Progress in the science of probiotics: from cellular microbiology and applied immunology to clinical nutrition

Identification, Biochemical Characterization, and Safety Attributes of Locally Isolated Lactobacillus fermentum from Bubalus bubalis (buffalo) Milk as a Probiotic

The demand of functional foods is on the rise, and researchers are trying to develop nutritious dairy products by using well-characterized strains of bacteria. In this study, we identified locally isolated strains of Lactobacillus fermentum from Bubalus bubalis (Nilli Ravi buffalo) milk and evaluated their potential as probiotics in food products like fermented milk. Fifteen Lactobacillus strains were initially isolated, and only four strains (NMCC-2, NMCC-14, NMCC-17, and NMCC-27) were examined for morphological and biochemical characterizations due to their ability of gas production in Durham tubes. Moreover, these strains were selected for further probiotic characterizations due to their extreme morphological resemblance with lactic acid bacteria for their antimicrobial activity, enzymatic potential, autoaggregation capability, hydrophobicity, and acid and bile tolerance. All selected isolates showed significant probiotic potential. However, NMCC-14 and NMCC-17 strains showed maximum probiotic potential. The isolates (NMCC-2, NMCC-14, NMCC-17, and NMCC-27) were identified as Lactobacillus fermentum utilizing 16S rRNA gene sequencing. The in vivo safety study of NMCC-14 (dose: 1010 CFU/day/mice; 21 days, orally) showed no histological dysfunctions in a mouse model. Pathogenic bacterial enzymes reduced the beneficial bacterial load in the host gastrointestinal tract. These results suggest that the NMCC-14 strain is safe and can be potentially used as a probiotic. Moreover, fermented milk was prepared by using the NMCC-14 strain. The results revealed that NMCC-14 strain-based fermented milk had significantly (p < 0.05) higher protein content (4.4 ± 0.06), water-holding capacity (WHC), and dynamic viscosity as compared to non-fermented milk. The results suggest that L. fermentum NMCC-14 is safe and nontoxic; hence, it can be a beneficial supplement to be used for the development of dairy products to be subjected to further clinical testing.

Immunomodulation of Antimicrobial Peptides Expression in the Gastrointestinal Tract by Probiotics in Response to Stimulation by Salmonella minnesota Lipopolysaccharides

The aim was to determine whether probiotics-feeding can affect the expression and localization of avian beta defensins (AvBDs) and proinflammatory cytokines in response to Salmonella minnesota lipopolysaccharide (LPS) in the gastrointestinal tract. One-day-old male Chunky broiler chicks were fed with or without 0.4% probiotics for 7 days (P-group and non-P-group, respectively). Then, they were orally challenged with no LPS (0-LPS), 1 µg LPS (1-LPS), or 100 µg LPS (100-LPS) (n = 5, each), in experiment 1, and with no LPS and 1 µg LPS (n = 6, each) in experiment 2. Five hours after LPS challenge, the proventriculi and ceca were collected. A total of seven and eight AvBDs were identified in proventriculus and cecum, respectively. The density of ir-AvBD12 in the surface epithelium of proventriculus increased in the P-group in response to 1-LPS and 100-LPS stimulation. In experiment 1, the expression of two AvBDs in the proventriculus and six AvBDs in the cecum of 1-LPS chicks was higher in P-group than in the non-P-group. Results of experiment 2 showed similar tendency to experiment 1. These results suggest that probiotics-feeding may enhance the immunodefense system mediated by AvBDs but not by cytokine, against infection by Gram-negative bacteria.

Effects of the Gut microbiota on Amygdalin and its use as an anti-cancer therapy: Substantial review on the key components involved in altering dose efficacy and toxicity

