Molecular and cellular signatures underlying superior immunity against Bordetella pertussis upon pulmonary vaccination

Mucosal immunity is often required for protection against respiratory pathogens but the underlying cellular and molecular mechanisms of induction remain poorly understood. Here, systems vaccinology was used to identify immune signatures after pulmonary or subcutaneous immunization of mice with pertussis outer membrane vesicles. Pulmonary immunization led to improved protection, exclusively induced mucosal immunoglobulin A (IgA) and T helper type 17 (Th17) responses, and in addition evoked elevated systemic immunoglobulin G (IgG) antibody levels, IgG-producing plasma cells, memory B cells, and Th17 cells. These adaptive responses were preceded by unique local expression of genes of the innate immune response related to Th17 (e.g., Rorc) and IgA responses (e.g., Pigr) in addition to local and systemic secretion of Th1/Th17-promoting cytokines. This comprehensive systems approach identifies the effect of the administration route on the development of mucosal immunity, its importance in protection against Bordetella pertussis, and reveals potential molecular correlates of vaccine immunity to this reemerging pathogen.

Molecular and cellular signatures underlying superior immunity against Bordetella pertussis upon pulmonary vaccination

This corrects the article DOI: 10.1038/mi.2017.81.

Adaptive immune response to whole cell pertussis vaccine reflects vaccine quality: A possible complementation to the Pertussis Serological Potency test

Whole cell Bordetella pertussis (wP) vaccines are still used in many countries to protect against the respiratory disease pertussis. The potency of whole-cell pertussis vaccine lots is determined by an intracerebral challenge test (the Kendrick test). This test is criticized due to lack of immunological relevance of the read-out after an intracerebral challenge with B. pertussis. The alternative in vivo test, which assesses specific antibody levels in serum after wP vaccination, is the Pertussis Serological Potency test (PSPT). Although the PSPT focuses on a parameter that contributes to protection, the protective immune mechanisms after wP vaccination includes more elements than specific antibody responses only. In this study, additional parameters were investigated, i.e. circulating pro-inflammatory cytokines, antibody specificity and T helper cell responses and it was evaluated whether they can be used as complementary readout parameters in the PSPT to assess wP lot quality. By deliberate manipulation of the vaccine preparation procedure, a panel of high, intermediate and low quality wP vaccines were made. The results revealed that these vaccines induced similar IL-6 and IP10 levels in serum 4h after vaccination (innate responses) and similar antibody levels directed against the entire bacterium. In contrast, the induced antibody specificity to distinct wP antigens differed after vaccination with high, intermediate and low quality wP vaccines. In addition, the magnitude of wP-induced Th cell responses (Th17, Th1 and Th2) was reduced after vaccination with a wP vaccine of low quality. T cell responses and antibody specificity are therefore correlates of qualitative differences in the investigated vaccines, while the current parameter of the PSPT alone was not sensitive enough to distinguish between vaccines of different qualities. This study demonstrates that assessment of the magnitude of Th cell responses and the antigen specificity of antibodies induced by wP vaccination could form valuable complementary parameters to the PSPT.

[Impaired immunity: risk groups and consequences for general practice]

- Due to medication use, comorbidities and/or age, an increasing number of patients have an impaired immunity to infection.- Impaired immunity may lead to an increased risk of (opportunistic) infection, complications from infections, and difficulties in the diagnosis of infections.- Guided by clinical parameters, a general practitioner can classify an impaired immunity as 'clinically irrelevant', 'limitedly relevant' or 'potentially serious'.- Tocilizumab impairs the production of CRP, which makes it unreliable as an infection parameter.- In case of a suspected infection in patients with severe immunosuppression, it will often be necessary to consult a specialist as quickly as possible about further diagnostic procedures and the need for, type and administration route of antimicrobials.- In patients with an impaired immunity, adaptation of the antibiotic policy and prophylactic measures, such as vaccination, may be indicated.- Patients with (functional) asplenia should immediately start antibiotic treatment in case of fever, pending clinical evaluation by a physician.

Protection against allergic airway inflammation during the chronic and acute phases of Trichinella spiralis infection

BACKGROUND

Modulation of the host immune response by helminths has been reported to be essential for parasite survival and also to benefit the host by suppressing inflammatory diseases such as allergies. We have previously shown that excretory-secretory products of Trichinella spiralis muscle larvae have immunomodulatory properties and induce in vitro the expansion of CD4(+) CD25(+) FOXP3(+) Treg cells in a TGF-β-dependent manner.

OBJECTIVE

We aimed at determining the effect of the acute (intestinal) and the chronic (muscle) phase of T. spiralis infection on experimental allergic airway inflammation (EAAI) to Ovalbumin (OVA) and the involvement of Treg cells.

METHODS

The chronic phase was established before OVA-sensitization/challenge and the acute phase at two-time points, before and after OVA-sensitization. Mice were infected with 400 T. spiralis larvae and after euthanasia different pathological features of EAAI were measured. Adoptive transfer of CD4(+) T cells from Trichinella infected mice to OVA sensitized/challenged recipients was also performed.

RESULTS

We found that the chronic as well as the acute phase of Trichinella infection suppress EAAI as indicated by reduction in airway inflammation, OVA-specific IgE levels in sera, Th2-cytokine production and eosinophils in bronchoalveolar lavage. This protective effect was found to be stronger during the chronic phase and to be associated with increased numbers of splenic CD4(+) CD25(+) FOXP3(+) Treg cells with suppressive activity. Adoptive transfer of splenic CD4(+) T cells from chronically infected mice with elevated numbers of Treg cells resulted in partial protection against EAAI.

CONCLUSIONS AND CLINICAL RELEVANCE

These results demonstrate that the protective effect of T. spiralis on EAAI increases as infection progresses from the acute to the chronic phase. Here, Treg cells may play an essential role in the suppression of EAAI. Elucidating the mechanisms and molecular helminth structures responsible for this regulatory process is relevant to develop alternative tools for preventing or treating allergic asthma.

Mycobacterial and mouse HSP70 have immuno-modulatory effects on dendritic cells

Previously, it has been shown that heat shock protein 70 (HSP70) can prevent inflammatory damage in experimental autoimmune disease models. Various possible underlying working mechanisms have been proposed. One possibility is that HSP70 induces a tolerogenic phenotype in dendritic cells (DCs) as a result of the direct interaction of the antigen with the DC. Tolerogenic DCs can induce antigen-specific regulatory T cells and dampen pathogenic T cell responses. We show that treatment of murine DCs with either mycobacterial (Mt) or mouse HSP70 and pulsed with the disease-inducing antigen induced suppression of proteoglycan-induced arthritis (PGIA), although mouse HSP70-treated DCs could ameliorate PGIA to a greater extent. In addition, while murine DCs treated with Mt- or mouse HSP70 had no significantly altered phenotype as compared to untreated DCs, HSP70-treated DCs pulsed with pOVA (ovalbumin peptide 323-339) induced a significantly increased production of IL-10 in pOVA-specific T cells. IL-10-producing T cells were earlier shown to be involved in Mt HSP70-induced suppression of PGIA. In conclusion, this study indicates that Mt- and mouse HSP70-treated BMDC can suppress PGIA via an IL-10-producing T cell-dependent manner.

