten patients were mechanically ventilated and three died. Leukocytosis in peripheral veins was found in twenty-one patients and nine had a C-reactive protein serum concentration over 50 mg/l. Nineteen patients had a cerebrospinal fluid leukocyte count exceeding 100 x 10(6)/l and a cerebrospinal fluid protein concentration was over the cut-off value of 0.45 g/l in majority. The findings of the present study confirmed some previous reports about clinical, epidemiological and laboratory characteristics of patients with severe tick-borne encephalitis. We have found that tick-borne encephalitis in Slovenia has a relatively low fatality rate. However, the severe course with long-lasting sequelae of the disease justifies vaccination of a risk population in endemic areas.

Qualitative evidence of anti-Yo-specific intrathecal antibody synthesis in patients with paraneoplastic cerebellar degeneration

We investigated the presence of anti-Yo-specific oligoclonal antibody bands in cerebrospinal fluid (CSF) and serum samples of 9 patients with anti-Yo syndrome and 11 controls. Isoelectric focusing combined with affinity blotting, revealed anti-Yo-specific intrathecal antibody synthesis in all patients with anti-Yo syndrome: Four patients had positive anti-Yo-specific oligoclonal IgG bands in CSF which were not demonstrable in their sera; five CSF/serum pairs showed additional, more intensive, oligoclonal bands in CSF compared to the corresponding serum. Interestingly, four patients with absence of oligoclonal bands of total IgG in CSF revealed positive anti-Yo-specific oligoclonal bands in the same sample. This speaks for a higher sensitivity of detection of oligoclonal bands using an affinity blot loaded with Yo-specific antigen compared to an affinity blot coated with anti-human IgG used for the detection of oligoclonal bands of total IgG. In conclusion, the presence of anti-Yo-specific oligoclonal IgG bands in CSF which were absent, or less strong, in patients sera provides qualitative evidence of anti-Yo-specific IgG synthesis by intrathecal B-cell clones. These results could be of interest in detection of intrathecal-specific IgG synthesis in nervous system infectious diseases provided that the target antigen is known.

Prospective assessment of the etiology of acute febrile illness after a tick bite in Slovenia

A prospective study established the etiology of febrile illnesses in residents of Slovenia that occurred within 6 weeks after a tick bite. A combination of laboratory and clinical criteria identified 64 (49.2%) of 130 patients as having confirmed, probable, or possible cases of tickborne disease during 1995 and 1996. Of the 130 patients, 36 (27.7%) had laboratory evidence of tickborne encephalitis, all of whom had clinically confirmed disease. Evidence of infection with Borrelia burgdorferi sensu lato was identified in 26 patients; 10 (7.7%) had confirmed Lyme borreliosis. Of 22 patients with evidence of Ehrlichia phagocytophila infection, 4 (3.1%) had confirmed ehrlichiosis. Infection by multiple organisms was found in 19 (14.6%) of 130 patients. Patients with meningeal involvement (43 [72.3%] of 59) were more likely to have confirmed tickborne disease than were patients with illness of undefined localization (18 [26.5%] of 68; P<.0001). Tickborne viral and bacterial infections are an important cause of febrile illness in Slovenia.

Demonstration of anti-HuD specific oligoclonal bands in the cerebrospinal fluid from patients with paraneoplastic neurological syndromes. Qualitative evidence of anti-HuD specific IgG-synthesis in the central nervous system

The presence of HuD-specific oligoclonal IgG bands in the CSF was investigated in five patients with paraneoplastic neurological syndromes. All patients revealed intrathecal synthesis of HuD specific antibodies in the CSF, as estimated from elevated antibody indices (>1.5) in an IgG-ELISA using recombinant HuD-protein as antigen. Isoelectrofocussing combined with affinity blotting showed reactivity of IgG bands with recombinant HuD antigen in all CSF samples. These data support the idea that HuD specific antibodies in the CSF are produced mainly by B-cell clones in the central nervous system. These findings support the hypothesis of autoimmunity in the pathogenesis of anti-Hu associated paraneoplastic neurological syndromes.

Concomitant infection with tick-borne encephalitis virus and Borrelia burgdorferi sensu lato in patients with acute meningitis or meningoencephalitis

From September 1992 to August 1993, 338 patients over the age of 15 years presented to the Department of Infectious Diseases, University Medical Centre Ljubljana, with acute lymphocytic meningitis. In 89 of these patients (26.3%) serum IgM and IgG antibodies against tick-borne encephalitis (TBE) virus were detected, and in 59 patients (17.5%) a borrelial etiology of disease was demonstrated by one or more of the following presence of intrathecal antibody production, seroconversion to borrelial antigens, presence of erythema migrans, and/or isolation of Borrelia burgdorferi sensu lato from skin or cerebrospinal fluid. Of the 148 patients who fulfilled criteria for TBE or borrelial infection, concomitant infection with TBE virus and B. burgdorferi sensu lato was demonstrated in 12 patients (3.6% of all patients presenting with acute lymphocytic meningitis). In the majority of patients with concomitant infection the clinical features at presentation were characteristic of, or consistent with, TBE. In addition, during follow-up studies, eight of the 12 patients subsequently developed signs and symptoms compatible with minor and/or major manifestations of Lyme borreliosis. Six patients were diagnoses with neuroborreliosis based on signs or symptoms and/or laboratory tests. These findings show that in patients with acute lymphocytic meningitis or meningoencephalitis, originating in TBE and Lyme borreliosis endemic regions, the possibility of concomitant infection should be considered.

Analysis of the intrathecal immune response in neuroborreliosis to a sonicate antigen and three recombinant antigens of Borrelia burgdorferi sensu stricto

The intrathecal synthesis of borrelial-specific IgM- and IgG-antibodies was studied in 67 patients with neuroborreliosis and in 14 patients with neurosyphilis (controls). Antibody concentrations in serum and in the cerebrospinal fluid were determined by an enzyme immunoassay (EIA) using, as antigens, a sonicate of Borrelia burgdorferi, the recombinant 14 kDa flagellin fragment, the outer surface protein C (22 kDa), and the high molecular mass protein p83 (83 kDa). In the sonicate EIA, IgG- and/or IgM-antibodies to Borrelia burgdorferi in serum were detected in all patients with neuroborreliosis and in 71% of patients with neurosyphilis. Intrathecal synthesis of borrelial-specific IgG- and/or IgM-antibodies was demonstrated in 82% of patients with neuroborreliosis and in 71% of patients with neurosyphilis. Immunoglobulin G- and/or IgM-antibodies in serum against any of the recombinant antigens were detected in 92% of patients with neuroborreliosis and in none of those with neurosyphilis. Intrathecal synthesis of IgG- and/or IgM-antibodies to individual recombinant antigens was demonstrated in 67% of patients with neuroborreliosis and in none of those with neurosyphilis. The sensitivity of the recombinant antigens in serum was almost equal to that of the sonicate EIA, whereas the recombinant antigens were clearly less sensitive in the estimation of the intrathecal specific immune response. It was concluded that in suspected cases of neuroborreliosis, the estimation of high specific antibodies in the recombinant EIA will be helpful in confirming the diagnosis.