BBI blocks LPS-mediated inhibitory effect on tight junction protein of intestinal epithelial cells / 中国感染控制杂志

Objective To evaluate the blocking effect and mechanism of Soybean-derived Bowman-Birk inhibitor (BBI)on LPS-mediated downregulation for tight junction protein(HT-29 cells)in intestinal epithelial cells(IECs). Methods The toxic effect of LPS and BBI on HT-29 cells was detected by CCK8 Kit.HT-29 cells were pretreated by BBI for 6 hours prior to LPS stimulation, the expression of tight junction protein(ZO-1 and Occludin), TLR4, and MyDD8 was detected by the quantitative real-time polymerase chain reaction(PCR)and Western Blot;activation of NF-κB was measured by Western Blot.Results LPS(1 000ng/mL)and BBI(1 000μg/mL)showed no cytotoxicity on HT-29 cells.LPS could significantly upregulate the expression of TLR4 in HT-29 cells, the up-regulation had time-dose effect, and could significantly downregulate the expression of tight junction protein, the down-regulation effect was directly proportional to the concentration of LPS, could activate NF-κB, and had dose effect, effect of LPS on HT-29 cells could be significantly inhibited by BBI.Conclusion By inhibiting the expression of TLR4 and activation of NF-κB in IECs induced by LPS, BBI can significantly block the LPS-mediated inhibitory effect on tight junction protein in intestinal epithelial cells.

BBI inhibits LPS-induced expression of inflammatory cytokines in intesti-nal epithelial cells / 中国感染控制杂志

Objective To investigate the inhibitory effect and mechanism of soybean-derived Bowman-Birk inhibi-tor (BBI)on LPS-induced expression of inflammatory cytokines in intestinal epithelial cells.Methods Cytotoxicity effect of LPS and BBI on intestinal epithelial cells was analyzed by MTT assay.Intestinal epithelial cells were pre-treated with BBI,followed by LPS stimulation,expression of inflammatory cytokines(TNF-α,IL-1β,IL-8,and MCP-1)was detected by quantitative real-time polymerase chain reaction;the activation of NF-κB was measured by pNF-κB-luc system and Western Blot.Results The maximum concentration of LPS (10000 ng/mL)and BBI (1000 μg/mL)had no cytotoxicity effect on intestinal epithelial cells.LPS could potently up-regulate the expression of inflammatory cytokines(TNF-α,IL-1β,IL-8,and MCP-1 ),the up-regulation was positively correlated to the concentration of LPS;LPS-induced expression of inflammatory cytokines in intestinal epithelial cells could achieve the highest level,then decreased over time.The up-regulation of LPS on inflammatory cytokines in intestinal epi-thelial cells had dose-time effect;when intestinal epithelial cells were pretreated by BBI for 6 hours,the inhibitory effect of BBI on LPS-induced expression of inflammatory cytokines in intestinal epithelial cells was most obvious, and had dose-time effect.Conclusion BBI can potently inhibit LPS-induced expression of inflammatory cytokines through inhibiting NF-κB in intestinal epithelial cells.

BBI inhibits LPS-induced expression of inflammatory cytokines in intesti-nal epithelial cells / 中国感染控制杂志

Objective To investigate the inhibitory effect and mechanism of soybean-derived Bowman-Birk inhibi-tor (BBI)on LPS-induced expression of inflammatory cytokines in intestinal epithelial cells.Methods Cytotoxicity effect of LPS and BBI on intestinal epithelial cells was analyzed by MTT assay.Intestinal epithelial cells were pre-treated with BBI,followed by LPS stimulation,expression of inflammatory cytokines(TNF-α,IL-1β,IL-8,and MCP-1)was detected by quantitative real-time polymerase chain reaction;the activation of NF-κB was measured by pNF-κB-luc system and Western Blot.Results The maximum concentration of LPS (10000 ng/mL)and BBI (1000 μg/mL)had no cytotoxicity effect on intestinal epithelial cells.LPS could potently up-regulate the expression of inflammatory cytokines(TNF-α,IL-1β,IL-8,and MCP-1 ),the up-regulation was positively correlated to the concentration of LPS;LPS-induced expression of inflammatory cytokines in intestinal epithelial cells could achieve the highest level,then decreased over time.The up-regulation of LPS on inflammatory cytokines in intestinal epi-thelial cells had dose-time effect;when intestinal epithelial cells were pretreated by BBI for 6 hours,the inhibitory effect of BBI on LPS-induced expression of inflammatory cytokines in intestinal epithelial cells was most obvious, and had dose-time effect.Conclusion BBI can potently inhibit LPS-induced expression of inflammatory cytokines through inhibiting NF-κB in intestinal epithelial cells.

Action of plant proteinase inhibitors on enzymes of physiopathological importance

Obtained from leguminous seeds, various plant proteins inhibit animal proteinases, including human, and can be considered for the development of compounds with biological activity. Inhibitors from the Bowman-Birk and plant Kunitz-type family have been characterized by proteinase specificity, primary structure and reactive site. Our group mostly studies the genus Bauhinia, mainly the species bauhinioides, rufa, ungulata and variegata. In some species, more than one inhibitor was characterized, exhibiting different properties. Although proteins from this group share high structural similarity, they present differences in proteinase inhibition, explored in studies using diverse biological models.