Conventional and Alternative Medicine (CAM) is popularly used due to side-effects and failure of approved methods, for diseases like Epilepsy and Cancer. Amygdalin, a cyanogenic diglycoside is commonly administered for cancer with other CAM therapies like vitamins and seeds of fruits like apricots and bitter almonds, due to its ability to hydrolyse to hydrogen cyanide (HCN), benzaldehyde and glucose. Over the years, several cases of cyanide toxicity on ingestion have been documented. In-vitro and in-vivo studies using various doses and modes of administration, like IV administration studies that showed no HCN formation, point to the role played by the gut microbiota for the commonly seen poisoning on consumption. The anaerobic Bacteriodetes phylum found in the gut has a high β-glucosidase activity needed for amygdalin hydrolysis to HCN. However, there are certain conditions under which these HCN levels rise to cause toxicity. Case studies have shown toxicity on ingestion of variable doses of amygdalin and no HCN side-effects on consumption of high doses. This review shows how factors like probiotic and prebiotic consumption, other CAM therapies, obesity, diet, age and the like, that alter gut consortium, are responsible for the varying conditions under which toxicity occurs and can be further studied to set-up conditions for safe oral doses. It also indicates ways to delay or quickly treat cyanide toxicity due to oral administration and, reviews conflicts on amygdalin's anti-cancer abilities, dose levels, mode of administration and pharmacokinetics that have hindered its official acceptance at a therapeutic level.

Ecoimmunology and microbial ecology: Contributions to avian behavior, physiology, and life history

Bacteria have had a fundamental impact on vertebrate evolution not only by affecting the evolution of the immune system, but also generating complex interactions with behavior and physiology. Advances in molecular techniques have started to reveal the intricate ways in which bacteria and vertebrates have coevolved. Here, we focus on birds as an example system for understanding the fundamental impact bacteria have had on the evolution of avian immune defenses, behavior, physiology, reproduction and life histories. The avian egg has multiple characteristics that have evolved to enable effective defense against pathogenic attack. Microbial risk of pathogenic infection is hypothesized to vary with life stage, with early life risk being maximal at either hatching or fledging. For adult birds, microbial infection risk is also proposed to vary with habitat and life stage, with molt inducing a period of increased vulnerability. Bacteria not only play an important role in shaping the immune system as well as trade-offs with other physiological systems, but also for determining digestive efficiency and nutrient uptake. The relevance of avian microbiomes for avian ecology, physiology and behavior is highly topical and will likely impact on our understanding of avian welfare, conservation, captive breeding as well as for our understanding of the nature of host-microbe coevolution.

Effects of Probiotics on the Expression of Cathelicidins in Response to Stimulation by Salmonella Minnesota Lipopolysaccharides in the Proventriculus and Cecum of Broiler Chicks

The aim of this study was to determine whether probiotic-feeding affected the expression of cathelicidins (CATHs), a major family of antimicrobial peptides, in response to lipopolysaccharides (LPS) challenge in the proventriculus and cecum of broiler chicks. One-day-old male Chunky broiler chicks were fed with or without 0.4% probiotics for 7 days (P-group and non-P-group, respectively). Then, they were orally challenged with no LPS (0-LPS), 1 µg LPS (1-LPS), or 100 µg LPS (100-LPS) (n=5 in all groups) in Experiment 1, and with no LPS or 1 µg LPS (n=6 in all groups) in Experiment 2. Five hours after LPS challenge, the proventriculi and ceca were collected to analyze CATHs expression. Expression of CATHs was examined at first by reverse transcription-polymerase chain reaction (RT-PCR) using the 0-LPS chicks of non-P-group. The differences in CATHs expression upon probiotics-feeding and LPS were analyzed by real time-PCR. All four CATHs (CATH1, 2, 3 and 4) were expressed in the proventriculus and cecum of chicks. In the proventriculus, the expression of CATHs after LPS challenge did not show significant differences between non-P and P-groups in Experiment 1 and 2. In the cecum, the interactions of the effects of probiotics and LPS on the expression of CATH2 in Experiment 1 and CATH1 and 2 in Experiment 2 were significant, and their expression in 1-LPS chicks was higher in P-group than in non-P-group. However, CATH3 and 4 did not show any significant differences between non-P- and P-groups challenged with LPS. These results suggest that probiotics-feeding may stimulate the immunodefense system mediated by CATH2 and possibly CATH1 against infection by Gram-negative bacteria in the cecum.

