Autoimmunity to heat shock protein 60 and antigen-specific production of interleukin-10

The role of infected epithelial cells in Chlamydia-associated fibrosis

Ocular, genital, and anogenital infection by the obligate intracellular pathogen Chlamydia trachomatis have been consistently associated with scar-forming sequelae. In cases of chronic or repeated infection of the female genital tract, infection-associated fibrosis of the fallopian tubes can result in ectopic pregnancy or infertility. In light of this urgent concern to public health, the underlying mechanism of C. trachomatis-associated scarring is a topic of ongoing study. Fibrosis is understood to be an outcome of persistent injury and/or dysregulated wound healing, in which an aberrantly activated myofibroblast population mediates hypertrophic remodeling of the basement membrane via deposition of collagens and other components of the extracellular matrix, as well as induction of epithelial cell proliferation via growth factor signaling. Initial study of infection-associated immune cell recruitment and pro-inflammatory signaling have suggested the cellular paradigm of chlamydial pathogenesis, wherein inflammation-associated tissue damage and fibrosis are the indirect result of an immune response to the pathogen initiated by host epithelial cells. However, recent work has revealed more direct routes by which C. trachomatis may induce scarring, such as infection-associated induction of growth factor signaling and pro-fibrotic remodeling of the extracellular matrix. Additionally, C. trachomatis infection has been shown to induce an epithelial-to-mesenchymal transition in host epithelial cells, prompting transdifferentiation into a myofibroblast-like phenotype. In this review, we summarize the field's current understanding of Chlamydia-associated fibrosis, reviewing key new findings and identifying opportunities for further research.

Problems with Understanding Chlamydia trachomatis Immunology

The pay off for understanding Chlamydia. trachomatis (CT) immunology is the development of a vaccine. Two lines of research have contributed to our current understanding of CT immunology. The first is the Grayston model of type specific immunity and genus specific pathology which was elaborated by Caldwell and Morrison as the major outer membrane protein (MOMP) and heat shock protein 60 (HSP60) paradigm. The second is the murine model of C. muridarum (CM) infection which established the essential role of major histocompatibility complex class II and CD4 T cells in immunity. However neither approach has yielded a vaccine. I review these two lines of research and conclude with six problem areas in human CT immunology whose resolution may result in a vaccine.(122 words)

Suppressors of Cytokine Signaling (SOCS)1 and SOCS3 Proteins Are Mediators of Interleukin-10 Modulation of Inflammatory Responses Induced by Chlamydia muridarum and Its Major Outer Membrane Protein (MOMP) in Mouse J774 Macrophages

The immunopathology of chlamydial diseases is exacerbated by a broad-spectrum of inflammatory mediators, which we reported are inhibited by IL-10 in macrophages. However, the chlamydial protein moiety that induces the inflammatory mediators and the mechanisms by which IL-10 inhibits them are unknown. We hypothesized that Chlamydia major outer membrane protein (MOMP) mediates its disease pathogenesis, and the suppressor of cytokine signaling (SOCS)1 and SOCS3 proteins are mediators of the IL-10 inhibitory actions. Our hypothesis was tested by exposing mouse J774 macrophages to chlamydial stimulants (live Chlamydia muridarum and MOMP) with and without IL-10. MOMP significantly induced several inflammatory mediators (IL-6, IL-12p40, CCL5, CXCL10), which were dose-dependently inhibited by IL-10. Chlamydial stimulants induced the mRNA gene transcripts and protein expression of SOCS1 and SOCS3, with more SOCS3 expression. Notably, IL-10 reciprocally regulated their expression by reducing SOCS1 and increasing SOCS3. Specific inhibitions of MAPK pathways revealed that p38, JNK, and MEK1/2 are required for inducing inflammatory mediators as well as SOCS1 and SOCS3. Chlamydial stimulants triggered an M1 pro-inflammatory phenotype evidently by an enhanced nos2 (M1 marker) expression, which was skewed by IL-10 towards a more M2 anti-inflammatory phenotype by the increased expression of mrc1 and arg1 (M2 markers) and the reduced SOCS1/SOCS3 ratios. Neutralization of endogenously produced IL-10 augmented the secretion of inflammatory mediators, reduced SOCS3 expression, and skewed the chlamydial M1 to an M2 phenotype. Inhibition of proteasome degradation increased TNF but decreased IL-10, CCL5, and CXCL10 secretion by suppressing SOCS1 and SOCS3 expressions and dysregulating their STAT1 and STAT3 transcription factors. Our data show that SOCS1 and SOCS3 are regulators of IL-10 inhibitory actions, and underscore SOCS proteins as therapeutic targets for IL-10 control of inflammation for Chlamydia and other bacterial inflammatory diseases.

Cutaneous Vasculitis in Cogan's Syndrome: A Report of Two Cases Associated with Chlamydia Infection

Cogan's syndrome (CS) is defined by the combination of hearing loss, vertigo, and ocular inflammation of uncertain cause, and can be associated with variable vessel vasculitis. Vasculitic manifestations may include arteritis (affecting large, medium or small arteries), aortitis, and aortic and mitral valvulitis. Cutaneous manifestations including erythema, papules, subcutaneous nodules, and purpura sometimes occur; however, to date, only six cases have been histologically confirmed to have genuine vasculitis. Here, we report two cases of CS, one of which involved a patient who developed the typical symptoms of Takayasu arteritis and purpuric lesions in the legs, with histologic findings consistent with small vessel vaculitis in the dermis. The second case involved a patient who developed subcutaneous nodules in the legs and the axilla, and histologic findings revealed a necrotizing vasculitis of the small arteries in the interlobular area. Both cases were successfully treated with systemic steroid therapy. Based on the clinical features and the examination data, there is a possibility that a Chlamydia trachomatis infection played a pivotal role in the pathogenesis of those vasculitides.

The evaluation of immunogenic impact of selected bacterial, recombinant Hsp60 antigens in DBA/2J mice

Heat Shock Proteins (HSP) are highly conserved proteins that are widely spread throughout all organisms. They function in the cytoplasm as chaperones; however, they could be expressed on the cell surface. It has been shown that Hsp60 obtained from gram-negative bacteria are able to stimulate cells of the acquired and innate immune system. The aim of this study was the evaluation of the immunogenic properties of recombinant Hsp60 proteins derived from four common pathogenic bacteria: Escherichia coli, Histophilus somni, Pasteurella multocida and Salmonella Enteritidis. The analysis of the humoral immune response in DBA/2J mice hyperimmunized with selected rHsp60 revealed high levels of IgG rHsp60-antibody with the predominance of the IgG₁ subclass, in the reaction with both homologous and heterologous antigens. The presence of IgG_2a and IgG_2b was also observed; however, no antibodies of subclass IgG₃ were detected. The comparison of plasma IgG antibody reactivity of mice immunized with two different doses of rHsp60 (10/20 μg) showed that the lower dose was sufficient to induce a strong humoral response. The reactivity of the IgG rHsp60-antibody with whole bacterial cells showed a significantly higher reaction with H. somni compared with other pathogens. It was demonstrated that the addition of all rHsp60 with polymyxin B to the culture medium stimulated splenocytes isolated from hyperimmunized mice to release IL-1β and IL-6. As a strong stimulator of the immune system, bacterial-origin Hsp60 seems to be an interesting potential component of subunit vaccines aimed at the development of protection for animals during infections caused by gram-negative bacteria.

