Human abdominal aortic aneurysm (AAA): Evidence for an autoimmune antigen-driven disease.

Abdominal aortic aneurism (AAA) is a complex immunological disease with a strong genetic component, and one of the ten leading causes of death of individuals 55-74 years old worldwide. Strong evidence has been accumulated suggesting that AAA is an autoimmune specific antigen-driven disease. Mononuclear cells infiltrating AAA lesions comprised of T and B lymphocytes and other cells expressing early-, intermediate- and late-activation antigens, and the presence of antigen-presenting cells have been documented, demonstrating an ongoing immune response. The three components of the trimolecular complex, T-cell receptor (TCR)/peptide (antigen)/HLA have been identified in AAA, and specifically: (i) clonal expansions of T-cell clones in AAA lesions; (ii) the association of AAA with particular HLA Class I and Class II; and (iii) self or nonself putative AAA-associated antigens. IgG autoantibodies recognizing proteins present in normal aortic tissue have been reported in patients with AAA. Molecular mimicry, defined as the sharing of antigenic epitopes between microorganisms (bacteria, viruses) and self antigens, maybe is responsible for T-cell responses and antibody production in AAA. Also, the frequency and the suppressor activity of CD4+ CD25+ FOXP3+ Tregs and the expression of FOXP3 transcripts and protein have been reported to be significantly impaired in AAA patients vs normal donors.

Clonally expanded alpha-chain T-cell receptor (TCR) transcripts are present in aneurysmal lesions of patients with Abdominal Aortic Aneurysm (AAA).

Abdominal aortic aneurysm (AAA) is a life-threatening immunological disease responsible for 1 to 2% of all deaths in 65 year old or older individuals. Although mononuclear cell infiltrates have been demonstrated in AAA lesions and autoimmunity may be responsible for the initiation and account for the propagation of the disease, the information available about the pathogenesis of AAA is limited. To examine whether AAA lesions from patients with AAA contain clonally expanded α-chain TCR transcripts, we amplified by the non-palindromic adaptor-PCR (NPA-PCR)/Vα-specific PCR and/or the Vα-specific PCR these α-chain TCR transcripts. The amplified transcripts were cloned and sequenced. Substantial proportions of identical α-chain TCR transcripts were identified in AAA lesions of 4 of 5 patients, demonstrating that clonally expanded T cells are present in these AAA lesions. These results were statistically significant by the bimodal distribution. Three of 5 of these patients were typed by DNA-based HLA-typing and all three expressed DRB1 alleles containing the DRßGln70 amino acid residue that has been demonstrated to be associated with AAA. All three patients exhibited clonally expanded T cells in AAA lesions. Four of the 5 patients with AAA who exhibited clonal expansions of α-chain TCR transcripts, also exhibited clonal expansions of ß-chain TCR transcripts in AAA lesions, as we have demonstrated previously (J Immunol 192:4897, 2014). αß TCR-expressing T cells infiltrating AAA lesions contain T-cell clones which have undergone proliferation and clonal expansion in vivo in response to as yet unidentified specific antigens that may be self or nonself. These results provide additional evidence supporting the hypothesis that AAA is a specific antigen-driven T-cell autoimmune disease.

Aneurysmal lesions of patients with abdominal aortic aneurysm contain clonally expanded T cells.

Abdominal aortic aneurysm (AAA) is a common disease with often life-threatening consequences. This vascular disorder is responsible for 1-2% of all deaths in men aged 65 years or older. Autoimmunity may be responsible for the pathogenesis of AAA. Although it is well documented that infiltrating T cells are essentially always present in AAA lesions, little is known about their role in the initiation and/or progression of the disease. To determine whether T cells infiltrating AAA lesions contain clonally expanded populations of T cells, we amplified ß-chain TCR transcripts by the nonpalindromic adaptor-PCR/Vß-specific PCR and/or Vß-specific PCR, followed by cloning and sequencing. We report in this article that aortic abdominal aneurysmal lesions from 8 of 10 patients with AAA contained oligoclonal populations of T cells. Multiple identical copies of ß-chain TCR transcripts were identified in these patients. These clonal expansions are statistically significant. These results demonstrate that αß TCR(+) T lymphocytes infiltrating aneurysmal lesions of patients with AAA have undergone proliferation and clonal expansion in vivo at the site of the aneurysmal lesion, in response to unidentified self- or nonself Ags. This evidence supports the hypothesis that AAA is a specific Ag-driven T cell disease.