Refrigerated Shelf Life of a Coconut Water-Oatmeal Mix and the Viability of Lactobacillus Plantarum Lp 115-400B

Non-dairy probiotic products have the advantage of being lactose-free and can be manufactured to sustain the growth of probiotics. In this study, coconut water and oatmeal were used with the probiotic, Lactobacillus plantarum Lp 115-400B (L. plantarum) as a starter culture. Two separate treatments were carried out probiotic (P) and probiotic and prebiotic (PP) added. In both treatments, oatmeal-coconut water matrix was inoculated with 7 log CFU/g of L. plantarum and fermented at 27 °C for 10 h. For the PP treatment, 1 g of inulin/100 mL of the product was added additionally. The fermented products were then refrigerated (4 °C) and the viability of L. plantarum, pH, total acidity, and apparent viscosity of the matrix were monitored at selected time intervals. The shelf life to reach was defined by maintenance of L. plantarum count of 7 log CFU/g product. Refrigerated shelf life was determined to be seven-weeks for the P treatment and five-weeks for PP treatment. A significant reduction of pH was observed at the end of the considered shelf life; conversely, the apparent viscosity of the product did not change significantly.

Effects of probiotic supplementation on markers of acute pancreatitis in rats

BACKGROUND

Intestinal barrier disruption followed by bacterial translocation seems to play a role in secondary pancreatic infection in acute pancreatitis. The use of probiotics as a possible adjuvant strategy in the treatment of acute pancreatitis needs to be investigated.

OBJECTIVE

The aim of this study was to determine the effects of dietary supplementation with a prophylactically administered multispecies probiotic mixture on the markers of acute pancreatitis and on the occurrence of bacterial translocation.

METHODS

Thirty adult male Wistar rats were randomly assigned to 1 of 3 groups of 10 rats each: (1) the PS group, in which the rats were given probiotic supplementation prior to induction of acute pancreatitis; (2) the WP group, in which the rats underwent surgery to induce acute pancreatitis without prior probiotic supplementation; and (3) the control group, in which the rats underwent sham surgery. For 14 days before surgery, animals in the PS group received a single daily dose containing ~1.2 × 10(9) colony-forming units of a probiotic mixture administered intragastrically as a bolus. On day 15, the animals underwent surgery to induce acute pancreatitis (PS and WP groups) or simulated surgery (control group). Blood samples were collected to determine leukocyte count, amylase and lipase activities, and glucose and calcium concentrations immediately before and 6 and 12 hours after the beginning of the procedure. Samples of pancreas, spleen, liver, and mesenteric lymph nodes were harvested for microbiologic and histopathologic analysis after the last blood sample collection. The pathologist examining the histopathology was blinded to treatment assignment.

RESULTS

The mean leukocyte count was significantly increased in the PS group compared with the WP group (P = 0.018), whereas the serum amylase and lipase activities and the serum glucose and calcium concentrations were not significantly different between the 2 groups. Comparing the risk for tissue colonization in the PS group with that of the WP group, the odds ratio (OR) for pancreas was 2.91 (95% CI, 0.13-67.10); liver, 66.55 (95% CI, 1.89-2282.66); spleen, 88.58 (95% CI, 3.04-2583.08); and mesenteric lymph nodes, 1.23 (95% CI, 0.06-25.48). When the risks for histopathologic changes were compared between the 2 groups, the OR for acinar necrosis was 1.73 (95% CI, 0.21-12.17); steatonecrosis, 12.08 (95% CI, 1.26-115.54); hemorrhage, 1.38 (95% CI, 0.21-9.53); and leukocyte infiltration, 5.91 (95% CI, 0.64-54.89).

CONCLUSION

Probiotic supplementation before the induction of acute pancreatitis was associated with a greater degree of bacterial translocation and pancreatic tissue damage in this animal model.

Necrotizing enterocolitis: have we made any progress in reducing the risk?

Necrotizing enterocolitis (NEC) is a disease affecting premature infants with potentially devastating complications in the neonatal intensive care unit (NICU). Inadequate knowledge regarding the underlying pathophysiology of this disease has contributed to the minimal progress made in decreasing the incidence and severity of NEC. Because of an improved survival rate of the most immature infants, the number of diagnosed cases of NEC is anticipated to increase. Unfortunately, decades of research have failed to reduce the risk or improve the prognosis of NEC, magnifying the need for risk-reduction strategies for decreasing significant NEC-related morbidity and mortality. Advancements in our understanding of this disease process have facilitated the development of several strategies that have been investigated in the risk reduction of NEC. This article discusses the pathophysiology and causes of NEC and presents strategies investigated regarding risk reduction of this devastating disease.

