La inhibición de los puntos de control inmunológico, una terapia en evolución: remembranza del Premio Nobel de Medicina 2018 / Immune checkpoint inhibitors: a breakthrough in cancer therapy

Professors James P. Allison and Tasuku Honjo were awarded with the 2018 Nobel Prize in Medicine for their contributions in cancer immunotherapy. The latter is a breakthrough in cancer therapy, aimed to overcome tumor-induced immunosuppression, leading to the reactivation of the immune system against cancer cells. Under physiological conditions, the CTLA-4 and PD-1 proteins expressed on T-cells and discovered by the awarded scientists, lead to immune tolerance. Cancer cells exploit these control points to enhance the inhibition of T-cells. The expression of PD ligands (PD-L1) in tumor cells and CTLA-4 ligands in antigen presenting cells, which bind the PD-1 receptor and CTLA-4 respectively, block anti-tumor immunity. This situation led to a biotechnological race focused on the development of effective antibodies able to "turn-on" the immune system cheated by the tumor. Anti-CTLA-4 and anti-PD-1 antibodies improve life-expectancy in cancer patients. In this review, we perform an historical overview of Professors Allison and Honjo contribution, as well as the immunological basis of this new and powerful therapeutic strategy, highlighting the clinical benefits of such intervention.

Anti-PD-1 and anti-PD-l1 antibodies as immunotherapy against cancer: a structural perspective

ABSTRACT Programmed cell death protein 1 (PD-1) and its ligand, programmed death-ligand-1 (PD-L1), play key roles in the suppression of the cytotoxic activity of T cells. PD-L1 is overexpressed on various types of cancer cells, leading to immune evasion. In the past decade, therapeutic antibodies that target the PD-1/PD-L1 axis have been developed to inhibit the immune suppression triggered by these two proteins. At present, five antibodies (two anti-PD-1 and three anti-PD-L1) have received approval by regulatory agencies in the US and Europe. In this work, we aimed to review their clinical applications and adverse effects. Furthermore, using their reported crystal structures, we discuss the similarities and differences between the PD-1/PD-L1 interface and the epitopes that are recognized by the antibodies. Detailed analyses of the contact residues involved in the ligand-receptor and target-antibody interactions have shown partial overlap. Altogether, the data presented here demonstrate that: (1) in contrast to other therapeutic antibodies, anti-PD-1/PD-L1 has a wide range of clinical applications; (2) these targeted therapies are not exempt from adverse effects; and (3) the characterization of the structural domains that are recognized by the antibodies can guide the development of new PD-1- and PD-L1-blocking agents. (REV INVEST CLIN. 2021;73(1):8-16)

PD-1 blockade as a future treatment for colorectal cancer with microsatellite instability / Bloqueio do PD-1 como futuro tratamento do cancro colorretal com instabilidade de microssatélites

ABSTRACT Introduction: Colorectal cancer is the third most common cancer worldwide, with about 15% of these tumours related with microsatellite instability, which confers distinct characteristics to these tumours, both clinicopathological and in the response to treatments. In fact, the poor response to chemotherapy in these tumours has led to the investigation for new treatments, with immunotherapy being the most successful one to date. The focus of this review is to assess the response of microsatellite unstable colorectal cancer to PD-1 blockade, and the mechanisms behind that response. Methods: A PubMed research was conducted, resulting in the inclusion of 47 articles in this review. Results: Microsatellite instability results in a high neoantigen load, leading to a highly active immune microenvironment of the tumour, mainly due to T-cells. To counteract this, there is an upregulation of PD-1, acting as a "brake" for immune cells, facilitating tumour growth and metastasis. This upregulation makes these tumours great candidates for treatment with PD-1 blockade, as seen in many clinical trials, where the overall responses and progression free survival rates were higher than those observed in microsatellite stable tumours. Conclusion: With the importance of colorectal cancer with microsatellite instability new treatments are necessary. Therefore, PD-1 blockade is a promising treatment for colorectal cancer with microsatellite instability, with improvement in survival rates and a better prognosis for these patients.

