Lyme neuroborreliosis: infection, immunity, and inflammation

Cytokines and chemokines at the crossroads of neuroinflammation, neurodegeneration, and neuropathic pain

Cytokines and chemokines are proteins that coordinate the immune response throughout the body. The dysregulation of cytokines and chemokines is a central feature in the development of neuroinflammation, neurodegeneration, and demyelination both in the central and peripheral nervous systems and in conditions of neuropathic pain. Pathological states within the nervous system can lead to activation of microglia. The latter may mediate neuronal and glial cell injury and death through production of proinflammatory factors such as cytokines and chemokines. These then help to mobilize the adaptive immune response. Although inflammation may induce beneficial effects such as pathogen clearance and phagocytosis of apoptotic cells, uncontrolled inflammation can result in detrimental outcomes via the production of neurotoxic factors that exacerbate neurodegenerative pathology. In states of prolonged inflammation, continual activation and recruitment of effector cells can establish a feedback loop that perpetuates inflammation and ultimately results in neuronal injury. A critical balance between repair and proinflammatory factors determines the outcome of a neurodegenerative process. This review will focus on how cytokines and chemokines affect neuroinflammation and disease pathogenesis in bacterial meningitis and brain abscesses, Lyme neuroborreliosis, human immunodeficiency virus encephalitis, and neuropathic pain.

Chronic Lyme; diagnostic and therapeutic challenges

In this review, we aim to discuss the definition, clinical and laboratory features, diagnostics, and management of chronic Lyme. Chronic Lyme is a rare condition caused by long-lasting and ongoing infection with the spirochete Borrelia burgdorferi (Bb). The most common manifestations are progressive encephalitis, myelitis, acrodermatitis chronica atrophicans with or without neuropathy, and arthritis. Chronic Lyme is not considered to present with isolated subjective symptoms. Direct detection of Bb has low yield in most manifestations of chronic Lyme, while almost 100% of the cases are seropositive, that is, have detectable Bb IgG antibodies in serum. Detection of Bb antibodies only with Western blot technique and not with ELISA and detection of Bb IgM antibodies without simultaneous detection of Bb IgG antibodies should be considered as seronegativity in patients with long-lasting symptoms. Patients with chronic Lyme in the nervous system (neuroborreliosis) have, with few exceptions, pleocytosis and production of Bb antibodies in their cerebrospinal fluid. Strict guidelines should be applied in diagnostics of chronic Lyme, and several differential diagnoses, including neurological disease, rheumatologic disease, post-Lyme disease syndrome, chronic fatigue syndrome, and psychiatric disease, should be considered in the diagnostic workup. Antibiotic treatment with administration route and dosages according to current guidelines are recommended. Combination antimicrobial therapy or antibiotic courses longer than 4 weeks are not recommended. Patients who attribute their symptoms to chronic Lyme on doubtful basis should be offered a thorough and systematic diagnostic approach, and an open and respectful dialogue.

Rapid progressive bilateral hearing loss due to granulomatous otitis media in Lyme disease

We report on a patient with Lyme disease who presented with chronic bilateral otitis media and cranial neuropathy with rapid progressive hearing loss. After ceftriaxone and high-dose intravenous immunoglobulins, the disease was controlled only with methylprednisolone and cyclophosphamide. The relationship between Lyme disease and granulomatous vasculitis is discussed. Lyme disease should be kept in mind in the differential diagnosis of various otolaryngological and neurological presentations.

Lyme neuroborreliosis

Lyme neuroborreliosis (LNB) designates the nervous system disorders caused by the tick-borne spirochete Borrelia burgdorferi (Bb). The clinical syndromes are usually distinct and are classified as early and the rare late or chronic LNB. Early LNB occurs 3-6 weeks after infection most frequently as a lymphocytic meningoradiculoneuritis (LMR). Symptoms are mainly due to a painful sensory radiculitis and a multifocal motor radiculo-neuritis. Fifty percent have cranial nerve involvement predominantly uni- or bilateral facial nerve palsies. Meningitic symptoms occur primarily in children. Nerve biopsies, autopsies, animal models, and nerve conduction studies showed that the pathology is a lymphocytic perineuritis leading to multisegmental axonal injury of nerve roots, spinal ganglia, and distal nerve segments. Due to meningeal and root inflammation cerebrospinal fluid (CSF) shows lymphocytic inflammation. The only evidence that Bb causes peripheral neuropathy without CSF inflammation is seen in patients with acrodermatitis chronica atrophicans (ACA), a chronic dermatoborreliosis. In the rare chronic or late LNB the pathology and thus the clinical presentation is primarily due to chronic meningitis and meningovascular CNS involvement, whereas the peripheral nervous system is not primarily affected. In early and late LNB the diagnosis is based on a characteristic clinical appearance and CSF inflammation with Bb-specific intrathecal antibody production. Both conditions, but not the ACA-associated neuropathy, respond to antibiotic therapy.