Enterocolite necrosante em recém-nascidos de muito baixo peso em uma unidade neonatal de alto risco do Nordeste do Brasil (2003-2007)

OBJETIVOS: avaliar a incidência de enterocolite necrosante (ECN), no período de 2003 a 2007, em crianças nascidas com muito baixo peso e descrever as características da assistência prestada a esses recém-nascidos. MÉTODOS: estudo longitudinal retrospectivo conduzido em uma unidade neonatal de alto risco com uma amostra de 1028 recém-nascidos de muito baixo peso, excluindo-se os menores de 750 g. A frequência de ECN foi observada do primeiro até o trigésimo dia de vida, ou até a sua ocorrência ou óbito, considerando-se o que ocorresse primeiro em um período de cinco anos. ECN foi definida pelo critério de Bell (estágio ≥2). Utilizou-se o qui-quadrado de tendência para avaliar o comportamento das variáveis categóricas ao longo dos cinco anos. RESULTADOS: ECN ocorreu em 55 dos 1028 recém-nascidos (5,3%). Observou-se maior incidência de ECN no ano de 2005 (19/204) com uma significante redução no ano de 2007 (8/195), entretanto, essa variação não caracterizou uma tendência (p=0,45). Observou-se aumento significante do uso de antibióticos,de nutrição parenteral, de corticóide antenatal e do consumo de leite materno e uma redução na média da idade gestacional de 2,4 semanas entre 2003 e 2007. CONCLUSÕES: a incidência de ECN foi variável, sem tendência de ascensão ou queda. Observou-se um incremento na cobertura de corticoide antenatal, aumento na utilização de leite materno e redução no consumo de fórmula. Mais estudos são necessários para melhor avaliar a contribuição dessas medidas na não progressão da incidência da ECN, apesar de tratar-se de uma população com risco elevado para essa doença.

Colon-specific delivery of a probiotic-derived soluble protein ameliorates intestinal inflammation in mice through an EGFR-dependent mechanism

Probiotic bacteria can potentially have beneficial effects on the clinical course of several intestinal disorders, but our understanding of probiotic action is limited. We have identified a probiotic bacteria-derived soluble protein, p40, from Lactobacillus rhamnosus GG (LGG), which prevents cytokine-induced apoptosis in intestinal epithelial cells. In the current study, we analyzed the mechanisms by which p40 regulates cellular responses in intestinal epithelial cells and p40's effects on experimental colitis using mouse models. We show that the recombinant p40 protein activated EGFR, leading to Akt activation. Activation of EGFR by p40 was required for inhibition of cytokine-induced apoptosis in intestinal epithelial cells in vitro and ex vivo. Furthermore, we developed a pectin/zein hydrogel bead system to specifically deliver p40 to the mouse colon, which activated EGFR in colon epithelial cells. Administration of p40-containing beads reduced intestinal epithelial apoptosis and disruption of barrier function in the colon epithelium in an EGFR-dependent manner, thereby preventing and treating DSS-induced intestinal injury and acute colitis. Furthermore, p40 activation of EGFR was required for ameliorating colon epithelial cell apoptosis and chronic inflammation in oxazolone-induced colitis. These data define what we believe to be a previously unrecognized mechanism of probiotic-derived soluble proteins in protecting the intestine from injury and inflammation.

Efficacy of Bifidobacterium breve and Lactobacillus casei oral supplementation on necrotizing enterocolitis in very-low-birth-weight preterm infants: a double-blind, randomized, controlled trial

BACKGROUND

Probiotics are used for the prevention of necrotizing enterocolitis (NEC) because of their positive effects on intestinal motor function, modulation of inflammatory response, and mucosal barrier function.

OBJECTIVE

The objective was to assess whether the combined use of Lactobacillus casei and Bifidobacterium breve may prevent the occurrence of NEC stage ≥ 2 by the criteria of Bell in very-low-birth-weight preterm infants.