T cell receptor (TCR) signal strength controls arthritis severity in proteoglycan-specific TCR transgenic mice

T cell receptor transgenic (TCR-Tg) mice specific for the arthritogenic 5/4E8 epitope in the G1 domain of cartilage proteoglycan were generated and back-crossed into arthritis-prone BALB/c background. Although more than 90% of CD4(+) T cells of all TCR-Tg lines were 5/4E8-specific, one (TCR-TgA) was highly sensitive to G1-induced or spontaneous arthritis, while another (TCR-TgB) was less susceptible. Here we studied whether fine differences in TCR signalling controlled the onset and severity of arthritis. Mice from the two TCR-Tg lines were immunized side by side with purified recombinant human G1 (rhG1) domain for G1 domain of cartilage proteoglycan (PG)-induced arthritis (GIA). TCR-TgA mice developed severe and early-onset arthritis, whereas TCR-TgB mice developed weaker arthritis with delayed onset, although TCR-TgB CD4(+) T cells expressed approximately twice more TCR-Vβ4 chain protein. The more severe arthritis in TCR-TgA mice was associated with higher amounts of anti-G1 domain-specific antibodies, larger numbers of B cells and activated T helper cells. Importantly, TCR-TgB CD4(+) T cells were more sensitive to in vitro activation-induced apoptosis, correlating with their higher TCR and CD3 expression and with the increased TCR signal strength. These findings indicate that TCR signal strength determines the clinical outcome of arthritis induction: 'optimal' TCR signal strength leads to strong T cell activation and severe arthritis in TCR-TgA mice, whereas 'supra-optimal' TCR signal leads to enhanced elimination of self-reactive T cells, resulting in attenuated disease.

Considerations in the design of vaccines that induce CD8 T cell mediated immunity

The protective capacity of many currently used vaccines is based on induction of neutralizing antibodies. Many pathogens, however, have adapted themselves in different ways to escape antibody-based immune protection. In particular, for those infections against which conventional neutralizing antibody-based vaccinations appear challenging, CD8 T-cells are considered to be promising candidates for vaccine targeting. The design of vaccines that induce robust and long-lasting protective CD8 T-cell responses however imposes new challenges, as many factors such as kinetics and efficiency of antigen-processing and presentation by antigen presenting cells, T-cell repertoire and cytokine environment during T cell priming contribute to the specificity and functionality of CD8 T-cell responses. In the following, we review the most prominent aspects that underlie CD8 T-cell induction and discuss how this knowledge may help to improve the design of efficient CD8 T-cell inducing vaccines.

Cartilage proteoglycan aggrecan epitopes induce proinflammatory autoreactive T-cell responses in rheumatoid arthritis and osteoarthritis

OBJECTIVES

To explore potential T-cell epitopes of the core protein of human cartilage proteoglycan aggrecan (PG) in patients with rheumatoid arthritis (RA) or osteoarthritis.

METHODS

Peptide-specific T-cell proliferation and cytokine/chemokine production in response to PG-specific peptides were measured in RA and osteoarthritis patients and in healthy controls.

RESULTS

Peptides representing amino acid regions 16-39 and 263-282 of PG were most frequently recognised by T cells in a subset of patients with RA or osteoarthritis. Peripheral blood mononuclear cells from these PG-reactive RA and osteoarthritis patients showed increased production of proinflammatory cytokines/chemokines in response to PG peptide stimulation. As PG p263-282 was found to show high sequence homology with Yersinia Yop protein, the corresponding bacterial (Yersinia) peptide was also tested. Remarkably, RA and osteoarthritis patients responding to the Yersinia peptide also responded to p263-282 of PG suggesting a possibility of molecular mimicry in these patients.

CONCLUSIONS

These results indicate that PG-specific peptides, located in the G1 domain of PG, can induce (auto)antigenic T-cell responses in RA and osteoarthritis patients. These peptides might thus be involved in the immune pathogenesis and/or cartilage degradation in RA and osteoarthritis.

Activation of nucleotide oligomerization domain 2 exacerbates a murine model of proteoglycan-induced arthritis

In addition to its role in innate immunity, nucleotide oligomerization domain 2 (NOD2) has been shown to play a suppressive role in models of colitis. Notably, mutations in NOD2 cause the inherited granulomatous disease of the joints called Blau syndrome, thereby linking NOD2 with joint disease as well. However, the role of NOD2 in joint inflammation has not been clarified. We demonstrate here that NOD2 is functional within the mouse joint and promotes inflammation, as locally or systemically administered muramyl dipeptide (MDP; the NOD2 agonist) resulted in significant joint inflammation that was abolished in NOD2-deficient mice. We then sought to investigate the role of NOD2 in a mouse model of inflammatory arthritis dependent on adaptive immunity using TCR-transgenic mice whose T cells recognized the dominant epitope of proteoglycan (PG). Mice immunized with PG in the presence of MDP developed a more severe inflammatory arthritis and histopathology within the joints. Antigen-specific activation of splenocytes was enhanced by MDP with respect to IFN-gamma production, which would be consistent with the Th1-mediated disease in vivo. Intriguingly, NOD2 deficiency did not alter the PG-induced arthritis, indicating that NOD2 does not play an essential role in this model of joint disease when it is not activated by MDP. In conclusion, we demonstrate that in a model of inflammatory arthritis dependent on T and B cell priming, NOD2 activation potentiates disease. However, the absence of NOD2 does not alter the course of inflammatory arthritis, in contrast to models of intestinal inflammation.

ELISPOT and intracellular cytokine staining: novel assays for quantifying T cell responses in the chicken

The measurement of T cell responses in chickens, not only for quantitative aspects but also for the qualitative nature of the responses, becomes increasingly important. However, there are very few assays available to measure T cell function. Therefore, we have developed enzyme-linked immunosorbent spot assay (ELISPOT) and an intracellular cytokine staining (ICCS) assay. ELISPOT assay for the detection of chicken interferon-gamma (ChIFN-gamma) production was set up and shown to be reproducible for both polyclonal and antigen-specific stimuli such as Newcastle disease virus (NDV). However, the ELISPOT assay lacks the ability to identify individual cytokine-producing cells. Separation of CD4+ and CD8+ T cell populations gave additional information, but appeared to have the disadvantage of a loss of cell interactions during stimulation. In a further refinement, individual cells were identifiable by ICCS, which gives the possibility to characterize for multiple characteristics, such as cytokine production and phenotype of the cell. Using ICCS, ChIFN-gamma production was evaluated. Although cells were detected at only low frequencies, polyclonal stimulation of peripheral blood mononuclear cell (PBMC) or spleen cells resulted in a significant increase in ChIFN-gamma production by CD4+ and CD8+ cells.

Anterior uveitis accompanies joint disease in a murine model resembling ankylosing spondylitis

BACKGROUND

Uveitis is often associated with a systemic inflammatory disease such as ankylosing spondylitis. Our understanding of the eye's susceptibility to immune-mediated uveitis as in the apparent absence of infection has been limited by a relative lack of experimental models. Here we sought to assess whether ocular inflammation occurs in a previously described murine model of proteoglycan-induced spondylitis, wherein mice develop progressive spondylitis, sacroiliitis and peripheral arthritis--features common to the clinical presentations of ankylosing spondylitis.

METHODS

Using intravital microscopy we examined the ocular inflammatory response after the onset of arthritis in mice that overexpressed the T cell receptor (TCR) specific for a dominant arthritogenic epitope of cartilage proteoglycan [TCR-Tg (transgenic) mice] or BALB/c controls.

RESULTS

Immunized TCR-Tg mice showed a significant increase in the number of rolling and adhering cells within the iris vasculature compared to adjuvant control mice. Cellular infiltration within the iris tissue, as assessed by intravital microscopy and histology, was also increased. Our initial temporal analysis has revealed that immunized TCR-Tg mice show a significant increase in intravascular inflammation by 2 weeks after immunization, but it diminishes at 4 weeks after immunization.

CONCLUSIONS

Although these data are preliminary, this model has the potential to clarify the mechanisms accounting for the coexistence of eye and sacroiliac inflammation as occurs in patients with ankylosing spondylitis.

Induction of oral tolerance to HSP60 or an HSP60-peptide activates T cell regulation and reduces atherosclerosis

OBJECTIVE

HSP60-specific T cells contribute to the development of the immune responses in atherosclerosis. This can be dampened by regulatory T cells activated via oral tolerance induction, and we explored the effect of oral tolerance induction to HSP60 and the peptide HSP60 (253 to 268) on atherosclerosis.

