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Benefits Of Kefir For IBD

What is kefir?

Fermentation of a matrix produces kefir. Milk is the matrix generally used, resulting in a beverage acidic, slightly alcoholic, and with a creamy consistency. It results from milk fermentation by microorganisms that live in symbiosis in kefir grains. Kefir differs from other fermented milk because it is a metabolic result of a diversity of microorganisms. Lactose fermenting and nonfermenting yeast species (Kluyveromyces, Pichia, and Saccharomyces), with a predominance of lactic acid bacteria (Lactobacillus, Lactococcus, Leuconostoc, and Streptococcus), besides acetic acid bacteria make up the grain’s microbiota.

Regular consumption of kefir has been associated to the reduction of severity of inflammatory bowel disease, antihypertensive effect, anticarcinogenic effect, increased insulin sensitivity, improved lipid profile, therapeutic effects on osteoporosis, and neurodegenerative disease. The positive health effects have been related to the antioxidant capacity and modulation of the intestinal microbiota by the kefir drink. Bioactive compounds present in kefir, produced by microorganisms during fermentation and storage of beverage, have been attributed to these benefits; kefiran, exopolysaccharides, bioactive peptides, and organic acids are the bioactive compounds commonly implicated with the therapeutic potential of kefir. There is still a need for study of the bioactive compounds present in the kefir to distinguish them according to their therapeutic potential for each disease.

The possible difference in the functional potential between artisanal and industrial kefir is controversial in the literature. The use of kefir grains results in artisanal kefir, while previously selected starter culture of bacteria and yeast species leads to commercial or industrial kefir. Some studies have reported artisanal kefir with greater therapeutic potential due to its greater microbiological diversity, while other studies have found no significant difference between both. A meta-analysis could be helpful to elucidate the inconsistencies observed between studies. More microbiota characterization from artisanal and industrial kefir is necessary. Kefir grain’s microorganisms can present the ability to
produce bioactive compounds during the fermentation and storage of kefir beverages. Consistently, from 48 strains isolated from Russian kefir grains, ten species of Lactobacillus sp. were recognized with probiotic potential. Some yeast strains, such as Saccharomyces cerevisiae KU200284, present
double importance: a starter culture and a probiotic. In Korean kefir, the acetic acid bacterial strain Acetobacter fabarum DH1801 had viability as a functional starter with food preservative mechanisms and the potential as a probiotic agent. In addition, the species of LAB has a fundamental role in the formation of exopolysaccharide (EPS), which is a significant bioactive compound in kefir. In
this scenario, the Lactobacillus kefiranofaciens is considered the main piece in the formation of kefir grains  since its genes demonstrate a great capacity to produce exopolysaccharides (such as kefiran) which make up the structure of the kefir grain. Similarly, Lactococcus lactis ssp. cremoris was found to be capable of producing conjugated linoleic acid (CLA), a bioactive compound, from milk fat.

Kefir And IBD

Inflammatory bowel disease (IBD) Are a heterogeneous group of chronic, multifactorial, relapsing inflammatory diseases of the gastro-intestinal tract. Common clinical signs observed in IBD patients are chronic diarrhea, vomiting and weight loss associated to histopathological evidence of inflammation in various portions of GI tract. In humans, Crohn’s disease (CD) and ulcerative colitis (UC) are the principal types of IBD. There are several acceptable research models to study IBD some of which were used to help demonstrate the following.

Chemical and pathogen assault modeling for colitis in vitro and in vivo used for assessing the benefits of kefir and its bioactive components and compounds 