Misleading presentation of acute Lyme neuroborreliosis

A young man presented with recent-onset non-specific symptoms like headache, sleepiness and weight loss, interfering with normal daily life. Physical and biochemical irregularities were absent. Because extensive examination by neurologist and psychiatrist including brain imaging did not reveal any clues, the complaints were initially considered psychosomatic. As the symptoms deteriorated with ongoing weight loss, the patient was re-admitted to the hospital. Again, extensive additional investigation did not reveal any abnormalities. Because of previous exposition to the woods Lyme serology was determined. Surprisingly, it appeared to be a remarkable presentation of acute Lyme neuroborreliosis which was successfully treated with ceftriaxon. Clinicians must be aware of the fact that this severe illness can present without any typical symptoms.

Cerebrospinal fluid Alzheimer's biomarker profiles in CNS infections

The cerebrospinal fluid (CSF) biomarker profile in Alzheimer's disease (AD) is characterized by decreased beta amyloid (Aβ(1-42)), increased total and hyperphosphorylated tau (t-tau and p-tau, respectively), which is a useful diagnostic tool and gives insight in the pathogenesis of AD. It is of importance to study how these biomarkers react in other CNS diseases; therefore, we decided to analyse amyloid and tau biomarkers in different CNS infections. We also included analysis of soluble amyloid precursor proteins (sAPPα and -β). CSF Aβ(1-42), sAPPα and -β, t-tau and p-tau were analysed in bacterial meningitis (n = 12), Lyme neuroborreliosis (n = 13), herpes simplex virus type 1 (HSV-1) encephalitis (n = 10), HIV-associated dementia (HAD) (n = 21), AD (n = 21) and healthy controls (n = 42). Concurrent with AD, Aβ(1-42) was decreased in all groups except neuroborreliosis compared to controls. HSV-1 encephalitis, bacterial meningitis and HAD showed lower concentrations of sAPPα and -β compared to AD. T-tau was increased in AD and HSV-1 encephalitis compared to all other groups. P-tau was higher in AD and HSV-1 encephalitis compared to bacterial meningitis, HAD and control. Decreased CSF Aβ(1-42), sAPPα and -β in various CNS infections imply an effect of neuroinflammation on amyloid metabolism which is similar in regard to AD concerning Aβ(1-42), but differs concerning sAPPα and -β. These results clearly indicate different pathologic pathways in AD and infectious CNS disease and may provide help in the differential biomarker diagnostics. Increased p-tau in HSV-1 encephalitis probably reflect acute neuronal damage and necrosis.

Pattern and motion-related visual-evoked potentials in neuroborreliosis: follow-up study

Visual-evoked potentials (VEPs) were used for objective testing of visual functions during treatment courses of Lyme neuroborreliosis (LNB) in adult patients in the Czech Republic. In 30 LNB patients with originally delayed VEP latencies, pattern-reversal (R-VEP) and motion onset (M-VEP) VEPs were repeatedly examined within 1 to 8 years. Six patients had Lyme optic neuritis (ON), five of them displayed prolonged latencies in both R-VEPs and M-VEPs, and one had only abnormal R-VEPs. The VEP recovery to normal latency values was in three of them. In the group of 24 LNB patients without ON, 14 patients displayed prolonged latencies only to motion stimuli, and 10 patients had abnormal latencies in both R-VEPs and M-VEPs. During the follow-up period, 7 patients displayed shortening to normal latencies. In 5 patients, VEPs latencies improved only partially, and in the remaining 12 patients, VEPs did not improve at all. This study provides objective evidence that in LNB, most of the patients without clinically manifesting ON display optic pathway involvement-predominantly magnocellular system/dorsal stream function changes. In patients with ON, however, mainly the parvocellular system is affected. About half of the patients without ON improved with a relatively long-time course of latency shortening.

