Dietary Bioactives: Establishing a Scientific Framework for Recommended Intakes

In the United States, dietary reference intakes describe the relations between nutrient intakes and indicators of adequacy, prevention of disease, and avoidance of excessive intakes among healthy populations for essential nutrients but not dietary bioactive components (DBCs), whose absence from the diet is presumably not deleterious to health (i.e., does not cause a deficiency syndrome). An appropriate framework is needed for establishing recommended intakes for which public health messages and food labeling for DBCs can be derived, because their putative health benefits may not be readily defined in the context of nutritional essentiality. In addition, a myriad of factors make determining their intake and status and investigating their discrete contributions to health particularly challenging. Therefore, the ASN Dietary Bioactive Components Research Interest Section felt it worthwhile to convene a special “hot topic” session at the 2014 Experimental Biology meeting to discuss this issue and serve as a call for future scientific dialogue on establishing a framework for recommended intakes of DBCs. This session summary captures the discussions and presentations that transpired during this session.     

Surgery for ulcerative colitis

The type of surgery performed for UC varies from patient to patient and must take into account the nutritional status and health of the patient, the presence of dysplasia or cancer, the desire of the patient to maintain continence, the preoperative anorectal function, the degree of confidence in the diagnosis of UC, and the technical constraint because of certain body habituses. A total proctocolectomy is the surgical procedure of choice for UC. A restorative proctocolectomy is the preferred surgical approach that not only cures the patient of the disease and prevents the development of colorectal cancer, but also maintains continence with an improved quality of life.     

Long-term granulocyte transfusion in patients with malignant neoplasms.

Thirty-eight episodes of culture-documented antibiotic-resistant bacterial or fungal infection in patients with malignant neoplasms were treated with daily granulocyte transfusions until the infection improved or the patient died. Cumulative summation temperature plotting allowed easier interpretation of recipient fever response. Seventy-one percent of recipients had a favorable response to transfusion. There was no difference in mortality between patients treated with cells collected by filtration (FL) or intermittent flow centrifugation (IFCL) leukapheresis techniques. Transfusion reactions were more than twice as common with FL than IFCL collected cells. Seventy-four percent of recipients were alive 21 days after completion of transfusions; of the ten deaths, five could be classified as granulocyte transfusion failures. This study suggests that long-term granulocyte transfusion may be required in infected recipients when autologous granulocytes do not return after chemotherapy.     

The multiple roles of major histocompatibility complex class-I-like molecules in mucosal immune function

The human major histocompatibility complex (MHC) on chromosome 6 encodes three classical class-I genes: human leukocyte antigens (HLA) A, B, and C. These polymorphic genes encode a 43- to 45-kDa cell surface glycoprotein that, in association with the 12-kDa β₂-microglobulin molecule, functions in the presentation of nine amino acid peptides to the T-cell receptor of CD8-bearing T lymphocytes and killer inhibitory receptors on natural killer cells. In addition to these ubiquitously expressed, polymorphic proteins, the human genome also encodes several nonclassical MHC class-I-like, or class Ib, genes that, in general, encode nonpolymorphic molecules involved in various specific immunological functions. Many of these genes, including CD1, the neonatal Fc receptor for IgG, HLA-G, HLA-E, the MHC class-I chainrelated gene A, and Hfe, are prominently displayed on epithelial cells, suggesting an important role in epithelial cell biology.     

Update on biologic pathways in inflammatory bowel disease and their therapeutic relevance

Results of recent genetic and immunologic studies have brought to the forefront several biologic pathways that allow for a better understanding of the mechanisms of tissue homeostasis, on the one hand, and inflammatory bowel disease (IBD) on the other. The explosion of research activity as a result of these newly identified targets is bringing the pathogenesis of these complex disorders into focus as well as creating new therapeutic opportunities. The greatest advances with perhaps the largest impact on our understanding of the etiology of Crohn’s disease are those related to bacterial sensing, such as through nucleotide-binding oligomerization domain-containing protein 2 (NOD2) and its relationships to autophagy and the unfolded protein response as a consequence of endoplasmic reticulum stress. Interestingly, it appears as though these pathways, which are rooted in microbial sensing and regulation, are interrelated. Genetic studies have also renewed interest in previously studied pathways in IBD, such as the formation and function of the inflammasome and its relationship to interleukin (IL) 1-beta signaling. With the recent success of therapeutic agents designed to block tumor necrosis factor, the IL-12/23 pathways, and lymphocyte homing, insights have been gained into the biologic relevance and impact of these various inflammatory pathways in IBD. In this review, the exciting recent advances in these biologic pathways of IBD are discussed, particularly in light of their therapeutic relevance.