RESUMO Introdução: O câncer colorretal é o terceiro mais comum em todo o mundo, com cerca de 15% desses tumores relacionados com instabilidade dos microssatélites, o que confere características distintas a esses tumores, tanto clínico patológicas quanto na resposta aos tratamentos. De fato, a fraca resposta à quimioterapia nesses tumores levou à investigação de novos tratamentos, sendo a imunoterapia a mais bem sucedida até o momento. O foco desta revisão é avaliar a resposta do câncer colorretal com microssatélites instáveis ao bloqueio do PD-1 e os mecanismos por trás dessa resposta. Métodos: Foi realizada uma pesquisa na base de dados PubMed, resultando na inclusão de 47 artigos nesta revisão. Resultados: A instabilidade de microssatélites resulta em uma alta carga de neoantígenos, levando a um microambiente imunológico altamente ativo do tumor, principalmente devido às células T. Para neutralizar isso, há uma maior expressão do PD-1, atuando como um "freio" para as células imunes, facilitando o crescimento do tumor e suas metástases. Essa expressão faz desses tumores grandes candidatos ao tratamento com bloqueio PD-1, como demonstrado em vários ensaios clínicos, onde as respostas globais e as taxas de sobrevivência livres de progressão foram maiores do que as observadas em tumores com microssatélites estáveis. Conclusão: Com a importância do câncer colorretal com instabilidade de microssatélites, novos tratamentos são necessários. Portanto, o bloqueio do PD-1 é um tratamento promissor para o câncer colorretal com instabilidade de microssatélites, com melhora nas taxas de sobrevivência e melhor prognóstico para esses pacientes.

Immunotherapy treatment against cervical cancer

ABSTRACT Cervical cancer (CC) is one of the most common gynecological tumors and an important health problem, especially in developing countries. The vast majority of patients in early stages are cured of the disease with surgical treatment and with concomitant chemoradiotherapy in locally advanced stages. However, in patients with recurrent, persistent, or metastatic cervical CC, the effectiveness of treatment is limited, except for the combination of chemotherapy based on platinum doublets plus bevacizumab, the treatment that has achieved the best results to date. Programmed cell death-1/PD ligand-1 (PD-1/PD-L1) inhibitors could be a novel and cutting-edge therapeutic option to improve clinical outcomes in this group of patients. Thus far, there are a few Phase I/II clinical trials that have assessed the usefulness of pembrolizumab and nivolumab in this group of patients; these include the KEYNOTE 028, KEYNOTE 158, and CHECKMATE 358 trials, in which clinical benefit has been proven with PD-1/PD-L1 inhibitors in recurrent, persistent, or metastatic CC, as second-line treatment. There are also some ongoing trials that could provide further evidence on the PD-1/PD-L1 pathway as a therapeutic target in CC. In this review, we will focus on the usefulness of these PD-1/PDL1 inhibitors in CC, as well as on trials that are still in the recruitment phase, to confirm their effectiveness in this clinical setting.

Efectos adversos inmunomediados por inhibidores de PD-1 / PD-1 inhibitors immune-mediated side effects

Los anticuerpos monoclonales que inhiben los puntos de control PD-1 y CTLA-4 se usan actualmente en el tratamiento del melanoma y cáncer metastásico de pulmón de células no pequeñas, entre otros. Se refiere el caso de una paciente con cáncer de pulmón en tratamiento con pembrolizumab. La paciente se presentó con edema facial y parálisis facial periférica. En el laboratorio se observó la hormona tirotrofina (TSH) elevada y se llegó al diagnóstico de hipotiroidismo por pembrolizumab. Inició tratamiento con levotiroxina con mejoría clínica. Se presenta este caso por el importante papel del dermatólogo en el manejo multidisciplinario del paciente oncológico. (AU)