[Successful treatment of neuroborreliosis with combined administration of antibiotics and steroids: a case report]

A 66-year-old woman developed bilateral facial paralysis as well as sensory and motor disturbances of extremities. Two months after the onset of paralysis, she also developed sensory disturbance of her trunk and vesicorectal disturbance, and her symptoms worsened gradually. Because the interferon-γ level in the cerebrospinal fluid was elevated, we suspected that her symptoms were caused by polyneuropathy and myelitis associated with infection. Her serum IgM and IgG antibodies against Borrelia garinii and B. afzelli were positive. Therefore, we diagnosed her as having neuroborreliosis. Her symptoms gradually improved after the combined administration of antibiotics and steroids. The present case report showed that it might be better to consider the possibility of neuroborreliosis when there are increasing concentrations of cytokine and chemokine, and that combination treatment with antibiotics and steroids can be used for the treatment of this disease.

Synovial Lesions in Experimental Canine Lyme Borreliosis

Borrelia burgdorferi is the causative agent of Lyme disease, which is mainly characterized by lameness in dogs. More than 95% of naturally infected dogs are asymptomatic or subclinical; however, in experimental studies, histologic synovial lesions are consistently observed in asymptomatic dogs inoculated with B. burdgorferi. This study investigates the ability of a synovial histopathologic scoring system, clinicopathologic data, and polymerase chain reaction (PCR) testing to differentiate between B. burgdorferi–infected and uninfected dogs. Eighteen 18-week-old beagles were subject to challenge with B. burgdorferi–infected wild-caught ticks ( Ixodes scapularis), and 4 uninfected dogs served as controls. Infection was confirmed by serology (ELISA) and PCR amplification of B. burgdorferi–specific DNA of skin biopsies taken at the tick attachment site. A synovial scoring system from human medicine was adapted and implemented on postmortem synovial samples to discriminate infected and noninfected animals. Application of this system to elbows and stifles with a cumulative joint score cutoff  > 4 showed a sensitivity of 88.2% and a specificity of 100%, with a positive likelihood ratio of infinity and a negative likelihood ratio of 0.12. Complete blood count, serum biochemistry, urinalysis, urine protein:creatinine, urine PCR, synovial and lymph node cytology, and synovial PCR were evaluated but were not reliable indicators of clinical disease.

European neuroborreliosis: neuropsychological findings 30 months post-treatment

BACKGROUND

The aim of this study was to compare neuropsychological (NP) functioning in patients with Lyme neuroborreliosis (LNB) 30months after treatment to matched controls.

METHODS

We tested 50 patients with LNB and 50 controls with the trail-making test (TMT), Stroop test, digit symbol test, and California Verbal Learning test (CVLT). A global NP sumscore was calculated to express the number of low scores on 23 NP subtasks.

RESULTS

Mean scores were lower amongst LNB-treated patients than amongst controls on tasks assessing attention/executive functions: (Stroop test 4: 77.6 vs. 67.0, P=0.015), response/processing speed (TMT 5: 23.4 vs. 19.2, P=0.004), visual memory (digit symbol recall: 6.6 vs. 7.2, P=0.038), and verbal memory (CVLT list B: 4.68 vs. 5.50, P=0.003). The proportion of patients and controls with NP sumscores within one SD from the mean in the control group (defined as normal) and between one and two SD (defined as deficit) were similar, but more LNB-treated patients than controls had a sumscore more than two SD from the mean (defined as impairment) (8 vs. 1, P=0.014).

CONCLUSIONS

As a group, LNB-treated patients scored lower on four NP subtasks assessing processing speed, visual and verbal memory, and executive/attention functions, as compared to matched controls. The distribution of NP dysfunctions indicates that most LNB-treated patients perform comparable to controls, whilst a small subgroup have a debilitating long-term course with cognitive problems.

Long-term intrathecal infusion of outer surface protein C from Borrelia burgdorferi causes axonal damage

Lyme neuroborreliosis (LNB) is the most frequent tick-borne infectious disease of the central nervous system. In acute LNB and the rare chronic state of infection, patients can experience cognitive deficits such as attention and memory disturbances. During LNB, single compounds of Borrelia burgdorferi sensu lato are released into the subarachnoid space.To investigate the pathogenesis of neurologic dysfunction in LNB, we determined that the outer surface protein C (OspC), a major virulence factor of B. burgdorferi, stimulated mouse microglial cells in a dose-dependent manner to release nitric oxide (EC50 = 0.24 mg/L) in vitro. To mimic pathophysiologic conditions of long-term release of this bacterial component in vivo, we treated C57BL/6 mice with recombinant OspC from Borrelia garinii or buffer by intraventricular infusion and tested them for behavioral deficits. After 4weeks, brains were examined by routine histology and immunohistochemistry. Assessment of spatial learning and memory of treated mice during OspC exposure did not reveal significant differences from controls. Continuous exposure to intrathecal B. burgdorferi OspC led to activation of microglia and axonal damage without demonstrable cognitive impairment in experimental mice. These results suggest that long-term intrathecal exposure to OspC resulted in axonal damage that may underlie the neurologic manifestations in chronic LNB.