Update on Chlamydia trachomatis Vaccinology

Attempts to produce a vaccine to protect against Chlamydia trachomatis-induced trachoma were initiated more than 100 years ago and continued for several decades. Using whole organisms, protective responses were obtained. However, upon exposure to C. trachomatis, disease exacerbation developed in some immunized individuals, precluding the implementation of the vaccine. Evidence of the role of C. trachomatis as a sexually transmitted pathogen started to emerge in the 1960s, and it soon became evident that it can cause acute infections and long-term sequelae in women, men, and newborns. The main focus of this minireview is to summarize recent findings and discuss formulations, including antigens, adjuvants, routes, and delivery systems for immunization, primarily explored in the female mouse model, with the goal of implementing a vaccine against C. trachomatis genital infections.

Modulation of Costimulatory Molecules CD80/CD86 on B Cells and Macrophages by Stress Proteins GroEL, GroES and DnaK

The aim of this study was to evaluate the effect of the Heat Shock Proteins GroES, GroEL and DnaK on the expression of the costimulatory molecules CD80/CD86 in B cells and macrophages. The interactions among these molecules are able to highly influence the immune response through the regulation of cytokine liberation which, on their own, are able to regulate the immunological response by a feedback mechanism. Our results showed that, on B cells, GroES and GroEL stimulated the expression of CD86 but did not induce the increase of the CD80 expression. CD86 peak expression showed a peak after 24–48 h of culture and decreaseed 60h after the stimulation. GroES and GroEL also stimulated the expression of CD80 and CD86 on macrophages. The same HSPs did not modify the expression of CD80 and CD86 on cells having characteristics of activated macrophages, the A-THP-1 cell line. DnaK did not induce any increase in the expression of CD80 and CD86 on lymphocytes or macrophages.

A vaccine formulated with the major outer membrane protein can protect C3H/HeN, a highly susceptible strain of mice, from a Chlamydia muridarum genital challenge

C3H/HeN female mice were vaccinated with native Chlamydia muridarum major outer membrane protein (MOMP), using Montanide+CpG or Alum+CpG as adjuvants. Negative control groups were immunized with ovalbumin (OVA) and the same adjuvants. As positive control, mice were inoculated intranasally with live Chlamydia. Mice were challenged in the ovarian bursa with 10(5) C. muridarum inclusion forming units. Six weeks after the genital challenge the animals were caged with male mice and monitored for pregnancy. Mice vaccinated with MOMP+Montanide+CpG developed high levels of C. muridarum-specific antibodies, with a high IgG2a/IgG1 ratio and neutralizing titres. Animals immunized using Alum+CpG had low antibody levels. Cellular immune responses were significantly higher in mice vaccinated with MOMP and Montanide+CpG, but not with Alum+CpG, when compared with negative controls. Following the genital challenge, only 20% (4/20) of mice vaccinated with MOMP+CpG+Montanide had positive vaginal cultures whereas 100% (9/9) of mice immunized with MOMP+CpG+Alum had positive cultures. Of the positive control animals inoculated with live Chlamydia only 15% (3/20) had positive vaginal cultures. In contrast, 100% (20/20) of mice immunized with OVA+CpG+Montanide, or minimal essential medium, had positive cultures. Following mating, 80% (16/20) of mice vaccinated with MOMP+CpG+Montanide, and 85% (17/20) of animals inoculated intranasally with live C. muridarum carried embryos in both uterine horns. No protection against infertility was observed in mice immunized with MOMP and CpG+Alum or OVA. In conclusion, this is the first time that a subunit vaccine has been shown to elicit a protective immune response in the highly susceptible C3H/HeN strain of mice against an upper genital challenge.

Dynamics of NKT-Cell Responses to Chlamydial Infection

Natural killer T (NKT) cells have gained great attention owing to their critical functional roles in immunity to various pathogens. In this review, we provide an overview of the current knowledge on the role of NKT cells in host defense against and pathogenesis due to Chlamydia, which is an intracellular bacterial pathogen that poses a threat to the public health worldwide. Accumulating evidence has demonstrated that NKT cells, particularly invariant NKT (iNKT) cells, play a crucial role in host defense against chlamydial infections, especially in C. pneumoniae infection. iNKT cells can promote type-1 protective responses to C. pneumoniae by inducing enhanced production of IL-12 by dendritic cells (DCs), in particular CD8α+ DCs, which promote the differentiation of naive T cells into protective IFN-γ-producing Th1/Tc1 type CD4+/CD8+ T cells. This iNKT-cell-mediated modulation of DC function is largely dependent upon CD40–CD40L interaction, IFN-γ production, and cell-to-cell contact. In addition, iNKT cells modulate the function of natural killer cells. NKT cells may be also involved in the pathogenesis of some chlamydial diseases by inducing different patterns of cytokine production. A better understanding of NKT-cell biology will enable us to rationally design prophylactic and therapeutic tools to combat infectious diseases.

Association of tubal factor infertility with elevated antibodies to Chlamydia trachomatis caseinolytic protease P

OBJECTIVE

The objective of the study was to assess antibodies against Chlamydia trachomatis heat shock proteins (HSP) in patients with tubal factor infertility (TFI), infertility controls (IFC), and fertile controls (FC). HSPs assist organisms in surviving caustic environments such as heat.

STUDY DESIGN

Twenty-one TFI, 15 IFC, and 29 FC patients were enrolled after laparoscopic tubal assessment. The titers of antibodies against C trachomatis organisms and 14 chlamydial HSPs were compared among the 3 groups.

RESULTS

TFI patients developed significantly higher levels of antibodies against C trachomatis and specifically recognizing chlamydial HSP60 and caseinolytic protease (Clp) P, a subunit of the ATP-dependent Clp protease complex involved in the degradation of abnormal proteins.

CONCLUSION

In addition to confirming high titers of antibodies against C trachomatis organisms and HSP60 in TFI patients, we identified a novel link of TFI with anti-ClpP antibodies. These findings may provide useful information for developing a noninvasive screening test for TFI and constructing subunit anti-C trachomatis vaccines.

