Tick-borne diseases and the central nervous system : clinical and immunological aspects

Lyme neuroborreliosis (LNB) is the dominating form of disseminated infection by the tick-borne bacteria Borrelia (B.) burgdorferi in Sweden as well as in Europe. The diagnosis of the manifestation is based on typical symptoms, together with elevated mononuclear cell count in the cerebrospinal fluid (CSF) and elevated levels of Borrelia-specific antibodies in the CSF. The diagnostic arsenal has, in recent years, been complemented by analysis of the chemokine CXCL13 in the CSF, with increasing levels in the early phase of the disease, even before antibodies can be detected in the CSF. Most patients recover within a couple of months after antibiotic treatment, but a few can suffer from residual symptoms. The mechanisms behind this are still puzzling, but there are indications that the host´s immune response may play a role. Prognostic markers would be desirable and in-creased understanding of pathogenetic mechanisms may provide a basis for development of new treatment strategies. Other agents besides B. burgdorferi have, however, also been detected in ticks collected in Sweden, but the knowledge of their impact on human health and their ability to invade the central nervous system (CNS) is limited.    The aims of this thesis were to investigate a set of cytokines and chemokines associated with Th1 (CXCL10), Th2 (CCL22), Th17 (IL-17A, CXCL1, CCL20) and B cell (APRIL, BAFF, CXCL13) -related im-munity and its association with recovery in patients with LNB included both retrospectively and prospectively. The chemokine CXCL13 was further analysed, comparing the performance of two different diagnostic methods. In a large cohort of patients investigated for LNB we investigated signs of other tick-borne diseases by analysing serum and CSF using both molecular and serological techniques.   In the retrospective cytokine/chemokine study, all investigated cytokines and chemokines; namely, APRIL, BAFF, CXCL13, IL-17A, CXCL1, and CCL20 could be detected at elevated levels in patients with LNB compared to controls. Patients with recovery &gt; 3 months had higher levels of APRIL, BAFF, and IL-17A. In the prospective study, patients with short recovery (&lt; 1 month) had lower levels of CCL20 and patients with prolonged recovery (&gt; 6 months) had higher levels of IL-17A. The analysis of the chemokine CXCL13 with both an enzyme-linked immunosorbent assay (ELISA) with a best-performanced cut-off of 56 pg/mL and bead-based (Luminex) method with a best-performance cut-off of 158 pg/mL (both assays with 100% sensitivity and specificity) displayed the im-portance of different cut-offs depending on which method that is used. In 600 patients, we analysed serum and CSF with PCR for the different tick-borne agents Ana-plasma phagocytophilum, B. burgdorfer spp. (including B. miyamotoi), Neoehrlichia (N.) mikurensis, Rickettsia spp., Babesia spp. and tick-borne encephalitis virus. N. mikurensis and B. burgdorferi could be detected by PCR in sera from two patients. Neither PCR, nor serological analysis could detect any potential co-infections. In conclusion, we can corroborate the Th17-related immunity in the pathogenesis of LNB where IL-17A and CCL20 are plausible prognostic markers. Other tick-borne pathogens with possible dissemination to the CNS seems to be uncommon in south-eastern Sweden.   Funding agencies: This thesis was funded by grants from Futurum – the Academy of Health and Care, Region Jönköping County and the Medical Research Council of Southeast Sweden, FORSS.</p

Whipples disease : the great masquerader - a high level of suspicion is the key to diagnosis

Background: Whipples disease is a chronic infectious disease that primarily affects the small intestine, but several organs can simultaneously be involved. The disease is caused by a gram-positive bacterium called Tropheryma whipplei. The disease is difficult to suspect because it is rare with unspecific and long-term symptoms; it can be lethal if not properly treated. Case presentation: We here present three patients who presented with a plethora of symptoms, mainly long-standing seronegative arthritis and gastrointestinal symptoms in the form of diarrhea with blood, weight loss, fever, and lymphadenopathy. They were after extensive investigations diagnosed with Whipples disease, in two of them as long as 8 years after the first occurrence of joint manifestations. The diagnosis was made by PCR targeting the T. whipplei 16S rRNA gene from small bowel specimen in all three patients, and, besides from histopathologic findings from the duodenum and distal ileum in one and mesenteric lymph nodes in another patient. Conclusions: This report aims to raise awareness of a very rare disease that presents with a combination of symptoms mimicking other and significantly more common diseases

