Dietary bovine lactoferrin alters mucosal and systemic immune cell responses in neonatal piglets.

Lactoferrin (LF) is a multifunctional immune protein found at high concentrations in human milk. Herein, the effect of dietary bovine LF (bLF) on mucosal and systemic immune development was investigated. Colostrum-deprived piglets were fed formula containing 130 [control (Ctrl)], 367 (LF1), or 1300 (LF3) mg of bLF/(kg body weight · d). To provide passive immunity, sow serum was provided orally during the first 36 h of life. Blood, spleen, mesenteric lymph node (MLN), and ascending colon (Asc) contents were collected on day 7 (n = 10-14/group) and day 14 (n = 10-12/group). Immune cell populations were quantified by flow cytometry and immunoglobulins (Igs) were measured by ELISA. Additionally, immune cells were isolated from spleen and MLNs (n = 7/group) on day 7 and stimulated ex vivo with phytohemagglutinin or lipopolysaccharide (LPS) ± LF for 72 h. Secreted cytokine concentrations were quantified by multiplex assay. Lymphocyte populations [cluster determinant (CD)4, CD8, and natural killer cells] developed normally and were unaffected by dietary bLF. LF3 piglets tended to have 1.4 to 2 times more serum IgG than Ctrl piglets (P = 0.07) or LF1 piglets (P = 0.03), but IgA in Asc contents was unaffected by bLF. Asc IgA was 4 times higher on day 14 than day 7. Spleen cells from LF3 piglets produced 2 times more interleukin (IL)-10 and tumor necrosis factor (TNF)-α ex vivo than those from Ctrl or LF1 piglets. MLN cells from LF1 and LF3 piglets produced 40% more IL-10 and tended to produce 40% more IL-6 (P = 0.05) than those from Ctrl piglets. However, ex vivo bLF did not affect the cytokine response of spleen or MLN cells to LPS. In summary, dietary bLF alters the capacity of MLN and spleen immune cells to respond to stimulation, supporting a role for LF in the initiation of protective immune responses in these immunologically challenged neonates.

Dietary bovine lactoferrin increases intestinal cell proliferation in neonatal piglets.

Lactoferrin is a bioactive milk protein that stimulates cell proliferation in vitro; however, limited in vivo evidence exists to allow lactoferrin to be incorporated into infant formula. Herein, the effect of dietary bovine lactoferrin (bLF) on neonatal intestinal growth and maturation was investigated guided by the hypothesis that bLF would increase cellular proliferation leading to functional differences in neonatal piglets. Colostrum-deprived piglets were fed formula containing 0.4 [control (Ctrl)], 1.0 (LF1), or 3.6 (LF3) g bLF/L for the first 7 or 14 d of life. To provide passive immunity, sow serum was provided orally during the first 36 h of life. Intestinal cell proliferation, histomorphology, mucosal DNA concentration, enzyme activity, gene expression, and fecal bLF content were measured. Intestinal enzyme activity, DNA concentration, and villus length were unaffected by bLF. However, crypt proliferation was 60% greater in LF1- and LF3-fed piglets than in Ctrl piglets, and crypt depth and area were 20% greater in LF3-fed piglets than in Ctrl piglets. Crypt cells from LF3-fed piglets had 3-fold higher ß-catenin mRNA expression than did crypt cells from Ctrl piglets. Last, feces of piglets fed bLF contained intact bLF, suggesting that some bLF was resistant to digestion and could potentially affect intestinal proliferation through direct interaction with intestinal epithelial cells. This study is the first to our knowledge to show that dietary bLF stimulates crypt cell proliferation in vivo. The increased ß-catenin expression indicates that Wnt signaling may in part mediate the stimulatory effect of bLF on intestinal cell proliferation.

Local and Systemic Effects of Bioactive Food Ingredients: Is There a Role for Functional Foods to Prime the Gut for Resilience?

Scientific advancements in understanding the impact of bioactive components in foods on the gut microbiota and wider physiology create opportunities for designing targeted functional foods. The selection of bioactive ingredients with potential local or systemic effects holds promise for influencing overall well-being. An abundance of studies demonstrate that gut microbiota show compositional changes that correlate age and disease. However, navigating this field, especially for non-experts, remains challenging, given the abundance of bioactive ingredients with varying levels of scientific substantiation. This narrative review addresses the current knowledge on the potential impact of the gut microbiota on host health, emphasizing gut microbiota resilience. It explores evidence related to the extensive gut health benefits of popular dietary components and bioactive ingredients, such as phytochemicals, fermented greens, fibres, prebiotics, probiotics, and postbiotics. Importantly, this review distinguishes between the potential local and systemic effects of both popular and emerging ingredients. Additionally, it highlights how dietary hormesis promotes gut microbiota resilience, fostering better adaptation to stress-a hallmark of health. By integrating examples of bioactives, this review provides insights to guide the design of evidence-based functional foods aimed at priming the gut for resilience.