A genome-wide profiling of the humoral immune response to Chlamydia trachomatis infection reveals vaccine candidate antigens expressed in humans

A whole genome scale proteome array consisting of 908 open reading frames encoded in Chlamydia trachomatis genome and plasmid was used to profile anti-chlamydial Ab responses. A total of 719 chlamydial proteins was recognized by one or more antisera from 99 women urogenitally infected with C. trachomatis. Revealing such a large C. trachomatis ANTIGENome in humans might partially be attributed to the significantly improved detection sensitivity of the whole genome scale proteome array assay because both linear and conformation-dependent Abs were detected by the array assay. Twenty-seven of the 719 Ags were recognized by >or=50% antisera, thus designated as immunodominant Ags. Comparison of Ag profiles recognized by live chlamydial organism-infected versus dead organism-immunized hosts led to the identification of infection-dependent or in vivo expressed Ags. The infection-dependent Ags induced Abs only in live organism-infected, but not in dead organism-immunized hosts. Many of these Ags were highly expressed during replication, but only minimally packaged into the infectious elementary bodies. Because inactivated whole chlamydial organism-based vaccines failed to induce protection in humans, identification of the infection-dependent or in vivo expressed immunodominant Ags in humans should greatly facilitate the selection of promising chlamydial subunit vaccine candidates for further evaluation. This approach may also be applicable to other pathogens.

Chlamydia trachomatis, a hidden epidemic: effects on female reproduction and options for treatment

The number of genital tract Chlamydia trachomatis infections is steadily increasing worldwide, with approximately 50-70% of infections asymptomatic. There is currently no uniform screening practice, current antibiotic treatment has failed to prevent the increased incidence, and there is no vaccine available. We examined studies on the epidemiology of C. trachomatis infections, the effects infections have on the female reproductive tract and subsequent reproductive health and what measures are being taken to reduce these problems. Undetected or multiple infections in women can lead to the development of severe reproductive sequelae, including pelvic inflammatory disease and tubal infertility. There are two possible paradigms of chlamydial pathogenesis, the cellular and immunological paradigms. While many vaccine candidates are being extensively tested in animal models, they are still years from clinical trials. With no vaccine available and antibiotic treatment unable to halt the increased incidence, infection rates will continue to increase and cause a significant burden on health care systems.

Chlamydia trachomatis antigens in enteroendocrine cells and macrophages of the small bowel in patients with severe irritable bowel syndrome

BACKGROUND

Inflammation and immune activation have repeatedly been suggested as pathogentic factors in irritable bowel syndrome (IBS). The driving force for immune activation in IBS remains unknown. The aim of our study was to find out if the obligate intracellular pathogen Chlamydia could be involved in the pathogenesis of IBS.

METHODS

We studied 65 patients (61 females) with IBS and 42 (29 females) healthy controls in which IBS had been excluded. Full thickness biopsies from the jejunum and mucosa biopsies from the duodenum and the jejunum were stained with a monoclonal antibody to Chlamydia lipopolysaccharide (LPS) and species-specific monoclonal antibodies to C. trachomatis and C. pneumoniae. We used polyclonal antibodies to chromogranin A, CD68, CD11c, and CD117 to identify enteroendocrine cells, macrophages, dendritic, and mast cells, respectively.

RESULTS

Chlamydia LPS was present in 89% of patients with IBS, but in only 14% of healthy controls (p < 0.001) and 79% of LPS-positive biopsies were also positive for C. trachomatis major outer membrane protein (MOMP). Staining for C. pneumoniae was negative in both patients and controls. Chlamydia LPS was detected in enteroendocrine cells of the mucosa in 90% of positive biopsies and in subepithelial macrophages in 69% of biopsies. Biopsies taken at different time points in 19 patients revealed persistence of Chlamydia LPS up to 11 years. The odds ratio for the association of Chlamydia LPS with presence of IBS (43.1; 95% CI: 13.2-140.7) is much higher than any previously described pathogenetic marker in IBS.

CONCLUSIONS

We found C. trachomatis antigens in enteroendocrine cells and macrophages in the small bowel mucosa of patients with IBS. Further studies are required to clarify if the presence of such antigens has a role in the pathogenesis of IBS.

Expression of IL-6, IL-8, TNF-alpha, IL-10, HSP-60, anti-HSP-60 antibodies, and anti-sperm antibodies, in semen of men with leukocytes and/or bacteria

PROBLEM

Different cellular and biochemical markers have been proposed as indicators of infection-inflammation of male genital tract.

METHOD OF STUDY

Semen samples from 80 men attending an andrologic clinic were evaluated to determine the presence of leukocyte, bacteria, antibodies against Chlamydia trachomatis, levels of IL-6, IL-8, IL-10, and TNF-alpha, HSP-60, anti-HSP-60 antibodies, and anti-sperm antibodies.

RESULTS

Leukocytes in semen significantly correlated with an increase in IL-6, IL-8, and TNF-alpha. The simultaneous presence of pathogens and leukocytes was associated with high levels of IL-8 and TNF-alpha, whereas IL-6 was more associated with the presence of leukocytes. Anti-HSP-60 antibodies positively correlated with IL-6 and IL-8. The presence of anti-sperm antibodies highly associated with an increase in anti-HSP-60 antibodies.

CONCLUSIONS

The type of cytokines present in the semen will depend on the single or simultaneous presence of leukocytes and/or pathogens. Chronic male genital tract infections could be associated with the development of anti-HSP-60 antibodies and anti-sperm antibodies.

A comparative analysis of the products of GROEL-1 gene from Chlamydia trachomatis serovar D and the HSP60 var1 transcript from Homo sapiens suggests a possible autoimmune response

Chlamydia trachomatis serovar D produces large quantities of HSP60-1 during infections, which accumulate inside the host cell inducing autoimmunity. We compare the aminoacid sequences of the human HSP60 with the bacterial counterpart to better elucidate how CTHSP60 may simulate HSP60 from human origin during infection and may induce an autoimmune response. As a result of the comparison we suggest several possible epitopes of the CTHSP60, which may induce autoimmunity.

Airflow limitation, asthma, and Chlamydia pneumoniae-specific heat shock protein 60

BACKGROUND

Chlamydia pneumoniae has been associated with asthma. It has also been suggested that C pneumoniae infection may lead to lung remodeling in a subset of asthmatic patients. Seroreactivity against Chlamydia trachomatis heat shock protein 60 (hsp60), a highly conserved, immunoreactive chaperone protein, is associated with immunopathologic abnormalities, leading to blinding trachoma and tubal infertility. This suggests that the host response to infection may affect chronic inflammatory damage to the eye and the fallopian tubes. The pathogenesis of C trachomatis disease associations is thought to include molecular mimicry (autoimmunity), direct activation of the innate immune response via the CD14/toll-like receptor 4 complex, or both.

OBJECTIVE

To study whether airflow limitation in asthma in C pneumoniae-exposed individuals is associated with a specific antibody response to the C pneumoniae hsp60 molecule and not with a genus-specific response to the hsp60 molecule.

METHODS

In a case-control study, we evaluated 138 C pneumoniae-exposed primary care patients (86 adult asthmatic cases and 52 nonasthmatic controls) for seroreactivity against a C pneumoniae-specific hsp60 fragment and against the C trachomatis hsp60 molecule. We analyzed associations with asthma and irreversible lung remodeling as measured by means of postbronchodilator forced expiratory volume in 1 second.