Evaluation of two assays for CXCL13 analysis in cerebrospinal fluid for laboratory diagnosis of Lyme neuroborreliosis

We evaluated the diagnostic performance of two assays, one bead-based assay and one enzyme-linked immunosorbent assay (ELISA), for the determination of CXCL13 levels in cerebrospinal fluid (CSF) from patients with suspected Lyme neuroborreliosis (LNB). Patients investigated for LNB were retrospectively included (n = 132): 35 with definite LNB, 8 with possible LNB with CSF pleocytosis but normal antibody index (AI), 6 with possible LNB with elevated AI but no CSF pleocytosis and 83 non-LNB patients. CSF samples had been drawn before antibiotic treatment and were analysed for CXCL13 by Quantikine ELISA (Ramp;D Systems) and recomBead (Mikrogen). Receiver operating characteristic analyses based on the definite LNB and non-LNB groups revealed a best performance cut-off of 56 pg/mL for Quantikine and 158 pg/mL for recomBead (sensitivity and specificity 100% for both assays). When applying these cut-off levels on the study groups, the two assays performed equally well regarding sensitivity and specificity. In the group of patients with pleocytosis but negative AI, the majority of whom were children with short symptom duration, the CXCL13 analysis supported the LNB diagnosis in half of the cases. We consider CSF-CXCL13 analysis a useful diagnostic tool, in addition to Borrelia-specific AI, in laboratory diagnostics of LNB.Funding Agencies|Division of Medical Services, Region Jonkoping County; ScandTick Innovation, an Interreg V A project</p

Intrathecal Th17-driven inflammation is associated with prolonged post-treatment convalescence for patients with Lyme neuroborreliosis

Lyme neuroborreliosis (LNB) is associated with increased levels of pro-inflammatory cytokines and chemokines in the cerebrospinal fluid (CSF). Residual symptoms after antibiotic treatment can have deleterious effects on patients and knowledge regarding the pathogenesis linked to prolonged recovery is lacking. In this prospective follow-up study, we investigated the B cell-associated and T helper (Th) cell-associated immune responses in well-characterized patients with LNB and controls. The aims were to assess the kinetics of selected cytokines and chemokines involved in the inflammatory response and to identify potential prognostic markers. We investigated 13 patients with LNB according to a standardized clinical protocol before antibiotic treatment and after 1, 6 and 12 months of follow-up. CSF and blood samples were obtained at baseline and after 1 month. As controls, we used CSF samples from 37 patients who received spinal anesthesia during orthopedic surgery. The CSF samples were analyzed for CXCL10 (Th1-related), CCL22 (Th2-related) and IL-17A, CXCL1 and CCL20 (Th17-related), as well as for the B cell-related cytokines of a proliferation-inducing ligand (APRIL), B cell-activating factor (BAFF) and CXCL13. The CSF levels of all the cytokines and chemokines, with the exception of APRIL, were significantly higher at baseline in patients with LNB compared with controls. All the cytokines and chemokines, except for IL-17A were significantly reduced at 1-month follow-up. Patients with quick recovery (&amp;lt; 1 month, n = 3) had significantly lower levels of CCL20 at baseline and lower levels of IL-17A at 1-month follow-up. Patients with time of recovery &amp;gt; 6 months (n = 7) had significantly higher levels of IL-17A at the one-month follow-up. No other cytokines or chemokines were associated with prolonged recovery. Dominating residual symptoms were fatigue, myalgia, radiculitis and/or arthralgia. In this prospective follow-up study of patients with LNB, we found significantly lower levels of CCL20 in those who recovered rapidly, and increased levels of IL-17A in patients with delayed recovery post-treatment. Our findings indicate persistent Th17-driven inflammation in the CSF, possibly contributing to a longer convalescence, and suggest IL-17A and CCL20 as potential biomarker candidates for patients with LNB