Following a tick bite: double infections by tick-borne encephalitis virus and the spirochete Borrelia and other potential multiple infections

In Central Europe and large parts of Asia, tick-borne-encephalitis (TBE) and Lyme borreliosis caused by the spirochetal bacterium of the genus Borrelia are among the most common diseases transmitted by the bite of a tick. When in regions with overlapping TBE virus and Borrelia endemicity, a tick bite causes the victim to become ill, it is important that appropriate serological and other laboratory investigations form part of the differential diagnosis. Account must always be taken of the fact that a tick bite may be followed by a double infection with the TBE virus and Borrelia. For this reason, a comprehensive diagnostic work-up aimed at detecting co-infection by both pathogens, even when the tick bite occurs in an endemic region for both pathogens but the initial clinical symptoms suggest an infection with only one of the two pathogens. The present article discusses a number of published cases of a co-infection with TBE virus and Borrelia and other potential multiple infections.

The N-terminal domain of α-dystroglycan, released as a 38 kDa protein, is increased in cerebrospinal fluid in patients with Lyme neuroborreliosis

α-Dystroglycan is an extracellular adhesion protein that is known to interact with different ligands. The interaction is thought to stabilize the integrity of the plasma membrane. The N-terminal part of α-dystroglycan may be proteolytically processed to generate a small 38 kDa protein (α-DG-N). The physiological significance of α-DG-N is unclear but has been suggested to be involved in nerve regeneration and myelination and to function as a potential biomarker for neurodegenerative and neuromuscular diseases. In this report we show that α-DG-N is released into different body fluids, such as lachrimal fluid, cerebrospinal fluid (CSF), urine and plasma. To investigate the significance of α-DG-N in CSF we examined the levels of α-DG-N and known neurodegenerative markers in CSF from patients diagnosed with Lyme neuroborreliosis (LNB) and healthy controls. In untreated acute phase LNB patients, 67% showed a significant increase of CSF α-DG-N compared to healthy controls. After treatment with antibiotics the CSF α-DG-N levels were normalized in the LNB patients.

Molecular and pathological investigations of the central nervous system in Borrelia burgdorferi-infected dogs

Although neurological signs have been reported sporadically in dogs with systemic Lyme disease, it is unknown if neuroborreliosis occurs in dogs. The current study systematically evaluates canine brains for evidence of Borrelia burgdorferi infection. Twelve Beagles were experimentally challenged with B. burgdorferi-infected ticks at 18 weeks of age, and 2 unexposed dogs served as controls. One of the uninfected dogs and 6 infected dogs were each given 5 daily immunosuppressive doses of dexamethasone starting at 153 days post-infection. Eleven dogs were confirmed as infected by skin punch biopsy polymerase chain reaction (PCR) and serology. Neurological signs were not seen in any dogs through the end of the 190-day study. Whole blood, serum, cerebrospinal fluid (CSF), and brains from all dogs were collected. DNA was extracted from blood, CSF, and brain and evaluated by PCR for B. burgdorferi. Formalin-fixed brain tissue was examined by histopathology, immunohistochemistry, and PCR. Immunohistochemical staining for B. burgdorferi antigen was negative in all cases. The CSF analysis was normal, and PCR was uniformly negative for B. burgdorferi in all dogs. Six of the 11 (45%) infected dogs had mild to moderate lymphoplasmacytic choroid plexitis, which was more pronounced in the immunosuppressed dogs. The lack of B. burgdorferi DNA and immunohistochemical evidence of organisms, including within the choroid plexus lesions, suggests that B. burgdorferi does not have a direct role in the etiopathogenesis of canine central nervous system pathology.

Depletion of plasma gelsolin in patients with tick-borne encephalitis and Lyme neuroborreliosis

BACKGROUND/AIMS

Cell damage during the course of inflammation results in cytoplasmic actin release, which if not eliminated by the extracellular actin scavenger system, composed of gelsolin and vitamin D binding protein, can cause dysfunction of hemostasis and toxicity towards surrounding cells. In this study, we test the hypothesis that an inflammatory reaction induced by central nervous system infections such as tick-borne encephalitis (TBE) or Lyme neuroborreliosis (LNB) will result in plasma gelsolin concentration changes in the blood and cerebrospinal fluid (CSF).

