The emerging role of the gut in chronic heart failure

Gastrointestinal and Liver Issues in Heart Failure

Heart failure affects ≈23 million people worldwide and continues to have a high mortality despite advancements in modern pharmacotherapy and device therapy. HF is a complex clinical syndrome that can result in the impairment of endocrine, hematologic, musculoskeletal, renal, respiratory, peripheral vascular, hepatic, and gastrointestinal systems. Although gastrointestinal involvement and hepatic involvement are common in HF and are associated with increased morbidity and mortality, their bidirectional association with HF progression remains poorly fathomed. The current understanding of multiple mechanisms, including proinflammatory cytokine milieu, hormonal imbalance, and anabolic/catabolic imbalance, has been used to explain the relationship between the gut and HF and has been the basis for many novel therapeutic strategies. However, the failure of these novel therapies such as anti–tumor necrosis factor-α has resulted in further complexity. In this review, we describe the involvement of the gastrointestinal and liver systems within the HF syndrome, their pathophysiological mechanisms, and their clinical consequences.

Proteome profiles of HDL particles of patients with chronic heart failure are associated with immune response and also include bacteria proteins

Besides modulation of reverse cholesterol transport, high density lipoprotein (HDL) is able to modulate vascular function by stimulating endothelial nitric oxide synthase. Recently, it could be documented that this function of HDL was significantly impaired in patients with chronic heart failure (CHF). We investigated alterations in the HDL proteome in CHF patients. Therefore, HDL was isolated from 5 controls (HDLhealthy) and 5 CHF patients of NYHA-class IIIb (HDLCHF). Proteome analysis of HDL particles was performed by two-dimensional liquid chromatography-mass spectrometry (SCX/RP LC-MS/MS). In total, we identified 494 distinct proteins, of which 107 proteins were commonly found in both groups (HDLCHF and HDLhealthy) indicating a high inter-subject variability across HDL particles. Several important proteins (e.g. ITGA2, APBA1 or A2M) varied in level. Functional analysis revealed regulated pathways. A minor proportion of bacteria-derived proteins were also identified in the HDL-particles. The extension of the list of HDL-associated proteins allows besides their mere description new insights into alterations in HDL function in diseases. In addition, the detection of bacterial proteins bound to HDL will broaden our view of HDL not only as a cholesterol carrier but also as a carrier of proteins.

Pathogenic Gut Flora in Patients With Chronic Heart Failure

OBJECTIVES

The goal of this study was to measure the presence of pathogenic gut flora and intestinal permeability (IP) and their correlations with disease severity, venous blood congestion, and inflammation in patients with chronic heart failure (CHF).

BACKGROUND

Evidence suggests that translocation of gut flora and/or their toxins from the intestine to the bloodstream is a possible trigger of systemic CHF inflammation. However, the relation between pathogenic gut flora and CHF severity, as well as IP, venous blood congestion as right atrial pressure (RAP), and/or systemic inflammation (C-reactive protein [CRP]), is still unknown.

METHODS

This study analyzed 60 well-nourished patients in stable condition with mild CHF (New York Heart Association [NYHA] functional class I to II; n = 30) and moderate to severe CHF (NYHA functional class III to IV; n = 30) and matched healthy control subjects (n = 20). In all subjects, the presence and development in the feces of bacteria and fungi (Candida species) were measured; IP according to cellobiose sugar test results was documented. The study data were then correlated with RAP (echocardiography) and systemic inflammation.

RESULTS

Compared with normal control subjects, the entire CHF population had massive quantities of pathogenic bacteria and Candida such as Campylobacter (85.3 ± 3.7 CFU/ml vs. 1.0 ± 0.3 CFU/ml; p < 0.001), Shigella (38.9 ± 12.3 CFU/ml vs. 1.6 ± 0.2 CFU/ml; p < 0.001), Salmonella (31.3 ± 9.1 CFU/ml vs 0 CFU/ml; p < 0.001), Yersinia enterocolitica (22.9 ± 6.3 CFU/ml vs. 0 CFU/ml; p < 0.0001), and Candida species (21.3 ± 1.6 CFU/ml vs. 0.8 ± 0.4 CFU/ml; p < 0.001); altered IP (10.2 ± 1.2 mg vs. 1.5 ± 0.8 mg; p < 0.001); and increased RAP (12.6 ± 0.6 mm Hg) and inflammation (12.5 ± 0.6 mg/dl). These variables were more pronounced in patients with moderate to severe NYHA functional classes than in patients with the mild NYHA functional class. Notably, IP, RAP, and CRP were mutually interrelated (IP vs. RAP, r = 0.55; p < 0.0001; IP vs. CRP, r = 0.78; p < 0.0001; and RAP vs. CRP, r = 0.78; p < 0.0001).