Monoclonal antibodies that inhibit PD-1 and CTLA-4 control points are currently used in the treatment of melanoma and metastatic non-small cell lung cancer, among others. The case of a patient, with lung cancer being treated with Pembrolizumab. The patient was presented with facial edema and peripheral facial paralysis and in the laboratory the elevated hormone Tyrotrophin (TSH) was observed, the diagnosis of pembrolizumab hypothyroidism was reached. She started treatment with levothyroxine with clinical improvement. This case is presented by the important role of the dermatologist in the multidisciplinary management of the cancer patient. (AU)

Carcinomas de ovário associados à endometriose: expressão de marcadores proteicos de terapia alvo e prognóstico / Endometriosis-associated ovarian carcinomas: expression of protein biomarkers associated to target therapies and prognosis

Resumo: Introdução: endometriose é uma doença benigna, capaz de progredir extensamente e gerar clones atípicos. Considerada precursora dos carcinomas de células claras (CCOC) e endometrióide (EOC) de ovário, atualmente chamados carcinomas de ovário associados à endometriose (EAOC). Objetivos: comparar o perfil epidemiológico, a associação com endometriose e a expressão de marcadores imuno-histoquímicos para ARID1A, VEGF, PD-L1 e PARP-1 em mulheres com CCOC e EOC, e sua correlação com a sobrevida livre de progressão (SLP) e sobrevida global (SG). Métodos: estudo de coorte reconstituída, com 50 casos incluídos de CCOC e EOC tratados no CAISM-UNICAMP entre 1995 até 2016, acompanhados até 02/2017. Microarranjos de tecido com amostras de CCOC, EOC e endometriose foram corados com anticorpos monoclonais contra ARID1A, e para os biomarcadores proteicos VEGF, PD-L1, PARP-1 através de imuno-histoquímica. A expressão de ARID1A foi classificada (0 a 100) conforme a porcentagem de células não coradas. A expressão de VEGF, PD-L1 e PARP-1 foi classificada (0 a 300) conforme a multiplicação da porcentagem de células coradas por um fator da intensidade de expressão (ausente=0; fraco=1; moderado=2; forte=3). Idade ao diagnóstico; menopausa; índice de massa corpórea (IMC); CA-125; diagnóstico de endometriose; datas do diagnóstico, da progressão, do óbito e da última consulta foram recuperados dos prontuários. Comparação entre grupos foi realizada através de testes T e de ?2. A SLP (diferença de tempo entre o diagnóstico e a data de progressão) e a SG (diferença de tempo entre o diagnóstico e o óbito ou data da última data de consulta) foi avaliada através de curvas de Kaplan-Meyer e teste de Log-Rank ou regressão de COX. Resultados: 23 mulheres com CCOC (46%), e 27 com EOC (54%) foram incluídas; 80% tinham endometriose associada, 42% eram nulíparas, 42% eram pré-menopausa e CA125 foi elevado em todos estádios (FIGO I-II= média 614.7Ui/mL; FIGO III-IV= media 2361.2Ui/mL). A média de idade ao diagnóstico foi 7 anos menor em mulheres com EOC do que naquelas com CCOC. O CCOC foi mais diagnosticado em estágios iniciais quando associado à endometriose (p=0,03). O prognóstico dos EOC e CCOC em estádios iniciais foi semelhante (p=0,96). Os CCOC não associado à endometriose tiveram menor SG (p=0,04). A expressão de todos os biomarcadores esteve presente nos EAOC e na endometriose. O aumento da expressão de VEGF entre endometriose e câncer foi significativo (p=0,0002). A hiperexpressão de PARP-1 correlacionou-se negativamente com a SLP (p=0,03) e SG (p=0,01) em estádios iniciais. Conclusão: Os CCOC e EOC são comumente diagnosticados em estádios iniciais (FIGO I-II= 68%) e estão frequentemente associados à endometriose (80% dos casos). Quando associados à endometriose, os CCOC foram mais diagnosticados em estádios iniciais e tiveram SG maior. Houve elevada porcentagem de células com ARID1A mutado nos EAOC (>40%). VEGF se expressou mais intensamente nos CCOC e EOC que na endometriose, já a expressão de PD-L1 e de PARP-1 foi similar. Apenas a hiperexpressão de PARP-1 reduziu significativamente a SLP e a SG nos CCOC e EOC nos estádios iniciais(AU)