RESULTS

Twenty-seven percent of asthmatic patients were C pneumoniae hsp60 seropositive vs 8% of controls (P < .01). Controlling for age, sex, and smoking, C pneumoniae hsp60 seropositivity was associated with lower postbronchodilator forced expiratory volume in 1 second in asthmatic patients (P < .05). No comparable associations were present for C trachomatis hsp60.

CONCLUSIONS

In individuals with evidence of previous exposure to C pneumoniae infection, a host antibody response against a C pneumoniae hsp60 fragment but not against C trachomatis hsp60 was associated with airflow limitation in adults with asthma.

In infertile women, cells from Chlamydia trachomatis infected sites release higher levels of interferon-gamma, interleukin-10 and tumor necrosis factor-alpha upon heat-shock-protein stimulation than fertile women

BACKGROUND

The magnitude of reproductive morbidity associated with sexually transmitted Chlamydia trachomatis infection is enormous. Association of antibodies to chlamydial heat shock proteins (cHSP) 60 and 10 with various disease sequelae such as infertility or ectopic pregnancy has been reported. Cell-mediated immunity is essential in resolution and in protection to Chlamydia as well as is involved in the immunopathogenesis of chlamydial diseases. To date only peripheral cell mediated immune responses have been evaluated for cHSP60. These studies suggest cHSPs as important factors involved in immunopathological condition associated with infection. Hence study of specific cytokine responses of mononuclear cells from the infectious site to cHSP60 and cHSP10 may elucidate their actual role in the cause of immunopathogenesis and the disease outcome.

METHODS

Female patients (n = 368) attending the gynecology out patient department of Safdarjung hospital, New Delhi were enrolled for the study and were clinically characterized into two groups; chlamydia positive fertile women (n = 63) and chlamydia positive infertile women (n = 70). Uninfected healthy women with no infertility problem were enrolled as controls (n = 39). cHSP60 and cHSP10 specific cytokine responses (Interferon (IFN)-gamma, Interleukin (IL)-10, Tumor Necrosis Factor (TNF)-alpha, IL-13 and IL-4) were assessed by ELISA in stimulated cervical mononuclear cell supernatants.

RESULTS

cHSP60 and cHSP10 stimulation results in significant increase in IFN-gamma (P = 0.006 and P = 0.04 respectively) and IL-10 levels (P = 0.04) in infertile group as compared to fertile group. A significant cHSP60 specific increase in TNF-alpha levels (P = 0.0008) was observed in infertile group as compared to fertile group. cHSP60 and cHSP10 specific IFN-gamma and IL-10 levels were significantly correlated (P < 0.0001, r = 0.54 and P = 0.004, r = 0.33 respectively) in infertile group.

CONCLUSION

Our results suggest that exposure to chlamydial heat shock proteins (cHSP60 and cHSP10) could significantly affect mucosal immune function by increasing the release of IFN-gamma, IL-10 and TNF-alpha by cervical mononuclear cells.

Chlamydia antibodies, chlamydia heat shock protein, and adverse sequelae after pelvic inflammatory disease: the PID Evaluation and Clinical Health (PEACH) Study

BACKGROUND

Among women with pelvic inflammatory disease (PID), we assessed the associations among antibodies to Chlamydia trachomatis elementary bodies (EB), antibodies to chlamydia heat shock protein (Chsp60), rates of pregnancy, and PID recurrence.

METHODS

Four hundred forty-three women with clinical signs and symptoms of mild to moderate PID enrolled in the PID Evaluation and Clinical Health Study were followed for a mean of 84 months for outcomes of time-to-pregnancy and time-to-PID recurrence. Antibodies to EB and Chsp60 were assessed in relation to these long-term sequelae of PID.

RESULTS

Rates of pregnancy were significantly lower (adj. hazard ratio 0.47, 95% confidence interval 0.28-0.79) and PID recurrence higher (adj. hazard ratio 2.48, 95% confidence interval 1.00-6.27) after adjusting for confounding factors among women whose antibody titers to chlamydia EB measured in the final year of follow-up were in the highest tertile.

CONCLUSION

Among women with mild to moderate PID, antibodies to C. trachomatis were independently associated with reduced rates of pregnancy and elevated rates of recurrent PID.

Chlamydia trachomatis infection: host immune responses and potential vaccines

Chlamydia trachomatis causes genital tract infections that affect men, women, and children on a global scale. This review focuses on innate and adaptive immune responses in the female reproductive tract (FRT) to genital tract infections with C. trachomatis. It covers C. trachomatis infections and highlights our current knowledge of genital tract infections, serovar distribution, infectious load, and clinical manifestations of these infections in women. The unique features of the immune system of the FRT will be discussed and will include a review of our current knowledge of innate and adaptive immunity to chlamydial infections at this mucosal site. The use of animal models to study the pathogenesis of, and immunity to, Chlamydia infection of the female genital tract will also be discussed and a review of recent immunization and challenge experiments in the murine model of chlamydial FRT infection will be presented.

Chlamydia and antigenic mimicry

Chlamydial infections are among the most common human infections. Every year, in millions of humans, they cause infections of the eyes, the respiratory tract, the genital tract, joints, and the vasculature. Chlamydiae are obligate intracellular prokaryotic pathogens. Chlamydiae promote, in susceptible host cells that include mucosal epithelial cells, vascular endothelial cells, smooth muscle cells, and monocytes and macrophages, their survival while causing disease of varying clinical importance and consequence in their hosts. Chlamydia infections often precede the initiation of autoimmune diseases, and Chlamydiae are often found within autoimmune lesions. Thus, they have been suspected in the etiology and pathogenesis of autoimmune diseases. Autoimmune diseases have many causes. Genes, notably genes encoding cell-surface proteins that display peptides for immune recognition, the major histocompatibility complex (MHC), the environment, and the microbial diversity within the human body determine the susceptibility to autoimmune diseases. One mechanism by which infection is linked to the initiation of autoimmunity is termed molecular mimicry. Molecular mimicry describes the phenomenon of protein products from dissimilar genes sharing similar structures that elicit an immune response to both self and microbial proteins. Molecular mimicry might thus be a mechanism by which infections trigger autoimmune diseases. For the purpose of this chapter, we will focus on chlamydial proteins that mimic host self-proteins and thus contribute to initiation and maintenance of autoimmune diseases. Thus far, the strongest cases for molecular mimicry seem to have been made for chlamydial heat shock proteins 60, the DNA primase of Chlamydia trachomatis, and chlamydial OmcB proteins.

