Tick-specific borrelial antigens appear to be upregulated in American but not European patients with Lyme arthritis, a late manifestation of Lyme borreliosis

Disease-specific T cell receptors maintain pathogenic T helper cell responses in postinfectious Lyme arthritis

BACKGROUNDAntibiotic-Refractory Lyme Arthritis (ARLA) involves a complex interplay of T cell responses targeting Borrelia burgdorferi antigens progressing toward autoantigens by epitope spreading. However, the precise molecular mechanisms driving the pathogenic T cell response in ARLA remain unclear. Our aim was to elucidate the molecular program of disease-specific Th cells.METHODSUsing flow cytometry, high-throughput T cell receptor (TCR) sequencing, and scRNA-Seq of CD4+ Th cells isolated from the joints of patients with ARLA living in Europe, we aimed to infer antigen specificity through unbiased analysis of TCR repertoire patterns, identifying surrogate markers for disease-specific TCRs, and connecting TCR specificity to transcriptional patterns.RESULTSPD-1hiHLA-DR+CD4+ effector T cells were clonally expanded within the inflamed joints and persisted throughout disease course. Among these cells, we identified a distinct TCR-β motif restricted to HLA-DRB1*11 or *13 alleles. These alleles, being underrepresented in patients with ARLA living in North America, were unexpectedly prevalent in our European cohort. The identified TCR-β motif served as surrogate marker for a convergent TCR response specific to ARLA, distinguishing it from other rheumatic diseases. In the scRNA-Seq data set, the TCR-β motif particularly mapped to peripheral T helper (TPH) cells displaying signs of sustained proliferation, continuous TCR signaling, and expressing CXCL13 and IFN-γ.CONCLUSIONBy inferring disease-specific TCRs from synovial T cells we identified a convergent TCR response in the joints of patients with ARLA that continuously fueled the expansion of TPH cells expressing a pathogenic cytokine effector program. The identified TCRs will aid in uncovering the major antigen targets of the maladaptive immune response.FUNDINGSupported by the German Research Foundation (DFG) MO 2160/4-1; the Federal Ministry of Education and Research (BMBF; Advanced Clinician Scientist-Program INTERACT; 01EO2108) embedded in the Interdisciplinary Center for Clinical Research (IZKF) of the University Hospital Würzburg; the German Center for Infection Research (DZIF; Clinical Leave Program; TI07.001_007) and the Interdisciplinary Center for Clinical Research (IZKF) Würzburg (Clinician Scientist Program, Z-2/CSP-30).

Profiling disease burden and Borrelia seroprevalence in Canadians with complex and chronic illness

Lyme disease, caused by vector-borne Borrelia bacteria, can present with diverse multi-system symptoms that resemble other conditions. The objective of this study was to evaluate disease presentations and Borrelia seroreactivity in individuals experiencing a spectrum of chronic and complex illnesses. We recruited 157 participants from Eastern Canada who reported one or more diagnoses of Lyme disease, neurological, rheumatic, autoimmune, inflammatory, gastrointestinal, or cardiovascular illnesses, or were asymptomatic and presumed healthy. Intake categories were used to classify participants based on their perceived proximity to Lyme disease, distinguishing between those with a disclosed history of Borrelia infection, those with lookalike conditions (e.g. fibromyalgia syndrome), and those with unrelated ailments (e.g. intestinal polyps). Participants completed three questionnaires, the SF-36 v1, SIQR, and HMQ, to capture symptoms and functional burden, and provided blood serum for analysis at an accredited diagnostic lab. Two-tiered IgG and IgM serological assessments (whole cell ELISA and Western blot) were performed in a blinded fashion on all samples. The pattern of symptoms and functional burden were similarly profound in the presumptive Lyme and Lyme-like disease categories. Borrelia seroprevalence across the study cohort was 10% for each of IgG and IgM, and occurred within and beyond the Lyme disease intake category. Western blot positivity in the absence of reactive ELISA was also substantial. Fibromyalgia was the most common individual diagnostic tag disclosed by two-tier IgG-positive participants who did not report a history of Lyme disease. Within the IgG seropositive cohort, the presence of antibodies against the 31 kDa Outer Surface Protein A (OspA) was associated with significantly better health outcomes. Previously, this marker has been linked to treatment-refractory Lyme arthritis. Overall, our findings support prior observations of phenotypic overlap between Lyme and other diseases. Seropositivity associated with non-specific symptoms and functional impairment warrants further mechanistic investigation and therapeutic optimization.