Abstract: Introduction: Endometriosis is a benign disease, able to progress widely and generate atypical clones. It is a precursor of clear cell ovarian carcinomas (CCOC) and endometrioid ovarian carcinomas (EOCs), now called endometriosis-associated ovarian carcinomas (EAOC). Objectives: To compare the epidemiological profile, association with endometriosis and the expression of immunohistochemical markers for ARID1A, VEGF, PD-L1 and PARP-1 in women with CCOC and EOC, and its correlation with progression-free survival (PFS) and overall survival (OS). Methods: A reconstituted cohort study with 50 cases of CCOC and EOC included. Cases were treated at CAISM-UNICAMP between 1995 and 2016, followed up until 02/2017. Tissue microarrays with CCOC, EOC and endometriosis samples were stained with monoclonal antibodies against ARID1A, and for VEGF, PD-L1, PARP-1 biomarkers by immunohistochemistry. The expression of ARID1A was classified (0 to 100) according to the percentage of unstained cells. The expression of VEGF, PD-L1 and PARP-1 was classified (0 to 300) multiplying the percentage of stained cells by an intensity of expression factor (absent=0, weak=1, moderate=2, strong=3). Age at diagnosis; menopause; BMI (body mass index); CA-125 levels; diagnosis of endometriosis; date of diagnosis, date of progression, date of death and date of last consultation were retrieved from the medical records. Comparison between groups was performed through T and ?2 tests. The PFS (difference in time between diagnosis and progression date) and OS (difference in time between diagnosis and death or the last date of consultation) was assessed using Kaplan-Meyer curves and Log-Rank test or COX multivariate models. Results: twenty-three women with CCOC (46%), and 27 with EOC (54%) were included; 80% had associated endometriosis, 42% were nulliparous, 42% were premenopausal, and CA125 was elevated at all stages (FIGO I-II = mean 614.7Ui / mL; FIGO III-IV = mean 2361.2Ui / mL). The mean age at diagnosis was 7 years lower in women with EOC than in those with CCOC. CCOC when associated with endometriosis were more diagnosed at early stages (p=0.03). The prognosis of EOC and CCOC at early stages was similar (p=0.96). CCOCs not associated with endometriosis had shorter OS (p=0.04). Expression of all biomarkers was present in the EAOC and endometriosis. The increase in VEGF expression between endometriosis and cancer was significant (p=0.0002). The overexpression of PARP-1 correlated negatively with PFS (p=0.03) and OS (p=0.01) at FIGO I-II stages. Conclusion: The diagnosis of women with EOC was made earlier than in those with CCOC. CCOC and EOC are commonly diagnosed in early stages (FIGO I-II - 68%) and were associated with endometriosis (80% of cases). When associated with endometriosis, clear cell carcinomas are more likely diagnosed at early stages, and the association of endometriosis with CCOC improves OS. There was a high percentage of cells with mutated ARID1A gene in EAOC (> 40%). VEGF was expressed more intensely in CCOC and EOC than in endometriosis, whereas expression of PD-L1 and PARP-1 was similar. Only the overexpression of PARP-1 significantly reduced PFS and OS in CCOC and EOC at early stages(AU)

Cancer immunology and melanoma immunotherapy

Abstract: The stimulation of the immune system, in order to generate an attack against cancer cells, similarly to that which occurs in infectious disease, has long been matter of interest in oncology; however, only limited success has been achieved, with different treatment strategies tested in recent years. The development of new immune checkpoint inhibitors is currently changing this scenario, and immunotherapy is becoming a real choice among traditional cytotoxic treatments to fight cancer. Recent reports have shown efficacy and safety with the use of pembrolizumab, nivolumab, and ipilimumab for the treatment of different neoplasms, especially melanoma. In this article, we propose a review of the mechanisms of action involved in cancer immunology, the response evaluation of immunotherapies, and its toxicity profile, as well as a summary of the main clinical trials that led to the adoption of these new drugs for melanoma treatment.

