Characterization of immune and enteric systems of broilers after imunosupression with dexamethasone

Background: Bursa of Fabricius (BF) and the thymus are primary lymphoid organs of poultry and play a major role in avian immunity. Enteric system is also involved in immunity. Several pathologic conditions directly impact BF and thymus size, and also affect intestinal parameters. Besides, there are several immune system depressor agents which affect birds. The selection of glucocorticoid as inducer of immunosuppression is applied in many experiments; however there are few studies that are applied to the reality in the field. In this context, the aim of this study was to evaluate the effects of dexamethasone as an inducer of immunosuppression on lymphoid organs and microscopic structures of the jejunum.Materials, Methods & Results: One-day-old chicks were used as a control group (n = 8) and the treated group (n = 25) received intramuscular dexamethasone on 21, 23, 24 and 26 day-old. Control birds and treated birds were euthanized 8, 16, 24, 32 and 40 h after inoculation; four control birds and six treated birds were euthanized on the eighth day after the last inoculation. Thymus, BF and jejunum were collected during the necropsy. The selected organs were processed, stained with hematoxylin and eosin and photographed. The BF and thymus cuts were evaluated by three histopathologists to determine the depletion score. Ten villi of each jejunum were evaluated for width and length of villi, depth crypt, microvillus length, enterocyte length of each villus, and wall thickness. Treated birds presented a mean weight lower than control group during all the experiment. The mean weight and the relative weight of the BF and thymus of control birds were significantly higher than treated ones. The lymphocyte depletion in BF and thymus scores differed significantly between groups, being higher in the group challenged with dexamethasone. There were no significant differences between groups for depth of crypt, height of core and height of microvilli.[...]

Characterization of immune and enteric systems of broilers after imunosupression with dexamethasone

Background: Bursa of Fabricius (BF) and the thymus are primary lymphoid organs of poultry and play a major role in avian immunity. Enteric system is also involved in immunity. Several pathologic conditions directly impact BF and thymus size, and also affect intestinal parameters. Besides, there are several immune system depressor agents which affect birds. The selection of glucocorticoid as inducer of immunosuppression is applied in many experiments; however there are few studies that are applied to the reality in the field. In this context, the aim of this study was to evaluate the effects of dexamethasone as an inducer of immunosuppression on lymphoid organs and microscopic structures of the jejunum.Materials, Methods & Results: One-day-old chicks were used as a control group (n = 8) and the treated group (n = 25) received intramuscular dexamethasone on 21, 23, 24 and 26 day-old. Control birds and treated birds were euthanized 8, 16, 24, 32 and 40 h after inoculation; four control birds and six treated birds were euthanized on the eighth day after the last inoculation. Thymus, BF and jejunum were collected during the necropsy. The selected organs were processed, stained with hematoxylin and eosin and photographed. The BF and thymus cuts were evaluated by three histopathologists to determine the depletion score. Ten villi of each jejunum were evaluated for width and length of villi, depth crypt, microvillus length, enterocyte length of each villus, and wall thickness. Treated birds presented a mean weight lower than control group during all the experiment. The mean weight and the relative weight of the BF and thymus of control birds were significantly higher than treated ones. The lymphocyte depletion in BF and thymus scores differed significantly between groups, being higher in the group challenged with dexamethasone. There were no significant differences between groups for depth of crypt, height of core and height of microvilli.[...](AU)

Evaluation of thymic lymphocyte loss of broiler using Digital Analysis of the Lymphoid Depletion System (ADDL) / Avaliação de perda de linfócitos do timo em frangos usando análise digital do sistema de depleção linfóide (ADDL)

The thymus is a lymphoid organ and usually evaluated for the degree of lymphocyte loss with subjective histological techniques. This study aimed to adapt and to apply of the digital analysis of the lymphoid depletion system (ADDL) in the thymus in order to obtain a more accurate analysis. Glucocorticoid was used to induce immunosuppression in 55 broilers at 21 days of age; other 15 broilers were the control group. After euthanasia of the broilers, postmortem examination was made. Both thymic chains were collected and six lobes were selected for histological examination of the degree of lymphocyte depletion (scores 1 to 5) and for submission to all stages of processing by the ADDL system. The artificial constructed neural networks (ANN) obtained 94.03% of correct classifications. In conclusion, it was possible to adopt objective criteria to evaluate thymic lymphoid depletion with the ADDL system.(AU)

