Colonic energy salvage in chronic pancreatic exocrine insufficiency

Pancreatic exocrine insufficiency after pancreaticoduodenectomy: Current evidence and management

Pancreaticoduodenectomy (PD) is the commonest procedure performed for pancreatic cancer. Pancreatic exocrine insufficiency (PEI) may be caused or exacerbated by surgery and remains underdiagnosed and undertreated. The aim of this review was to ascertain the incidence of PEI, its consequences and management in the setting of PD for indications other than chronic pancreatitis. A literature search of databases (MEDLINE, EMBASE, Cochrane and Scopus) was carried out with the MeSH terms “pancreatic exocrine insufficiency” and “Pancreaticoduodenectomy”. Studies that analysed PEI and its complications in the setting of PD for malignant and benign disease were included. Studies reporting PEI in the setting of PD for chronic pancreatitis, conference abstracts and reviews were excluded. The incidence of PEI approached 100% following PD in some series. The pre-operative incidence varied depending on the characteristics of the patient cohort and it was higher (46%-93%) in series where pancreatic cancer was the predominant indication for surgery. Variability was also recorded with regards to the method used for the diagnosis and evaluation of pancreatic function and malabsorption. Pancreatic enzyme replacement therapy is the mainstay of the management. PEI is common and remains undertreated after PD. Future studies are required for the identification of a well-tolerated, reliable and reproducible diagnostic test in this setting.

Fecal dysbiosis in infants with cystic fibrosis is associated with early linear growth failure

Most infants with cystic fibrosis (CF) have pancreatic exocrine insufficiency that results in nutrient malabsorption and requires oral pancreatic enzyme replacement. Newborn screening for CF has enabled earlier diagnosis, nutritional intervention, and enzyme replacement for these infants, allowing most infants with CF to achieve their weight goals by 12 months of age¹. Nevertheless, most infants with CF continue to have poor linear growth during their first year of life¹. Although this early linear growth failure is associated with worse long-term respiratory function and survival^2,3, the determinants of stature in infants with CF have not been defined. Several characteristics of the CF gastrointestinal (GI) tract, including inflammation, maldigestion and malabsorption, could promote intestinal dysbiosis^4,5. As GI microbiome activities are known to affect endocrine functions^6,7, the intestinal microbiome of infants with CF might also impact growth. We identified an early, progressive fecal dysbiosis that distinguished infants with CF and low length from infants with CF and normal length. This dysbiosis included altered abundances of taxa that perform functions important for GI health, nutrient harvest, and growth hormone signaling, including decreased Bacteroidetes and increased Proteobacteria. Thus, the GI microbiota represent a potential therapeutic target to correct linear growth defects among infants with CF.

The nutritional management of type 3c (pancreatogenic) diabetes in chronic pancreatitis

Type 3c diabetes mellitus (T3cDM), also known as pancreatogenic diabetes, refers to diabetes caused by disease of the exocrine pancreas. T3cDM is not commonly recognised by clinicians and frequently it is misclassified as T1DM, or more commonly, T2DM. T3cDM can be difficult to distinguish from T1DM and T2DM, and it often co-exists with the latter. The aim of this review is to describe T3cDM, along with its complications, diagnosis and management. We focus on the nutritional implications of T3cDM for those with chronic pancreatitis, and provide a practical guide to the nutritional management of this condition.

Metagenomic evidence for taxonomic dysbiosis and functional imbalance in the gastrointestinal tracts of children with cystic fibrosis

Cystic fibrosis (CF) results in inflammation, malabsorption of fats and other nutrients, and obstruction in the gastrointestinal (GI) tract, yet the mechanisms linking these disease manifestations to microbiome composition remain largely unexplored. Here we used metagenomic analysis to systematically characterize fecal microbiomes of children with and without CF, demonstrating marked CF-associated taxonomic dysbiosis and functional imbalance. We further showed that these taxonomic and functional shifts were especially pronounced in young children with CF and diminished with age. Importantly, the resulting dysbiotic microbiomes had significantly altered capacities for lipid metabolism, including decreased capacity for overall fatty acid biosynthesis and increased capacity for degrading anti-inflammatory short-chain fatty acids. Notably, these functional differences correlated with fecal measures of fat malabsorption and inflammation. Combined, these results suggest that enteric fat abundance selects for pro-inflammatory GI microbiota in young children with CF, offering novel strategies for improving the health of children with CF-associated fat malabsorption.