CXCL13 in laboratory diagnosis of Lyme neuroborreliosis-the performance of the recomBead and ReaScan CXCL13 assays in human cerebrospinal fluid samples

The chemokine CXCL13 is used as complement to serology in the diagnostics of Lyme neuroborreliosis (LNB). We evaluated and compared the semi-quantitative, cassette-based ReaScan CXCL13 assay with the quantitative recomBead CXCL13 assay using a collection of 209 cerebrospinal fluid samples. The categorical agreement between results interpreted as negative, grey zone, and positive by the two methods was 87%. The diagnostic sensitivity was higher using the recomBead assay, whereas specificity was higher using ReaScan. Few manual steps, and a short turn-around time with no batching of samples makes the ReaScan CXCL13 assay an attractive complement to serology in the diagnostics of LNB.Funding Agencies|European Union through the European Regional Development FundEuropean Commission; Interreg North Sea Region Programme [J-No: 38-2-7-19]</p

Cerebrospinal fluid markers of inflammation and brain injury in Lyme neuroborreliosis - a prospective follow-up study

OBJECTIVES: The purpose of this study was to evaluate levels and kinetics of cerebrospinal fluid (CSF) markers of inflammation and brain injury in patients with Lyme neuroborreliosis (LNB). METHODS: Adult patients with clinically suspected LNB were enrolled, in a prospective clinical study in the South East of Sweden. Patients were classified according to the European Federation of Neurological Societies’ guidelines. Definite cases of LNB were re-examined one month later including a repeat CSF investigation. Routine laboratory parameters were investigated along with CSF levels of neurodegenerative markers glial fibrillary acidic protein (GFAp), total tau (t-tau) and neurofilament light protein (NFL), as well as neuroinflammatory markers soluble triggering receptor expressed on myeloid cells 2 (sTREM2), YKL-40 and CXCL13. Non-LNB served as controls. An additional comparison group consisted of spinal anesthesia subjects (SAS) without known central nervous system conditions. RESULTS: CSF levels of sTREM2 and CXCL13 were elevated in definite LNB patients at diagnosis compared with non-LNB patients (p<0.001) and SAS (p≤0.01). In addition, CSF levels of sTREM2, YKL-40 and CXCL13 rapidly declined in at follow-up after antibiotic treatment. In contrast, CSF levels of GFAp and t-tau did not differ across LNB groups, and did not change after treatment. CONCLUSIONS: Although in a limited number of LNB patients, the results indicate a predominance of microglial and neuroinflammatory involvement rather than parenchymal CNS injury in CSF at diagnosis of LNB with a prompt decline after antibiotic treatment. The findings provide pathogenetic insights and may be of value in differential diagnosis of CSF findings

Low risk of seroconversion or clinical disease in humans after a bite by an Anaplasma phagocytophilum-infected tick

The risk of contracting human granulocytic anaplasmosis (HGA) after a tick bite is mainly unknown. In this study we investigated the clinical and serological response in 30 humans bitten by ticks positive for Anaplasma phagocytophilum (Group A), 30 humans bitten by Borrelia burgdorferi sensu lato (s.l.)-positive ticks (Group B), and 30 humans bitten by ticks negative for both A. phagocytophilum and B. burgdorferi s.l. (Group C). Ticks, blood samples and questionnaires were collected from tick-bitten humans at 34 primary healthcare centres in Sweden and in the Åland Islands, Finland, at the time of the tick bite and after three months. A total of 2553 ticks detached from humans in 2007-2009 were analyzed by polymerase chain reaction, and 31 (1.2%) were positive for A. phagocytophilum, 556 (21.8%) were positive for B. burgdorferi s.l., and eight (0.3%) were co-infected by A. phagocytophilum and B. burgdorferi s.l. The overall prevalence of Anaplasma IgG antibodies in the included participants (n=90) was 17%, and there was no significant difference between the groups A-C. Only one of the participants (in Group C) showed a four-fold increase of IgG antibodies against A. phagocytophilum at the three-month follow-up, but reported no symptoms. The frequency of reported symptoms did not differ between groups A-C, and was unrelated to the findings of A. phagocytophilum and B. burgdorferi s.l. in the detached ticks. We conclude that the risk for HGA or asymptomatic seroconversion after a tick bite in Sweden or in the Åland Islands is low, even if the tick is infected by A. phagocytophilum.Funding text: Swedish Research Council; Medical Research Council of Southeast Sweden (FORSS); Futurum Academy of Healthcare; Jonkoping County Council; Interreg IV A Programme ScandTick; Division of Medical Services, Ryhov County Hospital, Jonkoping</p