Phytonutrients in the promotion of healthspan: a new perspective.

Considering a growing, aging population, the need for interventions to improve the healthspan in aging are tantamount. Diet and nutrition are important determinants of the aging trajectory. Plant-based diets that provide bioactive phytonutrients may contribute to offsetting hallmarks of aging and reducing the risk of chronic disease. Researchers now advocate moving toward a positive model of aging which focuses on the preservation of functional abilities, rather than an emphasis on the absence of disease. This narrative review discusses the modulatory effect of nutrition on aging, with an emphasis on promising phytonutrients, and their potential to influence cellular, organ and functional parameters in aging. The literature is discussed against the backdrop of a recent conceptual framework which describes vitality, intrinsic capacity and expressed capacities in aging. This aims to better elucidate the role of phytonutrients on vitality and intrinsic capacity in aging adults. Such a review contributes to this new scientific perspective-namely-how nutrition might help to preserve functional abilities in aging, rather than purely offsetting the risk of chronic disease.

Lactation and neonatal nutrition: defining and refining the critical questions.

This paper resulted from a conference entitled "Lactation and Milk: Defining and refining the critical questions" held at the University of Colorado School of Medicine from January 18-20, 2012. The mission of the conference was to identify unresolved questions and set future goals for research into human milk composition, mammary development and lactation. We first outline the unanswered questions regarding the composition of human milk (Section I) and the mechanisms by which milk components affect neonatal development, growth and health and recommend models for future research. Emerging questions about how milk components affect cognitive development and behavioral phenotype of the offspring are presented in Section II. In Section III we outline the important unanswered questions about regulation of mammary gland development, the heritability of defects, the effects of maternal nutrition, disease, metabolic status, and therapeutic drugs upon the subsequent lactation. Questions surrounding breastfeeding practice are also highlighted. In Section IV we describe the specific nutritional challenges faced by three different populations, namely preterm infants, infants born to obese mothers who may or may not have gestational diabetes, and infants born to undernourished mothers. The recognition that multidisciplinary training is critical to advancing the field led us to formulate specific training recommendations in Section V. Our recommendations for research emphasis are summarized in Section VI. In sum, we present a roadmap for multidisciplinary research into all aspects of human lactation, milk and its role in infant nutrition for the next decade and beyond.

Genetic Biomarkers of Metabolic Detoxification for Personalized Lifestyle Medicine.

Metabolic detoxification (detox)-or biotransformation-is a physiological function that removes toxic substances from our body. Genetic variability and dietary factors may affect the function of detox enzymes, thus impacting the body's sensitivity to toxic substances of endogenous and exogenous origin. From a genetic perspective, most of the current knowledge relies on observational studies in humans or experimental models in vivo and in vitro, with very limited proof of causality and clinical value. This review provides health practitioners with a list of single nucleotide polymorphisms (SNPs) located within genes involved in Phase I and Phase II detoxification reactions, for which evidence of clinical utility does exist. We have selected these SNPs based on their association with interindividual variability of detox metabolism in response to certain nutrients in the context of human clinical trials. In order to facilitate clinical interpretation and usage of these SNPs, we provide, for each of them, a strength of evidence score based on recent guidelines for genotype-based dietary advice. We also present the association of these SNPs with functional biomarkers of detox metabolism in a pragmatic clinical trial, the LIFEHOUSE study.

Personalized Lifestyle Intervention and Functional Evaluation Health Outcomes SurvEy: Presentation of the LIFEHOUSE Study Using N-of-One Tent-Umbrella-Bucket Design.