Pancreatic exocrine insufficiency following pancreatic resection

BACKGROUND/OBJECTIVES

Untreated pancreatic exocrine dysfunction is associated with poor quality of life and reduced survival, but is difficult to diagnose following pancreatic resection. Many factors including the extent of the surgery, the health of the residual pancreas and the type of reconstruction must be considered. Patients remain undertreated, and consequently there is much debate to whether or not pancreatic enzyme replacement therapy should be routinely prescribed following pancreatic resection.

METHODS

A review of the literature was undertaken to establish the incidence of PEI and factors identifying treatment.

RESULTS

Forty two to forty five percent of patients undergoing pancreatico-duodenectomy (PD) experience pancreatic exocrine insufficiency pre-operatively, whilst the post-operative incidence is 56-98% in PD, and 12-80% following distal and central pancreatectomy.

CONCLUSIONS

Routine use of pancreatic enzyme replacement should be considered at a starting dose of 50 to 75,000 units lipase with meals and 25,000 to 50,000 units with snacks in this patient group. Patients who have had a central or distal pancreatectomy should be individually assessed for pancreatic exocrine insufficiency in the post operative period, with those undergoing extensive resection most likely to experience insufficiency. Patients who fail to respond to pancreatic enzyme replacement therapy should be referred to a specialist dietitian, be advised on dose adjustment, and undergo investigation to exclude other gastro-intestinal pathology, including small bowel bacterial overgrowth and bile acid malabsorption.

Fecal biomarkers of intestinal health and disease in children

The identification of various fecal biomarkers has provided insight into the intestinal milieu. Most of these markers are associated with the innate immune system of the gut, apart from the more novel M2-pyruvate kinase. The innate immunity of the gut plays a role in maintaining a fine balance between tolerance to commensal bacteria and immune response to potential pathogens. It is a complex system, which comprises of multiple elements, including antimicrobial peptides (e.g., defensins, cathelicidins, lactoferrin, and osteoprotegerin), inflammatory proteins (e.g., calprotectin and S100A12), and microbial products (e.g., short-chain fatty acids). Dysfunction of any component can lead to the development of intestinal disease, and different diseases have been associated with different fecal levels of these biomarkers. Each fecal biomarker provides information on specific biological and disease processes. Therefore, stool quantification of these biomarkers provides a non-invasive method to define potential pathways behind the pathogenesis of diseases and can assist in the assessment and diagnosis of various gastrointestinal conditions. The abovementioned fecal biomarkers and their role in intestinal health and disease will be reviewed in this paper with a pediatric focus.

The gut microbiota suppresses insulin-mediated fat accumulation via the short-chain fatty acid receptor GPR43

The gut microbiota affects nutrient acquisition and energy regulation of the host, and can influence the development of obesity, insulin resistance, and diabetes. During feeding, gut microbes produce short-chain fatty acids, which are important energy sources for the host. Here we show that the short-chain fatty acid receptor GPR43 links the metabolic activity of the gut microbiota with host body energy homoeostasis. We demonstrate that GPR43-deficient mice are obese on a normal diet, whereas mice overexpressing GPR43 specifically in adipose tissue remain lean even when fed a high-fat diet. Raised under germ-free conditions or after treatment with antibiotics, both types of mice have a normal phenotype. We further show that short-chain fatty acid-mediated activation of GPR43 suppresses insulin signalling in adipocytes, which inhibits fat accumulation in adipose tissue and promotes the metabolism of unincorporated lipids and glucose in other tissues. These findings establish GPR43 as a sensor for excessive dietary energy, thereby controlling body energy utilization while maintaining metabolic homoeostasis.