METHODS AND RESULTS

HSP60 and HSP60 (253 to 268) were administered orally to LDLr(-/-) mice before induction of atherosclerosis and resulted in a significant 80% reduction in plaque size in the carotid arteries and in a 27% reduction in plaque size at the aortic root. Reduction in plaque size correlated with an increase in CD4(+)CD25(+)Foxp3(+) regulatory T cells in several organs and in an increased expression of Foxp3, CD25, and CTLA-4 in atherosclerotic lesions of HSP60-treated mice. The production of interleukin (IL)-10 and transforming growth factor (TGF)-beta by lymph node cells in response to HSP60 was observed after tolerance induction.

CONCLUSIONS

Oral tolerance induction to HSP60 and a small HSP60-peptide leads to an increase in the number of CD4(+)CD25(+)Foxp3(+) regulatory T cells, resulting in a decrease in plaque size as a consequence of increased production of IL-10 and TGF-beta. We conclude that these beneficial results of oral tolerance induction to HSP60 and HSP60 (253 to 268) may provide new therapeutic approaches for the treatment of atherosclerosis.

Induction of oral tolerance to oxidized low-density lipoprotein ameliorates atherosclerosis

BACKGROUND

Oxidation of low-density lipoprotein (LDL) and the subsequent processing of oxidized LDL (oxLDL) by macrophages results in activation of specific T cells, which contributes to the development of atherosclerosis. Oral tolerance induction and the subsequent activation of regulatory T cells may be an adequate therapy for the treatment of atherosclerosis.

METHODS AND RESULTS

Tolerance to oxLDL and malondialdehyde-treated LDL (MDA-LDL) was induced in LDL receptor-/- mice fed a Western-type diet by oral administration of oxLDL or MDA-LDL before the induction of atherogenesis. Oral tolerance to oxLDL resulted in a significant attenuation of the initiation (30% to 71%; P<0.05) and progression (45%; P<0.05) of atherogenesis. Tolerance to oxLDL induced a significant increase in CD4+ CD25+ Foxp3+ cells in spleen and mesenteric lymph nodes, and these cells specifically responded to oxLDL with increased transforming growth factor-beta production. Tolerance to oxLDL also increased the mRNA expression of Foxp3, CTLA-4, and CD25 in the plaque. In contrast, tolerance to MDA-LDL did not affect atherogenesis.

CONCLUSIONS

OxLDL-specific T cells, present in LDL receptor-/- mice and important contributors in the immune response leading to atherosclerotic plaque, can be counteracted by oxLDL-specific CD4+ CD25+ Foxp3+ regulatory T cells activated via oral tolerance induction to oxLDL. We conclude that the induction of oral tolerance to oxLDL may be a promising strategy to modulate the immune response during atherogenesis and a new way to treat atherosclerosis.

Mycobacterium avium ssp. paratuberculosis recombinant heat shock protein 70 interaction with different bovine antigen-presenting cells

Abstract Heat shock proteins (Hsp) can deliver antigen into the major histocompatibility complex class I presentation pathway of antigen-presenting cells (APC), a process called cross priming, thus stimulating antigen-specific CD8+ T-cell reactions. Hsp were shown to elicit proinflammatory responses in APC. Both processes require interaction of Hsp with APC via specific receptors. This study describes the interaction of recombinant Hsp70 (rHsp70) of Mycobacterium avium subspecies paratuberculosis with bovine peripheral blood mononuclear cells that was restricted to CD14+ cells. Characterized monocyte-derived macrophages, monocyte-derived dendritic cells (DC) and BoMac, an immortalized bovine macrophage cell line, were used to investigate the interaction of rHsp70 with different bovine APC. Saturation of immature DC with high concentrations of rHsp70 is demonstrated, and it was found that interaction of rHsp70 with DC was related to the maturation stage of the DC. Involvement of CD91 as a cellular receptor for rHsp70 was demonstrated; however, competition studies with immature DC demonstrated that other receptors exist on bovine APC. These data suggest that rHsp70-based vaccines may be useful for the successful immunization of cattle.

No epidemiological evidence for infant vaccinations to cause allergic disease

CONTEXT

The prevalence of allergic diseases has increased considerably over the last decades. The hygiene hypothesis has emerged, linking reduced microbial exposure and infections early in life with the development of allergic diseases. Especially some of currently available non-replicating infant vaccines are unlikely to mimic a natural infection-mediated immune response that protects against the development of allergic diseases. Moreover, several studies suggested infant vaccinations to increase the risk of allergic diseases.

OBJECTIVE

To determine whether infant vaccinations increase the risk of developing allergic disease.

DATA SOURCES

We searched MEDLINE from 1966 to March 2003 and bibliography lists from retrieved articles, and consulted experts in the field to identify all articles relating vaccination to allergy.

STUDY SELECTION AND DATA EXTRACTION

We selected epidemiological studies with original data on the correlation between vaccination with diphtheria, pertussis, tetanus (DPT), measles, mumps, rubella (MMR) and Bacillus Calmette-Guérin (BCG) vaccine in infancy and the development of allergic diseases, and assessed their quality and validity.

DATA SYNTHESIS

Methodological design and quality varied considerably between the studies we reviewed. Many studies did not address possible confounders, such as the presence of lifestyle factors, leaving them prone to bias. The studies that offer the stronger evidence, including the only randomized controlled trial at issue published to date, indicate that the infant vaccinations we investigated do not increase the risk of developing allergic disease. Furthermore, BCG does not seem to reduce the risk of allergies.

CONCLUSIONS

The reviewed epidemiological evidence indicates that, although possibly not contributing to optimal stimulation of the immune system in infancy, current infant vaccines do not cause allergic diseases.

The spontaneous remission of juvenile idiopathic arthritis is characterized by CD30+ T cells directed to human heat-shock protein 60 capable of producing the regulatory cytokine interleukin-10

OBJECTIVE

To test the hypothesis that T cell reactivity to self heat-shock protein 60 (Hsp60) in patients with remitting juvenile idiopathic arthritis (JIA) is part of an antiinflammatory, regulatory mechanism.

METHODS

Using peripheral blood-derived mononuclear cells (PBMCs) and synovial fluid-derived mononuclear cells (SFMCs) obtained from patients with JIA, we analyzed the expression of CD30 and the induction of regulatory cytokines in response to human and mycobacterial Hsp60.

RESULTS

In oligoarticular JIA patients, in vitro activation of PBMCs and SFMCs with Hsp60 induced a high expression of CD30 on CD4+, activated (HLA-DR-positive), memory (CD45RO+) T cells. The expression of CD30 induced by human Hsp60 was much higher than that induced by mycobacterial Hsp60. In oligoarticular JIA patients with active disease, the expression of CD30 in response to human Hsp60 was paralleled by a high interleukin-10 (IL-10):interferon-gamma (IFNgamma) ratio. In addition, restimulated human Hsp60-specific T cell lines from oligoarticular JIA patients showed a high production of IL-10 and a low production of IFNgamma. In contrast, PBMCs and SFMCs from polyarticular JIA patients responded to human Hsp60 with virtually no expression of CD30 and a low IL-10:IFNgamma ratio.

CONCLUSION

The results show that T cells responding to human Hsp60 in oligoarticular JIA patients express CD30, and during active phases of the disease, these T cells have a cytokine profile with a high IL-10:IFNgamma ratio. These findings suggest that in oligoarticular JIA patients, human Hsp60-specific CD4+ cells have a regulatory function and contribute to disease remission.