Differential expression of CD3zeta message and protein in tumor infiltrating lymphocytes from solid tumor specimens and malignant ascites from patients with ovarian carcinoma.

The expression of the CD3zeta subunit was investigated in fresh (uncultured) tumor-infiltrating lymphocytes (TILs) isolated from either solid tumor (ST) specimens or ascites (ASC) from patients with epithelial ovarian carcinoma (EOC). Western blot analysis of CD3zeta immunoprecipitates using anti-CD3zeta rabbit serum revealed that in 6 out of 6 patients with EOC, the CD3zeta protein was absent from ST-TILs. Immunoprecipitation with anti-phosphotyrosine monoclonal antibody (anti-PY20) from ST-TILs from one patient revealed bands co-migrating with the phosphorylated CD3zeta. CD3zeta protein was found to be expressed in only 1 out of 7 ST-TILs from patients with EOC. ASC-TILs were available in 5 of these patients and immunoprecipitation/Western blotting experiments using anti-CD3zeta rabbit serum revealed that CD3zeta protein was expressed in all 5. In addition, CD3zeta protein was expressed in 3 additional ASC-TIL specimens for which ST-TILs were not available. Therefore, the CD3zeta protein was expressed in ASC-TIL isolated from 8 out of 8 patients with EOC. CD3zeta protein was also expressed on peripheral blood mononuclear cells (PBMCs) from patients with EOC and from normal donors. RT-PCR studies of fresh ST-TIL specimens, using CD3zeta-specific primers, revealed that CD3zeta transcripts were absent from 13 out of 21 patients with EOC, down-regulated in 4 patients and present at levels comparable to those found in PBMCs in 4 other patients. In contrast, CD3delta transcripts were present at comparable levels in all specimens. Treatment with recombinant interleukin-2 (rIL-2) (600 IU/ml) restored the expression of CD3zeta protein and transcripts in cultured ST-TILs, whereas fresh ST-TILs did not express CD3zeta, in contrast to fresh ASC-TILs. These results demonstrate differential expression of CD3zeta in ST-TILs versus ASC-TILs in patients with EOC. CD3zeta transcripts and protein were found to be absent from most ST-TILs from patients with EOC, whereas they were expressed in ASC-TILs and PBMCs from such patients.

Human autoimmune diseases are specific antigen-driven T-cell diseases: identification of the antigens.

We are investigating the hypothesis that most human autoimmune diseases are specific antigen-driven T-cell diseases. T-cell clones responding to specific antigenic epitopes are responsible for the initiation and/or the propagation of these diseases. Similarly, specific antigen-driven T-cell responses are responsible for the rejection of organ allografts and the immune response to tumors. Activated T cells provide the "engine" for the chronic inflammation that is associated with autoimmune diseases, organ graft rejection and tumor immunity. The best way to identify whether specific antigen-driven T cell responses are involved in the initiation and/or propagation of these disorders is to investigate whether T cells that infiltrate relevant tissues from these diseases contain monoclonal or oligoclonal, that is to say clonally expanded, populations of T cells. Identification of the T-cell antigen receptor (TCR) transcripts employed by the clonally expanded T cells in these patients permits the identification of the specific antigens that elicit these T-cell responses. These antigens may be responsible for the pathogenesis of these diseases. We will summarize here certain of our findings in this area of research.

Abdominal aortic aneurysm is a specific antigen-driven T cell disease.

To determine whether monoclonal/oligoclonal T cells are present in abdominal aortic aneurysm (AAA) lesions, we amplified beta-chain T cell receptor (TCR) transcripts from these lesions by the nonpalindromic adaptor (NPA)-polymerase chain reaction (PCR)/V-beta-specific PCR followed by cloning and sequencing. Sequence analysis revealed the presence of substantial proportions of identical beta-chain TCR transcripts in AAA lesions in 9 of 10 patients examined, strongly suggesting the presence of oligoclonal populations of alphabeta TCR+ T cells. We have also shown the presence of oligoclonal populations of gammadelta TCR+ T cells in AAA lesions. Sequence analysis after appropriate PCR amplification and cloning revealed the presence of substantial proportions of identical VgammaI and VgammaII TCR transcripts in 15 of 15 patients examined, and of Vdelta1 and Vdelta2 TCR transcripts in 12 of 12 patients. These clonal expansions were very strong. All these clonal expansions were statistically significant by the binomial distribution. In other studies, we determined that mononuclear cells infiltrating AAA lesions express early- (CD69), intermediate- (CD25, CD38), and late- (CD45RO, HLA class II) activation antigens. These findings suggest that active ongoing inflammation is present in the aortic wall of patients with AAA. These results demonstrate that oligoclonal alphabeta TCR+ and gammadelta TCR+T cells are present in AAA lesions. These oligoclonal T cells have been clonally expanded in vivo in response to yet unidentified antigens. Although the antigenic specificity of these T cells remains to be determined, these T cells may play a significant role in the initiation and/or the propagation of the AAA. It appears that AAA is a specific antigen-driven T cell disease.