Lyme arthritis: linking infection, inflammation and autoimmunity

Infectious agents can trigger autoimmune responses in a number of chronic inflammatory diseases. Lyme arthritis, which is caused by the tick-transmitted spirochaete Borrelia burgdorferi, is effectively treated in most patients with antibiotic therapy; however, in a subset of patients, arthritis can persist and worsen after the spirochaete has been killed (known as post-infectious Lyme arthritis). This Review details the current understanding of the pathogenetic events in Lyme arthritis, from initial infection in the skin, through infection of the joints, to post-infectious chronic inflammatory arthritis. The central feature of post-infectious Lyme arthritis is an excessive, dysregulated pro-inflammatory immune response during the infection phase that persists into the post-infectious period. This response is characterized by high amounts of IFNγ and inadequate amounts of the anti-inflammatory cytokine IL-10. The consequences of this dysregulated pro-inflammatory response in the synovium include impaired tissue repair, vascular damage, autoimmune and cytotoxic processes, and fibroblast proliferation and fibrosis. These synovial characteristics are similar to those in other chronic inflammatory arthritides, including rheumatoid arthritis. Thus, post-infectious Lyme arthritis provides a model for other chronic autoimmune or autoinflammatory arthritides in which complex immune responses can be triggered and shaped by an infectious agent in concert with host genetic factors.

Laboratory Diagnosis of Lyme Borreliosis

Lyme borreliosis is caused by a growing list of related, yet distinct, spirochetes with complex biology and sophisticated immune evasion mechanisms. It may result in a range of clinical manifestations involving different organ systems, and can lead to persistent sequelae in a subset of cases. The pathogenesis of Lyme borreliosis is incompletely understood, and laboratory diagnosis, the focus of this review, requires considerable understanding to interpret the results correctly. Direct detection of the infectious agent is usually not possible or practical, necessitating a continued reliance on serologic testing. Still, some important advances have been made in the area of diagnostics, and there are many promising ideas for future assay development. This review summarizes the state of the art in laboratory diagnostics for Lyme borreliosis, provides guidance in test selection and interpretation, and highlights future directions.

The Functional and Molecular Effects of Doxycycline Treatment on Borrelia burgdorferi Phenotype

Recent studies have shown that Borrelia burgdorferi can form antibiotic-tolerant persisters in the presence of microbiostatic drugs such as doxycycline. Precisely how this occurs is yet unknown. Our goal was to examine gene transcription by B. burgdorferi following doxycycline treatment in an effort to identify both persister-associated genes and possible targets for antimicrobial intervention. To do so, we performed next-generation RNA sequencing on doxycycline-treated spirochetes and treated spirochetes following regrowth, comparing them to untreated B. burgdorferi. A number of genes were perturbed and most of those which were statistically significant were down-regulated in the treated versus the untreated or treated/re-grown. Genes upregulated in the treated B. burgdorferi included a number of Erp genes and rplU, a 50S ribosomal protein. Among those genes associated with post-treatment regrowth were bba74 (Oms28), bba03, several peptide ABC transporters, ospA, ospB, ospC, dbpA and bba62. Studies are underway to determine if these same genes are perturbed in B. burgdorferi treated with doxycycline in a host environment.