Bioactive compounds from kefir exerted an anti- or proinflammatory impact depending on the IBD model’s presence or absence of inflammatory insult. Thus, they exerted an inhibitory effect in inflammatory diseases’ models, while they had an immunostimulatory effect for models without inflammatory insult. The predominantly studied inflammatory disease model was that of acute colitis, both in vitro and in vivo. For colitis, mainly EPS (exopolysaccarides) and extracellular vesicles, but also lactate have been described to have an anti-inflammatory role against a variety of acute inflammatory insults: DSS (dextran sulfate sodium), TNFα, FliC (flagellin), IL-1β, and TNBS (2,4,6-trinitrobenzene sulfonic acid). For chronic colitis, extracellular vesicles presented an anti-inflammatory effect against piroxicam. Kefiran, in turn, had an inhibitory effect on cotton-induced granuloma in rats. The L. kefirgranum, L. kefir, L. kefiranofaciens, and L. paracasei species were responsible for producing these bioactive compounds. Therefore, the Lactobacillus genus seems relevant for making anti-inflammatory compounds in the kefir. Galactose and glucose, and to a lesser extent, mannose, arabinose, and rhamnose, were the significant precursors of the polysaccharide component of the bioactive compounds. Extracellular vesicles from L. kefir granum reduced the gene expression of proinflammatory cytokines by 58, 64, and 67%, respectively, in Caco-2 cells for DSS-induced acute colitis model. Extracellular vesicles also inhibited TNFα-induced colitis. They reduced the expression and secretion of IL-8 by 65 and 96%, respectively, in the Caco2 cell line. Extracellular vesicles were just as effective as budesonide, a glucocorticoid steroid commonly used to treat Crohn’s disease (inflammatory bowel disease). Still, treatment of Caco-2 cells with extracellular vesicles showed a longer intervention time than treatments with EPS or lactate. In addition, the effect observed with preincubation of cells with EPS or lactate indicates the potential of these compounds as preventive agents of intestinal inflammation. In mice, oral administration of extracellular vesicles could mitigate acute and chronic colitis, corroborating the previous findings in vitro. For DSS-induced acute colitis, both high and low dosages of vesicles prevented weight loss in mice by up to 16% and reduced damage to colon tissue by up to 63%. However, only the highest dosage (3 mg/kg bw) reduced colon atrophy by 29.6%. Similarly, only the highest dosage mitigated colon atrophy by 14.3% for chronic colitis aggravated by piroxicam. Nevertheless, both dosages reduced colon histological damage by up to 85%.

In contrast to acute colitis, ingestion of extracellular vesicles was ineffective in preventing weight loss in chronic colitis. Therefore, due to the broader effects obtained  the high dosage seemed more effective for chronic and acute colitis treatment. Vesicles’ administration against TNBS induced acute colitis also effectively prevented the mouse weight loss by up to 12.5%. Moreover, the administration reduced rectal bleeding and diarrheal condition severity by 75 and 91%, respectively.

Damage to colon tissue, in turn, was decreased by up to 85%. Therapy with vesicles from Lactobacillus of kefir was more effective than the prednisolone drug in preventing weight loss, the severity of rectal bleeding, and diarrheal conditions well as in mitigating colon  damage. Prednisolone is an anti-inflammatory steroid used to treat inflammation in colitis and Crohn’s disease; however, it does not prevent recurrence of the disease, in addition to having several side effects. Therefore, treatment with bioactive compounds from kefir would be promising both for effectiveness and reduced side effects. Suspensions of EPS-producer Lactobacillus paracasei inhibited by up to 55% the induction of the proinflammatory promoter in Caco-2 cells for flagellin-induced acute colitis model. Lactobacillus paracasei strain showed more dramatic anti-inflammatory potential than the other tested strains, which indicates that the functional potential of the EPS is strain-dependent. Similarly, lactate  inhibited by 78, 80, and 42% the promoter induction by flagellin, IL-1β, and TNFα, respectively, in Caco-2 cells. Inline, human intestinal epithelial cells express the lactate receptor. Still, lactate solution and supernatant from kefir with corresponding lactate concentration showed similar inhibitory effects on Caco-2 cells, indicating that the kefir matrix does not reduce the impact of this bioactive compound. In vivo, oral administration of kefiran-rich kefir supernatant was responsible for reducing the weight of cotton-induced abdominal granulomas by 44% in rats. Kefir was as effective as dexamethasone in reducing these granulomas. Dexamethasone is a corticosteroid medication used as a primary option in the treatment of granulomas. This evidence reinforces the anti-inflammatory potential of bioactive compounds from kefir. Therefore, in general, bioactive agents inhibited the expression of proinflammatory cytokines and the activation of the CCL20 promoter for in vitro inflammatory models with Caco-2 cells. In in vivo colitis models, bioactive compounds reduced weight loss, atrophy, and colon histological damage. The compounds displayed anti-inflammatory action mechanisms by inhibiting the NF-κB pathway in the Caco2 cells and the colon mucosa due to the expression of the IκBα inhibitor. In addition, bioactive agents promoted the integrity of the intestinal barrier. Additional anti-inflammatory mechanisms proposed for EPS were nitric oxide radical scavenging ability and inhibition of hyaluronidase activity in cell-free in vitro systems. Hydrolysis of the extracellular matrix by hyaluronidase releases compounds, like hyaluronan, throughout inflammatory pathologies. For extracellular vesicles, blocking myeloperoxidase activation in the mouse
plasma has also been reported. Oxidative stress in inflammatory bowel disease activates inflammatory cells, such as neutrophils, whose myeloperoxidase catalyzes the production of reactive oxygen species. In this scenario, extracellular vesicles were as effective as the prednisolone drug in inhibiting myeloperoxidase. Bioactive compounds from kefir play a decisive anti-inflammatory role. However, EPS, including kefiran, can also have the opposite effect, acting as immunostimulants, in cases where there is no inflammatory insult; this role was also corroborated in an in vivo model. Their precursors in milk were glucose and galactose. In a minority way, bioactive peptides have also been reported as immunostimulants. The Lactobacillus genus was relevant to produce these immunostimulants, especially the L. helveticus, L. pentosus, and L. kefiranofaciens species. 