The working definition of health is often the simple absence of diagnosed disease. This common standard is limiting given that changes in functional health status represent early warning signs of impending health declines. Longitudinal assessment of functional health status may foster prevention of disease occurrence and modify disease progression. The LIFEHOUSE (Lifestyle Intervention and Functional Evaluation-Health Outcomes SurvEy) longitudinal research project explores the impact of personalized lifestyle medicine approaches on functional health determinants. Utilizing an adaptive tent-umbrella-bucket design, the LIFEHOUSE study follows the functional health outcomes of adult participants recruited from a self-insured employee population. Participants were each allocated to the tent of an all-inclusive N-of-one case series. After assessing medical history, nutritional physical exam, baseline functional status (utilizing validated tools to measure metabolic, physical, cognitive, emotional and behavioral functional capacity), serum biomarkers, and genomic and microbiome markers, participants were assigned to applicable umbrellas and buckets. Personalized health programs were developed and implemented using systems biology formalism and functional medicine clinical approaches. The comprehensive database (currently 369 analyzable participants) will yield novel interdisciplinary big-health data and facilitate topological analyses focusing on the interactome among each participant's genomics, microbiome, diet, lifestyle and environment.

Immune responses of female BALB/c and C57BL/6 neonatal mice to vaccination or intestinal infection are unaltered by exposure to breast milk lycopene.

Lycopene, a carotenoid produced by some commonly consumed plants such as tomatoes, is not synthesized by animals. Thus, the levels of lycopene found in the breast milk of lactating females reflect the dietary lycopene supply. Lycopene has potent antioxidant activity but has also been implicated in modulating immune function. Therefore, lycopene in breast milk has the potential to affect the development and/or function of the immune system in the suckling pups. Here, we have investigated the impact of breast milk lycopene on systemic and mucosal immunity in mouse neonates. Diets containing 0.3 g/kg lycopene (Lyc) or control (Con) diets were fed to mouse dams beginning at late gestation and continuing throughout lactation. Seven-day-old female BALB/c pups were parenterally immunized with a model vaccine antigen dinitrophenyl-keyhole limpet hemocyanin (DNP-KLH) and then reimmunized as adults. The levels of DNP-KLH-specific IgG in the sera as well as keyhole limpet hemocyanin-specific IFNγ and IL-4 production by splenic CD4(+) cells were similar in the Lyc and Con pups. In addition, female neonatal (d7) C57BL/6 Lyc and Con pups were infected orally with the enteropathogen Yersinia enterocolitica. Breast milk lycopene had no effect on the recruitment of neutrophils to intestinal lymphoid tissues or on bacterial tissue colonization of the intestines, spleens, and livers. Thus, suckling pups exposed to lycopene in breast milk appear to develop normal innate and adaptive responses both systemically and at intestinal mucosal surfaces.

Impact of 2'-Fucosyllactose on Gut Microbiota Composition in Adults with Chronic Gastrointestinal Conditions: Batch Culture Fermentation Model and Pilot Clinical Trial Findings.

Intestinal dysbiosis has been described in patients with certain gastrointestinal conditions including irritable bowel syndrome (IBS) and ulcerative colitis. 2'-fucosyllactose (2'-FL), a prebiotic human milk oligosaccharide, is considered bifidogenic and butyrogenic. To assess prebiotic effects of 2'-FL, alone or in combination with probiotic strains (potential synbiotics), in vitro experiments were conducted on stool from healthy, IBS, and ulcerative colitis adult donors. In anaerobic batch culture fermenters, Bifidobacterium and Eubacterium rectale-Clostridium coccoides counts, and short-chain fatty acids (SCFAs) including butyrate increased during fermentation with 2'-FL and some of the 2'-FL/probiotic combinations. In a subsequent open-label pilot trial, the effect of a 2'-FL-containing nutritional formula was evaluated in twelve adults with IBS or ulcerative colitis. Gastrointestinal Quality of Life Index (GIQLI) total and gastrointestinal symptoms domain scores, stool counts of Bifidobacterium and Faecalibacterium prausnitzii, and stool SCFAs including butyrate, increased after six weeks of intervention. Consistent with documented effects of 2'-FL, the batch culture fermentation experiments demonstrated bifidogenic and butyrogenic effects of 2'-FL during fermentation with human stool samples. Consumption of the 2'-FL-containing nutritional formula by adults with IBS or ulcerative colitis was associated with improvements in intra- and extra-intestinal symptoms, and bifidogenic and butyrogenic effects.

Peyer's patch dendritic cells process viral antigen from apoptotic epithelial cells in the intestine of reovirus-infected mice.