CONCLUSIONS

This study showed that patients with CHF may have intestinal overgrowth of pathogenic bacteria and Candida species and increased IP associated with clinical disease severity, venous blood congestion, and inflammation.

Safety of parenteral nutrition in patients receiving a ventricular assist device

Patients with advanced heart failure and poor nutritional status are predisposed to higher rates of infection, bleeding, and mortality. We have increasingly used perioperative parenteral nutrition (PN) in ventricular assist device (VAD) patients and now report our initial experience. We performed a retrospective review of 43 consecutive patients who received implantable VADs from 2006 to 2009. We compared outcomes for patients receiving PN for >7 days perioperatively vs ≤7 days. In addition, we compared patients who received preoperative enteral nutrition (EN) with those who did not. Fourteen patients received perioperative PN in addition to EN for >7 days compared with 29 patients who received either PN for ≤7 days or EN alone. Univariate analysis showed no differences in infection, bleeding, thrombus, stroke, length of stay, or mortality. Multivariate stepwise regression including EN, preoperative PN, Interagency Registry for Mechanically Assisted Circulation score, age, gender, and VAD indication showed that only EN was associated with infection. Prolonged use of perioperative PN appears to be safe and well tolerated in patients undergoing VAD implantation. Preoperative EN, while increasing infection risk, seems to have no harmful effect on survival.

A New, Discontinuous 2 Phases of Aging Model: Lessons from Drosophila melanogaster

Aging is commonly described as being a continuous process affecting progressively organisms as time passes. This process results in a progressive decrease in individuals fitness through a wide range of both organismal-decreased motor activity, fertility, resistance to stress-and molecular phenotypes-decreased protein and energy homeostasis, impairment of insulin signaling. In the past 20 years, numerous genes have been identified as playing a major role in the aging process, yet little is known about the events leading to that loss of fitness. We recently described an event characterized by a dramatic increase of intestinal permeability to a blue food dye in aging flies committed to die within a few days. Importantly, flies showing this so called 'Smurf' phenotype are the only ones, among a population, to show various age-related changes and exhibit a high-risk of impending death whatever their chronological age. Thus, these observations suggest that instead of being one continuous phenomenon, aging may be a discontinuous process well described by at least two distinguishable phases. In this paper we addressed this hypothesis by implementing a new 2 Phases of Aging mathematiCal model (2PAC model) to simulate longevity curves based on the simple hypothesis of two consecutive phases of lifetime presenting different properties. We first present a unique equation for each phase and discuss the biological significance of the 3 associated parameters. Then we evaluate the influence of each parameter on the shape of survival curves. Overall, this new mathematical model, based on simple biological observations, is able to reproduce many experimental longevity curves, supporting the existence of 2 phases of aging exhibiting specific properties and separated by a dramatic transition that remains to be characterized. Moreover, it indicates that Smurf survival can be approximated by one single constant parameter for a broad range of genotypes that we have tested under our environmental conditions.

Malnutrition and Gut Flora Dysbiosis: Specific Therapies for Emerging Comorbidities in Heart Failure

Chronic heart failure is a complicated multifactorial disease with wide-spread social-economic consequences. In spite of the recent development of new drugs and therapeutic strategies, CHF-related mortality and morbidity remain high. Recent evidence suggests that changes in organs such as skeletal muscle and gut flora may play an important and independent role in CHF prognosis. This paper illustrates these phenomena, proposing how to identify them and presenting current therapies which treat organs all too often underestimated but which have a fundamental role in worsening CHF.

Role of Nrf2 dysfunction in uremia-associated intestinal inflammation and epithelial barrier disruption

BACKGROUND

Gut inflammation is prevalent in chronic kidney disease (CKD) and likely contributes to systemic inflammation via disruption of the epithelial tight junction with subsequent endotoxin and bacterial translocation.

AIMS

To study the expression profile of inflammatory and tight junction proteins in the colon from CKD rats compared to healthy controls, and demonstrate the role of Nrf2 (transcription factor nuclear factor erythroid 2-related factor 2) using a potent Nrf2 activator.

METHODS

CKD was induced via 5/6 nephrectomy in Sprague-Dawley rats, and dh404 (2 mg/kg/day) was used to study the effects of systemic Nrf2 activation. The experimental groups included sham, CKD and CKD+ dh404 rats. Blood and colon tissues were analyzed after a 10-week study period.