Mycobacterium paratuberculosis heat shock protein 70 as a tool in control of paratuberculosis

Paratuberculosis in cattle is a chronic intestinal disease in which a distinctive cellular reactivity of a Th1-type preceeds the phase in which antibody titers are easily detectable and the animal becomes clinically ill. During infection with Mycobacterium avium ssp. paratuberculosis (M.a.p), a decrease in CD4 T-helper cells has been observed in the clinical phase. Our ultimate aim is to elicit a cytotoxic reaction against infected macrophages, using recombinant Hsp70 (rHsp70) of M.a.p. as a tool to shuttle antigen into the MHC class I antigen presentation pathway. To investigate the mechanism of rHsp70 as a carrier for antigen into the cell, we studied the interaction between APC and Fitc-labelled rHsp70, using FACS analysis and confocal microscopy. Interaction of rHsp70 with the cell surface of bovine APC, presumably via a receptor, was shown on monocytes, monocyte derived macrophages and dendritic cell (DC). The interaction is detectable on the complete population of freshly derived monocytes, although peak intensity of fluorescence is lower on these cells than on macrophages and DCs. DCs show interaction on a high percentage of the cells, with high intensity, while in the case of macrophages only a subpopulation interacts with rHsp70. Efficient uptake of rHsp70 as compared to OVA is shown. Preincubation of DC with unlabelled rHsp70 leads to a decreased interaction with rHsp70-FITC. DC interacting with rHsp70 in addition showed high expression of MHC I, MHC II, Myd-1 (CD172a) and CD40. Further research will focus on loading of the rHsp70 with M.a.p. antigen for presentation in MHC class I.

Dynamics of mycobacterial HSP65-induced T-cell cytokine expression during oral tolerance induction in adjuvant arthritis

OBJECTIVE

To investigate whether oral administration of mycobacterial heat-shock protein 65 (HSP65) during adjuvant arthritis (AA) induces regulatory cells and cytokines.

METHODS

AA was induced in Lewis rats and from the time of disease onset HSP65 in the presence of soya bean trypsin inhibitor (STI) was administered orally every other day. The number of splenic CD4+CD25+ T cells and antigen-induced cytokine mRNA expression were determined.

RESULTS

Oral treatment with HSP65/STI reduced AA symptoms. After one feeding of HSP65/STI, the number of CD4+CD25+ splenic T cells increased and HSP65-specific T cells expressed increased levels of interferon gamma and interleukin 10. After two feedings, the expression of interleukin-10 mRNA remained increased, whereas there was low expression of interferon gamma mRNA. The number of CD4+CD25+ splenic T cells remained increased.

CONCLUSIONS

Oral treatment with HSP65/STI after AA onset reduces disease symptoms via dynamic changes in the number of CD4+CD25+ splenocytes and in antigen-induced cytokine production.

16-year remission of rheumatoid arthritis after unusually vigorous treatment of closed dental foci

This report describes a remission of rheumatoid arthritis (RA) of 16 years duration, apparently caused by the extraction of endodontically well-treated, healthy looking teeth. The only clue that the teeth were contributing to the disease pathogenesis in this case of RA was that the patient was able to reproducibly induce severe attacks of arthritis after prolonged, heavy pressure on some of his teeth treated with root canal fillings. After extraction, a small pus layer was found to cover the apices of the clinically healthy looking teeth. The rheumatoid factor (RF) became negative and the patient remained symptom free for the next 16 years. The possible connections between micro-organisms in closed dental foci under constant pressure and the chronicity and exacerbations of RA are discussed.

Induction of IL-10 and inhibition of experimental arthritis are specific features of microbial heat shock proteins that are absent for other evolutionarily conserved immunodominant proteins

Bacterial heat shock proteins (hsp) are evolutionary conserved immunodominant proteins that manifest amino acid homologies with hsp present in mammalian cells. Preimmunization with mycobacterial hsp65 has been found to protect against various forms of experimental arthritis. As these protective effects have previously been attributed to induction of self homologue cross-reactive T cell responses, the question was raised as to whether this protective effect could be extended to other highly conserved and immunodominant microbial Ags with mammalian homologues. Therefore, we immunized Lewis rats with conserved bacterial Ags (superoxide dismutase, aldolase, GAPDH, and hsp70). Although all Ags appeared highly immunogenic, we only found a protective effect in experimental arthritis after immunization with bacterial hsp70. The protective effect of hsp70 was accompanied with a switch in the subclasses of hsp70-specific Abs, suggesting the induction of Th2-like response. The most striking difference between immunization with hsp70 and all other immunodominant Ags was the expression of IL-10 found after immunization with hsp70. Even more, while immunization with hsp70 led to Ag-induced production of IL-10 and IL-4, immunization with aldolase led to increased production of IFN-gamma and TNF-alpha. Thus, the protective effect of conserved immunodominant proteins in experimental arthritis seems to be a specific feature of hsp. Therefore, hsp may offer unique possibilities for immunological intervention in inflammatory diseases.

Arthritis protective regulatory potential of self-heat shock protein cross-reactive T cells

Immunization with heat shock proteins has protective effects in models of induced arthritis. Analysis has shown a reduced synovial inflammation in such protected animals. Adoptive transfer and immunization with selected T cell epitopes (synthetic peptides) have indicated the protection to be mediated by T cells directed to conserved hsp epitopes. This was shown first for mycobacterial hsp60 and later for mycobacterial hsp70. Fine specificity analysis showed that such T cells were cross-reactive with the homologous self hsp. Therefore protection by microbial hsp reactive T cells can be by cross-recognition of self hsp overexpressed in the inflamed tissue. Preimmunization with hsp leads to a relative expansion of such self hsp cross-responsive T cells. The regulatory nature of such T cells may originate from mucosal tolerance maintained by commensal flora derived hsp or from partial activation through recognition of self hsp as a partial agonist (Altered Peptide Ligand) or in the absence of proper costimulation. Recently, we reported the selective upregulation of B7.2 on microbial hsp600 specific T cells in response to self hsp60. Through a preferred interaction with CTLA-4 on proinflammatory T cells this may constitute an effector mechanism of regulation. Also, regulatory T cells produced IL10.

Differential changes in heat shock protein-, lipoarabinomannan-, and purified protein derivative-specific immunoglobulin G1 and G2 isotype responses during bovine Mycobacterium avium subsp. paratuberculosis infection

Bovine paratuberculosis is caused by infection of young calves with Mycobacterium avium subsp. paratuberculosis. In some of the chronically infected cows the long asymptomatic stage (2 to 4 years) is followed by a rapid progression to a clinical stage due to protein-losing enteropathy, which will ultimately be fatal. The current dogma is that in early stages of disease the cell-mediated responses predominate, whereas in the clinical stage of the disease the humoral responses prevail, possibly signaling a switch in immune reactivity related to disease progression. We developed immunoglobulin M (IgM)-, IgA-, and IgG1- and IgG2-isotype-specific enzyme-linked immunosorbent assays for M. avium subsp. paratuberculosis-derived antigens (heat shock proteins of 70 kDa [Hsp70] and 65 kDa [Hsp65], lipoarabinomannan [LAM], and M. avium subsp. paratuberculosis purified protein derivative PPD [PPDP]). The serological responses of cows in different stages of paratuberculosis were used to evaluate the putative shift in immune responsiveness. In the clinical stage the PPDP-specific IgG1 responses were increased compared to those in the asymptomatic stage. However, total IgG1 and IgG2 and the Hsp70-, Hsp65-, and LAM-specific isotype responses were decreased in the clinical stage were decreased compared to those in the asymptomatic stage of disease. Thus, the classical pattern was found only for PPDP antigens and the IgG1 isotype. For other antigens and isotypes and the total IgG levels, the response pattern is different and indicates that there is no uniform association with increased antibody responses during the progression from the asymptomatic stage to the clinical stage of bovine paratuberculosis.