Association of uterine and salpingeal fibrosis with chlamydial hsp60 and hsp10 antigen-specific antibodies in Chlamydia-infected koalas

Infection by Chlamydia pneumoniae or Chlamydia pecorum commonly causes chronic, fibrotic disease of the urogenital tracts of female koalas. Studies of humans have associated titers of serum immunoglobulin G (IgG) against chlamydial hsp60 and hsp10 antigens with chronic infection, salpingeal fibrosis, and tubal infertility. To determine whether a similar relationship exists in Chlamydia-infected koalas, samples were collected opportunistically from 34 wild female koalas and examined by gross pathology and histopathology, PCR, and immunohistochemistry for Chlamydia spp. and enzyme-linked immunosorbent assay for serological responses to chlamydial hsp10 and hsp60 antigens. Greater anti-hsp titers occurred in Chlamydia-infected koalas with fibrous occlusion of the uterus or uterine tube than in other Chlamydia-infected koalas (for hsp10 IgG, P = 0.005; for hsp60 IgG, P = 0.001; for hsp10 IgA, P = 0.04; for hsp60 IgA, P = 0.09). However, as in humans, some koalas with tubal occlusion had low titers. Among Chlamydia-infected koalas with tubal occlusion, those with low titers were more likely to have an active component to their ongoing uterine or salpingeal inflammation (P = 0.007), such that the assay predicted, with 79% sensitivity and 92% specificity, tubal occlusion where an active component of inflammation was absent. Findings of this study permit advancement of clinical and epidemiological studies of host-pathogen-environment interactions and pose intriguing questions regarding the significance of the Th1/Th2 paradigm and antigen-presenting and inflammation-regulating capabilities of uterine epithelial cells and the roles of latency and reactivation of chlamydial infections in pathogenesis of upper reproductive tract disease of koalas.

Stress proteins as inducers and targets of regulatory T cells in arthritis

Immunization with microbial or mammalian stress proteins or heat-shock proteins in models of experimental autoimmunity has been observed to lead to increased disease resistance. Furthermore, such immunization has been proposed to result in the induction and expansion of T cells that suppress disease upon transfer. Comparisons of microbial heat-shock proteins with other conserved immunogenic proteins of bacterial origin have indicated a unique capacity for heat-shock proteins to induce a regulatory phenotype in T cells, such as reflected by the production of IL10. Also, studies in children with chronic arthritis have indicated that T-cell responses to heat-shock proteins are associated with a benign course of the disease and with remission. Furthermore, in patients, heat-shock-protein-(HSP-) activated T cells were shown to display regulatory phenotypes consistent with CD4+ CD25+ T regulatory cells.

Chlamydia trachomatis persistence: an update

Chlamydial persistence is a reversible state generated during conditions deleterious to growth. In persistence, Chlamydia trachomatis remains viable but atypical, with an enlarged, aberrant form and quiescent metabolism. It favours chronic chlamydiosis, leading to serious sequelae. Although the mechanism of persistence formation is still unknown, more reliable molecular approaches tend to confirm that its occurs in vivo, even lasting 3 years. One approach consists of identifying unprocessed rRNA found only in viable Chlamydia, when infection is not apparent. Another approach, referring to the fact that immunity is type-specific, consists of showing by genotyping that multiple recurrences are due to the same genovar. At the molecular level, persistence is characterized by increased expression of ct755, one of the three heat shock protein (hsp60)-coding genes. In addition, chromosomal replication occurs continuously, and cell division is blocked possibly due to the repression of genes such as ftsW and amiA. At the immunological level, persistence reveals the failure of host-defence mechanisms because of reduced or suppressed pro-inflammatory or cytotoxic responses.

Heat shock protein 60 autoimmunity and early lipid lesions in cholesterol-fed C57BL/6JBom mice during Chlamydia pneumoniae infection

Chronic Chlamydia pneumoniae infection and autoimmunity to heat shock protein 60 (Hsp60) have both been documented to be associated with atherosclerosis. Herein, we studied the effects of C. pneumoniae infection and a diet with a low-cholesterol supplement on the development of autoantibodies to mouse Hsp60 and early lipid lesions in the aortic valve of C57BL/6JBom mice. In addition, pulmonary infection was investigated. C57BL/6JBom mice were given one to three C. pneumoniae inoculations and fed either a regular diet or a diet enriched with 0.2% cholesterol. Autoantibody responses against mouse Hsp60 developed in both diet groups when the mice were infected with C. pneumoniae and in uninfected mice fed a cholesterol-enriched diet. C. pneumoniae infections increased subendothelial foam cell accumulation in mice on a 0.2% cholesterol-enriched diet (p = 0.022), without apparent hypercholesterolemia. These in vivo data suggest that autoantibodies against mouse Hsp60 develop as a consequence of cholesterol feeding and repeated C. pneumoniae infections. Further, infectious burden increased early lipid lesions in C57BL/6JBom mice fed a cholesterol-enriched diet.

Immunology of Chlamydia infection: implications for a Chlamydia trachomatis vaccine

Sexually transmitted Chlamydia trachomatis infections are a serious public-health problem. With more than 90 million new cases occurring annually, C. trachomatis is the most common cause of bacterial sexually transmitted disease worldwide. Recent progress in elucidating the immunobiology of Chlamydia muridarum infection of mice has helped to guide the interpretation of immunological findings in studies of human C. trachomatis infection and has led to the development of a common model of immunity. In this review, we describe our current understanding of the immune response to infection with Chlamydia spp. and how this information is improving the prospects for development of a vaccine against infection with C. trachomatis.

T-bet deficiency reduces atherosclerosis and alters plaque antigen-specific immune responses

The influence of the immune system on atherosclerosis involves both helper T (Th) cell and antibody responses to plaque antigens. These responses may have proatherogenic and protective effects. T-bet is a transcription factor required for Th1 differentiation and regulates the balance between Th1 and Th2 responses in inflammatory diseases. To clarify how helper T cell subset differentiation influences atherosclerosis, we compared lesion development and immune responses to plaque antigens in low-density lipoprotein receptor-deficient (Ldlr-/-) mice with or without functional T-bet genes. Atherosclerosis was significantly reduced in T-bet-deficient Ldlr-/- mice compared with Ldlr-/- controls, and the lesions that did develop in the absence of T-bet had less smooth muscle cell content. Furthermore, T-bet deficiency caused a Th2 switch in the response to the atherosclerosis-associated antigen heat shock protein-60, and a change in T-dependent isotypes of oxidized LDL-specific antibodies. Of particular significance, T-bet deficiency caused a >250% increase in the titer of E06 antibodies, which are known to be atheroprotective and whose production by B-1 B cells is enhanced by IL-5. These findings establish that T cell subset differentiation influences both T cell and antibody responses that modulate atherosclerosis, and validate the therapeutic goal of skewing T responses to atherosclerosis-associated antigens.