Pediatric Antibiotic-refractory Lyme Arthritis: A Multicenter Case-control Study

OBJECTIVE

Few factors have consistently been linked to antibiotic-refractory Lyme arthritis (ARLA). We sought to identify clinical and treatment factors associated with pediatric ARLA.

METHODS

We performed a case-control study in 3 pediatric rheumatology clinics in a Lyme-endemic region (2000-2013). Eligible children were aged ≤ 18 years with arthritis and had positive testing for Lyme disease by Western blot. Cases were 49 children with persistently active arthritis despite ≥ 8 weeks of oral antibiotics or ≥ 2 weeks of parenteral antibiotics; controls were 188 children whose arthritis resolved within 3 months of starting antibiotics. We compared preselected demographic, clinical, and treatment factors between groups using logistic regression.

RESULTS

Characteristics positively associated with ARLA were age ≥ 10 years, prolonged arthritis at diagnosis, knee-only arthritis, and worsening after starting antibiotics. In contrast, children with fever, severe pain, or other signs of systemic inflammation were more likely to respond quickly to treatment. Secondarily, low-dose amoxicillin and treatment nonadherence were also linked to higher risk of ARLA. Greater antibiotic use for children with ARLA was accompanied by higher rates of treatment-associated adverse events (37% vs 15%) and resultant hospitalization (6% vs 1%).

CONCLUSION

Older children and those with prolonged arthritis, arthritis limited to the knees, or poor initial response to antibiotics are more likely to have antibiotic-refractory disease and treatment-associated toxicity. Children with severe symptoms of systemic inflammation have more favorable outcomes. For children with persistently active Lyme arthritis after 2 antibiotic courses, pediatricians should consider starting antiinflammatory treatment and referring to a pediatric rheumatologist.

Cerebrospinal fluid Lyme multiplex assay results are not diagnostic in horses with neuroborreliosis

BACKGROUND

The accuracy of the Lyme multiplex assay for the diagnosis of neuroborreliosis in horses is unknown.

HYPOTHESIS/OBJECTIVES

To describe Lyme multiplex results in horses with a postmortem diagnosis of neuroborreliosis. The hypothesis was that paired serum and cerebrospinal fluid (CSF) results and a CSF : serum ratio would allow differentiation of horses with neuroborreliosis from those with other neurologic diseases.

ANIMALS

Ninety horses that had neurologic examinations, serum and CSF Lyme multiplex analyses, and postmortem examination of the nervous system performed.

METHODS

Retrospective study. Data collected included signalment, ante- and postmortem diagnoses, and serum and CSF Lyme multiplex results. The CSF : serum ratio was calculated by dividing CSF median fluorescent intensity (MFI) by serum MFI for each result.

RESULTS

Ten horses had a final diagnosis of neuroborreliosis, 70 were diagnosed with other neurologic diseases, and 10 had no neurologic disease. Not all horses with neuroborreliosis had positive results: 4/10 had at least 1 positive serum result, 5/10 had at least 1 positive CSF result, and 3/10 had at least 1 CSF result 4-fold higher than the corresponding serum result. Results were similar for the 70 horses with other neurologic diseases: 53% had at least 1 positive serum result, 50% had at least 1 positive CSF result, and 16% had at least 1 CSF result 4-fold higher than the corresponding serum result.

CONCLUSIONS AND CLINICAL IMPORTANCE

Positive Lyme multiplex results were common in horses with neurologic diseases and did not adequately differentiate horses with neuroborreliosis from horses with other disorders.

