The use of stem cells for the treatment of autoimmune diseases

Autoimmune diseases constitute a heterogeneous group of conditions commonly treated with anti-inflammatory, immunosuppressant and immunomodulating drugs, with satisfactory results in most cases. Nevertheless, some patients become resistant to conventional therapy. The use of high doses of drugs in such cases results in the need for bone marrow reconstitution, a situation which has stimulated research into the use of hematopoietic stem cells in autoimmune disease therapy. Stem cell transplantation in such diseases aims to destroy the self-reacting immune cells and produce a new functional immune system, as well as substitute cells for tissue damaged in the course of the disease. Significant results, such as the reestablishment of tolerance and a decrease in the recurrence of autoimmune disease, have been reported following stem cell transplantation in patients with autoimmune disease in Brazil and throughout the world. These results suggest that stem cell transplantation has the potential to become an important therapeutic approach to the treatment of various autoimmune diseases including rheumatoid arthritis, juvenile idiopathic arthritis, systemic lupus erythematosus, multiple sclerosis, systemic sclerosis, Crohn's disease, autoimmune blood cytopenias, and type I diabetes mellitus.

Mesenchymal stem cells from patients with chronic myeloid leukemia do not express BCR-ABL and have absence of chimerism after allogeneic bone marrow transplant

Bone marrow is a heterogeneous cell population which includes hematopoietic and mesenchymal progenitor cells. Dysregulated hematopoiesis occurs in chronic myelogenous leukemia (CML), being caused at least in part by abnormalities in the hematopoietic progenitors. However, the role of mesenchymal stem cells (MSCs) in CML has not been well characterized. The objectives of the present study were to observe the biological characteristics of MSCs from CML patients and to determine if MSCs originate in part from donors in CML patients after bone marrow transplantation (BMT). We analyzed MSCs from 5 untreated patients and from 3 CML patients after sex-mismatched allogeneic BMT. Flow cytometry analysis revealed the typical MSC phenotype and in vitro assays showed ability to differentiate into adipocytes and osteoblasts. Moreover, although some RT-PCR data were contradictory, combined fluorescence in situ hybridization analysis showed that MSCs from CML patients do not express the bcr-abl gene. Regarding MSCs of donor origin, although it is possible to detect Y target sequence by nested PCR, the low frequency (0.14 and 0.34 percent) of XY cells in 2 MSC CML patients by fluorescence in situ hybridization analysis suggests the presence of contaminant hematopoietic cells and the absence of host-derived MSCs in CML patients. Therefore, we conclude that MSCs from CML patients express the typical MSC phenotype, can differentiate into osteogenic and adipogenic lineages and do not express the bcr-abl gene. MSCs cannot be found in recipients 12 to 20 months after BMT. The influence of MSCs on the dysregulation of hematopoiesis in CML patients deserves further investigation.

Secondary prevention of type 1 diabetes mellitus: stopping immune destruction and promoting ß-cell regeneration

Type 1 diabetes mellitus results from a cell-mediated autoimmune attack against pancreatic ß-cells. Traditional treatments involve numerous daily insulin dosages/injections and rigorous glucose control. Many efforts toward the identification of ß-cell precursors have been made not only with the aim of understanding the physiology of islet regeneration, but also as an alternative way to produce ß-cells to be used in protocols of islet transplantation. In this review, we summarize the most recent studies related to precursor cells implicated in the regeneration process. These include embryonic stem cells, pancreas-derived multipotent precursors, pancreatic ductal cells, hematopoietic stem cells, mesenchymal stem cells, hepatic oval cells, and mature ß-cells. There is controversial evidence of the potential of these cell sources to regenerate ß-cell mass in diabetic patients. However, clinical trials using embryonic stem cells, umbilical cord blood or adult bone marrow stem cells are under way. The results of various immunosuppressive regimens aiming at blocking autoimmunity against pancreatic ß-cells and promoting ß-cell preservation are also analyzed. Most of these regimens provide transient and partial effect on insulin requirements, but new regimens are beginning to be tested. Our own clinical trial combines a high dose immunosuppression with mobilized peripheral blood hematopoietic stem cell transplantation in early-onset type 1 diabetes mellitus.