A cardiac myosin-specific autoimmune response is induced by immunization with Trypanosoma cruzi proteins

Trypanosoma cruzi is the protozoan parasite that causes Chagas' heart disease, a potentially fatal cardiomyopathy prevalent in Central and South America. Infection with T. cruzi induces cardiac myosin autoimmunity in susceptible humans and mice, and this autoimmunity has been suggested to contribute to cardiac inflammation. To address how T. cruzi induces cardiac myosin autoimmunity, we investigated whether immunity to T. cruzi antigens could induce cardiac myosin-specific autoimmunity in the absence of live parasites. We immunized A/J mice with a T. cruzi Brazil-derived protein extract emulsified in complete Freund's adjuvant and found that these mice developed cardiac myosin-specific delayed-type hypersensitivity (DTH) and autoantibodies in the absence of detectable cardiac damage. The induction of autoimmunity was specific since immunization with extracts of the related protozoan parasite Leishmania amazonensis did not induce myosin autoimmunity. The immunogenetic makeup of the host was important for this response, since C57BL/6 mice did not develop cardiac myosin DTH upon immunization with T. cruzi extract. Perhaps more interesting, mice immunized with cardiac myosin developed T. cruzi-specific DTH and antibodies. This DTH was also antigen specific, since immunization with skeletal myosin and myoglobin did not induce T. cruzi-specific immunity. These results suggest that immunization with cardiac myosin or T. cruzi antigen can induce specific, bidirectionally cross-reactive immune responses in the absence of detectable cardiac damage.

B7-1/B7-2 costimulation regulates plaque antigen-specific T-cell responses and atherogenesis in low-density lipoprotein receptor-deficient mice

BACKGROUND

Several lines of evidence indicate that T-cell responses influence the progression of atherosclerotic disease. Interferon-gamma (IFN-gamma)-producing T cells specific for lesional antigens, including oxidized LDLs and heat shock protein 60 (HSP60), may promote lesion development as well as plaque instability. B7-1 and B7-2 are closely related molecules expressed on antigen-presenting cells that provide costimulatory signals for T-cell activation. This study tested the hypothesis that the ability of T cells to influence atherosclerosis depends on B7-1/B7-2 costimulation.

METHODS AND RESULTS

B7-1/B7-2/LDL receptor (LDLR)-deficient mice and LDLR-deficient control mice were fed a 1.25% cholesterol or control diet for 8 and 20 weeks. Total serum cholesterol levels and extent and phenotype of atherosclerosis were analyzed. Splenic and lymph node CD4+ T cells from the animals were cultured with mouse recombinant HSP60 or media and antigen-presenting cells and analyzed for IFN-gamma and interleukin-4 production. The absence of B7-1 and B7-2 significantly reduced early cholesterol diet-induced atherosclerotic lesion development in LDLR-deficient mice compared with B7-1/B7-2-expressing control mice. Furthermore, CD4+ T cells from the cholesterol-fed B7-deficient mice secreted a significantly lower amount of IFN-gamma in response to mouse HSP60 in vitro than did T cells from B7-expressing control mice.

CONCLUSIONS

The data show that B7-1 and B7-2 regulated the development of atherosclerotic lesions and the priming of lesional antigen-specific T cells. This study highlights the B7-CD28 pathway as a potentially important target for immunomodulation of atherosclerosis.

Synergistic effect of persistent Chlamydia pneumoniae infection, autoimmunity, and inflammation on coronary risk

BACKGROUND

Given the role of chronic infections, autoimmunity, and inflammation in atherosclerosis, we studied the joint effect of chronic Chlamydia pneumoniae infection, persistently elevated human heat-shock protein 60 (hHsp60) antibodies, and C-reactive protein (CRP) on coronary risk.

METHODS AND RESULTS

The participants for this prospective nested case-control study were obtained from the Helsinki Heart Study, during which 241 nonfatal myocardial infarctions or coronary deaths occurred among 4081 dyslipidemic middle-aged men. Serum samples taken at baseline and 3 to 6 months before the coronary events that occurred during the 8.5-year period were analyzed for antibodies to C pneumoniae and hHsp60 and the CRP concentration. Compared with persistently low levels, the risk of coronary events was 2-fold for persistently elevated immunocomplex (IC)-bound and/or serum IgA antibodies to C pneumoniae (OR, 1.96; 95% CI, 1.14 to 3.36) and also for serum IgA antibodies to hHsp60 (OR, 2.11; 95% CI, 1.08 to 4.13). The risks associated with elevated antibodies were much higher when CRP was also elevated. Compared with low or transiently elevated levels, the risk of coronary events, with adjustment for age and smoking, was 4.5-fold for persistently elevated CRP and C pneumoniae IC/IgA antibodies together (OR, 4.47; 95% CI, 1.84 to 10.83) and was similar for CRP and hHsp60 IgA antibodies together (OR, 4.36; 95% CI, 1.53 to 12.39).

CONCLUSIONS

Persistently but not transiently elevated C pneumoniae IC/IgA and hHsp60 IgA antibodies, especially when present together with an elevated CRP level, predicted coronary events.

Influence of interferon-gamma on the extent and phenotype of diet-induced atherosclerosis in the LDLR-deficient mouse

OBJECTIVE

The aim of this study was to investigate the influence of interferon-gamma (IFN-gamma) on atherosclerosis in low density lipoprotein receptor (LDLR)-null mice.

METHODS AND RESULTS

We cross-bred IFN-gamma-deficient mice with LDLR-null mice and analyzed lipoprotein profiles and atherosclerosis in the compound mutant progeny after 8 and 20 weeks on a cholesterol-enriched diet. IFN-gamma deficiency did not affect serum cholesterol levels or lipoprotein profiles, but it did affect the extent and phenotype of atherosclerosis. Atherosclerotic lesions in IFN-gamma-deficient mice were reduced by 75% in the aortic arch and by 46% in the descending aorta compared with control mice after 8 weeks on the diet. After 20 weeks, arch lesions were reduced by 43%, and descending aorta lesions were reduced by 65% in IFN-gamma-deficient mice compared with controls. At 8 weeks, percent lesional macrophage and smooth muscle content was significantly less in the IFN-gamma-deficient mice, but not at 20 weeks. Although there were fewer class II major histocompatibility complex-positive cells in the lesions of IFN-gamma-deficient animals compared with controls, class II major histocompatibility complex expression on endothelial cells overlying lesions persisted in the absence of IFN-gamma.

CONCLUSIONS

These data provide direct evidence that IFN-gamma influences atherosclerosis development and phenotype in the LDLR-deficient mouse, independent of changes in blood lipoprotein profiles.

Chlamydia trachomatis heat shock protein-60 induced interferon-gamma and interleukin-10 production in infertile women

Chlamydia trachomatis-associated tubal factor infertility (TFI) involves enhanced humoral and cell-mediated immune response to the chlamydial 60 kDa heat shock protein (CHSP60). We evaluated the role of CHSP60-induced immune response in TFI by studying lymphocyte proliferation and cytokine (interferon (IFN)-gamma, interleukin (IL)-12 and IL-10) secretion in response to C. trachomatis elementary body (EB) and CHSP60 antigens in 57 women with TFI and in 76 women with other causes of infertility. Positive proliferative response of PBMC to CHSP60 was more common in the TFI group (20/57; 36%) than in the other groups (17/76; 22%) although the frequency or the median responses did not differ significantly (1.6, range 0.2-22.1 versus 1.4; 0.2-24.4). C. trachomatis EB induced significantly higher IFN-gamma and lower IL-10 secretion in the TFI group compared to the other groups. The EB and CHSP60 induced IL-12 secretion was similar in all study groups and correlated with IFN-gamma secretion in the other but not in the TFI group. The lack of correlation between EB-induced IL-12 and IFN-gamma production and simultaneously found prominent IL-10 secretion in response to CHSP60 in the TFI group suggests that the CHSP60 may have a specific role in regulating the immune reactions during chlamydial infection and may consequently contribute to the immunopathogenesis of TFI.