The human endoplasmic reticulum molecular chaperone BiP is an autoantigen for rheumatoid arthritis and prevents the induction of experimental arthritis

Rheumatoid arthritis (RA) is the most common, crippling human autoimmune disease. Using Western blotting and tandem mass spectroscopy, we have identified the endoplasmic reticulum chaperone BiP, a 78-kDa glucose-regulated protein, as a possible autoantigen. It preferentially stimulated increased proliferation of synovial T cells from patients with RA but not from patients with other arthritides. Mice with established collagen- or pristane-induced arthritis developed IgG Abs to BiP. Although BiP injected in CFA failed to induce arthritis in several strains of rats and mice, including HLA-DR4(+/-)- and HLA-DR1(+/+)-transgenic animals, it completely inhibited the development of arthritis when given i.v. 1 wk before the injection of type II collagen arthritis. Preimmunization with BiP suppressed the development of adjuvant arthritis in Lewis rats in a similar manner. This is the first report of a mammalian chaperone that is an autoantigen in human RA and in experimental arthritis and that can also prevent the induction of experimental arthritis. These findings may stimulate the development of new immunotherapies for the treatment of RA.

Induction of antigen specific CD4+ T cell responses by invariant chain based DNA vaccines

In this report, the use of DNA vaccination to induce class II restricted antigen specific proliferative responses was studied. To this end, a construct encoding the invariant chain (Ii) was engineered in which the Class II associated invariant chain peptide (CLIP) sequence was replaced by an immunogenic epitope derived form Heat Shock Protein 60, HSP60 178-186. Transfection studies in vitro showed that this construct can be used to efficiently load MHC class II molecules and present epitopes to MHC class II restricted antigen specific T cells. In addition, we showed that intradermal immunisation of Lewis rats with these constructs induced antigen specific T cells in vivo. Therefore, our Ii-gene constructs can be used to immunise for defined CD4+ T cell epitope sequences.

Lewis rats are not susceptible to oral infection with Mycobacterium avium subsp. paratuberculosis

Pathogenesis studies of Mycobacterium avium subsp. paratuberculosis infection in ruminants are hampered by the long incubation time of the disease. A laboratory animal model with a shorter incubation time would facilitate research in this field. Although small rodents are usually considered to be resistant to M.a. paratuberculosis infection, several susceptible murine strains have been found. To our knowledge, there are no detailed reports with regard to susceptibility in rats. The Lewis rat is a valuable model for inflammatory bowel disease studies as well as autoimmune diseases involving mycobacteria as inducing agents. In this study Lewis rats were used to investigate their potential as a small laboratory animal model for paratuberculosis. In total 28 female Lewis rats were orally inoculated with M.a. paratuberculosis. The rats were first inoculated at 3 weeks of age, and 12 more inoculations followed in increasing intervals during the 3 months to follow. Eight control rats received a sham inoculation. Over 9 months, two rats from each group were sacrificed at regular intervals and immunological and histopathological examinations were performed on the gastrointestinal tract, the liver and the spleen. None of the rats developed lesions which were indicative of mycobacterial infection as determined by histology with HE and Ziehl-Neelsen staining. The bacteria could not be recultured from samples taken from the gut, the liver or the spleen. The immunological tests however, showed that bacteria had entered via the intestinal tract. From this study it appears that Lewis rats are resistant to oral inoculation with M. a. paratuberculosis, and not suitable as a model to study the immunopathogenesis of paratuberculosis as it occurs in ruminants.

Highly autoproliferative T cells specific for 60-kDa heat shock protein produce IL-4/IL-10 and IFN-gamma and are protective in adjuvant arthritis

Previously we have shown that T cell responses to the mycobacterial 60-kDa heat shock protein (hsp60) peptide M256-270 mediated protection against adjuvant arthritis in Lewis rats. We have demonstrated now that M256-270-primed T cells become highly reactive to naive syngeneic APC upon repetitive restimulation in vitro with peptide M256-265, comprising the conserved core of peptide M256-270. These autoproliferative responses in the absence of added Ag were MHC class II restricted and resulted in the production of IL-4/IL-10 and IFN-gamma. Enhanced autoproliferation and expression of the cell surface molecule B7.2 by these T cells were observed in response to syngeneic heat-shocked APC, which indicated that the autoproliferation and expression of B7.2 resulted from the recognition of endogenously expressed and processed hsp. Despite their strong autoreactivity, upon transfer such T cells were found to induce a significant disease reduction in adjuvant arthritis. In contrast, T cells both primed and restimulated with peptide M256-270 became unresponsive toward syngeneic APC as well as toward the conserved core peptide M256-265, and they were devoid of protective capacity. This study demonstrates that the loss of self-tolerance toward hsp60 does not necessarily lead to autoimmune disease, but that hsp60-specific self-reactive and autoproliferative T cells may mediate T cell regulation in arthritis.

The efficacy of immunotherapy in an experimental murine model of allergic asthma is related to the strength and site of T cell activation during immunotherapy

In the present study, the relation between the efficacy of immunotherapy, and the strength and site of T cell activation during immunotherapy was evaluated. We used a model of allergic asthma in which OVA-sensitized and OVA-challenged mice display increased airway hyperresponsiveness, airway inflammation, and Th2 cytokine production by OVA-specific T cells. In this model, different immunotherapy strategies, including different routes of administration, or treatment with entire OVA or the immunodominant T cell epitope OVA(323-339), or treatment with a peptide analogue of OVA(323-339) with altered T cell activation capacity were studied. To gain more insight in how immunotherapy affects allergen-specific T cells, the site of Ag-specific T cell activation and the magnitude of the T cell response induced during different immunotherapy strategies were determined using an adoptive transfer model. Our data suggest that amelioration of airway hyperresponsiveness and inflammation is associated with the induction of a strong, synchronized, and systemic T cell response, resulting in a decreased OVA-specific Th2 response. In contrast, deterioration of the disease after immunotherapy is associated with the induction of a weak nonsynchronized T cell response, resulting in the enhancement of the OVA-specific Th2 response after challenge.

Treatment of adjuvant-induced arthritis by oral administration of mycobacterial Hsp65 during disease

OBJECTIVE

Oral administration of antigen prior to disease induction has been shown to induce peripheral tolerance in several experimental autoimmune diseases. However, the clinical benefit of pretreatment with antigens is limited. The aim of this study was to investigate whether adjuvant-induced arthritis (AIA) could be treated by oral administration of mycobacterial heat-shock protein 65 (Hsp65) during ongoing disease.

METHODS

AIA was induced in Lewis rats by immunization with Mycobacterium tuberculosis in Freund's incomplete adjuvant. Oral feeding of Hsp65 in the presence or absence of soybean trypsin inhibitor (SBTI) was started on day 11 after immunization. Arthritis was monitored visually, and joint pathology was examined radiologically.

RESULTS

Oral treatment with Hsp65 during ongoing disease significantly reduced the activity of AIA. However, treatment with Hsp65 was only successful when SBTI was coadministered to prevent breakdown of the Hsp65. The beneficial effect of Hsp65/SBTI treatment during AIA was also represented by a clear reduction of articular destruction, as visualized by radiography. Moreover, feeding Hsp65/SBTI resulted in a lower number of both spleen and mesenteric lymph node (MLN) cells expressing the costimulatory molecule CD80 (B7-1). The number of cells expressing CD86 (B7-2) was not altered. Furthermore, MLN cells from AIA animals treated with Hsp65/SBTI contained a lower number of T cells expressing the activation marker CD134 (Ox-40). In addition, treatment with Hsp65/ SBTI was accompanied by an increased proliferative response of spleen cells to the Hsp65 antigen in vitro. Moreover, Hsp65/SBTI-treated rats showed less Hsp65-specific interferon-gamma and increased production of interleukin-10.

CONCLUSION

Ongoing AIA activity can be reduced by oral administration of Hsp65 only when protein breakdown in the gastrointestinal tract is inhibited.