We explored the role of Peyer's patch (PP) dendritic cell (DC) populations in the induction of immune responses to reovirus strain type 1 Lang (T1L). Immunofluorescence staining revealed the presence of T1L structural (sigma1) and nonstructural (sigmaNS) proteins in PPs of T1L-infected mice. Cells in the follicle-associated epithelium contained both sigma1 and sigmaNS, indicating productive viral replication. In contrast, sigma1, but not sigmaNS, was detected in the subepithelial dome (SED) in association with CD11c(+)/CD8alpha(-)/CD11b(lo) DCs, suggesting antigen uptake by these DCs in the absence of infection. Consistent with this possibility, PP DCs purified from infected mice contained sigma1, but not sigmaNS, and PP DCs from uninfected mice could not be productively infected in vitro. Furthermore, sigma1 protein in the SED was associated with fragmented DNA by terminal deoxy-UTP nick-end labeling staining, activated caspase-3, and the epithelial cell protein cytokeratin, suggesting that DCs capture T1L antigen from infected apoptotic epithelial cells. Finally, PP DCs from infected mice activated T1L-primed CD4(+) T cells in vitro. These studies show that CD8alpha(-)/CD11b(lo) DCs in the PP SED process T1L antigen from infected apoptotic epithelial cells for presentation to CD4(+) T cells, and therefore demonstrate the cross-presentation of virally infected cells by DCs in vivo during a natural viral infection.

Effect of a Nutrition Support Formula in Adults With Inflammatory Bowel Disease: A Pilot Study.

BACKGROUND: Due to the high prevalence of nutrient deficiencies in patients with inflammatory bowel disease (IBD), routine monitoring of nutrient status and supplementation are recommended. OBJECTIVE: This preliminary study was implemented to prospectively identify potential effects of a nutrition support formula on blood nutrient parameters in adults with IBD. METHODS: Ten adults with Crohn's disease or ulcerative colitis were recruited from the Portland, Oregon, metropolitan area into a single-arm, open-label pilot study. Participants consumed a nutrition support beverage twice daily for 12 weeks. The formula contained a mixture of micronutrients (including methylated forms of folate and vitamin B12), macronutrients, and phytonutrients (including curcumin, xanthohumol, ginger compounds, and quercetin). Primary measures were the following parameters: folate, vitamin B12, red blood cell (RBC) count, hemoglobin, hematocrit, electrolytes, and albumin. Exploratory measures included a food frequency questionnaire, circulating blood cell counts, and inflammatory markers. RESULTS: Nine participants completed the study and one withdrew. Adherence was 98%. Serum folate increased 48.7% (P = .029), serum vitamin B12 increased 17.4% but did not reach statistical significance (P = .053), and red cell distribution width (RDW) decreased 9.2% (P = .012) over the 12-week study period. There were minimal shifts in total white blood cell (WBC) counts (-1.0%, P = .845), but percent neutrophils decreased 10.4% (P = .042) and absolute lymphocyte count increased 18.6% (P = .048). RBC count, hemoglobin, hematocrit, electrolytes, albumin, and inflammatory markers did not change significantly. Post hoc analysis demonstrated that neutrophil-lymphocyte ratio (NLR) decreased 18.4% (not significant, P = .061). CONCLUSION: Serum folate and RDW improved in adults with IBD after 12 weeks. Modulation of leukocyte subtypes was also observed, including a decrease in neutrophils and an increase in lymphocytes, with no change in total WBC count. A randomized, controlled study to further examine effects of the nutrition support formula will be initiated to follow up on this promising, but preliminary investigation.

Rice Protein Matrix Enhances Circulating Levels of Xanthohumol Following Acute Oral Intake of Spent Hops in Humans.

SCOPE: Xanthohumol (XN), a prenylated flavonoid found in hops, exhibits anti-inflammatory and antioxidant properties. However, poor bioavailability may limit therapeutic applications. As food components are known to modulate polyphenol absorption, the objective is to determine whether a protein matrix could enhance the bioavailability of XN post oral consumption in humans. METHODS AND RESULTS: This is a randomized, double-blind, crossover study in healthy participants (n = 6) evaluating XN and its major metabolites (isoxanthohumol [IX], 6- and 8-prenylnaringenin [6-PN, 8-PN]) for 6 h following consumption of 12.4 mg of XN delivered via a spent hops-rice protein matrix preparation or a control spent hops preparation. Plasma XN and metabolites are measured by LC-MS/MS. Cmax , Tmax , and area-under-the-curve (AUC) values were determined. Circulating XN and metabolite response to each treatment was not bioequivalent. Plasma concentrations of XN and XN + metabolites (AUC) are greater with consumption of the spent hops-rice protein matrix preparation. CONCLUSION: Compared to a standard spent hops powder, a protein-rich spent hops matrix demonstrates enhanced plasma levels of XN and metabolites following acute oral intake.

