Efeitos de probióticos e posbióticos na saúde óssea / Effects of probiotics and postbiotics in bone health

O envelhecimento da população tem sido acompanhado por um aumento significativo nas doenças crônicas, com destaque para a osteoporose. A busca por tratamentos alternativos tem levado ao estudo dos probióticos para prevenção e tratamento da perda óssea pós-menopáusica, com resultados encorajadores. Embora os benefícios dos probióticos sejam numerosos, eles são bactérias vivas e a administração de organismos vivos não é isenta de riscos. Os posbióticos são probióticos inativados ou seus produtos, e poucos são os estudos que avaliam seus efeitos ósseos. Nós revisamos a literatura sobre probióticos e posbióticos na saúde óssea e avaliamos os efeitos de Limosilactobacillus reuteri 6475 viável e inativado por calor em camundongos ovariectomizados. Mecanismos de ação semelhantes, como modulação da expressão de citocinas e ativação de sistemas de sinalização celular, são observados em probióticos e posbióticos, e os últimos têm vantagens como maior estabilidade e facilidade de incorporação em alimentos, embora seus efeitos a longo prazo, estabilidade e modo de ação ainda precisem ser estudados. Para que estas terapias sejam validadas clinicamente, é fundamental padronizar metodologias, aumentar o tamanho das amostras, realizar estudos randomizados e cegos, e definir detalhes como cepa, dose e duração do tratamento. Em um estudo in vivo, avaliamos os efeitos de L. reuteri (ATCC PTA 6475), e sua forma inativada (heat-killed) na perda óssea induzida por ovariectomia (ovx). Camundongos adultos, fêmeas, foram divididos aleatoriamente em quatro grupos: controle (sham); Ovx; Ovx + posbiótico; Ovx + probiótico. L. reuteri foi administrado aos grupos (109 UFC/dia) por gavagem. O tratamento se iniciou uma semana após a ovx e teve duração de 28 dias. Na análise por microscopia eletrônica de varredura, o probiótico manteve sua estrutura intacta, e no posbiótico foram observados alguns rompimentos na superfície celular. Foi avaliada a microarquitetura de fêmur, utilizando microtomografia computadorizada. Análise de expressão gênica em íleo foi feita para avaliar junções intercelulares intestinais e citocinas pró-inflamatórias, por meio dos marcadores Ocludina, Tnf-α e Il6. Os dados foram submetidos ao teste estatístico mais conveniente (α = 0,05). Os grupos Ovx apresentaram menor porcentagem de volume ósseo (BV/TV), menor número de trabéculas ósseas e maior porosidade total, em comparação ao grupo controle, porém os grupos que receberam L. reuteri apresentaram maior BV/TV quando comparados ao grupo Ovx. O tratamento com L. reuteri em suas duas formas levou à maior espessura trabecular, quando comparados ao controle e ao grupo Ovx. Todos apresentaram semelhança na expressão gênica da Ocludina, Tnf-α e Il-6 em intestino. Ambas as formas, viável e inativada por calor, preveniram a perda óssea induzida por depleção de estrógeno (AU)

The aging of the population has been accompanied by a significant increase in chronic diseases, with osteoporosis standing out. The search for alternative treatments has led to the study of probiotics for the prevention and treatment of postmenopausal bone loss, with encouraging results. Although the benefits of probiotics are numerous, they are live bacteria, and the administration of live organisms is not risk-free. Postbiotics are inactivated probiotics or their products, and few studies have evaluated their bone effects. We reviewed the literature on probiotics and postbiotics in bone health and assessed the effects of both viable and heat-killed Limosilactobacillus reuteri 6475 in ovariectomized mice. Similar mechanisms of action, such as the modulation of cytokine expression and activation of cellular signaling pathways, are observed in probiotics and postbiotics, and the latter have advantages such as greater stability and ease of incorporation into food, although their long-term effects, stability, and mode of action still need to be studied. To clinically validate these therapies, it is crucial to standardize methodologies, increase sample sizes, conduct randomized and blinded studies, and define details such as strain, dosage, and treatment duration. In an in vivo study, we evaluated the effects of L. reuteri (ATCC PTA 6475) and its heat-killed form on ovariectomy (ovx)-induced bone loss. Adult female mice were randomly divided into four groups: control (sham); OVX; OVX + postbiotic; OVX + probiotic. L. reuteri was administered to the groups (109 CFU/day) by gavage. Treatment began one week after ovx and lasted for 28 days. Scanning electron microscopy analysis showed that the probiotic maintained its intact structure, while some cell surface disruptions were observed in the postbiotic. Femur microarchitecture was evaluated using computerized microtomography. Gene expression analysis in the ileum was performed to assess intestinal intercellular junctions and pro-inflammatory cytokines, using markers Ocludin, Tnf-α, and Il-6. The data were subjected to the most appropriate statistical test (α = 0.05). The Ovx groups showed a lower percentage of bone volume (BV/TV), a lower number of trabecular bones, and greater total porosity compared to the control group. However, the groups that received L. reuteri showed higher BV/TV compared to the Ovx group. Treatment with both forms of L. reuteri led to greater trabecular thickness compared to the control and Ovx groups. All groups exhibited similarity in the gene expression of Ocludin, Tnf-α, and Il-6 in the intestine. Both viable and heatkilled forms prevented estrogen depletion-induced bone loss (AU)