DESIGN

A double-blind, randomized, controlled clinical trial was conducted in 231 preterm infants weighing from 750 to 1499 g at birth. The intervention group was composed of 119 infants who received human milk with probiotic supplementation (B. breve and L. casei) and a control group of 112 infants who received human milk containing no probiotics. The primary outcome was the occurrence of NEC stage ≥ 2 as defined by Bell's modified criteria.

RESULTS

Four confirmed cases of NEC stage ≥ 2 by Bell's criteria occurred only in the control group.

CONCLUSIONS

Oral supplementation of B. breve and L. casei reduced the occurrence of NEC (Bell's stage ≥ 2). It was considered that an improvement in intestinal motility might have contributed to this result. This trial was registered at www.isrctin.org as number 67165178 (International Standard Randomized Controlled Trial).

A randomized controlled trial of Lactobacillus GG in children with functional abdominal pain

OBJECTIVE

Our aim was to determine whether Lactobacillus rhamnosus GG (LGG) relieves symptoms in children with recurrent abdominal pain.

PATIENTS AND METHODS

A total of 141 children with irritable bowel syndrome (IBS) or functional pain were enrolled in 9 primary care sites and a referral center. Children entered a randomized, double-blind, placebo-controlled trial and received LGG or placebo for 8 weeks and entered follow-up for 8 weeks. The primary outcome was overall pain at the end of the intervention period. At entry and at the end of the trial, children underwent a double-sugar intestinal permeability test.

RESULTS

Compared with baseline, LGG, but not placebo, caused a significant reduction of both frequency (P < .01) and severity (P < .01) of abdominal pain. These differences still were significant at the end of follow-up (P < .02 and P < .001, respectively). At week 12, treatment success was achieved in 48 children in the LGG group compared with 37 children in the placebo group (P < .03); this difference still was present at the end of follow-up (P < .03). At entry, 59% of the children had abnormal results from the intestinal permeability test; LGG, but not placebo, determined a significant decrease in the number of patients with abnormal results from the intestinal permeability testing (P < .03). These effects mainly were in children with IBS.

CONCLUSIONS

LGG significantly reduces the frequency and severity of abdominal pain in children with IBS; this effect is sustained and may be secondary to improvement of the gut barrier.

Probiotics: progress toward novel therapies for intestinal diseases

PURPOSE OF REVIEW

As the beneficial effects of probiotics on health and disease prevention and treatment have been well recognized, the demand for probiotics in clinical applications and as functional foods has significantly increased in spite of limited understanding of the mechanisms. This review focuses on the most recent advances in probiotic research from genetics to biological consequences regulated by probiotics and probiotic-derived factors.

RECENT FINDINGS

Genomic and proteomic studies reveal genes and proteins involved in probiotic adaptation in the host and while exerting their beneficial effects. Recent studies in cell culture and in animal models emphasize probiotic functions in intestinal development, nutrition, host microbial balance, cytoprotection, barrier function, innate immunity, and inflammation. Most importantly, several novel and known probiotic-derived factors have been characterized, which regulate host-signaling pathways and mediate probiotic function.

SUMMARY

Progress in understanding probiotic mechanisms of action will increase our basic understanding of biological crosstalk and provide the rationale to support the development of new hypothesis-driven studies to define the clinical efficacy of probiotics for intestinal disorders.

Prospects for the development of probiotics and prebiotics for oral applications

There has been a paradigm shift towards an ecological and microbial community-based approach to understanding oral diseases. This has significant implications for approaches to therapy and has raised the possibility of developing novel strategies through manipulation of the resident oral microbiota and modulation of host immune responses. The increased popularity of using probiotic bacteria and/or prebiotic supplements to improve gastrointestinal health has prompted interest in the utility of this approach for oral applications. Evidence now suggests that probiotics may function not only by direct inhibition of, or enhanced competition with, pathogenic micro-organisms, but also by more subtle mechanisms including modulation of the mucosal immune system. Similarly, prebiotics could promote the growth of beneficial micro-organisms that comprise part of the resident microbiota. The evidence for the use of pro or prebiotics for the prevention of caries or periodontal diseases is reviewed, and issues that could arise from their use, as well as questions that still need to be answered, are raised. A complete understanding of the broad ecological changes induced in the mouth by probiotics or prebiotics will be essential to assess their long-term consequences for oral health and disease.