Late Disseminated Lyme Disease: Associated Pathology and Spirochete Persistence Posttreatment in Rhesus Macaques

Nonhuman primates currently serve as the best experimental model for Lyme disease because of their close genetic homology with humans and demonstration of all three phases of disease after infection with Borrelia burgdorferi. We investigated the pathology associated with late disseminated Lyme disease (12 to 13 months after tick inoculation) in doxycycline-treated (28 days; 5 mg/kg, oral, twice daily) and untreated rhesus macaques. Minimal to moderate lymphoplasmacytic inflammation, with a predilection for perivascular spaces and collagenous tissues, was observed in multiple tissues, including the cerebral leptomeninges, brainstem, peripheral nerves from both fore and hind limbs, stifle synovium and perisynovial adipose tissue, urinary bladder, skeletal muscle, myocardium, and visceral pericardium. Indirect immunofluorescence assays that combined monoclonal (outer surface protein A) and polyclonal antibodies were performed on all tissue sections that contained inflammation. Rare morphologically intact spirochetes were observed in the brains of two treated rhesus macaques, the heart of one treated rhesus macaque, and adjacent to a peripheral nerve of an untreated animal. Borrelia antigen staining of probable spirochete cross sections was also observed in heart, skeletal muscle, and near peripheral nerves of treated and untreated animals. These findings support the notion that chronic Lyme disease symptoms can be attributable to residual inflammation in and around tissues that harbor a low burden of persistent host-adapted spirochetes and/or residual antigen.

BB0744 Affects Tissue Tropism and Spatial Distribution of Borrelia burgdorferi

Borrelia burgdorferi, the etiologic agent of Lyme disease, produces a variety of proteins that promote survival and colonization in both the Ixodes species vector and various mammalian hosts. We initially identified BB0744 (also known as p83/100) by screening for B. burgdorferi strain B31 proteins that bind to α1β1 integrin and hypothesized that, given the presence of a signal peptide, BB0744 may be a surface-exposed protein. In contrast to this expectation, localization studies suggested that BB0744 resides in the periplasm. Despite its subsurface location, we were interested in testing whether BB0744 is required for borrelial pathogenesis. To this end, a bb0744 deletion was isolated in a B. burgdorferi strain B31 infectious background, complemented, and queried for the role of BB0744 following experimental infection. A combination of bioluminescent imaging, cultivation of infected tissues, and quantitative PCR (qPCR) demonstrated that Δbb0744 mutant B. burgdorferi bacteria were attenuated in the ability to colonize heart tissue, as well as skin locations distal to the site of infection. Furthermore, qPCR indicated a significantly reduced spirochetal load in distal skin and joint tissue infected with Δbb0744 mutant B. burgdorferi. Complementation with bb0744 restored infectivity, indicating that the defect seen in Δbb0744 mutant B. burgdorferi was due to the loss of BB0744. Taken together, these results suggest that BB0744 is necessary for tissue tropism, particularly in heart tissue, alters the ability of B. burgdorferi to disseminate efficiently, or both. Additional studies are warranted to address the mechanism employed by BB0744 that alters the pathogenic potential of B. burgdorferi.

The Cross-Talk between Spirochetal Lipoproteins and Immunity

Spirochetal diseases such as syphilis, Lyme disease, and leptospirosis are major threats to public health. However, the immunopathogenesis of these diseases has not been fully elucidated. Spirochetes interact with the host through various structural components such as lipopolysaccharides (LPS), surface lipoproteins, and glycolipids. Although spirochetal antigens such as LPS and glycolipids may contribute to the inflammatory response during spirochetal infections, spirochetes such as Treponema pallidum and Borrelia burgdorferi lack LPS. Lipoproteins are most abundant proteins that are expressed in all spirochetes and often determine how spirochetes interact with their environment. Lipoproteins are pro-inflammatory, may regulate responses from both innate and adaptive immunity and enable the spirochetes to adhere to the host or the tick midgut or to evade the immune system. However, most of the spirochetal lipoproteins have unknown function. Herein, the immunomodulatory effects of spirochetal lipoproteins are reviewed and are grouped into two main categories: effects related to immune evasion and effects related to immune activation. Understanding lipoprotein-induced immunomodulation will aid in elucidating innate immunopathogenesis processes and subsequent adaptive mechanisms potentially relevant to spirochetal disease vaccine development and to inflammatory events associated with spirochetal diseases.