Theiler's virus infection: a model for multiple sclerosis.

Both genetic background and environmental factors, very probably viruses, appear to play a role in the etiology of multiple sclerosis (MS). Lessons from viral experimental models suggest that many different viruses may trigger inflammatory demyelinating diseases resembling MS. Theiler's virus, a picornavirus, induces in susceptible strains of mice early acute disease resembling encephalomyelitis followed by late chronic demyelinating disease, which is one of the best, if not the best, animal model for MS. During early acute disease the virus replicates in gray matter of the central nervous system but is eliminated to very low titers 2 weeks postinfection. Late chronic demyelinating disease becomes clinically apparent approximately 2 weeks later and is characterized by extensive demyelinating lesions and mononuclear cell infiltrates, progressive spinal cord atrophy, and axonal loss. Myelin damage is immunologically mediated, but it is not clear whether it is due to molecular mimicry or epitope spreading. Cytokines, nitric oxide/reactive nitrogen species, and costimulatory molecules are involved in the pathogenesis of both diseases. Close similarities between Theiler's virus-induced demyelinating disease in mice and MS in humans, include the following: major histocompatibility complex-dependent susceptibility; substantial similarities in neuropathology, including axonal damage and remyelination; and paucity of T-cell apoptosis in demyelinating disease. Both diseases are immunologically mediated. These common features emphasize the close similarities of Theiler's virus-induced demyelinating disease in mice and MS in humans.

Identical alpha-chain T-cell receptor transcripts are present on T cells infiltrating coronary arteries of human cardiac allografts with chronic rejection.

Chronic cardiac allograft rejection is characterized by graft arteriopathy and is a major obstacle of graft survival. We investigated T-cell receptor (TCR) alpha-chain transcripts of T cells infiltrating human epicardial coronary arteries from cardiac allografts with chronic rejection. The non-palindromic adaptor-polymerase chain reaction (NPA-PCR) was used to specifically amplify TCR alpha-chain transcripts from five explanted cardiac allografts with chronic rejection. The amplified products were cloned and sequenced to obtain the entire ValphaJalpha region. Immuno-histochemistry was used to identify the mononuclear cell infiltrates in the coronary arteries. All the five coronary artery specimens exhibited large populations of infiltrating mononuclear cells, which were primarily comprised of T cells and macrophages. In three specimens, high proportions ( approximately 80%) of identical alpha-chain TCR transcripts were detected. In peripheral blood mononuclear cells from a healthy individual, alpha-chain TCR transcripts were unique when compared to each other. Endomyocardial biopsies collected from one patient six months before the allograft was explanted, contained identical alpha-chain TCR transcripts to those found to be clonally expanded in the coronary arteries from this patient. These results indicate that T cells infiltrating the epicardial arteries of cardiac allografts with chronic rejection undergo proliferation and clonal expansion in response to a specific antigen, which very likely is an (allo)antigen(s).

Apoptosis of infiltrating T cells in the central nervous system of mice infected with Theiler's murine encephalomyelitis virus.

Theiler murine encephalomyelitis virus (TMEV), DA strain, induces in susceptible strain of mice a biphasic disease consisting of early acute disease followed by late chronic demyelinating disease. Both phases of the disease are associated with inflammatory infiltrates of the central nervous system (CNS). Late chronic demyelinating disease induced by TMEV serves as an excellent model to study human demyelinating disease, multiple sclerosis. During early acute disease, the virus is partially cleared from the CNS by CD3(+) T cells. These T cells express Fas, FasL, negligible levels of Bcl-2 proteins and undergo activation-induced cell death as determined by TUNEL assay leading to resolution of the inflammatory response. In contrast, during late chronic demyelinating disease, and despite dense perivascular and leptomeningeal infiltrates, only very few cells undergo apoptosis. Mononuclear cells infiltrating the CNS express Bcl-2. It appears that the lack of apoptosis of T cells during late chronic demyelinating disease leads to the accumulation of these cells in the CNS. These cells may play a role in the pathogenesis of the demyelinating disease.