Low risk of seroconversion or clinical disease in humans after a bite by an Anaplasma phagocytophilum-infected tick

The risk of contracting human granulocytic anaplasmosis (HGA) after a tick bite is mainly unknown. In this study we investigated the clinical and serological response in 30 humans bitten by ticks positive for Anaplasma phagocytophilum (Group A), 30 humans bitten by Borrelia burgdorferi sensu lato (s.l.)-positive ticks (Group B), and 30 humans bitten by ticks negative for both A. phagocytophilum and B. burgdorferi s.l. (Group C). Ticks, blood samples and questionnaires were collected from tick-bitten humans at 34 primary healthcare centres in Sweden and in the Åland Islands, Finland, at the time of the tick bite and after three months. A total of 2553 ticks detached from humans in 2007-2009 were analyzed by polymerase chain reaction, and 31 (1.2%) were positive for A. phagocytophilum, 556 (21.8%) were positive for B. burgdorferi s.l., and eight (0.3%) were co-infected by A. phagocytophilum and B. burgdorferi s.l. The overall prevalence of Anaplasma IgG antibodies in the included participants (n=90) was 17%, and there was no significant difference between the groups A-C. Only one of the participants (in Group C) showed a four-fold increase of IgG antibodies against A. phagocytophilum at the three-month follow-up, but reported no symptoms. The frequency of reported symptoms did not differ between groups A-C, and was unrelated to the findings of A. phagocytophilum and B. burgdorferi s.l. in the detached ticks. We conclude that the risk for HGA or asymptomatic seroconversion after a tick bite in Sweden or in the Åland Islands is low, even if the tick is infected by A. phagocytophilum.Funding text: Swedish Research Council; Medical Research Council of Southeast Sweden (FORSS); Futurum Academy of Healthcare; Jonkoping County Council; Interreg IV A Programme ScandTick; Division of Medical Services, Ryhov County Hospital, Jonkoping</p

Are other tick-borne infections overlooked in patients investigated for Lyme neuroborreliosis? : A large retrospective study from South-eastern Sweden