The cellular paradigm of chlamydial pathogenesis

Diseases caused by Chlamydia are based on intense and chronic inflammation elicited and maintained by reinfection or persistent infection. The traditional view in the field is that disease is mediated by antigen-dependent delayed-type hypersensitivity or autoimmunity. This immunological paradigm has served as the basis for years of chlamydial research but the mechanism or the antigen that causes pathology has yet to be unequivocally revealed. Recent research on responses elicited in Chlamydia-infected cells defines a new direction for our understanding of this microorganism-host interaction and provides the basis for a reassessment of disease mechanisms. Chlamydia-infected non-immune mammalian cells produce proinflammatory chemokines, cytokines, growth factors and other cellular modulators. This cellular response to infection supports an alternative hypothesis for chlamydial pathogenesis: the inflammatory processes of chlamydial pathogenesis are elicited by infected host cells and are necessary and sufficient to account for chronic and intense inflammation and the promotion of cellular proliferation, tissue remodeling and scarring, the ultimate cause of disease sequelae.

Wolbachia in filarial nematodes: evolutionary aspects and implications for the pathogenesis and treatment of filarial diseases

The presence of intracellular bacteria in the body of various species of filarial nematodes, including important parasites such as Brugia malayi, Dirofilaria immitis, and Onchocerca volvulus, was observed as early as the mid-1970s. These bacteria were shown to be transovarially transmitted (from the female worm to the offspring) and to be present in significant amounts in the body of the nematode. As highlighted by their discoverers, the potential importance of these bacteria is fairly obvious: (1) bacteria-derived molecules should be considered as having an immunological and pathological role in filarial diseases; (2) the interaction between the bacteria and the filarial host deserves investigation, in view of the possibility that the bacteria are needed by the host nematode and could thus represent a target for therapy. Other authors, independently from the discovery of these intracellular bacteria, showed that the antibiotic tetracycline (which is well known for its efficacy on intracellular bacteria) had detrimental effects on two species of filarial nematodes (Brugia pahangi and Litomosoides sigmodontis). It is therefore surprising that for more than 20 years, no further investigations focused on the bacteria of filarial nematodes, nor on the anti-filarial properties of tetracycline. Recently, the bacteria of filarial nematodes have been independently "rediscovered" by research groups from the schools of Hamburg, Liverpool and Milan. These bacteria are now classified as Wolbachia, and the basic aspects of their phylogenetic history and relationship with the Wolbachia of arthropods have been reconstructed. In addition, their implications for the pathogenesis and treatment of filarial diseases have started to be uncovered. This paper, which is authored by representatives of the three European schools who reopened this research area, reviews our present knowledge of these fascinating microorganisms, highlighting the complexity of a symbiotic system which involves, in addition to the nematode and its bacterium, the vertebrate host.

Heat shock protein 60 specific T-cell response in chlamydial infections

Heat shock proteins (HSPs) of most pathogens, including Chlamydia, are major immune targets of both humoral- and cell-mediated immune mechanisms. During the last decade, many investigators have focused their research to elucidate the complex relationship of chlamydial HSPs, especially chlamydial HSP60, and the host immune response. A central issue is whether the pathologic mechanisms in chronic chlamydial diseases are associated with an enhanced immune response to chlamydial HSP60 which can mediate tissue destruction through cytotoxic reactions, or whether they are related to the Th2 type of response that eventually leads to partial or temporary suppression of an effective antichlamydial response. Our review highlights the available knowledge between immune responses to chlamydial HSP60 and chronic chlamydial infections in human.

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.

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.

Detection of Chlamydia pneumoniae-reactive T lymphocytes in human atherosclerotic plaques of carotid artery

Linkage between Chlamydia pneumoniae infection and atherosclerosis has been confirmed in several studies, but the precise role of this organism in the disease process is not known. We investigated the relation and reactivity of T lymphocytes of human carotid plaques to C pneumoniae antigens. Tissue specimens were obtained from 17 patients who underwent carotid endarterectomy. Immunohistological staining and/or in situ hybridization revealed the presence of C pneumoniae in 11 (64%) of the 17 of the cases. Inflammatory infiltration seen in the vessel walls consisted primarily of CD45RO+ T-memory lymphocytes (median 80%, range 50% to 90%), whereas CD20+ B cells and monocytes were in minor proportion. In vivo activated T lymphocytes were propagated from the specimens with interleukin-2, and the antigen specificity of the established T-cell lines (TLLs) was analyzed against C pneumoniae elementary body antigen. TLLs were established from all 17 carotid tissues but none from the control specimens of ascending aorta. C pneumoniae was recognized as a specific T-cell-stimulating antigen in 7 (41%) of 17 cases. Further analyses of the C pneumoniae-reactive TLLs showed that chlamydial 60-kDa heat-shock protein induced specific proliferation in 5 (71%) of 7 cases and revealed 2 haplotype (DRB1*1502 and DQB1*06) binding motifs in human 60-kDa heat-shock protein. C pneumoniae was identified as a specific microbial antigen recognized by 41% of TLLs propagated from in vivo activated plaque T cells. Our results suggests that cell-mediated immunity to C pneumoniae plays a role in the atherosclerotic process and that this response may involve autoimmunity.

Multispecific CD4+ T cell response to a single 12-mer epitope of the immunodominant heat-shock protein 60 of Yersinia enterocolitica in Yersinia-triggered reactive arthritis: overlap with the B27-restricted CD8 epitope, functional properties, and epitope presentation by multiple DR alleles

Yersinia heat-shock protein 60 (Ye-hsp60) has recently been found to be a dominant CD4 and CD8 T cell Ag in Yersinia-triggered reactive arthritis. The nature of this response with respect to the epitopes recognized and functional characteristics of the T cells is largely unknown. CD4+ T cell clones specific for Ye-hsp60 were raised from synovial fluid mononuclear cells from a patient with Yersinia-triggered reactive arthritis. and their specificity was determined using three recombinant Ye-hsp60 fragments, overlapping 18-mer synthetic peptides as well as truncated peptides. Functional characteristics were assessed by cytokine secretion analysis in culture supernatants after specific antigenic stimulation. Amino acid positions relevant for T cell activation were detected by single alanine substitutions within the epitopes. Fragment II comprising amino acid sequence 182-371 was recognized by the majority of clones. All these clones were specific for peptide 319-342. Th1 clones and IL-10-secreting clones occurred in parallel, sometimes with the same fine specificity. The 12-mer core epitope 322-333 is a degenerate MHC binder and is presented to some T cell clones in a "promiscuous" manner. This epitope is almost identical with a B27-restricted CTL epitope of Ye-hsp60. Cross-reactivity of Ye-hsp60-specific T cell clones with self-hsp60 was not observed. In conclusion, an interesting Ye-hsp60 T cell epitope has been identified and characterized. It remains to be determined whether this epitope is also relevant in other reactive arthritis patients.