Nasal application of a naturally processed and presented T cell epitope derived from TCR AV11 protects against adjuvant arthritis

Reactivity towards TCR peptides plays an important role in the regulation of several experimental autoimmune diseases. In a previous paper, we showed the TCRAV11 usage by an arthritogenic T cell clone isolated from a rat with adjuvant arthritis (AA). Moreover, we identified three immunogenic peptides in AV11: AV11 24-40, 41-55 and 66-80. In the present study, we show that T cells directed towards all three epitopes are part of the immune repertoire. The strongest delayed-type hypersensitivity (DTH) reaction was observed against the peptide derived from the third framework region, peptide AV11 66-80. DTH reactions to this peptide were detectable in naive rats and increased significantly after AA induction. Interestingly, modulation of the AV11 66-80 T cell response by nasal AV11 66-80 administration resulted in reduced DTH responses and in a strong inhibition of AA. These findings suggest that during the natural course of AA, T cells directed towards the third framework region of AV11 do not have a disease regulatory function, but instead play a role in the deterioration of AA.

T cell reactivity to heat shock protein 60 in diabetes-susceptible and genetically protected nonobese diabetic mice is associated with a protective cytokine profile

Spontaneous onset of pancreatic beta cell destruction in the nonobese diabetic (NOD) mouse is preceded by the induction of autoreactive T cells, which recognize a variety of autoantigens. The 60-kDa endogenous (murine) heat shock protein 60 (hsp60) has been proposed to be one of the key autoantigens. Here we demonstrate that subcutaneous immunization of normoglycemic NOD mice with highly homologous mycobacterial or murine hsp60 activates T cells in the spleen that produce high levels of IL-10 upon restimulation in vitro with either hsp60 protein. In time, increasing levels of hsp60-induced IL-10 could be detected in NOD mice, but not in age- and MHC class II-matched BiozziABH mice, which lack any sign of pancreatic inflammation. These results suggest that the IL-10 responses in NOD mice are primarily driven by endogenous inflammation. Genetically protected NOD-asp mice, showing a less progressive development of insulitis, demonstrated a similar increase in hsp60-induced IL-10 in time compared with wild-type NOD mice. Taken together, our results suggest that endogenous hsp60 is not a primary autoantigen in diabetes but is possibly associated with regulation of insulitis. Moreover, the capacity to respond to (self) hsp60 is independent of the MHC class II-associated genetic predisposition to diabetes.

Arthritis protective regulatory potential of self-heat shock protein cross-reactive T cells

Immunization with heat shock proteins has protective effects in models of induced arthritis. Analysis has shown a reduced synovial inflammation in such protected animals. Adoptive transfer and immunization with selected T cell epitopes (synthetic peptides) have indicated the protection to be mediated by T cells directed to conserved hsp epitopes. This was shown first for mycobacterial hsp60 and later for mycobacterial hsp70. Fine specificity analysis showed that such T cells were cross-reactive with the homologous self hsp. Therefore protection by microbial hsp reactive T cells can be by cross-recognition of self hsp overexpressed in the inflamed tissue. Preimmunization with hsp leads to a relative expansion of such self hsp cross-responsive T cells. The regulatory nature of such T cells may originate from mucosal tolerance maintained by commensal flora derived hsp or from partial activation through recognition of self hsp as a partial agonist (Altered Peptide Ligand) or in the absence of proper costimulation. Recently, we reported the selective upregulation of B7.2 on microbial hsp600 specific T cells in response to self hsp60. Through a preferred interaction with CTLA-4 on proinflammatory T cells this may constitute an effector mechanism of regulation. Also, regulatory T cells produced IL10.

Induction of experimental autoimmune arthritis by a public epitope of the T cell receptor variable alpha domain of an arthritogenic T cell clone

T cell receptor (TCR) peptide immunizations have been demonstrated to protect against experimental autoimmune diseases. These findings have led to clinical trials employing TCR peptides in multiple sclerosis and rheumatoid arthritis patients. Previously, we identified a strongly immunogenic region of the TCR alpha chain of an arthritogenic T cell clone (AV11 66-80). In this report, we show that rats immunized with AV11 66-80 developed arthritis with clinical symptoms and histology similar to adjuvant arthritis (AA). Transfer of this disease into naive rats using AV11 66-80-specific T cells proved the T cell-mediated character of the disease. The AV11 66-80 arthritic rats developed resistance to Mycobacterium tuberculosis-induced AA, indicating that both forms of arthritis depended on similar regulatory mechanisms. This first demonstration of TCR peptide-induced arthritis, together with an earlier report on a polymorphism in this very same AV11 66-80 region involved in arthritis resistance in mice, suggests a central role of the public epitope AV11 66-80 in the control of autoimmune arthritis. Although TCR peptide immunizations can be exploited to prevent experimental autoimmunity, caution should be taken in the induction of TCR peptide-specific T cells for immunotherapy to avoid adverse effects as shown here.

Generation and characterization of a clonotypic antibody specific for the T cell receptor of an arthritogenic T cell clone--studies in adjuvant arthritis

Adjuvant Arthritis (AA) can be induced by passive transfer of a T cell clone (A2b) derived from arthritic rats, specific for Heat Shock Protein 60, HSP60 176-190. Furthermore, a crucial role for T cells with HSP60 176-190 specificity in AA was shown by induction of tolerance using HSP60 176-190 or by immunization with an altered peptide ligand based on the same sequence. To study clonal expansion of A2b-like T cells during AA and to determine their role in AA induction, we generated a clonotypic antibody, 16C4, specific for the TCR of the A2b T cell clone (TCR AV11S1/BV18). This antibody stained A2b T cells in flow cytometry experiments, induced proliferation of A2b cells when fixed on a solid support, and inhibited antigen-induced A2b proliferation when added in solution. A2b-like T cells were detected in a low frequency in lymphoid organs of arthritic rats. Thus, as in vivo administration of 16C4 did not inhibit AA, cells containing the determinant recognized by 16C4 are possibly not the sole contributors to AA development. Furthermore, epitope specific interventions by antigen administration may be possible even in cases where the epitope specific T cell clonotype is of low frequency.

A self-hsp60 peptide acts as a partial agonist inducing expression of B7-2 on mycobacterial hsp60-specific T cells: a possible mechanism for inhibitory T cell regulation of adjuvant arthritis?

We previously reported that resistance to the induction of adjuvant arthritis after preimmunization with mycobacterial hsp60 was mediated by T cells recognizing a conserved epitope (M256-270) of mycobacterial hsp60. These T cells were cross-reactive with the homologous rat hsp60 peptide sequence and the natural self-epitope on stressed antigen-presenting cells. Recognition of peptide M256-265, the conserved core of peptide M256-270, was shown to be essential for the generation of self-reactive T cells. The rat homologue of peptide M256-265, peptide R256-265, differs with three conservative amino acid substitutions from the mycobacterial core peptide. Thus peptide R256-265 could act as an altered peptide ligand with the potential of inducing a different functional phenotype in M256-270-specific T cells. We now show that peptide R256-265 was recognized by M256-270-specific T cells as a partial agonist, inducing TCR down-regulation and up-regulation of activation/adhesion molecules in the absence of proliferative responses. Peptide R256-265 did not induce anergy but induced B7-2 (but not B7-1) expression on M256-270-specific T cells, as opposed to the mycobacterial peptide, which preferentially induced B7-1. These effects were more pronounced at low peptide concentrations. Therefore also in vivo at the more relevant low physiological level of expression, the self-hsp could induce such phenotype. It is discussed how this selective up-regulation of B7-2 expression on (self-hsp60) autoreactive T cells might be a way by which destructive autoimmune responses are controlled.