In Europe, the hard tick Ixodes ricinus is considered the most important vector of human zoonotic diseases. Human pathogenic agents spread by I. ricinus in Sweden include Borrelia burgdorferi sensu lato (s.l.), Anaplasma phagocytophilum, Rickettsia helvetica, the recently described Neoehrlichia mikurensis, Borrelia miyamotoi, tick-borne encephalitis virus (TBEV), and Babesia spp. (Babesia microti, Babesia venatorum and Babesia divergens). Since these pathogens share the same vector, co-infections with more than one tick-borne pathogen may occur and thus complicate the diagnosis and clinical management of the patient due to possibly altered symptomatology. Borrelia burgdorferi s.l., TBEV and B. miyamotoi are well-known to cause infections of the central nervous system (CNS), whereas the abilities of other tick-borne pathogens to invade the CNS are largely unknown. The aim of this study was to investigate the presence and clinical impact of tick-borne pathogens other than B. burgdorferi s.l. in the cerebrospinal fluid (CSF) and serum samples of patients who were under investigation for Lyme neuroborreliosis (LNB) in a tick-endemic region of South-eastern Sweden. CSF and serum samples from 600 patients, recruited from the Regions of center dot Ostergo center dot tland County, Jo center dot nko center dot ping County and Kalmar County in South-eastern Sweden and investigated for LNB during the period of 2009-2013, were retrospectively collected for analysis. The samples were analysed by real-time PCR for the presence of nucleic acid from B. burgdorferi s.l., B. miyamotoi, A. phagocytophilum, Rickettsia spp., N. mikurensis, TBEV and Babesia spp. Serological analyses were conducted in CSF and serum samples for all patients regarding B. burgdorferi s.l., and for the patients with CSF mononuclear pleocytosis, analyses of antibodies to B. miyamotoi, A. phagocytophilum, spotted fever group (SFG) rickettsiae, TBEV and B. microti in serum were performed. The medical charts of all the patients with CSF mononuclear pleocytosis and patients with positive PCR findings were reviewed. Of the 600 patients, 55 (9%) presented with CSF mononuclear pleocytosis, 13 (2%) of whom had Borrelia-specific antibodies in the CSF. One patient was PCRpositive for N. mikurensis, and another one was PCR-positive for Borrelia spp. in serum. No pathogens were detected by PCR in the CSF samples. Four patients had serum antibodies to B. miyamotoi, four patients to A. phagocytophilum, five patients to SFG rickettsiae, and six patients to TBEV. One patient, with antibodies to SFGFunding Agencies|Medical Research Council of Southeastern Sweden (FORSS), ALF Grants, Region Ostergotland; Futurum -the Academy for Health and Care, Department of Laboratory Medicine, Region Jonkoping County; EU Interreg IVA project ScandTick Innovation; North Sea Programme of the European Regional Development Fund of the European Union</p

Intrathecal Th17- and B cell-associated cytokine and chemokine responses in relation to clinical outcome in Lyme neuroborreliosis : a large retrospective study.

BACKGROUND: B cell immunity, including the chemokine CXCL13, has an established role in Lyme neuroborreliosis, and also, T helper (Th) 17 immunity, including IL-17A, has recently been implicated. METHODS: We analysed a set of cytokines and chemokines associated with B cell and Th17 immunity in cerebrospinal fluid and serum from clinically well-characterized patients with definite Lyme neuroborreliosis (group 1, n = 49), defined by both cerebrospinal fluid pleocytosis and Borrelia-specific antibodies in cerebrospinal fluid and from two groups with possible Lyme neuroborreliosis, showing either pleocytosis (group 2, n = 14) or Borrelia-specific antibodies in cerebrospinal fluid (group 3, n = 14). A non-Lyme neuroborreliosis reference group consisted of 88 patients lacking pleocytosis and Borrelia-specific antibodies in serum and cerebrospinal fluid. RESULTS: Cerebrospinal fluid levels of B cell-associated markers (CXCL13, APRIL and BAFF) were significantly elevated in groups 1, 2 and 3 compared with the reference group, except for BAFF, which was not elevated in group 3. Regarding Th17-associated markers (IL-17A, CXCL1 and CCL20), CCL20 in cerebrospinal fluid was significantly elevated in groups 1, 2 and 3 compared with the reference group, while IL-17A and CXCL1 were elevated in group 1. Patients with time of recovery &lt;3 months had lower cerebrospinal fluid levels of IL-17A, APRIL and BAFF compared to patients with recovery &gt;3 months. CONCLUSIONS: By using a set of markers in addition to CXCL13 and IL-17A, we confirm that B cell- and Th17-associated immune responses are involved in Lyme neuroborreliosis pathogenesis with different patterns in subgroups. Furthermore, IL-17A, APRIL and BAFF may be associated with time to recovery after treatment.Funding agencies: Medical Research Council of Southeast Sweden (FORSS); Futurum-the Academy for Health and Care; Division of Medical Services, Region Jonkoping County; EU-Interreg project ScandTick Innovation</p