Intestinal colonisation patterns in breastfed and formula-fed infants during the first 12 weeks of life reveal sequential microbiota signatures.

The establishment of the infant gut microbiota is a highly dynamic process dependent on extrinsic and intrinsic factors. We characterized the faecal microbiota of 4 breastfed infants and 4 formula-fed infants at 17 consecutive time points during the first 12 weeks of life. Microbiota composition was analysed by a combination of 16S rRNA gene sequencing and quantitative PCR (qPCR). In this dataset, individuality was a major driver of microbiota composition (P = 0.002) and was more pronounced in breastfed infants. A developmental signature could be distinguished, characterized by sequential colonisation of i) intrauterine/vaginal birth associated taxa, ii) skin derived taxa and other typical early colonisers such as Streptococcus and Enterobacteriaceae, iii) domination of Bifidobacteriaceae, and iv) the appearance of adultlike taxa, particularly species associated with Blautia, Eggerthella, and the potential pathobiont Clostridium difficile. Low abundance of potential pathogens was detected by 16S profiling and confirmed by qPCR. Incidence and dominance of skin and breast milk associated microbes were increased in the gut microbiome of breastfed infants compared to formula-fed infants. The approaches in this study indicate that microbiota development of breastfed and formula-fed infants proceeds according to similar developmental stages with microbiota signatures that include stage-specific species.

Overcoming the limited availability of human milk oligosaccharides: challenges and opportunities for research and application.

Human milk oligosaccharides (HMOs) are complex sugars highly abundant in human milk but currently not present in infant formula. Rapidly accumulating evidence from in vitro and in vivo studies, combined with epidemiological associations and correlations, suggests that HMOs benefit infants through multiple mechanisms and in a variety of clinical contexts. Until recently, however, research on HMOs has been limited by an insufficient availability of HMOs. Most HMOs are found uniquely in human milk, and thus far it has been prohibitively tedious and expensive to isolate and synthesize them. This article reviews new strategies to overcome this lack of availability by generating HMOs through chemoenzymatic synthesis, microbial metabolic engineering, and isolation from human donor milk or dairy streams. Each approach has its advantages and comes with its own challenges, but combining the different methods and acknowledging their limitations creates new opportunities for research and application with the goal of improving maternal and infant health.

Microbes central to human reproduction.

As studies uncover the breadth of microbes associated with human life, opportunities will emerge to manipulate and augment their functions in ways that improve health and longevity. From involvement in the complexities of reproduction and fetal/infant development, to delaying the onset of disease, and indeed countering many maladies, microbes offer hope for human well-being. Evidence is emerging to suggest that microbes may play a beneficial role in body sites traditionally viewed as being sterile. Although further evidence is required, we propose that much of medical dogma is about to change significantly through recognition and understanding of these hitherto unrecognized microbe-host interactions. A meeting of the International Scientific Association for Probiotics and Prebiotics held in Aberdeen, Scotland (June 2014), presented new views and challenged established concepts on the role of microbes in reproduction and health of the mother and infant. This article summarizes some of the main aspects of these discussions.

Involvement of dendritic cell subsets in the induction of oral tolerance and immunity.

Dendritic cells (DCs) play a central role in the generation of immune responses in the intestine. DCs induce differentiation and tolerance of T cells, and may have a direct role in B cell switching to IgA. Four distinct subsets of CD11c(+) DCs are present in murine Peyer's patches, which represent primary sites for the induction of mucosal T and B cell responses. Studies suggest that CD11b(+) DCs or plasmacytoid DCs may be specialized for the induction of regulatory T cells, and CD8alpha(+) DCs for the induction of clonal deletion in response to soluble oral antigen, while all DC subsets (including CD8alpha(-)/CD11b(-) DCs) may be involved in responses to pathogens. We are currently using reovirus type-1 Lang (TIL) to explore the role of DC populations in mucosal immunity in vivo, as oral administration of live T1L to mice induces strong mucosal and systemic antiviral immune responses, whereas oral administration of inactivated T1L results in tolerance to viral proteins. We found that primary infection with T1L occurs in epithelial cells of the PP follicle-associated epithelium, but that CD8alpha(-)/CD11b(-) DCs in the subepithelial dome region (SED) are loaded with T1L antigens in the absence of active DC infection. At least a portion of this antigen is associated with cell fragments from apoptotic epithelial cells, demonstrating that SED DCs cross-present antigens from apoptotic epithelial cells. In vitro, in contrast to exposure to several TLR-ligands or anti-CD40, exposure to T1L does not activate DCs to mature or to produce cytokines, despite clear loading of the DCs with viral antigens. These data suggest that T1L is taken up by a "silent" receptor on DCs, and that the induction of immunity to T1L is dependent on signals from non-DCs following active viral infection that induce DC maturation. Thus, the decision between tolerance and immunity to inactive and live virus, respectively, likely depends on whether there is active infection of epithelial cells by T1L, which results in the elaboration of molecules, such as cytokines, that induce DC maturation.