Mechanisms of probiotic action: Implications for therapeutic applications in inflammatory bowel diseases

Probiotics are defined as nonpathogenic living microorganisms, including some commensal bacterial flora, which have beneficial effects on host health and disease prevention and/or treatment. Clinical trials have shown beneficial effects of probiotics on several human diseases, such as inflammatory bowel diseases (IBDs), which are among the most-studied diseases testing probiotics as a potential therapy. However, a significant question regarding clinical use of probiotics is the mechanism underlying the wide range of actions. Studies discussed in this review suggest 3 distinct cellular and molecular mechanisms for probiotic regulation in IBD therapy: 1) Probiotics block pathogenic bacterial effects by producing bactericidal substances and competing with pathogens and toxins for adherence to the intestinal epithelium; 2) Probiotics regulate immune responses by enhancing the innate immunity and modulating pathogen-induced inflammation via toll-like receptor-regulated signaling pathways; and 3) Probiotics regulate intestinal epithelial homeostasis by promoting intestinal epithelial cell survival, enhancing barrier function, and stimulating protective responses. Probiotics modulate host cell signaling pathways, including Akt, mitogen-activated protein kinases, and nuclear factor-kappaB to mediate these intestinal epithelial functions. It is hoped that developing a mechanistic understanding of probiotic action will provide the rationale to support the development of new hypothesis-driven studies to define the clinical efficacy in preventive, adjunctive, or alternative treatments for IBD.

Clinical research on probiotics: the interface between science and regulation

Although there exists some evidence of the safety and efficacy of probiotics for treatment of disease, many of the clinical trials have lacked methodological quality, particularly with regard to protocol design, selection of population, and product characterization. Depending on the regulatory route, data need to be collected carefully to satisfy regulatory requirements in the United States and elsewhere. This article discusses how the regulations for probiotics affect clinical research. It also describes clinical trial design and issues that affect the design of trials for probiotics conducted to improve the scientific evidence for these products.

Yogurt containing probiotic Lactobacillus rhamnosus GR-1 and L. reuteri RC-14 helps resolve moderate diarrhea and increases CD4 count in HIV/AIDS patients

HIV/AIDS is changing the human landscape in sub-Saharan Africa. Relatively few patients receive antiretroviral therapy, and many suffer from debilitating diarrhea that affects their quality of life. Given the track record of probiotics to alleviate diarrhea, conventional yogurt fermented with Lactobacillus delbruekii var bulgaricus and Streptococcus thermophilus was supplemented with probiotic Lactobacillus rhamnosus GR-1 and L. reuteri RC-14. Twenty-four HIV/AIDS adult female patients (18 to 44 y) with clinical signs of moderate diarrhea, CD4 counts over 200, and not receiving antiretrovirals or dietary supplements, consumed either 100 mL supplemented or unsupplemented yogurt per day for 15 days. Hematologic profiles, CD4 cell counts, and quality of life was evaluated at baseline, 15 and 30 days postprobiotic-yogurt feeding. There was no significant alteration in the hematologic parameters of both groups before and after the probiotic-yogurt feeding. The probiotic yogurt group at baseline, 15 and 30 days had a mean WBC count of 5.8+/-0.76 x 10(9)/L, 6.0+/-1.02 x 10(9)/L, and 5.4+/-0.14 x 10(9)/L, respectively. However, the mean CD4 cell count remained the same or increased at 15 and 30 days in 11/12 probiotic-treated subjects compared to 3/12 in the control. Diarrhea, flatulence, and nausea resolved in 12/12 probiotic-treated subjects within 2 days, compared to 2/12 receiving yogurt for 15 days. This is the first study to show the benefits of probiotic yogurt on quality of life of women in Nigeria with HIV/AIDS, and suggests that perhaps a simple fermented food can provide some relief in the management of the AIDS epidemic in Africa.