O timo é um órgão linfóide, que é normalmente avaliado para o grau de perda de linfócitos a partir de técnicas histológicas subjetivas. Este trabalho teve como objetivo a adaptação e aplicação do sistema de análise digital de depleção linfóide (ADDL) para o timo, a fim de tornar sua análise mais acurada. Glicocorticóides foram utilizados a fim de induzir imunossupressão em 55 aves de 21 dias de idade. Outras 15 aves formaram o grupo controle. Posteriormente, para cada um dos aves, realizou-se a eutanásia e necropsia. Ambas as cadeias do timo foram coletadas e foram selecionadas seis lóbulos para processamento histológico, análise quanto ao grau de depleção linfocitária (escores de 1-5) e submissão a todas as fases do processamento pelo sistema ADDL. Observou-se que a rede neural artificial (RNA) construída obteve 94,03% de classificações corretas. Em conclusão, foi possível adotar critérios objetivos para avaliar a depleção linfóide tímica utilizando o sistema ADDL.(AU)

Evaluation of thymic lymphocyte loss of broiler using Digital Analysis of the Lymphoid Depletion System (ADDL) / Avaliação de perda de linfócitos do timo em frangos usando análise digital do sistema de depleção linfóide (ADDL)

The thymus is a lymphoid organ and usually evaluated for the degree of lymphocyte loss with subjective histological techniques. This study aimed to adapt and to apply of the digital analysis of the lymphoid depletion system (ADDL) in the thymus in order to obtain a more accurate analysis. Glucocorticoid was used to induce immunosuppression in 55 broilers at 21 days of age; other 15 broilers were the control group. After euthanasia of the broilers, postmortem examination was made. Both thymic chains were collected and six lobes were selected for histological examination of the degree of lymphocyte depletion (scores 1 to 5) and for submission to all stages of processing by the ADDL system. The artificial constructed neural networks (ANN) obtained 94.03% of correct classifications. In conclusion, it was possible to adopt objective criteria to evaluate thymic lymphoid depletion with the ADDL system.(AU)

O timo é um órgão linfóide, que é normalmente avaliado para o grau de perda de linfócitos a partir de técnicas histológicas subjetivas. Este trabalho teve como objetivo a adaptação e aplicação do sistema de análise digital de depleção linfóide (ADDL) para o timo, a fim de tornar sua análise mais acurada. Glicocorticóides foram utilizados a fim de induzir imunossupressão em 55 aves de 21 dias de idade. Outras 15 aves formaram o grupo controle. Posteriormente, para cada um dos aves, realizou-se a eutanásia e necropsia. Ambas as cadeias do timo foram coletadas e foram selecionadas seis lóbulos para processamento histológico, análise quanto ao grau de depleção linfocitária (escores de 1-5) e submissão a todas as fases do processamento pelo sistema ADDL. Observou-se que a rede neural artificial (RNA) construída obteve 94,03% de classificações corretas. Em conclusão, foi possível adotar critérios objetivos para avaliar a depleção linfóide tímica utilizando o sistema ADDL.(AU)