METHODS

Quantitative Western blot was used to determine gelsolin levels in 58 samples, which include: 29 patients without infection (diagnosed with conditions such as idiopathic cephalalgia, idiopathic Bell's facial nerve palsy and ischialgia due to discopathy in which standard CSF diagnostic tests show no abnormalities), 12 patients diagnosed with TBE, and 17 patients diagnosed with LNB sub forma meningitis.

RESULTS AND CONCLUSION

The gelsolin concentration in the blood of patients with TBE (163.2 ± 80.8 μg/ml) and LNB (113.6 ± 56.8 μg/ml) was significantly lower (p < 0.05 and p < 0.001, respectively) compared to the control group (226.3 ± 100.7 μg/ml). Furthermore, there was no statistically significant difference between the CSF gelsolin concentration in patients with TBE (3.9 ± 3.3 μg/ml), LNB (2.9 ± 1.2 μg/ml) and the control group (3.7 ± 3.3 μg/ml). An observed decrease in gelsolin concentration in the blood of TBE and LNB patients supports previous findings indicating the involvement of gelsolin in the pathophysiology of an inflammatory response. Therefore, evaluation of blood gelsolin concentration and administration of recombinant plasma gelsolin might provide a new tool to develop diagnostic and therapeutic strategies for TBE and LNB.

Associations between coinfection prevalence of Borrelia lusitaniae, Anaplasma sp., and Rickettsia sp. in hard ticks feeding on reptile hosts

An increasing number of studies reveal that ticks and their hosts are infected with multiple pathogens, suggesting that coinfection might be frequent for both vectors and wild reservoir hosts. Whereas the examination of associations between coinfecting pathogen agents in natural host-vector-pathogen systems is a prerequisite for a better understanding of disease maintenance and transmission, the associations between pathogens within vectors or hosts are seldom explicitly examined. We examined the prevalence of pathogen agents and the patterns of associations between them under natural conditions, using a previously unexamined host-vector-pathogen system--green lizards Lacerta viridis, hard ticks Ixodes ricinus, and Borrelia, Anaplasma, and Rickettsia pathogens. We found that immature ticks infesting a temperate lizard species in Central Europe were infected with multiple pathogens. Considering I. ricinus nymphs and larvae, the prevalence of Anaplasma, Borrelia, and Rickettsia was 13.1% and 8.7%, 12.8% and 1.3%, and 4.5% and 2.7%, respectively. The patterns of pathogen prevalence and observed coinfection rates suggest that the risk of tick infection with one pathogen is not independent of other pathogens. Our results indicate that Anaplasma can play a role in suppressing the transmission of Borrelia to tick vectors. Overall, however, positive effects of Borrelia on Anaplasma seem to prevail as judged by higher-than-expected Borrelia-Anaplasma coinfection rates.

Lyme Neuroborreliosis in 2 Horses

Lyme neuroborreliosis—characterized as chronic, necrosuppurative to nonsuppurative, perivascular to diffuse meningoradiculoneuritis—was diagnosed in 2 horses with progressive neurologic disease. In 1 horse, Borrelia burgdorferi sensu stricto was identified by polymerase chain reaction amplification of B burgdorferi sensu stricto–specific gene targets ( ospA, ospC, flaB, dbpA, arp). Highest spirochetal burdens were in tissues with inflammation, including spinal cord, muscle, and joint capsule. Sequence analysis of ospA, ospC, and flaB revealed 99.9% sequence identity to the respective genes in B burgdorferi strain 297, an isolate from a human case of neuroborreliosis. In both horses, spirochetes were visualized in affected tissues with Steiner silver impregnation and by immunohistochemistry, predominantly within the dense collagenous tissue of the dura mater and leptomeninges.

Lyme borreliosis in dogs and cats: background, diagnosis, treatment and prevention of infections with Borrelia burgdorferi sensu stricto

Lyme borreliosis (LB), synonymous with the often-used term Lyme disease, is an infectious disease caused by the spirochetal bacterium Borrelia burgdorferi. LB is the most frequent vector-borne disease in humans in the Northern Hemisphere. In animals, clinically apparent disease is found primarily in dogs. Severe polyarthritis, fever and lameness in dogs are reported from the main endemic areas of North America: the New England States, and eastern parts of the United States; several cases of LB are also seen in California and the Midwest. Because of the difficulties in finding sufficient indicative clinical signs, additional information (detailed case history, laboratory testing for antibodies) is especially important to make the clinical diagnosis of Lyme borreliosis. This article reviews the etiology, diagnosis, therapy, and prevention of LB.

