Ruurd van der Zee

Heat-shock proteins induce T-cell regulation of chronic inflammation.

Immune responses to certain heat-shock proteins (HSPs) develop in almost all inflammatory diseases; however, the significance of such responses is only now becoming clear. In experimental disease models, HSPs can prevent or arrest inflammatory damage, and in initial clinical trials in patients with chronic inflammatory disease, HSP-derived peptides have been shown to promote the production of anti-inflammatory cytokines, indicating that HSPs have immunoregulatory potential. In this Review, we discuss the unique characteristics of HSPs that endow them with these immunoregulatory qualities.

The Coronavirus Spike Protein Is a Class I Virus Fusion Protein: Structural and Functional Characterization of the Fusion Core Complex

ABSTRACT Coronavirus entry is mediated by the viral spike (S) glycoprotein. The 180-kDa oligomeric S protein of the murine coronavirus mouse hepatitis virus strain A59 is posttranslationally cleaved into an S1 receptor binding unit and an S2 membrane fusion unit. The latter is thought to contain an internal fusion peptide and has two 4,3 hydrophobic (heptad) repeat regions designated HR1 and HR2. HR2 is located close to the membrane anchor, and HR1 is some 170 amino acids (aa) upstream of it. Heptad repeat (HR) regions are found in fusion proteins of many different viruses and form an important characteristic of class I viral fusion proteins. We investigated the role of these regions in coronavirus membrane fusion. Peptides HR1 (96 aa) and HR2 (39 aa), corresponding to the HR1 and HR2 regions, were produced in Escherichia coli. When mixed together, the two peptides were found to assemble into an extremely stable oligomeric complex. Both on their own and within the complex, the peptides were highly alpha helical. Electron microscopic analysis of the complex revealed a rod-like structure ∼14.5 nm in length. Limited proteolysis in combination with mass spectrometry indicated that HR1 and HR2 occur in the complex in an antiparallel fashion. In the native protein, such a conformation would bring the proposed fusion peptide, located in the N-terminal domain of HR1, and the transmembrane anchor into close proximity. Using biological assays, the HR2 peptide was shown to be a potent inhibitor of virus entry into the cell, as well as of cell-cell fusion. Both biochemical and functional data show that the coronavirus spike protein is a class I viral fusion protein.

Interleukin-4 therapy of psoriasis induces Th2 responses and improves human autoimmune disease

Selective skewing of autoreactive interferon-γ (IFN-γ)-producing T helper cells (Th1) toward an interleukin-4 (IL-4)-producing (Th2) phenotype can in experimental animals alleviate autoimmune disease without inducing general immunosuppression. In a prospective dose escalation study, we assessed treatment with human IL-4 (rhuIL-4) in 20 patients with severe psoriasis. The therapy was well tolerated, and within six weeks all patients showed decreased clinical scores and 15 improved more than 68%. Stable reduction of clinical scores was significantly better at 0.2–0.5 μg rhuIL-4 than at ≤0.1 μg rhuIL-4 (P = 0.009). In psoriatic lesions, treatment with 0.2–0.5 μg/kg rhuIL-4 reduced the concentrations of IL-8 and IL-19, two cytokines directly involved in psoriasis; the number of chemokine receptor CCR5+ Th1 cells; and the IFN-γ/IL-4 ratio. In the circulation, 0.2–0.5 μg/kg rhuIL-4 increased the number of IL-4+CD4+ T cells two- to three-fold. Thus, IL-4 therapy can induce Th2 differentiation in human CD4+ T cells and has promise as a potential treatment for psoriasis, a prototypic Th1-associated autoimmune disease.

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.

Cardiovascular Risk Factors and Atherosclerosis in Young Males: ARMY Study (Atherosclerosis Risk-Factors in Male Youngsters)

Background—Necropsy studies suggest that atherosclerosis begins in childhood, but in vivo confirmation of this concept is sparse and limited to selected population samples. Furthermore, new risk concepts of atherosclerosis focusing on inflammation, infections, and immunity have not yet been evaluated in this age group. Methods and Results—This study was conducted in a sample of 141 17- to 18-year-old white males homogenous in age and sex. In addition to classic risk factors, C-reactive protein and the humoral and cellular immune reactivity to heat-shock proteins (HSPs) were assessed. Intima-media thickness (IMT) was quantified at 4 vessel segments of the carotid and femoral arteries. High IMT was considered to be present if the IMT of at least 1 vessel segment exceeded the 90th percentile. In a multivariate logistic regression analysis, cigarette smoking, high diastolic blood pressure, prominent immune reactivity to human and/or mycobacterial HSP60s, alcohol consumption (inverse), and low HDL cholesterol levels were all associated with high IMT. The prevalence of high IMT substantially increased from 0 to 60% when the number of risk conditions in a single individual increased from 0 to 4 (P <0.001 for linear trend). Conclusions—Our study supports the concept that atherosclerosis begins in the first decades of life and suggests a role of the immune system, especially immunoreactivity against HSP60s, in atherosclerosis of young individuals.

