T-cell epitope mapping of the Borrelia garinii outer surface protein A in lyme neuroborreliosis.

We studied the T-cell reactivity to overlapping peptides of B. garinii OspA, in order to locate possible immunodominant T-cell epitopes in neuroborreliosis. Cells from cerebrospinal fluid (CSF) and blood from 39 patients with neuroborreliosis and 31 controls were stimulated with 31 overlapping peptides, and interferon-gamma secreting cells were detected by ELISPOT. The peptides OspA(17-36), OspA(49-68), OspA(105-124), OspA(137-156), OspA(193-212) and OspA(233-252) showed the highest frequency of positive responses, being positive in CSF from 38% to 50% of patients with neuroborreliosis. These peptides also elicited higher responses in CSF compared with controls (P = 0.004). CSF cells more often showed positive responses to these peptides than blood cells (P = 0.001), in line with a compartmentalization to the central nervous system. Thus, a set of potential T-cell epitopes were identified in CSF cells from patients with neuroborreliosis. Further studies may reveal whether these epitopes can be used diagnostically and studies involving HLA interactions may show their possible pathogenetic importance.

Decreased up-regulation of the interleukin-12Rbeta2-chain and interferon-gamma secretion and increased number of forkhead box P3-expressing cells in patients with a history of chronic Lyme borreliosis compared with asymptomatic Borrelia-exposed individuals.

Lyme borreliosis (LB) can, despite adequate antibiotic treatment, develop into a chronic condition with persisting symptoms such as musculoskeletal pain, subjective alteration of cognition and fatigue. The mechanism behind this is unclear, but it has been postulated that an aberrant immunological response might be the cause. In this study we investigated the expression of the T helper 1 (Th1) marker interleukin (IL)-12Rbeta2, the marker for T regulatory cells, forkhead box P3 (FoxP3) and the cytokine profile in patients with a history of chronic LB, subacute LB, previously Borrelia-exposed asymptomatic individuals and healthy controls. Fifty-four individuals (12 chronic LB, 14 subacute LB, 14 asymptomatic individuals and 14 healthy controls) were included in the study and provided a blood sample. Mononuclear cells were separated from the blood and stimulated with antigens. The IL-12Rbeta2 and FoxP3 mRNA expression was analysed with real-time reverse transcription-polymerase chain reaction (RT-PCR). The protein expression of IL-12Rbeta2 on CD3(+), CD4(+), CD8(+) and CD56(+) cells was assessed by flow cytometry. Furthermore, the secretion of interferon (IFN)-gamma, IL-4, IL-5, IL-10, IL-12p70 and IL-13 was analysed by enzyme-linked immunospot (ELISPOT) and/or enzyme-linked immunosorbent assay (ELISA). Chronic LB patients displayed a lower expression of Borrelia-specific IL-12Rbeta2 on CD8(+) cells and also a lower number of Borrelia-specific IFN-gamma-secreting cells compared to asymptomatic individuals. Furthermore, chronic LB patients had higher amounts of Borrelia-specific FoxP3 mRNA than healthy controls. We speculate that this may indicate that a strong Th1 response is of importance for a positive outcome of a Borrelia infection. In addition, regulatory T cells might also play a role, by immunosuppression, in the development of chronic LB.

Reduced number of interleukin-12 secreting cells in patients with Lyme borreliosis previously exposed to Anaplasma phagocytophilum.

Lyme borreliosis and human granulocytic ehrlichiosis are tick-borne diseases caused by Borrelia burgdorferi and Anaplasma phagocytophilum, respectively. Infection with A. phagocytophilum has been observed to induce immunosuppression and animal studies suggest that the bacteria might also have prolonged inhibitory effects on immune cells. The aim of this study was to investigate the cytokine secretion in patients exposed previously to A. phagocytophilum and currently infected with B. burgdorferi compared with patients infected with B. burgdorferi and seronegative for A. phagocytophilum. Eight patients with erythema migrans and antibodies against A. phagocytophilum, 15 patients with erythema migrans and negative A. phagocytophilum serology and 15 non-exposed healthy individuals were included in the study. Blood mononuclear cells were stimulated with Borrelia-antigen and the number of cytokine [interleukin (IL)-4, IL-5, IL-12, IL-13 and interferon (IFN)-gamma]-secreting cells was detected by enzyme-linked immunospot (ELISPOT). This study shows that patients with a previous exposure to A. phagocytophilum and a current infection with B. burgdorferi have a lower number of Borrelia-specific cells secreting IL-12 compared to Ap seronegative patients infected with B. burgdorferi (P < 0.001), indicating impairment in the ability to mount strong Th1-responses. We suggest that this mirrors a reduced Th1 response caused by A. phagocytophilum which could influence the outcome of the Borrelia infection and, speculatively, may also have implications in other conditions.

Phenotypes indicating cytolytic properties of Borrelia-specific interferon-gamma secreting cells in chronic Lyme neuroborreliosis.

The immuno-pathogenetic mechanisms underlying chronic Lyme neuroborreliosis are mainly unknown. Human Borrelia burgdorferi (Bb) infection is associated with Bb-specific secretion of interferon-gamma (IFN-gamma), which may be important for the elimination of Bb, but this may also cause tissue injury. In order to increase the understanding of the pathogenic mechanisms in chronic neuroborreliosis, we investigated which cell types that secrete IFN-gamma. Blood mononuclear cells from 13 patients with neuroborreliosis and/or acrodermatitis chronicum atrophicans were stimulated with Bb antigen and the phenotypes of the induced IFN-gamma-secreting cells were analyzed with three different approaches. Cells expressing CD8 or TCRgammadelta, which both have cytolytic properties, were the main phenotypes of IFN-gamma-secreting cells, indicating that tissue injury in chronic neuroborreliosis may be mediated by cytotoxic cells.