[Multiple ischemic strokes due to Borrelia garinii meningovasculitis]

The most frequent clinical manifestation of borreliosis in Switzerland is erythema migrans, with about 2500 patients each year. Neurological manifestations are rare, mostly hyperalgesic radiculitis (Bannwarth syndrome), aseptic meningitis or cranial nerve involvement. We report the first Swiss patient with meningovasculitis due to neuroborreliosis, with recurrent multiple ischemic strokes in multiple vascular territories. The treatment with ceftriaxone stopped the progression, but the patient is still suffering from severe invalidating cognitive disorders. We also comment on the pathophysiology and review the literature of other clinical cases.

Neuroinflammation Screening in Immunotherapy Trials against Alzheimer's Disease

Due to side effects in the form of meningoencephalitis in the interrupted phase II AN1792 trial of active antiamyloid β(Aβ) immunization against Alzheimer's disease (AD), there has been concern that anti-Aβ immunization may cause destructive neuroinflammation. Here, we report on two patients fulfilling clinical AD criteria who were diagnosed with Lyme neuroborreliosis during screening before inclusion in anti-Aβ immunotherapy trials. The two cases illustrate the necessity of careful biochemical screening for neuroinflammatory/neuroinfectious conditions before an AD diagnosis is made and before clinical AD patients are included in trials of therapy that could impact the immune system. Should the two cases have been included and deteriorated, additional investigations might have led to the erroneous conclusion that therapy-induced meningoencephalitis had occurred.

A twist on Lyme: the challenge of diagnosing European Lyme neuroborreliosis

Lyme neuroborreliosis is a tick-borne illness with central and peripheral nervous system manifestations. Clinical features and methods for accurate diagnosis differ across world regions owing to different causative Borrelia species. The importance of these distinctions is highlighted by a 12-year-old Canadian girl who acquired Lyme neuroborreliosis in Europe.

Lyme neuroborreliosis in children

Lyme neuroborreliosis (LNB) represents the second most frequent manifestation of Lyme disease (LD) in Europe after cutaneous involvement. In the USA, LNB represents the third most frequent manifestation of LD after cutaneous involvement and arthritis. The scope of this article is, in the light of recent publications, to review the specific manifestations of LNB in children including predictive models, and to discuss diagnosis criteria, new diagnostic tools and new therapeutic options. Differences in disease patterns between the USA and Europe are also highlighted.

Neuroinflammation in Lyme neuroborreliosis affects amyloid metabolism

Background

The metabolism of amyloid precursor protein (APP) and β-amyloid (Aβ) is widely studied in Alzheimer's disease, where Aβ deposition and plaque development are essential components of the pathogenesis. However, the physiological role of amyloid in the adult nervous system remains largely unknown. We have previously found altered cerebral amyloid metabolism in other neuroinflammatory conditions. To further elucidate this, we investigated amyloid metabolism in patients with Lyme neuroborreliosis (LNB).

Methods

The first part of the study was a cross-sectional cohort study in 61 patients with acute facial palsy (19 with LNB and 42 with idiopathic facial paresis, Bell's palsy) and 22 healthy controls. CSF was analysed for the β-amyloid peptides Aβ38, Aβ40 and Aβ42, and the amyloid precursor protein (APP) isoforms α-sAPP and β-sAPP. CSF total-tau (T-tau), phosphorylated tau (P-tau) and neurofilament protein (NFL) were measured to monitor neural cell damage. The second part of the study was a prospective cohort-study in 26 LNB patients undergoing consecutive lumbar punctures before and after antibiotic treatment to study time-dependent dynamics of the biomarkers.

Results

In the cross-sectional study, LNB patients had lower levels of CSF α-sAPP, β-sAPP and P-tau, and higher levels of CSF NFL than healthy controls and patients with Bell's palsy. In the prospective study, LNB patients had low levels of CSF α-sAPP, β-sAPP and P-tau at baseline, which all increased towards normal at follow-up.

Conclusions

Amyloid metabolism is altered in LNB. CSF levels of α-sAPP, β-sAPP and P-tau are decreased in acute infection and increase after treatment. In combination with earlier findings in multiple sclerosis, cerebral SLE and HIV with cerebral engagement, this points to an influence of neuroinflammation on amyloid metabolism.