Serotype-specific differences in inhibition of reovirus infectivity by human-milk glycans are determined by viral attachment protein σ1.

Human milk contains many bioactive components, including secretory IgA, oligosaccharides, and milk-associated proteins. We assessed the antiviral effects of several components of milk against mammalian reoviruses. We found that glucocerebroside (GCB) inhibited the infectivity of reovirus strain type 1 Lang (T1L), whereas gangliosides GD3 and GM3 and 3'-sialyllactose (3SL) inhibited the infectivity of reovirus strain type 3 Dearing (T3D). Agglutination of erythrocytes mediated by T1L and T3D was inhibited by GD3, GM3, and bovine lactoferrin. Additionally, α-sialic acid, 3SL, 6'-sialyllactose, sialic acid, human lactoferrin, osteopontin, and α-lactalbumin inhibited hemagglutination mediated by T3D. Using single-gene reassortant viruses, we found that serotype-specific differences segregate with the gene encoding the viral attachment protein. Furthermore, GD3, GM3, and 3SL inhibit T3D infectivity by blocking binding to host cells, whereas GCB inhibits T1L infectivity post-attachment. These results enhance an understanding of reovirus cell attachment and define a mechanism for the antimicrobial activity of human milk.

A rapid, automated approach for quantitation of rotavirus and reovirus infectivity.

Current microscopy-based approaches for immunofluorescence detection of viral infectivity are time consuming and labor intensive and can yield variable results subject to observer bias. To circumvent these problems, we developed a rapid and automated infrared immunofluorescence imager-based infectivity assay for both rotavirus and reovirus that can be used to quantify viral infectivity and infectivity inhibition. For rotavirus, monolayers of MA104 cells were infected with simian strain SA-11 or SA-11 preincubated with rotavirus-specific human IgA. For reovirus, monolayers of either HeLa S3 cells or L929 cells were infected with strains type 1 Lang (T1L), type 3 Dearing (T3D), or either virus preincubated with a serotype-specific neutralizing monoclonal antibody (mAb). Infected cells were fixed and incubated with virus-specific polyclonal antiserum, followed by an infrared fluorescence-conjugated secondary antibody. Well-to-well variation in cell number was normalized using fluorescent reagents that stain fixed cells. Virus-infected cells were detected by scanning plates using an infrared imager, and results were obtained as a percent response of fluorescence intensity relative to a virus-specific standard. An expected dose-dependent inhibition of both SA-11 infectivity with rotavirus-specific human IgA and reovirus infectivity with T1L-specific mAb 5C6 and T3D-specific mAb 9BG5 was observed, confirming the utility of this assay for quantification of viral infectivity and infectivity blockade. The imager-based viral infectivity assay fully automates data collection and provides an important advance in technology for applications such as screening for novel modulators of viral infectivity. This basic platform can be adapted for use with multiple viruses and cell types.

Cutting edge: Peyer's patch plasmacytoid dendritic cells (pDCs) produce low levels of type I interferons: possible role for IL-10, TGFbeta, and prostaglandin E2 in conditioning a unique mucosal pDC phenotype.

The organized lymphoid tissues of the intestine likely play an important role in the balance between tolerance harmless mucosal Ags and commensal bacteria and immunity to mucosal pathogens. We examined the phenotype and function of plasmacytoid dendritic cells (pDCs) from murine Peyer's patches (PPs). When stimulated with CpG-enriched oligodeoxynucleotides in vitro, PPs and spleen pDCs made equivalent levels of IL-12, yet PP pDCs were incapable of producing significant levels of type I IFNs. Three regulatory factors associated with mucosal tissues, PGE(2), IL-10, and TGFbeta, inhibited the ability of spleen pDCs to produce type I IFN in a dose-dependent fashion. These studies suggest that mucosal factors may regulate the production of type I IFN as well as IL-12 by pDCs. In the intestine, this may be beneficial in preventing harmful innate and adaptive immune responses to commensal microorganisms.