Immunotherapy and gene therapy as novel treatments for cancer / Inmunoterapia y terapia génica como nuevos tratamientos contra el cáncer

Abstract The immune system interacts closely with tumors during the disease development and progression to metastasis. The complex communication between the immune system and the tumor cells can prevent or promote tumor growth. New therapeutic approaches harnessing protective immunological mechanisms have recently shown very promising results. This is performed by blocking inhibitory signals or by activating immunological effector cells directly. Immune checkpoint blockade with monoclonal antibodies directed against the inhibitory immune receptors CTLA-4 and PD-1 has emerged as a successful treatment approach for patients with advanced melanoma. Ipilimumab is an anti-CTLA-4 antibody which demonstrated good results when administered to patients with melanoma. Gene therapy has also shown promising results in clinical trials. Particularly, Herpes simplex virus (HSV)-mediated delivery of the HSV thymidine kinase (TK) gene to tumor cells in combination with ganciclovir (GCV) may provide an effective suicide gene therapy for destruction of glioblastomas, prostate tumors and other neoplasias by recruiting tumor-infiltrating lymphocytes into the tumor. The development of new treatment strategies or combination of available innovative therapies to improve cell cytotoxic T lymphocytes trafficking into the tumor mass and the production of inhibitory molecules blocking tumor tissue immune-tolerance are crucial to improve the efficacy of cancer therapy.

Resumen El sistema inmune interactúa íntimamente con los tumores durante el proceso del desarrollo de la enfermedad y su progresión a metástasis. Esta compleja comunicación entre el sistema inmune y las células tumorales puede prevenir o promover el crecimiento del tumor. Los nuevos enfoques terapéuticos que aprovechan los mecanismos inmunológicos, ya sea por el bloqueo de señales inhibitorias o por la activación directa de células efectoras, han mostrado resultados prometedores. El bloqueo de puntos de control inmunológicos (immune-checkpoints) con anticuerpos monoclonales dirigidos contra receptores que normalmente inhiben el sistema inmune, como CTLA-4 o PD-1, ha resultado ser un tratamiento exitoso para pacientes con melanoma avanzado. El fármaco ipilimumab es un anticuerpo anti-CTLA-4 que ha demostrado buenos resultados terapéuticos en pacientes con melanoma. Por otro lado, la terapia génica también ha mostrado resultados prometedores en ensayos clínicos. En especial, la administración de la enzima timidina quinasa del virus Herpes simplex (HSV-TK) en combinación con el fármaco ganciclovir (GCV) ha mostrado ser una terapia suicida muy efectiva para la destrucción de diferentes neoplasias incluyendo glioblastomas y tumores prostáticos, por un mecanismo que involucra el reclutamiento de linfocitos infiltrantes de tumor. Es importante la búsqueda de nuevas estrategias o la combinación de terapias innovadoras, con el fin de involucrar tanto la atracción de linfocitos citotóxicos así como el empleo de moléculas que inhiban la inmunotolerancia del tejido tumoral para mejorar la eficiencia de los tratamientos contra el cáncer.

Association of PDCD1 polymorphism to systemic lupus erythematosus and rheumatoid arthritis susceptibility / Associação entre o polimorfismo do gene PDCD1 e a susceptibilidade ao lúpus eritematoso sistêmico e à artrite reumatoide

ABSTRACT Objective: This study aims to analyze the relationship of programmed cell death 1 (PDCD1) gene polymorphism (PD1.3G/A - rs11568821) with features of systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA) in a Southern Brazilian population. Methods: Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was performed in 95 SLE and 87 RA patients and 128 control group individuals from Santa Catarina, Southern Brazil. The Hardy-Weinberg equilibrium (HWE) test, and odds ratio (OR) were analyzed, considering CI 95% and p ≤ 0.05. Results: The PD1.3A allele frequencies were 0.095 (SLE), 0.115 (RA) and 0.078 (controls). The genotypes of the control group were in HWE, while those of SLE and RA patients were not. However, we found no association between PD1.3 polymorphism and the SLE or RA susceptibility, nor clinical or epidemiological data. Conclusion: There was no significant association between PD1.3 polymorphism and SLE or RA susceptibility in this Southern Brazilian population.