RESULTS

Colon from CKD rats showed histological evidence of colitis, depletion of epithelial tight junction proteins, significant reduction of Nrf2 and its measured target gene products (NQO1, catalase, and CuZn SOD), activation of NFkB, and upregulation of pro-inflammatory molecules (COX-2, MCP-1, iNOS, and gp91(phox)). Treatment with dh404 attenuated colonic inflammation, restored Nrf2 activity and levels of NQO1, catalase and CuZn SOD, decreased NFkB and lowered expression of COX-2, MCP-1, iNOS, and gp91(phox). This was associated with restoration of colonic epithelial tight junction proteins (occludin and claudin-1).

CONCLUSIONS

CKD rats exhibited colitis, disruption of colonic epithelial tight junction, activation of inflammatory mediators, and impairment of Nrf2 pathway. Treatment with an Nrf2 activator restored Nrf2 activity, attenuated colonic inflammation, and restored epithelial tight junction proteins.

Intestinal blood flow in patients with chronic heart failure: a link with bacterial growth, gastrointestinal symptoms, and cachexia

BACKGROUND

Blood flow in the intestinal arteries is reduced in patients with stable heart failure (HF) and relates to gastrointestinal (GI) symptoms and cardiac cachexia.

OBJECTIVES

The aims of this study were to measure arterial intestinal blood flow and assess its role in juxtamucosal bacterial growth, GI symptoms, and cachexia in patients with HF.

METHODS

A total of 65 patients and 25 controls were investigated. Twelve patients were cachectic. Intestinal blood flow and bowel wall thickness were measured using ultrasound. GI symptoms were documented. Bacteria in stool and juxtamucosal bacteria on biopsies taken during sigmoidoscopy were studied in a subgroup by fluorescence in situ hybridization. Serum lipopolysaccharide antibodies were measured.

RESULTS

Patients showed 30% to 43% reduced mean systolic blood flow in the superior and inferior mesenteric arteries and celiac trunk (CT) compared with controls (p < 0.007 for all). Cachectic patients had the lowest blood flow (p < 0.002). Lower blood flow in the superior mesenteric artery and CT was correlated with HF severity (p < 0.04 for all). Patients had more feelings of repletion, flatulence, intestinal murmurs, and burping (p < 0.04). Burping and nausea or vomiting were most severe in patients with cachexia (p < 0.05). Patients with lower CT blood flow had more abdominal discomfort and immunoglobulin A-antilipopolysaccharide (r = 0.76, p < 0.02). Antilipopolysaccharide response was correlated with increased growth of juxtamucosal but not stool bacteria. Patients with intestinal murmurs had greater bowel wall thickness of the sigmoid and descending colon, suggestive of edema contributing to GI symptoms (p < 0.05). In multivariate regression analysis, lower blood flow in the superior mesenteric artery, CT (p < 0.04), and inferior mesenteric artery (p = 0.056) was correlated with the presence of cardiac cachexia.

CONCLUSIONS

Intestinal blood flow is reduced in patients with HF. This may contribute to juxtamucosal bacterial growth and GI symptoms in patients with advanced HF complicated by cachexia.

Exploring the physiology and pathology of aging in the intestine of Drosophila melanogaster

The gastrointestinal tract, due to its role as a digestive organ and as a barrier between the exterior and interior milieus, is critically impacted by dietary, environmental, and inflammatory conditions that influence health and lifespan. Work in flies is now uncovering the multifaceted molecular mechanisms that control homeostasis in this tissue, and establishing its central role in health and lifespan of metazoans. The Drosophila intestine has thus emerged as a productive, genetically accessible model to study various aspects of the pathophysiology of aging. Studies in flies have characterized the maintenance of regenerative homeostasis, the development of immune senescence, the loss of epithelial barrier function, the decline in metabolic homeostasis, as well as the maintenance of epithelial diversity in this tissue. Due to its fundamental similarity to vertebrate intestines, it can be anticipated that findings obtained in this system will have important implications for our understanding of age-related changes in the human intestine. Here, I review recent studies exploring age-related changes in the fly intestine, and their insight into the regulation of health and lifespan of the animal.

Cachexia: a problem of energetic inefficiency

An alteration of energy balance is the immediate cause of the so-called cachexia. Although alterations of energy intake are often associated with cachexia, it has lately became clear that an increased energy expenditure is the main cause of wasting associated with different types of pathological conditions, such as cancer, infections or chronic heart failure among others. Different types of molecular mechanisms contribute to energy expenditure and, therefore, involuntary body weight loss; among them, adenosine triphosphate (ATP) consumption by sarcoplasmic reticulum Ca(2+) pumps could represent a key mechanism. In other cases, an increase in energy inefficiency will further contribute to energy imbalance.