Obtidas de sementes leguminosas, várias proteínas inibem proteinases de origem animal, incluindo humanas, e podem ser consideradas para o desenvolvimento de compostos com atividade biológica. Inibidores da família Bowman-Birk e da família Kunitz vegetal tem sido caracterizados em relação a especificidade para proteinase, estrutura primária e sitio reativo. O nosso grupo majoritariamente vem estudando o gênero Bauhinia, principalmente as espécies bauhinioides, rufa, ungulatae variegata. Em algumas espécies, mais de um inibidor com propriedades diferentes foi caracterizado. Embora tais proteínas apresentem alta similaridade estrutural, diferem quanto à inibição de proteinases, e foram exploradas em estudos utilizando diversos modelos biológicos.

BTCI enhances guanylin-induced natriuresis and promotes renal glomerular and tubular effects

Guanylin and uroguanylin are small cysteine-rich peptides involved in the regulation of fluid and electrolyte homeostasis through binding and activation of guanylyl cyclases signaling molecules expressed in intestine and kidney. Guanylin is less potent than uroguanylin as a natriuretic agent and is degraded in vitro by chymotrypsin due to unique structural features in the bioactive moiety of the peptide. Thus, the aim of this study was to verify whether or not guanylin is degraded by chymotrypsin-like proteases present in the kidney brush-border membranes. The isolated perfused rat kidney assay was used in this regard. Guanylin (0.2 µM) induced no changes in kidney function. However, when pretreated by the black-eyed pea trypsin and chymotrypsin inhibitor (BTCI - 1.0 µM; guanylin - 0.2 µM) it promoted increases in urine flow (deltaUF of 0.25 ± 0.09 mL.g-1/min, P < 0.05) and Na+ excretion ( percent delta ENa+ of 18.20 ± 2.17, P < 0.05). BTCI (1.0 µM) also increased percentENa+ (from 22.8 ± 1.30 to 34.4 ± 3.48, P < 0.05, 90 minutes). Furthermore, BTCI (3.0 µM) induced increases in glomerular filtration rate (GFR; from 0.96 ± 0.02 to 1.28 0.02 mL.g-1/min, P < 0.05, 60 minutes). The present paper strongly suggests that chymotrypsin-like proteases play a role in renal metabolism of guanylin and describes for the first time renal effects induced by a member of the Bowman-Birk family of protease inhibitors.

Guanilina e uroguanilina são peptídeos pequenos, ricos em cisteína, envolvidos na regulação da homeostase de fluidos e eletrólitos através da ligação e ativação da guanilato ciclase expressa no intestino e nos rins. A guanilina é menos potente do que a uroguanilina como agente natriurético e é degradada in vitro pela quimiotripsina devido a características estruturais únicas no domínio bioativo do peptídeo. Portanto o objetivo deste trabalho foi verificar se a guanilina é degradada por proteases tipo quimiotripsina, presentes na membrana da borda em escova dos rins. Para esta investigação, foi usado o modelo do rim isolado de rato perfundido. A Guanilina (0,2 µM) não induziu mudanças na função renal. Entretanto, quando pré-tratada com inibidor de tripsina e de quimiotripsina de black-eyed pea (BTCI - 1,0 µM; guanilina - 0,2 µM) promoveu um aumento no fluxo urinário (deltaUF de 0,25 ± 0,09 mL.g-1/min, P < 0,05) e na excreção de Na+ ( por centoDENa+ de 18,20 ± 2,17, P < 0,05). BTCI (1,0 µM) também aumenta por centoENa+ (de 22,8 ± 1,30 a 34,4 ± 3,48, P < 0,0590 minutos). Além disto, BTCI (3,0 µM) induziu um aumento da taxa de filtração glomerular (GFR; de 0,96 ± 0,02 para 1,28 ± 0,02 mL.g-1/min, P < 0,05, 60 minutos). O presente trabalho sugere fortemente que proteases semelhantes à quimiotripsina desempenham um papel no metabolismo renal de guanilinas e descreve, pela primeira vez, os efeitos renais induzidos por um membro da família de inibidores de proteases do tipo Bowman-Birk.

Studies on simultaneous inhibition of trypsin and chymotrypsin by horsegram Bowman-Birk inhibitor.

Bowman-Birk inhibitors (BBI) isolated from plant seeds are small proteins active against trypsin and/or chymotrypsin. These inhibitors have been extensively studied in terms of their structure, interactions, function and evolution. Examination of the known three-dimensional structures of BBIs revealed similarities and subtle differences. The hydrophobic core, deduced from surface accessibility and hydrophobicity plots, corresponding to the two tandem structural domains of the double headed BBI are related by an almost exact two-fold, in contrast to the reactive site loops which depart appreciably from the two-fold symmetry. Also, the orientations of inhibitory loops in soybean and peanut inhibitors were different with respect to the rigid core. Based on the structure of Adzuki bean BBI-trypsin complex, models of trypsin and chymotryspin bound to the monomeric soybean BBI (SBI) were constructed. There were minor short contacts between the two enzymes bound to the inhibitor suggesting near independence of binding. Binding studies revealed that the inhibition of one enzyme in the presence of the other is associated with a minor negative cooperativity. In order to assess the functional significance of the reported oligomeric forms of BBI, binding of proteases to the crystallographic and non-crystallographic dimers as found in the crystal structure of peanut inhibitor were examined. It was found that all the active sites in these oligomers cannot simultaneously participate in inhibition.