RESUMO Objetivo: Este estudo teve como objetivo analisar a relação entre o polimorfismo do gene PDCD1 (programmed cell death 1) (PD1.3G/A - rs11568821) com características do lúpus eritematoso sistêmico (LES) e da artrite reumatoide (AR) em uma população do sul do Brasil. Métodos: A técnica de PCR-RFLP (Polymerase Chain Reaction-Restriction Fragment Lenght Polymorphism) foi utilizada para analisar amostras de 95 pacientes com LES e 87 com AR, assim como em 128 indivíduos do grupo controle de Santa Catarina, sul do Brasil. Foi analisada a probabilidade de equilíbrio de Hardy-Weinberg (EHW) e a odds ratio (OR), considerando um IC 95% e p ≤ 0,05. Resultados: As frequências alélicas PD1.3 A foram de 0,095 (LES), 0,115 (AR) e 0,078 (controles). Os genótipos do grupo controle estavam em EHW, enquanto aqueles dos pacientes com LES e AR não estavam. No entanto, não foi encontrada associação entre o polimorfismo PD1.3 e a suscetibilidade ao LES ou à AR, nem com dados clínicos ou epidemiológicos. Conclusão: Não foi encontrada associação significativa entre o polimorfismo PD1.3 e a susceptibilidade ao LES ou à AR nessa população do sul do Brasil.

Acarbose versus trans-chalcone: comparing the effect of two glycosidase inhibitors on obese mice

Objective Acarbose and trans-chalcone are glucosidase inhibitors whose beneficial effects have been demonstrated in diabetes. The present study aimed at investigating their potential effects in obesity.Materials and methods NMRI male mice (n = 48) were subjected to a high fat diet for four weeks, which induced an initial state of obesity. One control group was given normal rodent diet. Obese animals were then switched to normal rodent diet, and divided to four groups (n = 12 in each): untreated, sham (receiving grape seed oil), and experimental groups receiving acarbose and trans-chalcone (12 mg/kg) during eight weeks. Body weight, blood glucose and other biochemical parameters including triglycerides (TG), cholesterol, HDL, AST, and ALT were measured, as well as leptin, adiponectin, TNF-α, and total antioxidant capacity (TAC). Histological studies were performed on adipose cells and liver tissue samples.Results All factors were affected in a positive manner by acarbose, save for body weight, blood sugar and leptin levels, on which acarbose effects, although observable, were not statistically significant. Grape seed oil, used as a solvent for trans-chalcone was found to possess significant effect on TG and TAC, and had beneficial effects on other factors including liver enzymes and cholesterol. Trans-chalcone effects were significant on HDL, leptin and ALT. All compounds seemed to be able to affect fat deposition in liver tissue, and decrease the size of adipose tissue cells to some extent.Conclusion In conclusion, the tested compounds were able to affect lipid accumulation in tissues and influence adipokines, which may result in an enhanced state with regard to inflammation and oxidative stress. Arch Endocrinol Metab. 2015;59(3):202-9.

Imbalanced expression of functional surface molecules in regulatory and effector T cells in systemic lupus erythematosus

