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.

FOXP3 expression in blood, synovial fluid and synovial tissue during inflammatory arthritis and intra-articular corticosteroid treatment

OBJECTIVE

To analyse the distribution of FOXP3+CD25+CD4+ regulatory T cells (Treg) in peripheral blood, synovial fluid and tissue of patients with rheumatic disease during relapse and after local treatment.

METHODS

FOXP3 expression was assessed by flow cytometry, immunohistochemistry, immunofluorescence and real-time polymerase chain reaction (RT-PCR). The functional suppressive capacity of Treg was analysed after co-culture with effector CD4+CD25- T cells through assessment of proliferation and cytokine secretion.

RESULTS

It was shown that FOXP3 protein and mRNA expression in synovial fluid T cells was not confined solely to CD25(bright) T cells as seen in blood, but included CD25(intermediate) and even CD25(neg) T cells. Indeed, synovial fluid CD25(high) T cells showed similar suppressive capacity as CD25(bright) T cells, indicating the presence of functional Treg in T cells with lower intensity of CD25. In synovial tissue, FOXP3+ cells were present in low numbers within T-cell infiltrates and decreased further after intra-articular glucocorticosteroid administration, in parallel with the general reduction in inflammation.

CONCLUSIONS

Identification of synovial fluid FOXP3+ Treg with varying intensities of CD25 opens up possibilities for thorough characterisation of this important T-cell subset in the inflammatory compartment. However, only scarce synovial membrane expression of FOXP3 was found even in the absence of overt inflammation, suggesting that the synovial membrane is a site that would benefit therapeutically from Treg expansion.

Multiple antibody reactivities to citrullinated antigens in sera from patients with rheumatoid arthritis: association with HLA-DRB1 alleles

BACKGROUND

Autoantibodies to cyclic citrullinated peptides (anti-CCP) are present in most patients with rheumatoid arthritis (RA), and associate with HLA-DRB1 shared epitope (SE) alleles.

OBJECTIVE

To investigate reactivities of anti-CCP to various citrullinated proteins/peptides, which represent potential autoantigens in RA, and to examine the relationship between such antibodies, and their association with genetic variants within HLA-DRB1 SE alleles.

METHODS

Serum samples from 291 patients with established RA and 100 sex- and age-matched healthy subjects were included in this study. Sera were first analysed for presence of anti-CCP antibodies and further for IgG and IgA antibodies towards candidate autoantigens in both their native and citrullinated form including: fibrinogen, alpha-enolase peptide-1 and the C1-epitope of type II collagen (C1(III)). Antibody specificity was confirmed by cross-reactivity tests. HLA-DR genotyping was performed.

RESULTS

72% of patients with RA were anti-CCP positive. Among the candidate autoantigens examined, IgG antibodies to citrullinated fibrinogen were found in 66% of patients' sera and in 41% for both citrullinated alpha-enolase peptide-1 and citrullinated C1(III). These antibodies were mainly seen in the anti-CCP-positive patient group; they were specific for their respective antigen and displayed limited cross reactivity. IgA responses were also detected, but less frequently than IgG. Anti-CCP and anti-citrullinated protein antibodies were associated with HLA-DRB1*04 rather than with HLA-DRB1*01 alleles.

CONCLUSIONS

Antibodies directed against several citrullinated antigens are present in CCP-positive RA, with many patients displaying multireactivity. All specific reactivities were primarily associated with the HLA-DRB1*04 alleles, suggesting common pathways of anti-citrulline immunity.

Increased expression of the Th1-inducing cytokines interleukin-12 and interleukin-18 in cerebrospinal fluid but not in sera from patients with Lyme neuroborreliosis

Lyme neuroborreliosis is a complex disease with different clinical outcomes and where immunopathological mechanisms are probably involved. In this study, sera and cerebrospinal fluid (CSF) from 21 neuroborreliosis patients and 26 control patients were analyzed for the Th1-inducing cytokines, interleukin (IL)-12 and IL-18, and the Th2 associated, soluble CD30 (sCD30) by ELISA. The results showed an increased number of neuroborreliosis patients expressing IL-12 (p<0.05) and IL-18 (p<0.05) in the CSF when compared with the controls, but no indication of increased levels in the sera. Nor were there any differences regarding levels of sCD30 in the sera or the CSF, indicating a local Th1-generating milieu in the target organ of neuroborreliosis.

IgG subclasses in Lyme borreliosis: a study of specific IgG subclass distribution in an interferon-gamma-predominated disease

Lyme borreliosis has shown a T helper type 1 (Th1)-like immune response with high production of interferon-gamma. Since the cytokine environment seems to be important in the regulation of immunoglobulin production and in the switch between different isotypes and subclasses, and since the subclasses of IgG have different functions, we wanted to examine the IgG subclass distribution in Lyme borreliosis. We have developed an ELISA measuring flagellin-specific antibodies of the different IgG subclasses in serum and cerebrospinal fluid (CSF). Thirty-five seropositive patients with varying manifestations of Lyme borreliosis were included in the study. According to the results, the predominating subclasses in both serum and CSF were IgG1 and IgG3. In samples taken early in disease this pattern was more pronounced in patients with a subacute disease, defined as recovery within 3 months, compared to patients that later on developed chronic borreliosis. The levels of IgG2 were generally low and IgG4 was below detection level. Thus, in the IFN-gamma-predominated immune response seen in Lyme borreliosis, mainly IgG1 and IgG3 were found, i.e. the subclasses that are complement activating as well as opsonizing in humans. Increased levels of these two subclasses early in disease might contribute to recovery and counteract the development of chronicity. The absence of IgG4 is in accordance with the presumed Th1-like situation of Lyme borreliosis.