Modulating immune responses with probiotic bacteria

Abstract

It has been known for years that commensal bacteria in our intestines play an important role metabolizing digesta in the lumen and in so doing provide an additional source of nutrients. The composition of commensal bacteria is highly stable and characteristic for an individual over time but does appear to vary considerably between individuals.1 Dietary changes, stress and consumption of antibiotics can disturb the balance of commensal bacteria and a healthy balance can be reestablished with probiotic supplementation. In recent years, lactic acid bacteria (LAB) have been marketed by the dairy industry as an important natural bacterium for the maintenance of gut health. Other Gram-positive bacteria, such as Streptococcus thermophilus and S. faecalis, have been used as probiotics for farm animals.2 Although not officially recognized as probiotic bacteria, S. thermophilus and Staphylococcus carnosus are often used as starter cultures in the production of cheeses and salami and are normally consumed in very large numbers in our diets. These bacteria may also have a biological impact on the consumer. To qualify as a probiotic, bacterial strains must satisfy a number of criteria, including the ability to survive in the gastrointestinal tract.4 Bifidobacterium species and LAB are naturally commensal bacteria in the small and large intestines. These bacteria protect the host against potential pathogens by competitive exclusion and also by the production of antibacterial agents known as bacteriocins. It has only been recently shown that another mechanism whereby probiotic bacteria may provide a health benefit is by modulating immune responses. The immune-stimulating effect of LAB has been investigated using several animal experimental models. Lactobacillus casei strain Shirota (LcS) is a strain of LAB that was selected for its specific biological activity in man and animals. LcS is widely used in the production of probiotic dairy products and also as a food ingredient in Japan and in Europe, because of its proven safety and functional characteristics. To examine a role for probiotic bacteria in the modulation of immune responses, we describe, in the present paper, recent studies that have been carried out to demonstrate that some probiotic bacteria appear to have the ability to affect innate, humoral and cellular arms of the immune system. Effect on innate immunityNatural killer (NK) cells are large granular lymphocytes derived from bone marrow and these cells display non-MHCrestricted cytotoxicity against a variety of tumours. It is well recognized that NK cells act as cytolytic effector cells of the innate immune system. Recent studies have revealed that NK cells, including gamma/delta T cells, also regulate the Summary For many years, probiotic bacteria have been known to confer health benefits to the consumer. One possible mechanism for this may be the ability of probiotic bacteria to modulate immune responses. Oral administration of Lactobacillus casei strain Shirota (LcS) has been found to enhance innate immunity by...

Alternatives to in-feed antibiotics in pigs: Evaluation of probiotics, zinc or organic acids as protective agents for the intestinal mucosa. A comparison of in vitro and in vivo results

“…Indeed, it has already been shown that probiotics may lead to an increased IgA production [59] and stimulation of macrophage and NK activity [15,46]. Moreover, several studies have reported that probiotics are able to regulate both anti-and pro-infammatory cytokine production.…”

Colostro humano: fonte natural de probióticos?

“…Em populações pediátricas, o efeito de agentes probióticos parece ser muito significante contra diarréias virais (rotavírus), sugerindo que um mecanismo imunológico seja responsá-vel pelos efeitos benéficos 33 . Já foi também verificado que a administração oral de Lactobacillus casei Shirota (LcS) aumenta a imunidade inata, estimulando a atividade de células Natural Killer 5 .…”

“…Dentre os benefícios apontados, citam-se o antagonismo aos agentes patogênicos, o efeito de barreira da microbiota e a modulação das funções imunes 2,[4][5][6] .…”

“…Essa função da microbiota intestinal denominase "resistência à colonização" 12 . Essa microbiota funciona como componente importante da barreira defensiva da mucosa intestinal 5 .…”

“…A resposta à microbiota intestinal leva à formação de anticorpos séricos contra numerosas estruturas das bactéri-as presentes no intestino e se estende a outras mucosas e às glândulas exócrinas como as salivares e as mamárias, durante a lactação 2,5 .…”