Regulatory T (TREG) cells play an important role in maintaining immune tolerance and avoiding autoimmunity. We analyzed the expression of membrane molecules in TREG and effector T cells in systemic lupus erythematosus (SLE). TREG and effector T cells were analyzed for the expression of CTLA-4, PD1, CD28, CD95, GITR, HLA-DR, OX40, CD40L, and CD45RO in 26 patients with active disease, 31 with inactive disease, and 26 healthy controls. TREG cells were defined as CD25+/highCD127Ø/lowFoxP3+, and effector T cells were defined as CD25+CD127+FoxP3Ø. The ratio of TREG to effector T cells expressing GITR, PD1, HLA-DR, OX40, CD40L, and CD45RO was determined in the three groups. The frequency of TREG cells was similar in patients with SLE and controls. However, SLE patients had a decreased frequency of CTLA-4+TREG and CD28+TREG cells and an increased frequency of CD40L+TREG cells. There was a decrease in the TREG/effector-T ratio for GITR+, HLA-DR+, OX40+, and CD45RO+ cells, and an increased ratio of TREG/effector-T CD40L+ cells in patients with SLE. In addition, CD40L+TREG cell frequency correlated with the SLE disease activity index (P=0.0163). In conclusion, our findings showed several abnormalities in the expression of functionally critical surface molecules in TREG and effector T cells in SLE that may be relevant to the pathogenesis of this disease.

Frecuencia del polimorfismo PD-1.3 del gen del receptor de muerte celular programada 1 (PD-1) y su asociación con diabetes tipo 1 / Frequency of polymorphism PD-1.3 of programmed cell death 1 (PD-1) and their association with type 1 diabetes

Background: The programmed cell death 1 (PDCD-1) immune-receptor is a key element in the negative regulation of peripheral tolerance in T cells. The gene has several polymorphisms and can be associated with susceptibility to autoimmune diseases. Aim: To analyze the frequency and distribution of PD-1.3 polymorphism of PDCD-1 gene and explore its possible contribution as a susceptibility gene for type 1 diabetes (T1D). Patients and Methods: We analyzed 248 cases with T1D with recent diagnosis and 160 control children under 15 years of Santiago. Genetic polymorphism in PD-1 gene variant for PD-1.3 (rs 11568821) was analyzed by polymerase chain reaction and restriction fragment length polymorphism. Comparison of genotype, allele frequency and consistency with respect to Hardy-Weinberg were analyzed using X2 tests and Fisher exact test. Results: There was a very low frequency of the genotype A/A, both in T1D patients and in controls (< 2 percent). The A/G genotype was more common in diabetic patients than in controls (41.6 and 18.8 percent respectively, p < 0.04). G/G genotype was more common in controls than in patients (79.4 and 56.8 percent respectively, p < 0.02). T1D patients carrying genotype G/G had a higher frequency of anti-GAD65 and anti-A-2 antibodies (81 and 67 percent respectively). Conclusions: The distribution of PD-1.3 genotype frequencies are similar to that reported elsewhere. Possibly, this genetic variant (rs 11568821) does not have an important marker role in Chilean T1D patients.

Differential expression of the costimulatory molecules CD86, CD28, CD152 and PD-1 correlates with the host-parasite outcome in leprosy

Leprosy is a spectral disease exhibiting two polar sides, namely, lepromatous leprosy (LL) characterised by impaired T-cell responses and tuberculoid leprosy in which T-cell responses are strong. Proper T-cell activation requires signalling through costimulatory molecules expressed by antigen presenting cells and their ligands on T-cells. We studied the influence of costimulatory molecules on the immune responses of subjects along the leprosy spectrum. The expression of the costimulatory molecules was evaluated in in vitro-stimulated peripheral blood mononuclear cells of lepromatous and tuberculoid patients and healthy exposed individuals (contacts). We show that LL patients have defective monocyte CD86 expression, which likely contributes to the impairment of the antigen presentation process and to patients anergy. Accordingly, CD86 but not CD80 blockade inhibited the lymphoproliferative response to Mycobacterium leprae. Consistent with the LL anergy, there was reduced expression of the positive signalling costimulatory molecules CD28 and CD86 on the T-cells in these patients. In contrast, tuberculoid leprosy patients displayed increased expression of the negative signalling molecules CD152 and programmed death-1 (PD-1), which represents a probable means of modulating an exacerbated immune response and avoiding immunopathology. Notably, the contacts exhibited proper CD86 and CD28 expression but not exacerbated CD152 or PD-1 expression, suggesting that they tend to develop a balanced immunity without requiring immunosuppressive costimulatory signalling.