AVALIAÇÃO DOS EFEITOS DA DEXAMETASONA EM ÓRGÃOS DO SISTEMA IMUNE- TIMO E BURSA DE FABRICIUS- E EM JEJUNO DE FRANGOS

A integridade do sistema imune e do trato gastrointestinal está diretamente relacionada à sanidade das aves e ao desempenho zootécnico. Com intenção de melhor compreender estes sistemas e sua interação, o presente estudo foi desenvolvido. O objetivo do trabalho foi avaliar os efeitos da dexametasona nos órgãos linfoides - timo e bursa de Fabricius (BF) - e nas estruturas do jejuno, relacionando-os entre si e ao peso final dos animais. Para tal, foram utilizadas 33 amostras de BF, timo e intestinos, os quais foram processados histologicamente e corados com H&E. As lâminas de BF e de timo foram avaliadas por pelo menos dois histopatologistas, sendo utilizada a moda para determinar o escore de depleção de cada amostra. Foram obtidas fotomicrografias digitais de dez vilosidades por jejuno, nas quais mensuraram-se o comprimento e a largura de vilo e a profundidade de uma cripta associada, a altura de núcleo de enterócito, o comprimento de núcleo e a altura de microvilosidade. As medições foram realizadas no Software Motic 2.0®. Após, foram aplicados testes estatísticos paramétricos, utilizando o Software SPSS e o Software JMP-SAS. Observou-se a média de 4,20g nas BF de aves controles, ao passo que em animais submetidos à dexametasona a média 0,74g (p<0,05). O peso relativo (PR) médio das BF controles foi de 0,26%, já em tratados o PR médio foi de 0,06%. Nos controles, a moda do escore de depleção das BF foi 1 e média 1,38. Por outro lado, BF de tratados apresentaram moda 3 e média 2,65 (p<0,05). Nos controles foi observada a média de peso do timo de 17,18g e PR de 1,08%. Já nos tratados a média foi de 6,3g (p<0,05) e PR de 0,57%. A média dos escores de depleção de timos das aves controles foi de 1,63 e moda de 2. Já nos animais tratados a média foi de 3,56 e moda de 3. Nas avaliações realizadas no intestino não houve significância estatística em profundidade de criptas, espessura de parede, tamanho de núcleo e microvilosidades (p>0,05). Intestinos de aves controles apresentaram comprimento em média 1366,4µm maiores e largura de vilosidades em média 58,4µm maiores que aves submetidas a tratamento (p<0,05). Aves tratadas obtiveram ganho de peso de 15,3% uma semana após o tratamento, enquanto aves controles apresentaram ganho de peso de 26,7% no mesmo período. Entre o peso do timo e o peso da BF obteve-se correlação de 93,1% e coeficiente de regressão (r 2 ) de 86,7%. Da mesma forma, entre o peso do timo e o peso da ave foi visto um r 2 de 86,4%. Já entre o peso de BF e peso da ave foi observado r 2 de 71,8%. Por outro lado, os parâmetros avaliados nos intestinos não apresentaram correlações consideráveis. O comprimento de vilosidade obteve correlação com peso de timo próximo a 50% e r 2 de 22,5%. Neste estudo foi possível avaliar os efeitos imunodepressores da dexametasona em timo e BF e nas estruturas do jejuno. Houve redução do ganho de peso das aves com a inoculação de dexametasona. Foi possível estabelecer relações entre sistema imune e peso final da ave e entre comprimento de vilos e peso do timo..

The integrity of the immune system and gastrointestinal tract are directly related to the health of birds and livestock performance. Intending to better understand those systems and their interaction, the current study was developed. The aim of this study was to evaluate the effects of dexamethasone in lymphoid organs thymus and bursa of Fabricius (BF) and in jejunum structures, linking the relationship between those structures, and to the final poultry weight. In this study, 33 samples of BF and intestines were histologically processed and stained with H&E. BF and thymus slides were evaluated by at least two histopathologists. Mode was used to determine the depletion score for each sample. Digital photomicrographs of ten jejunum villi were obtained, in which the length and width of villi were measured, as well as depth of an associated crypt, height of core enterocyte, core length and size of microvilli. Measurements were performed in the Software Motic 2.0®. Then, parametric statistical tests were applied using SPSS Software and JPM-SAS Software. The mean weight of control BF was 4,20g. Dexamethasone-treated group BF mean weight was 0,74g (p<0,05). Average relative weight (RW) of control BF was 0,26%, while in treated group, average RW was 0,06%. In control BF, depletion score mode was 1 and average was 1,38. On the other hand, treated poultry BF presented mode 3 and average 2,65 (P<0,05). Thymus average weight in control group was 17,18g and RW around 1,08%. In treated group, the average was 6,3g (P<0,05) and RW 0,57%. Average depletion score in control poultry thymus was 1,63, with mode 2. In treated animals, average was 3,56 and the mode was 3. Assessment of jejunum measures showed no statistical difference in crypt depth, wall length, core size and microvilli (p>0,05). Control poultry intestines showed, in average, 1366,4µm larger length, and 58,4µm higher mean width villi than poultry submitted to treatment (p<0,05). Treated poultry obtained 15,3% of weight gain in one week after finished the treatment, while control poultry presented 26,7% of weight gain in the same period. Between thymus weight and BF weight we obtained 93,1% correlation and regression coefficient (r2) of 86,7%. Likewise, between thymus weight and poultry weight the r2 was 86,4%. Among BF weight and poultry weight, we observed r2 of 71,8%. On the other hand, the parameters evaluated in the intestines sh owed no significant correlation. Length of villi and thymus weight presented correlation close to 50% and r2 of 22.5%. In this study, it was possible to evaluate the immunosuppressive effects of dexamethasone in thymus, BF and jejunum structures. There was reduction in weight gain in poultry treated with dexamethasone. It was possible to correlate lymphoid depletion and final weight of poultry. Correlation between villi length and thymus weight was also demonstrated.