Heat-Killed Saccharomyces cerevisiae, A Dectin-1 Agonist, Selectively Induces IgG4 Production by Human B Cells

Dectin-1 is a major receptor that recognizes fungal cell wall β-glucan. We previously reported that heat-killed Saccharomyces cerevisiae (HKSC), a Dectin-1 agonist, selectively induces IgG1 class switching in mouse B cells. Dectin-1 is also expressed on human B cells; however, Dectin-1 function in human B cells remains unknown. This study aimed to investigate the direct effect of in vitro stimulation using HKSC on Ig class switching in human B cells. HKSC selectively induced the expression of germline γ4 transcripts (GLTγ4) by human B cell line 2E2, and HKSC significantly augmented GLTγ4 promoter activity. Moreover, HKSC selectively enhanced GLTγ4 expression and IgG4 production by anti-CD40-activated human tonsillar resting B cells. Thus, these results suggest that Dectin-1 maybe involved in selective IgG4 class switching by human B cells.

A Study on the Prevention of Salmonella Infection by Using the Aggregation Characteristics of Lactic Acid Bacteria

Salmonella is one of the major pathogenic bacteria that cause food poisoning. This study investigated whether heat-killed as well as live Lactobacillus protects host animal against Salmonella infection. Live and heat-killed Lactobacillusacidophilus was administered orally to Sprague-Dawley rats for 2 weeks before the rats were inoculated with Salmonella. Rise in body temperature was moderate in the group that was treated with heat-killed bacteria as compared to the Salmonella control group. The mean amount of feed intake and water consumption of each rat in the heat-killed bacteria group were nearly normal. The number of fecal Salmonellae was comparable between the live and the heat-killed L. acidophilus groups. This finding shows that L. acidophilus facilitates the excretion of Salmonella. Moreover, the levels of pro inflammatory cytokines, including tumor necrosis factor (TNF)-alpha and interleukin (IL)-1 beta, in the heat-killed L. acidophilus group were significantly lower when compared to the levels in the Salmonella control group. These results indicate that nonviable lactic acid bacteria also could play an important role in preventing infections by enteric pathogens such as Salmonella.

Heat-killed Staphylococcus aureus induces a common early response in human monocytes in the presence of high concentration glucose / 中华微生物学和免疫学杂志

Objective To investigate the effects of heat-killed Staphylococcus aureus (HKSA) on the apoptosis and expression of iNOS and IL-1β in THP-1 monocytes in the presence of high concentration of glucose.Methods THP-1 cells were cultured in medium containing 25.0 mmol/L(HG) or 5.5 mmol/L (LG,control) D-glucose for 12 h-8 d.The THP-1 cells cultured for 6 d were extracted on the 0-48 h with or without HKSA,then apoptosis and expression of iNOS and IL-1β were examined.Apoptosis was analyzed by flow cytometry and expressions of IL-1β and iNOS were quantitated by real-time PCR.Results The expression of iNOS and IL-1β in THP-1 monocytes was increased significantly in the presence of high concentration of glucose for 12-48 h(P＜0.05),reaching the highest level at 24 h and returned to baseline after 4 d.The expression was significantly lower than that of control after 4-6 d.Apoptosis rate was also increased significantly after 48 h to 4 days.HKSA infection enhanced apoptosis,but inhibited the expression of iNOS and IL-1 β in the presence of high concentration of glucose.The expression of iNOS and IL-1β increased significantly at 6 h(P＜0.01),reaching the highest level at 12 h,but the levels were significantly lower than those in control groups (P＜0.05).Conclusion These data suggest that high concentration of glucose can interfere with the anti-bacterial function of monocytes by reducing their expression of iNOS and IL-1β and enhancing their apoptosis.

Establishment and evaluation of adjuvant-induced arthritis animal model by Mtb in Sprague-Dawley rats / 中国药理学通报

Aim To establish and evaluate the simple and effective animal model of rheumatoid arthritis in SD rats induced by heat-killed mycobacterium tuberculosis H37Ra(Mtb).Methods SD rats were immunized s.c.at the base of the tail with Mtb(1 mg/rat) in mineral oil,and then body weight,blood routine,clinical signs of arthritis were observed regularly.And also hind paw volume in SD rats with AA was tested.Meanwhile,T-lymphocyte subset was determined by flow cytometry in peripheral blood,the level of TNF-?in serum and IL-1 and IL-6 and vascular endothe-lial growth factor(VEGF) in joint tissue were tested by ELISA.The ankle pathological change and radiographic evidence of the hind paws of SD rats were observed to evaluate the AA model effects and availability in SD rats.Results When compared with normal control rats,the total number of white blood cells,platelets and monocytes in peripheral blood and ratio of CD4/CD8 was markedly raised after immunization with Mtb.But body weight of model rats was significantly low from day 14 to 28 after injection of Mtb.The inflammatory arthritic lesions such as edema and erythema in the paws appeared after 9～10 d.The peak of inflammation was 14～16 d.The level of TNF-?in serum and IL-1,IL-6 and VEGF in joint tissue was significantly higher in SD rats with Mtb than that in normal control rats at d 28.The histopathological examination revealed cellular infiltration,synovial and cartilage hyperplasia in ankle joints of SD rats.Conclusions The model induced by Mtb in SD rats is more similar in clinical characterization of rheumatoid arthritis in human being.It is a more efficient and simpler manipulative procedure for screening of new anti-arthritis drugs and experimental studying of anti-rheumatoid arthritis.