'Anergic' T cells modulate the T-cell activating capacity of antigen-presenting cells

Nowadays there is compelling evidence for immunoregulation by T cells. Recently, we showed that so-called 'anergic' T cells are not functionally inert but can act as regulatory cells by actively suppressing other T cell responses. We now show that 'anergic' T cells mediate this suppressive effect via modulation of the T-cell activating capacity of the antigen-presenting cell (APC). Upon removal of the 'anergic' T cells, the suppressive APC phenotype persisted, indicating that 'anergic' T cells conditioned the APC to become a mediator of T cell suppression. The inhibitory signal delivered by 'anergic' T cells depended on the presence of the cognate ligand for the 'anergic' T cell, and appeared to be dominant since previously activated APC were rendered inhibitory as well. These findings imply that APC upon cross-talk with T cells can adopt distinct functional phenotypes ranging from T-cell stimulatory to T-cell suppressive. The contribution of 'anergic' T cells to the functional tuning of APC offers an explanation for the maintenance of 'anergic' T cells in the repertoire, and for their role in immunoregulation.

Induction of T cell anergy by liposomes with incorporated major histocompatibility complex (MHC) II/peptide complexes

PURPOSE

The aim of this study was to use small unilamellar liposomes with incorporated MHC II/peptide complexes as a carrier system for multivalent antigen presentation to CD4 + T cells.

METHODS

Purified peptide pre-loaded MHC II molecules were incorporated into small unilamellar liposomes and tested for their ability to activate A2b T cells. The outcome of T cell activation by such liposomes in the absence of accessory cells was tested via flow cytometry and a T cell anergy assay.

RESULTS

Provided the presence of external co-stimulation, MHC II/ peptide liposomes were able to induce proliferation of the A2b T cell clone. More importantly incubation of these T cells with MHC II/ peptide liposomes in the absence of co-stimulation did not induce proliferation, however, a MHC/peptide ligand-density dependent down-regulation of the TCR was observed. Interestingly, when T cells after incubation with the MHC II/peptide liposomes were restimulated with their specific antigen in the presence of professional APC, these cells were anergic.

CONCLUSIONS

We propose MHC II/peptide liposomes as a novel means to induce T cell anergy. The possibility to prepare 'tailor-made' liposomal formulations may provide liposomes with an important advantage for applications in immunotherapy.

A conserved mycobacterial heat shock protein (hsp) 70 sequence prevents adjuvant arthritis upon nasal administration and induces IL-10-producing T cells that cross-react with the mammalian self-hsp70 homologue

Immunization with Mycobacterium tuberculosis heat shock protein (hsp) 60 has been shown to protect rats from experimental arthritis. Previously, the protection-inducing capacity was shown to reside in the evolutionary conserved parts of the molecule. Now we have studied the nature of the arthritis suppressive capacity of a distinct, antigenically unrelated protein, M. tuberculosis hsp70. Again, a conserved mycobacterial hsp70 sequence was found to be immunogenic and to induce T cells that cross-reacted with the rat homologue sequence. However, in this case parenteral immunization with the peptide containing the critical cross-reactive T cell epitope did not suppress disease. Upon analysis of cytokines produced by these peptide-specific T cells, high IL-10 production was found, as was the case with T cells responsive to whole hsp70 protein. Nasal administration of this peptide was found to lead to inhibition of subsequent adjuvant arthritis induction. The data presented here shows the intrinsic capacity of conserved bacterial hsp to trigger self-hsp cross-reactive T cells with the potential to down-regulate arthritis via IL-10.

Modulation of Th2 responses by peptide analogues in a murine model of allergic asthma: amelioration or deterioration of the disease process depends on the Th1 or Th2 skewing characteristics of the therapeutic peptide

Allergen-specific CD4+ Th2 cells play an important role in the immunological processes of allergic asthma. Previously we have shown that, by using the immunodominant epitope OVA323-339, peptide immunotherapy in a murine model of OVA induced allergic asthma, stimulated OVA-specific Th2 cells, and deteriorated airway hyperresponsiveness and eosinophilia. In the present study, we defined four modulatory peptide analogues of OVA323-339 with comparable MHC class II binding affinity. These peptide analogues were used for immunotherapy by s.c. injection in OVA-sensitized mice before OVA challenge. Compared with vehicle-treated mice, treatment with the Th2-skewing wild-type peptide and a Th2-skewing partial agonistic peptide (335N-A) dramatically increased airway eosinophilia upon OVA challenge. In contrast, treatment with a Th1-skewing peptide analogue (336E-A) resulted in a significant decrease in airway eosinophilia and OVA-specific IL-4 and IL-5 production. Our data show for the first time that a Th1-skewing peptide analogue of a dominant allergen epitope can modulate allergen-specific Th2 effector cells in an allergic response in vivo. Furthermore, these data suggest that the use of Th1-skewing peptides instead of wild-type peptide may improve peptide immunotherapy and may contribute to the development of a successful and safe immunotherapy for allergic patients.

Heat-shock protein-specific T-cell responses in various stages of bovine paratuberculosis

Bovine paratuberculosis is characterized by a chronic inflammation of the small intestine, caused by infection with Mycobacterium avium ssp. paratuberculosis. Research regarding diagnostic as well as immunopathogenic aspects of paratuberculosis are hampered by the lack of specific antigens. The aim of the present study was to evaluate the potential of mycobacterial heat-shock proteins, as specific antigens, to measure cell-mediated immune responses during various stages of the disease. In a cross-sectional study, peripheral blood mononuclear cells of 179 cows in different stages of M. avium ssp. paratuberculosis infection, vaccinated against paratuberculosis or noninfected, were used to evaluate lymphoproliferative responses to mycobacterial heat-shock protein of 70 kD (HSP70) and 65 kD (HSP65). In addition, lymphoproliferative responses were measured using purified protein derivate (PPD) preparations from M. avium ssp. paratuberculosis, M. avium and M. bovis as antigens. Responses to HSP70 were higher in the vaccinated animals and in asymptomatic animals that shed the organism in their faeces. Compared with these animals, responses were lower in cows with clinical signs of paratuberculosis. Mycobacterial HSP65 induced less prominent responses compared with HSP70, but showed a similar pattern with regard to the stages of disease. Vaccinated and shedding animals also showed the highest responses to PPD derived from M. avium ssp. paratuberculosis (PPD-P). Observations with short-term cell lines raised to PPD-P and to HSP70 indicated that the similarity between those two antigens was not due to the presence of HSP70 in PPD-P. In conclusion, our study indicated that, as for PPD antigens the mycobacterial heat-shock protein-specific cell-mediated immune responses decrease when comparing the asymptomatic stage to the clinical stage in bovine paratuberculosis. Furthermore, this study shows that HSP70, being a well-defined antigen in comparison with PPD antigens, can be used to monitor cell-mediated immune responses in studies regarding the immunopathogenesis of bovine paratuberculosis.

Depressed responsiveness of peripheral blood mononuclear cells to heat-shock proteins in periodontitis patients

The extensive homology between human and bacterial heat shock proteins (HSPs) may play a role in autoimmune reactions in periodontitis. Thus, we questioned whether peripheral blood mononuclear cell (PBMC) proliferative responses to HSPs are different between periodontitis patients and control subjects with gingivitis. The proliferative responses of PBMCs of patients (n = 10) and controls (n = 12) to recombinant mycobacterial HSP60 (MycHSP60) and HSP70 (MycHSP70), as well as recombinant human HSP60 (HumHSP60) and HSP70 (HumHSP70), were investigated. In addition, the proliferative responses to Candida albicans and purified protein derivatives of Mycobacterium (PPD) were included. Mean responses to HumHSP60, MycHSP60, and HumHSP70 were significantly lower for patients compared with controls. The responses to MycHSP70 showed a similar trend. However, when Candida and PPD were used as antigens, there was no difference in responses of the PBMCs between the periodontitis patients and controls. The level of IFN-gamma in the supernatants of the cells stimulated with HSPs was lower in the patients compared with controls. This concurs with the current hypothesis that periodontitis patients have a depressed Th1 response. Furthermore, we found that with an increasing estimated subgingival bacterial load, periodontitis patients mount a decreasing immune response to HSPs, while the controls showed a positive correlation between these two parameters. From these findings, we speculate that poor reactivity to HSPs may be a susceptibility factor for destructive periodontal disease and may need to be considered in the pathogenesis of this condition.