Inflammation and central nervous system Lyme disease

Lyme disease, caused by the bacterium Borrelia burgdorferi, can cause multi-systemic signs and symptoms, including peripheral and central nervous system disease. This review examines the evidence for and mechanisms of inflammation in neurologic Lyme disease, with a specific focus on the central nervous system, drawing upon human studies and controlled research with experimentally infected rhesus monkeys. Directions for future human research are suggested that may help to clarify the role of inflammation as a mediator of the chronic persistent symptoms experienced by some patients despite antibiotic treatment for neurologic Lyme disease.

Microglia are mediators of Borrelia burgdorferi-induced apoptosis in SH-SY5Y neuronal cells

Inflammation has long been implicated as a contributor to pathogenesis in many CNS illnesses, including Lyme neuroborreliosis. Borrelia burgdorferi is the spirochete that causes Lyme disease and it is known to potently induce the production of inflammatory mediators in a variety of cells. In experiments where B. burgdorferi was co-cultured in vitro with primary microglia, we observed robust expression and release of IL-6 and IL-8, CCL2 (MCP-1), CCL3 (MIP-1α), CCL4 (MIP-1β) and CCL5 (RANTES), but we detected no induction of microglial apoptosis. In contrast, SH-SY5Y (SY) neuroblastoma cells co-cultured with B. burgdorferi expressed negligible amounts of inflammatory mediators and also remained resistant to apoptosis. When SY cells were co-cultured with microglia and B. burgdorferi, significant neuronal apoptosis consistently occurred. Confocal microscopy imaging of these cell cultures stained for apoptosis and with cell type-specific markers confirmed that it was predominantly the SY cells that were dying. Microarray analysis demonstrated an intense microglia-mediated inflammatory response to B. burgdorferi including up-regulation in gene transcripts for TLR-2 and NFκβ. Surprisingly, a pathway that exhibited profound changes in regard to inflammatory signaling was triggering receptor expressed on myeloid cells-1 (TREM1). Significant transcript alterations in essential p53 pathway genes also occurred in SY cells cultured in the presence of microglia and B. burgdorferi, which indicated a shift from cell survival to preparation for apoptosis when compared to SY cells cultured in the presence of B. burgdorferi alone. Taken together, these findings indicate that B. burgdorferi is not directly toxic to SY cells; rather, these cells become distressed and die in the inflammatory surroundings generated by microglia through a bystander effect. If, as we hypothesized, neuronal apoptosis is the key pathogenic event in Lyme neuroborreliosis, then targeting microglial responses may be a significant therapeutic approach for the treatment of this form of Lyme disease.

Lyme disease, which is transmitted to humans through the bite of a tick, is currently the most frequently reported vector-borne illness in the northern hemisphere. Borrelia burgdorferi is the bacterium that causes Lyme disease and it is known to readily induce inflammation within a variety of infected tissues. Many of the neurological signs and symptoms that may affect patients with Lyme disease have been associated with B. burgdorferi-induced inflammation in the central nervous system (CNS). In this report we investigated which of the primary cell types residing in the CNS might be functioning to create the inflammatory environment that, in addition to helping clear the pathogen, could simultaneously be harming nearby neurons. We report findings that implicate microglia, a macrophage cell type in the CNS, as the key responders to infection with B. burgdorferi. We also present evidence indicating that this organism is not directly toxic to neurons; rather, a bystander effect is generated whereby the inflammatory surroundings created by microglia in response to B. burgdorferi may themselves be toxic to neuronal cells.

Laboratory data in children with Lyme neuroborreliosis, relation to clinical presentation and duration of symptoms

The occurrence of IgM and IgG antibodies against Borrelia burgdoferi in serum and cerebrospinal fluid (CSF) and intrathecal synthesis of antibodies (antibody index) were studied in relation to clinical presentation and the duration of symptoms before diagnosis in 146 children diagnosed with neuroborreliosis. Lymphocytic meningitis was demonstrated in 141 of these children. Levels of white blood cells (WBC) and protein in CSF correlated significantly to numbers of d with symptoms. Children were divided into 3 clinical groups: A (n = 37): only cranial neuropathy; B (n = 68): both cranial neuropathy and other neurological symptoms; C (n = 41): neurological symptoms without cranial neuropathy. Levels of WBC and protein in CSF as well as the proportion of children with antibodies in serum and CSF were generally lowest in group A, intermediate in group B and highest in group C. The proportion of children with antibodies in serum and CSF and a positive antibody index was also related to duration of symptoms; the antibody index was present in 51% of children with symptoms < or = 7 d, and in 80% of children with symptoms > 7 d (p<0.01). The clinical presentation and duration of symptoms must be considered when interpreting laboratory data in children with suspected neuroborreliosis.