For EPS, although the intervention time has been similar for both a pro- and anti-inflammatory effect assay, the EPS concentration employed was dramatically higher; in vitro, the concentration for immuno-stimulating varied from 50 to 5000 μg/mL, while for inhibition, it reached the maximum of 100 μg/mL. In vivo, 100 mg/kg bw was administered orally for immunostimulating, while to inhibit the immune response, the concentration ranged from 0.03 to 3 mg/kg bw. This fact suggests that the concentration of EPS is a significant factor in determining the role that it will play on the immune system. In line, EPS has been reported to stimulate or inhibit the secretion of TNFα, IL-10, and IL-6 by in vitro murine macrophages, depending on the concentration tested. Thus, it appears that EPS can act by different cell signaling pathways, according to its concentration. In vitro, the immunostimulatory role of EPS and bioactive peptides has been demonstrated in the macrophage’s cell line and primary culture, in addition to human peripheral blood mononuclear cells EPS stimulated proliferation, phagocytosis, phosphatase activity, IL-6 secretion, and NO production by macrophage cells. In the concentration range of 100 to 200 μg/mL, they stimulated the secretion of TNFα, IL-1β, and IL-10. EPSs were as efficient as lipopolysaccharides in promoting cell proliferation, phagocytosis, and cytokine secretion by macrophages. Kefiran at 1000 to 5000μg/mL increased IL-6 secretion, and concentrations from 2000 to 4000μg/mL stimulated cell proliferation of human PBMC culture by up to 200% after 24 hr. Bioactive peptide from L. kefiranofaciens, turn on, improved secretion of TNFα, IL-1β, IL-6, and IL-12 by 1000, 700, 1300, and 3000% by murine peritoneal macrophage culture. However, peptides from different microbial strains showed differences in immuno-stimulatory capacity, suggesting that the functional potential of the peptide is strain-dependent. In addition, bioactive peptide acted via the TLR2 receptor; Toll-like receptor 2 enables macrophages to recognize microbial ligands, thereby promoting inflammation. Consistently, oral administration of kefiran (100mg/kg bw) to healthy mice for up to 7 days enhanced IgA, IL-10, IL-6, and IL-12 in the mucosa of the small intestine, as well as IL-4 and IL-12 in the fluid of the small intestine. In serum, kefiran
increased IL-4, IL-6, IL-10, and IFN. However, broader immunostimulation occurred in the large intestine, increasing IgA, IgG, IL-4, IL-10, IL-6, INF, and TNF content. The most
evident stimulatory activity in the large intestine has been attributed to the kefiran fermentation by intestinal microbiota. Therefore, it appears that bioactivity may vary according to the biochemical transformations that these molecules undergo throughout the digestive process.
Finally, it is essential to highlight that immune stimulation can be interesting for a better prognosis of infectious conditions and stimulating immunoglobulin production after vaccination. Thus, the concentration and environmental context (presence or absence of inflammatory insult) are relevant factors to be considered according to the purpose of administering the bioactive compound. Analysis results corroborated the benefits of kefir bioactive compounds on immune modulation since the findings indicated that treatments had significant immune-modulatory activity compared to control.