Molecular Mimicry between Helicobacter pylori Antigens and H+,K+–Adenosine Triphosphatase in Human Gastric Autoimmunity

Autoimmune gastritis and Helicobacter pylori–associated gastric atrophy develop through similar mechanisms involving the proton pump H+,K+–adenosine triphosphatase as autoantigen. Here, we report that H. pylori–infected patients with gastric autoimmunity harbor in vivo–activated gastric CD4+ T cells that recognize both H+,K+–adenosine triphosphatase and H. pylori antigens. We characterized the submolecular specificity of such gastric T cells and identified cross-reactive epitopes from nine H. pylori proteins. Cross-reactive H. pylori peptides induced T cell proliferation and expression of T helper type 1 functions. We suggest that in genetically susceptible individuals, H. pylori infection can activate cross-reactive gastric T cells leading to gastric autoimmunity via molecular mimicry.

Heat shock proteins generate β‐chemokines which function as innate adjuvants enhancing adaptive immunity

Heat shock proteins (HSP) are widely distributed and highly immunogenic molecules. A novel property reported here is that stimulation with HSP70 of CD8‐enriched T cells derived from naive non‐human primates caused a dose‐dependent increase in concentrations of the β‐chemokines RANTES, macrophage inflammatory protein (MIP)‐1α or MIP‐1β. However, the concentrations of these β‐chemokines were greatly increased when the CD8 T cells derived from HSP70‐immunized non‐human primates were stimulated with HSP70. HSP linked to peptides or proteins combined generation of β‐chemokines with an adjuvant function by enhancing specific T cell proliferative responses and IgG and IgA antibodies. The β‐chemokine and adjuvant functions were also elicited by topical mucosal administration of HSP linked to an antigen. We postulate that microbial HSP can stimulate β‐chemokine production which may be responsible for innate adjuvanticity, as was found in cells eluted from normal rectal mucosal tissue, and constitutes a significant component of the mucosal‐associated lymphoid system. Furthermore, stimulation of innate immunity may drive adaptive immunity and account for the protective effects of HSP against tumors and viruses.

Do heat shock proteins control the balance of T-cell regulation in inlammatory diseases?

Abstract Heat shock proteins (Hsps) are remarkably immunogenic, despite their high degree of evolutionary conservation. Experimental and clinical observations on autoimmune diseases indicate that immune responses to Hsps arise spontaneously during the disease process. Based on current evidence, Willem van Eden and colleagues argue that such immunity to Hsps is part of a normal immunoregulatory T-cell response with disease controlling potential.

Role of γδ T cells in pathogenesis and diagnosis of Behçet's disease

Abstract Summary Background Behcets disease (BD) is a multisystem disorder of unknown pathogenesis. The diagnosis is based on a set of international clinical criteria. Previous investigations have suggested that immunological crossreactivity between peptides within streptococcal heat-shock proteins and human peptides might be involved in the pathogenesis of BD. We tested four peptides from mycobacterial heat-shock proteins to see if they specifically stimulated γδ T cells from BD patients. We then investigated this response to see whether it could be used as a laboratory test to diagnose BD. Methods We used a T-cell proliferative test to assay responses to four mycobacterial 65 kDa heat-shock-protein peptides and to four homologous peptides derived from the sequence of the human 60 kDa heat-shock protein. Findings We elicited significant γδ T-cell responses to the mycobacterial peptides in 25 (76%) of 33 patients with BD, compared with 2 (3·6%) of 55 controls with recurrent oral ulcers, systemic disease, or no disorders. The proportion of BD patients who had false-negative results decreased if the test was done during clinical manifestation of disease activity. There was a correlation between disease activity and T-cell responses. Four homologous peptides from human 60 kDa heat-shock protein also specifically stimulated T cells from patients with BD but with lower stimulation indices. Interpretation Activation of peripheral-blood mononuclear cells with the four heat-shock-protein peptides elicited significant T-cell proliferative responses by the γδ subset of T cells, which may regulate αβ T cells. Because these peptides have a high specificity for BD, this assay can be used as a laboratory diagnostic test for BD.

Cross-Reactive B-Cell Epitopes of Microbial and Human Heat Shock Protein 60/65 in Atherosclerosis

Objective—Growing evidence suggests that immune reactions to heat shock protein 60 (HSP60) are involved in atherogenesis. Because of the high phylogenetic conservation between microbial and human HSP60, bacterial infections might be responsible for breaking the tolerance to self-HSP60, which is expressed on the surface of stressed arterial endothelial cells. Methods and Results—We purified serum antibodies to Escherichia coli HSP60 (GroEL), the 60-kD chlamydial HSP, and HSP65 of Mycobacterium tuberculosis by affinity chromatography from clinically healthy subjects with sonographically proven carotid atherosclerosis. Reactivity of the purified antibodies with overlapping human HSP60 peptides was measured, and 8 shared common epitopes, recognized by all anti-bacterial HSP60/65 antibodies, were identified. Antisera specific for these cross-reactive epitopes were produced by immunizing rabbits with peptides derived from human HSP60. By immunohistochemistry, the epitopes were found to be present in the arterial wall of young subjects during the earliest stages of the disease. Conclusions—Antibodies to microbial HSP60/65 recognize specific epitopes on human HSP60. These cross-reactive epitopes were shown to serve as autoimmune targets in incipient atherosclerosis and might provide further insights into the mechanisms of early atherogenesis.