Lyme neuroborreliosis: manifestations of a rapidly emerging zoonosis

Lyme disease has a worldwide distribution and is the most common vector-borne disease in the United States. Incidence, clinical manifestations, and presentations vary by geography, season, and recreational habits. Lyme neuroborreliosis (LNB) is neurologic involvement secondary to systemic infection by the spirochete Borrelia burgdorferi in the United States and by Borrelia garinii or Borrelia afzelii species in Europe. Enhanced awareness of the clinical presentation of Lyme disease allows inclusion of LNB in the imaging differential diagnosis of facial neuritis, multiple enhancing cranial nerves, enhancing noncompressive radiculitis, and pediatric leptomeningitis with white matter hyperintensities on MR imaging. The MR imaging white matter appearance of successfully treated LNB and multiple sclerosis display sufficient similarity to suggest a common autoimmune pathogenesis for both. This review highlights differences in the epidemiology, clinical manifestations, diagnosis, and management of Lyme disease in the United States, Europe, and Asia, with an emphasis on neurologic manifestations and neuroimaging.

Lyme disease with lymphocytic meningitis, trigeminal palsy and silent thalamic lesion

We describe a follow-up in a 15-year-old boy with neuroborreliosis diagnosed by clinical symptoms, CSF and serum analysis. MRI revealed a thalamic lesion and an enhancement of the right trigeminal nerve clinically associated with mild hypasthesia in the right maxillary region. Both, clinical symptoms and radiological findings disappeared within 2 months after treatment. Borrelia burgdorferi specific IgM and IgG in CSF and IgG in serum became negative between 6 and 12 months after diagnosis. We show that neuroborreliosis at an early stage may present only with moderate neurological deficits and that at this stage MRI reveals distinct cerebral lesions which might even precede clinical manifestation. Thus, early diagnosis and treatment of neuroborreliosis may prevent persistent neurologic lesions.

[Recurrent ischemic strokes revealing Lyme meningovascularitis]

INTRODUCTION

Infectious vascularitis is an unusual cause of ischemic stroke (IS). We report a case of Lyme meningovascularitis complicated with multiple IS.

CASE REPORT

A 64-year-old man, without any cardiovascular risk factor, was admitted for a right hemiparesia with a left thalamic hypodensity on the initial cerebral CT scan. No cause for this presumed IS could be identified. Later, the patient developed cognitive impairment and a bilateral cerebellar syndrome. Multiple infarcts and multiple intracranial stenosis were seen on cerebral MRI with magnetic resonance angiography (MRA). Cerebrospinal fluid tests showed meningitis and positive Lyme serology with an intrathecal specific anti-Borrelia antibody index. Antibiotic treatment was followed by good biological and partial clinicoradiological outcome.

CONCLUSION

The diagnosis of Lyme neuroborreliosis should be entertained as a possible cause of IS in highly endemic zones.

Pediatric neurodegenerative white matter processes: leukodystrophies and beyond

Pediatric neurodegenerative white matter processes are complex, numerous and result from a vast array of causes ranging from white matter injury or inflammation to congenital metabolic disorders. When faced with a neurodegenerative white matter process on neuroimaging, the first step for the radiologist is to determine whether the findings represent a congenital metabolic leukodystrophy or one of various other white matter processes. In this review we first describe a general approach to neurodegenerative white matter disorders. We will briefly describe a few white matter diseases that mimic metabolic leukodystrophies. In the second half of the review we discuss an approach to distinguishing and classifying white matter leukodystrophies.

The pathogenesis of lyme neuroborreliosis: from infection to inflammation

This review describes the current knowledge of the pathogenesis of acute Lyme neuroborreliosis (LNB), from invasion to inflammation of the central nervous system. Borrelia burgdorferi (B.b.) enters the host through a tick bite on the skin and may disseminate from there to secondary organs, including the central nervous system. To achieve this, B.b. first has to evade the hostile immune system. In a second step, the borrelia have to reach the central nervous system and cross the blood-brain barrier. Once in the cerebrospinal fluid (CSF), the spirochetes elicit an inflammatory response. We describe current knowledge about the infiltration of leukocytes into the CSF in LNB. In the final section, we discuss the mechanisms by which the spirochetal infection leads to the observed neural dysfunction. To conclude, we construct a stringent concept of the pathogenesis of LNB.