Immunological effects of donor lymphocyte infusion in patients with chronic myelogenous leukemia relapsing after bone marrow transplantation

Allogeneic bone marrow transplantation (alloBMT) is the only curative therapy for chronic myelogenous leukemia (CML). This success is explained by the delivery of high doses of antineoplastic agents followed by the rescue of marrow function and the induction of graft-versus-leukemia reaction mediated by allogeneic lymphocytes against host tumor cells. This reaction can also be induced by donor lymphocyte infusion (DLI) producing remission in most patients with CML who relapse after alloBMT. The immunological mechanisms involved in DLI therapy are poorly understood. We studied five CML patients in the chronic phase, who received DLI after relapsing from an HLA-identical BMT. Using flow cytometry we evaluated cellular activation and apoptosis, NK cytotoxicity, lymphocytes producing cytokines (IL-2, IL-4 and IFN-gamma), and unstimulated (in vivo) lymphocyte proliferation. In three CML patients who achieved hematological and/or cytogenetic remission after DLI we observed an increase of the percent of activation markers on T and NK cells (CD3/DR, CD3/CD25 and CD56/DR), of lymphocytes producing IL-2 and IFN-gamma, of NK activity, and of in vivo lymphocyte proliferation. These changes were not observed consistently in two of the five patients who did not achieve complete remission with DLI. The percent of apoptotic markers (Fas, FasL and Bcl-2) on lymphocytes and CD34-positive cells did not change after DLI throughout the different study periods. Taken together, these preliminary results suggest that the therapeutic effect of DLI in the chronic phase of CML is mediated by classic cytotoxic and proliferative events involving T and NK cells but not by the Fas pathway of apoptosis.

Association of Alport's syndrome with HDL-DR2 antigen in a group of unrelated patients

A few studies have evaluated HLA antigens in Alport's syndrome; however, there are no large population studies. In the present report, we studied 40 unrelated white patients with Alport's syndrome seen at the Unit of Renal Transplantation, Faculty of Medicine of Ribeirao Preto, Sao Paulo, Brazil. HLA-A, -B, -DR and -DQ antigens were typed using a complement-dependent microlymphocytotoxicity assay. A control white populations (N=403) from the same geographical area was also typed for HLA antigens. Although the frequencies of HLA-A and -B antigens of patients were not statistically different from controls, the frequency of HLA-DR2 antigen observed in patients (65 percent) was significantly increased in relation to controls (26 percent; P<0.001). The relative risk and etiologic fraction for HLA-DR2 antigen were 5.2 and 0.525, respectively. Although few immunological abnormalities have been shown in Alport's syndrome, in this report we emphasize the association of HLA molecules and Alport's syndrome. Besides the well-known inherited molecular defects encoded by tyope IV collagen genes in Alport's syndrome, the major histocompatibility alleles may be in linkage disequilibrium with these defective collagen genes.

Expansion of a subset of TCR gamma/delta human lymphocytes from various lymphoid organs cultured with recombinant IL-2

1. TCR1 cells are a minor component of CD3+ lymphocytes which bear the gamma/delta T-cell receptor. There are limited data concerning the activation of TCR1 cells or TCR1 cell subsets in human lymphoid organs. We analyzed a subset of TCR1 cells (delta TCS1+) in peripheral blood (PBL), spleen (SPL), lymph nodes (LN), bone marrow (BM), and thymus (THY) after activation with IL-2. Lymphoid cells from these organs were cultured with 1500 U/ml IL-2 for 14 days and analyzed at periodic intervals for delta TCS1+ cells. 2. We found increased numbers of delta TCS1+ cells in 6- and 14-day cultures from SPL (20.8 +/- 11.8 per cent positive cells after 14 days of culture), LN, BM and THY but not in peripheral blood (1.8 +/- 0.9 per cent ). These delta TCS1+ cells coexpressed CD2, CD3, CD8 and CD56, but were negative for TCR alpha/beta and CD4. We also detected an expansion of TCR1+ cells in IL-2-stimulated PBL employing the pan-gamma/delta marker TCR delta 1; however, in contrast to solid organs, these TCR1+ cells were delta TCS1 negative. 3. Sorting experiments demonstrated directly that delta TCS1 cells from spleen cultures mediate high cytotoxic activity against K562 cell targets (39.4 per cent median specific cytotoxicity) and low activity against Daudi (9.6 per cent ), COLO (2.7 per cent ) and an antibody-sensitized human B-cell line (17 per cent ). 4. These results show expansion and cytotoxic activation by IL-2 of a subset of human TCR1 cells in solid lymphoid organs