The gut microbiota produces metabolites such as short-chain fatty acids (SCFAs), which can influence the development of obesity. Here Kimura et al. show that SCFAs act via the receptor GPR43, which acts as a sensor for excessive dietary energy and controls body energy utilization as well as metabolic homoeostasis.

Short-chain fatty acids and ketones directly regulate sympathetic nervous system via G protein-coupled receptor 41 (GPR41)

The maintenance of energy homeostasis is essential for life, and its dysregulation leads to a variety of metabolic disorders. Under a fed condition, mammals use glucose as the main metabolic fuel, and short-chain fatty acids (SCFAs) produced by the colonic bacterial fermentation of dietary fiber also contribute a significant proportion of daily energy requirement. Under ketogenic conditions such as starvation and diabetes, ketone bodies produced in the liver from fatty acids are used as the main energy sources. To balance energy intake, dietary excess and starvation trigger an increase or a decrease in energy expenditure, respectively, by regulating the activity of the sympathetic nervous system (SNS). The regulation of metabolic homeostasis by glucose is well recognized; however, the roles of SCFAs and ketone bodies in maintaining energy balance remain unclear. Here, we show that SCFAs and ketone bodies directly regulate SNS activity via GPR41, a Gi/o protein-coupled receptor for SCFAs, at the level of the sympathetic ganglion. GPR41 was most abundantly expressed in sympathetic ganglia in mouse and humans. SCFA propionate promoted sympathetic outflow via GPR41. On the other hand, a ketone body, β-hydroxybutyrate, produced during starvation or diabetes, suppressed SNS activity by antagonizing GPR41. Pharmacological and siRNA experiments indicated that GPR41-mediated activation of sympathetic neurons involves Gβγ-PLCβ-MAPK signaling. Sympathetic regulation by SCFAs and ketone bodies correlated well with their respective effects on energy consumption. These findings establish that SCFAs and ketone bodies directly regulate GPR41-mediated SNS activity and thereby control body energy expenditure in maintaining metabolic homeostasis.

Nutrition treatment of deficiency and malnutrition in chronic pancreatitis: a review

Chronic pancreatitis results in exocrine and endocrine dysfunction, affecting normal digestion and absorption of nutrients. In individuals with chronic pancreatitis, nutrition status may be further affected by poor dietary intake, often related to alcoholism. However, some deficiencies may be overlooked, potentially leading to nutrition-related problems with bone health and fatigue. The aim of this article is to describe the deficiencies that occur and to propose an evidence-based algorithm for the nutrition assessment and treatment of patients with chronic pancreatitis.

Bowel necrosis associated with early jejunal tube feeding: A complication of postoperative enteral nutrition

HYPOTHESIS

Postoperative enteral nutrition may sometimes be responsible for severe complications such as mesenteri ischemia.

DATA SOURCES

Studies in the English literature were identified by a computer-assisted search of the MEDLINE database using the key words "enteral feeding OR jejunostomy" AND "complications OR mesenteric ischemia." Cited references of each retrieved paper were checked for relevance.

STUDY SELECTION

All reports of mesenteric ischemia in the setting of postoperative enteral feeding were included. In cases of multiple articles from the same institution with overlapping patients, the most exhaustive article was included.

DATA EXTRACTION

All reports were abstracted for number of patients, presence of preoperative comorbidities, development of perioperative hypotension or mesenteric occlusion, and outcome.

DATA SYNTHESIS

Nine studies were retrieved in which enteral feedings were responsible for bowel ischemia; we report an additional case. The common clinical picture is that of a patient without significant risk factors for mesenteric ischemia, which during the early postoperative course develops nonspecific abdominal symptoms and then rapidly progresses to septic shock and eventually to multisystem organ failure and death. Mesenteric ischemia may present in up to 3.5% of enterally fed surgical patients; the associated mortality approaches 100%. The lack of specific symptoms requires a high index of suspicion for diagnosis; prompt abdominal exploration and bowel resection are the only chance for survival.

CONCLUSIONS

The benefits of enteral nutrition outweigh the likelihood of severe complications; when mesenteric ischemia develops, early diagnosis is challenging and the prognosis is poor.