Cytokines and the immunopathology of the spondyloarthropathies

In contrast to rheumatoid arthritis (RA), the triggering antigens are known in reactive arthritis (ReA) and Lyme arthritis. Thus, in these arthritides the antigen-specific T-cell response can be investigated in much detail and lessons possibly learned for other spondyloarthropathies (SpA) such as ankylosing spondylitis (AS) where T cells may well also play an important role in the pathogenesis. This article focusses on the immunopathology of the SpA, ReA, and AS with special reference to T cells and cytokines.

Pathogenesis of Chlamydia induced pelvic inflammatory disease

Further research is necessary to elucidate the pathogenesis of chlamydial PID. It is hoped that these endeavours will eventually lead to a vaccine to prevent not only chlamydia infection, but also chlamydia associated infertility, ectopic pregnancy, and chronic pelvic pain. In the meantime we need to develop strategies to prevent primary and secondary chlamydia infection and its sequelae. Recently, Scholes et. al demonstrated that a population based approach to identify and test women at high risk for cervical C trachomatis infection effectively reduced risk of PID. Hopefully, through the use of public health measures, we can see similar decreases of chlamydia associated genital tract disease worldwide.

Chlamydial heat shock proteins and disease pathology: new paradigms for old problems?

The mucosal pathogen Chlamydia trachomatis affects hundreds of millions of people worldwide and is a significant cause of sexually transmitted disease. Although most acute infections can be easily managed, complications often occur that can be especially severe in women. It has been proposed that increased exposure to conserved chlamydial antigens, such as through reinfection or persistent infection, results in chronic inflammation and tissue scarring and contributes to the pathogenesis of endometrial and fallopian tube damage. This immunopathologic damage is believed to be a principal cause of ectopic pregnancy and tubal factor infertility. The chlamydial heat shock protein Hsp60, a homolog of Escherichia coli GroEL, has been identified as one protein capable of eliciting intense mononuclear inflammation. Furthermore, several studies have revealed a correlation between Hsp60 responses and the immunopathologic manifestations of human chlamydial disease. The role of additional antigens in the immunopathologic response to chlamydiae is currently undefined. A prime candidate, however, is the chlamydial GroES homolog Hsp10, which is genetically and physiologically linked to Hsp60. Recent studies provide data to suggest that immune reactivity to Hsp10 is significantly associated with tubal infertility in a chlamydiae-exposed population. Chlamydia pneumoniae is a more recently defined chlamydial species that has been implicated in a variety of ways with chronic disease processes, such as adult onset asthma and atherosclerosis. Evidence indicates that Hsp60 is present in human atheroma and may play a role in lesion development by direct activation of macrophages. Hsp60 causes the elaboration of inflammatory cytokines, the induction of metalloproteinase, and the oxidation of low density lipoprotein. Each of these events is directly associated with the progress of atherosclerosis. Thus, chlamydial heat shock proteins may function in at least two ways to promote chronic disease: first by direct antigenic stimulation and second as signal transducers that result in macrophage activation. These concepts in disease pathology are discussed in the context of chlamydial infections.

Cellular and humoral immune responses to mycobacterial stress proteins in experimental pulmonary tuberculosis

OBJECTIVE

Immunity to mycobacterial stress protein antigens was studied in response to vaccination and/or virulent infection.

DESIGN

Guinea pigs, either vaccinated with Mycobacterium bovis bacille Calmette-Guérin (BCG), infected by the pulmonary route with virulent M. tuberculosis, or vaccinated then infected, were studied for the development of cellular and humoral immunity to two recombinant mycobacterial stress proteins, hsp 65 and hsp 70.

RESULTS

Recombinant hsp 70 stimulated good proliferation in blood lymphocytes and, to a lesser extent, spleen and bronchotracheal lymph node lymphocytes from BCG-vaccinated guinea pigs. The proliferative responses to hsp 70 were diminished in both the spleen and lymph node cells following subsequent pulmonary challenge alone, but were boosted significantly by prior vaccination. Recombinant hsp 65 was much less active at inducing the proliferation of spleen and lymph node cells, with lowest responses observed in blood lymphocytes occurring in the cells from BCG-vaccinated, aerosol-challenged guinea pigs. Using a semi-quantitative dot blot procedure, serum antibodies to both hsp 65 and hsp 70 developed gradually following BCG vaccination, with all guinea pigs studied exhibiting significant seroreactivity after 15 weeks post-vaccination. In guinea pigs exposed to virulent M. tuberculosis by aerosol, serologic reactivity to hsp 70 was consistently stronger 6 weeks post-challenge in both vaccinated and non-vaccinated guinea pigs. In fact, 6 weeks following pulmonary exposure to M. tuberculosis in previously naive guinea pigs, 3 out of 6 animals had no detectable serum antibodies to hsp 65. Somewhat surprisingly, antibody levels to both hsp 65 and hsp 70 were only slightly increased by prior BCG vaccination in guinea pigs exposed to virulent M. tuberculosis by the respiratory route.

CONCLUSION

These results demonstrate that both hsp 65 and hsp 70 stimulate detectable humoral and cell-mediated immunity in guinea pigs vaccinated and/or infected under highly relevant conditions. There is little evidence that vaccination with BCG primes the guinea pig to make an anamnestic response to hsp 65 following virulent pulmonary challenge. The precise contribution of immunity to mycobacterial stress proteins to the pathogenesis of tuberculosis in this model remains to be elucidated.

Failure of elevated heat shock protein 70 antibodies to alter cochlear function in mice

Heat shock protein 70 (HSP70) has been suggested as the putative cochlear antigen underlying a proposed autoimmune etiology in certain cases of Meniere's disease and idiopathic hearing loss. To determine if antibodies to this cellular protein are capable of altering cochlear function, BALB/c (N= 3) and CBA/J (N= 9) mice were inoculated with bovine HSP70 by intraperitoneal injections (10 microg in saline) every 10 days for 7 or 10 months, respectively. An equal number of control mice were injected with PBS according to the same schedule. ABR thresholds at 4, 8, 16, and 32 kHz in the HSP70-inoculated mice did not change over the 10 month period and were similar to saline controls. Furthermore, serum immune complexes and antinuclear antibodies did not increase over the inoculation period. ELISA analysis demonstrated the mice created antibodies to the foreign HSP70, but these apparently caused no abnormalities in the auditory or immune systems. It was concluded that foreign HSP70 is antigenic and inoculation with it will raise antibodies, but these antibodies were neither immunopathogenic nor cochleopathic. Therefore, these findings do not support current theories that elevated anti-HSP70 antibodies are the underlying cause of hearing loss in patients with such antibodies present.