Adrenal response to adrenocorticotropin hormone and HLA typing of subjects with different degrees of 21-hydroxylase deficiency

1. To evaluate different degrees of 21-hydroxylase (21-OH) deficiency we studied the 17-hydroxyprogesterone (17-OHP) and cortisol response to the adrenocorticotropin hormone (ACTH) stimulation test. In a study of 13 families we characterized the relatives of patients with classical 21-OH deficiency using HLA antigen typing and the ACTH test. The subjects were divided into five groups: 12 patients with the classical form, 11 patients with the nonclassical form, 38 heterozygotes, 6 normal homozygotes and 33 controls. 2. The 17-hydroxyprogesterone response to ACTH (mean +/- SD) varied as follows according to the degree of 21-OH deficiency: 25442 +/- 15718 ng/dl for the classical group, 4198 +/- 1637 ng/dl for the nonclassical group, 348 +/- 267 ng/dl for the heterozygotes, 127 +/- 81 ng/dl for normal homozygotes, and 164 +/- 120 ng/dl for the controls. Basal plasma cortisol did not differ among the five groups. The cortisol response to ACTH was not different among controls (30 +/- 8 micrograms/dl), normal homozygotes (28 +/- 7 micrograms/dl) and heterozygotes (26.5 +/- 7 micrograms/dl). The cortisol response was decreased in the patient groups and was lower in the classical (14 +/- 10 micrograms/dl) than in the nonclassical group (20 +/- 4 micrograms/dl). 3. In most families (11/13), HLA typing was informative in identifying the 21-OH deficiency containing haplotype, which correlated with the hormonal profile. In two families there was no correlation between the HLA genotype and the clinical expression of 21-OH activity for two HLA identical pairs of siblings

Lymphocyte subpopulations and neutrophil function in chronic human Chagas' disease

Numeros absolutos de leucocitos e linfocitos, de celulas T totais, indutoras/auxiliares, supresorras/citotoxicas e de celulas B estavam diminuidos no sangue periferico de pacientes com doenca de Chagas cronica. Como anticorpos antilinfocitarios estavam presentes em apenas uma minoria de pacientes, eles provavelmente nao sao responsaveis pelas anormalidades das subpopulacoes de linfocitos. Neutrofilos de pacientes estimulados por plasma autologo tratado por endotoxina mostravam atiividade quimiotatica diminuida que deve ser devida a um defeito celular intrinseco e nao a inibicao plasmatica. A migracao aleatoria dos neutrofilos estava normal. A reducao do corante "nitroblue tetrazolium" (NBT) por neutrofilos estimulados por endotoxina tambem estava diminuioda nos pacientes. Estes achados estendem a documentacao da imunossupressao na doenca de Chagas humana. Eles podem ser relevantes para autoimunidade e para defesa contra microorganismos e celulas tumorais, pelo menos em um subgrupo de pacientes com anormalidades mais pronunciadas

O sistema HLA e doencas oculares. / HLA system and eye diseases

O sistema HLA e um conjunto genico extremamente complexo e polimorfico existente em todas as celulas humanas exceto nas hemacias e que controla varias funcoes imunologicas. A associacao entre antigenos HLA e doencas, embora sem mecanismo completamente elucidado permitiria se aplicar a tipagem HLA no diagnostico, prognostico, classificacao e previsao da ocorrencia destas doencas. A revisao das associacoes entre antigenos HLA e 24 doencas oculares mostrou que, na maioria dos casos, as evidencias para estas associacoes sao inconsistentes e contraditorias. Devido a isto e ao alto custo do exame, as aplicacoes praticas da tipagem HLA em doencas oculares estao restritas a um pequeno numero de situacoes, que sao discutidas neste trabalho