Antigen presentation by T cells versus professional antigen-presenting cells (APC): differential consequences for T cell activation and subsequent T cell-APC interactions

We compared the effects of antigen (Ag) presentation by T cells and professional antigen-presenting cells (APC) on T cell proliferation, cytokine production and surface molecule expression. Ag presentation by T cells (T-T presentation) induced an initial T cell activation phase as measured by proliferation and IL-2 production. These activated T cells became anergic upon antigenic restimulation by professional APC, as shown by a failure to proliferate or produce IL-2 or IFN-gamma. Interestingly, such T cells were not intrinsically defective in their signal transduction pathways since they did proliferate and produce cytokines upon restimulation with mitogenic stimuli. Flow cytometric analysis revealed a more profound TCR and CD3 down-regulation during T-T presentation than during APC-T presentation. However, no up-regulation of CD80, CD86, CD45RC and OX40 (CD134) was observed on T cells during T-T presentation or subsequent antigenic restimulation of anergic T cells in the presence of professional APC, whereas increased expression of these molecules was observed during professional APC-T presentation of non-anergic T cells. The impaired expression of co-stimulatory and activation molecules on T cells after T-T presentation of Ag might lead to altered interactions between T cells and professional APC upon antigenic restimulation. We propose that T cell anergy is a functional consequence of these altered T cell-APC interactions.

Dose-dependent induction of distinct anergic phenotypes: multiple levels of T cell anergy

T cell anergy has been proposed as one of the mechanisms underlying peripheral T cell tolerance. In recent years, the functional relevance of T cell anergy has been studied extensively in vitro and in vivo, using different species, cell systems, and ways to induce anergy. Although these studies concurred about the induction of unresponsiveness, conflicting findings were obtained with respect to the function of anergic T cells and to the persistence of T cell anergy. In the present study, T cell anergy was induced through T-T presentation of the specific Ag by rat MHC class II+ T cells in the absence of professional APC. We show that, depending on the Ag dose with which T cells were incubated, distinct anergic phenotypes were induced. Incubation of T cell clones with a low (suboptimal) Ag dose induced hyporesponsiveness. Incubation with a higher (optimal) Ag dose induced an anergic state capable of exerting immunoregulatory effects. Incubation with a high (supraoptimal) Ag dose led to an anergic suppressive phenotype that was persistent and was not reversed by APC, Ag, and rIL-2. These findings demonstrate that T cell anergy is not confined to a single state of functional inactivation. Instead, multiple levels of T cell anergy exist. Thus, anergic T cells can contribute to the regulation of the immune response either in a persistent and active manner or in a passive manner, depending on their level of T cell anergy.

Liposomes with incorporated MHC class II/peptide complexes as antigen presenting vesicles for specific T cell activation

PURPOSE

The purpose of this study was to design a well-characterized liposomal carrier system for multivalent antigen presentation in order to activate T cells.

METHODS

MHC class II molecules were loaded with peptide and subsequently reconstituted into liposomes. A FACS assay was developed to monitor peptide loading and MHC class II incorporation in the liposomes. For in vitro testing of the resulting MHC class II/peptide liposomes, a T cell hybridoma assay was employed.

RESULTS

The FACS assay provided a qualitative means to visualize the amount of incorporated MHC class II and peptide molecules that were oriented in the appropriate way for antigen presentation to the T cells. Interestingly, when MHC class II molecules were loaded with the appropriate peptide prior to liposome incorporation, such liposomes were fully capable of inducing IL-2 production of a T cell hybridoma.

CONCLUSIONS

This is the first article showing that MHC class II/peptide liposomes can serve as 'artificial antigen presenting cells' for activation of a CD4+ T cell hybridoma. As compared to soluble MHC class II/peptide complexes, the multivalency of liposomal complexes may be an important advantage when studying possible applications in immunotherapy.

Immunity to heat shock proteins and arthritic disorders

Adjuvant arthritis (AA) is a frequently used model of experimental arthritis. Because of its histopathology, which is reminiscent of rheumatoid arthritis in humans, AA is used as a model for the development of novel anti-inflammatory drugs. Recently, it has become evident that AA is a typical T-cell-mediated autoimmune condition. Therefore, novel immunotherapies targeted to T cells can be developed in this model. Analysis of responding T cells in AA have now led to the definition of various antigens with potential relevance to arthritis, including human arthritic conditions. One such antigen defined in AA is the 60kD heat shock protein. Both T-cell vaccination approaches and active antigen immunizations and antigen toleration approaches have turned out to be effective in suppressing AA.

Anergic T cells actively suppress T cell responses via the antigen-presenting cell

We here show that anergic T cells are active mediators of T cell suppression. In co-culture experiments, we found that anergic T cells, derived from established rat T cell clones and rendered anergic via T cell presentation of the specific antigen (Ag), were active inhibitors of T cell responses. Anergic T cells inhibited not only the responses of T cells with the same Ag specificity as the anergic T cells, but were also capable of efficiently inhibiting polyclonal T cell responses directed to other epitopes. This suppression required close cell-cell contact between antigen-presenting cells (APC), anergic T cells and responder T cells, and only occurred when the epitope recognized by the anergic T cell was present. The suppression was not caused by passive competition for ligands on the APC surface, IL-2 consumption, or cytolysis, and was not mediated by soluble factors derived from anergic T cells that were stimulated with their specific Ag. When responder T cells were added 24 h after co-culturing anergic cells in the presence of Ag and APC, T cell responses were still suppressed, indicating that the suppressive effect was persistently present. However, anergic T cells were not able to suppress responder T cells that had already received a full activation signal. We propose that suppression by anergic T cells is mediated via the APC, either through modulation of the T cell-activating capacity of the APC (APC/T cell interaction), or by inhibition of T cells recognizing their ligand in close proximity on the same APC (T/T cell interaction).

Heat-shock protein T-cell epitopes trigger a spreading regulatory control in a diversified arthritogenic T-cell response

Adjuvant arthritis (AA) in Lewis rats is T-cell mediated and seems to depend on T cells recognising the 180-188 epitope of mycobacterial heat-shock protein (hsp) 60. Analysis of arthritogenic T-cell clone A2b has revealed a mimicry of this particular epitope with an articular cartilage-associated target T-cell epitope. Nasal administration of synthetic peptides covering this 180-188 sequence led to epitope-specific tolerance and resistance to AA. Since this tolerisation protocol also inhibited avridine arthritis, one may conclude that this form of epitope-specific tolerance had effectuated a spreading tolerisation at the level of target antigens that included a diverse set of possible arthritis-associated antigens. In vitro anergised T cells exhibited suppressive activity in a co-culture system. As in this case--depending on the presence of the antigen of the anergic T cell--such T cells suppressed responder T cells of a different antigenic specificity, we postulated that anergic T cells may be responsible for a spreading of tolerance. It seemed that such spreading of tolerance was channelled through the antigen-presenting cells (APC) and was dependent on direct cell-cell contact. This and additional forms of spreading of tolerance could be responsible for specific nasal tolerance, causing inhibition of the development of an arthritogenic inflammatory response. This can be similarly the case for the arthritis protection that resulted from immunisation with hsps. Analysis of T-cell responses following hsp immunisations revealed that the arthritis inhibitory activity resided in T cells with specificity for a conserved part of microbial hsp 60. The same T cells cross-responded to rat self-hsp60. Low level expression of the latter molecule on non-professional APC could possibly have induced a suppressive anergic state in these autoreactive cells. Thus, immunisation with microbial hsp would have led to an expansion of such T cells, leading to raised disease-suppressive potential when selectively trapped and activated in the inflamed self-hsp-overexpressing joint. Alternatively, the cross-recognised self-hsp epitope could have the regulatory qualities of an altered peptide ligand or a partial agonist for T cells that see the microbial homologue as the full agonist.