Intestinal microbiota-dependent phosphatidylcholine metabolites, diastolic dysfunction, and adverse clinical outcomes in chronic systolic heart failure

BACKGROUND

Trimethylamine-N-oxide (TMAO) has been linked to increased cardiovascular risk. We aimed to determine the prognostic value of TMAO and its dietary precursors, choline and betaine, in heart failure (HF).

METHODS AND RESULTS

In 112 patients with chronic systolic HF with comprehensive echocardiographic evaluation, we measured plasma TMAO, choline, and betaine by mass spectrometry. Median (interquartile range) TMAO levels, choline, and betaine levels were 5.8 (3.6-12.1) μmol/L, 10.9 (8.4-14.0) μmol/L, and 43.8 (37.1-53.0) μmol/L, respectively, and were correlated with each other (all P < .0001 for both). TMAO levels were significantly higher in patients with diabetes mellitus (9.4 [4.9-13.2] vs 4.8 [3.4-9.8] μmol/L; P = .005) and in subjects with New York Heart Association functional class III or greater (7.0 [4.7-14.8] vs 4.7 [3.4-11.3] μmol/L; P = .02). Elevated TMAO, choline, and betaine levels were each associated with higher plasma N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels and more advanced left ventricular diastolic dysfunction, but not systolic dysfunction or inflammatory and endothelial biomarkers. Higher choline (hazard ratio [HR] 1.64, 95% CI 1.22-2.20; P = .001), betaine (HR 1.51, 95% CI 1.10-2.08; P = .01), and TMAO (HR 1.48, 95% CI 1.10-1.96; P = .01) predicted increased risk for 5-year adverse clinical events (death/transplantation). Only higher TMAO levels predicted incident adverse clinical events independently from age, estimated glomerular filtration rate, mitral E/septal Ea, and NT-proBNP levels (HR 1.46, 95% CI 1.03-2.14; P = .03).

CONCLUSION

Elevated plasma TMAO, choline, and betaine levels are each associated with more advanced left ventricular diastolic dysfunction and portend poorer long-term adverse clinical outcomes in chronic systolic HF. However, only higher plasma TMAO was associated with poor prognosis after adjustment for cardiorenal indices.

Endotoxemia in end-stage kidney disease

Chronic unexplained inflammation remains a prevalent and clinically significant problem for patients with end-stage kidney disease (ESKD), especially in the dialysis population. The causes of persistent inflammation are likely to be multifactorial, but the underlying mechanisms remain to be elucidated. Endotoxins are reported to play a significant role in the pathogenesis of inflammation in patients with ESKD. However, blood endotoxin measurement with the Limulus amoebocyte lysate (LAL) assay is difficult with current detection systems. The reported degree and prevalence of endotoxemia varies in the literature. There are questions as to whether endotoxemia is truly present; whether the varied findings are due to methodological issues with the LAL assay and whether any endotoxemia that might be present plays a role in chronic inflammation frequently observed in ESKD patients. This review will discuss the challenges of accurate blood endotoxin detection, the potential source of blood endotoxins, and the significance of endotoxemia to patient with ESKD.

L-Threonine induces heat shock protein expression and decreases apoptosis in heat-stressed intestinal epithelial cells

OBJECTIVES

Osmotically acting amino acids can be cytoprotective following injury. As threonine (THR) induces osmotic cell swelling, our aim was to investigate the potential for THR to induce cellular protection in intestinal epithelial cells and evaluate possible mechanisms of protection.

METHODS

Cells treated with a range of THR doses were evaluated following heat stress (HS) injury. Alpha-aminoisobutyric acid (AIB), a non-metabolizable amino acid analog, was used as an osmotic control. MTS assays were used to assess cell survival. Heat shock protein (HSP) expression and cleaved caspase-3 (CC3) were evaluated via Western blot. Cell morphology and cell size were analyzed via microscopy.

RESULT

Following HS, THR treatment increased cell viability in a dose dependent manner vs. non-THR treated cells (CT). The non-metabolized amino acid analogue, AIB, also increased cell survival in heat-stressed cells versus HS controls. HSP70 and HSP25 expression increased with THR and AIB treatment versus HS controls. THR also increased HSP25 in non-stressed cells. Microscopic evaluation revealed both THR and AIB preserved the structural integrity of the actin cytoskeleton in heat-stressed cells versus HS controls. THR, but not AIB, enhanced nuclear translocation of HSP25 during HS. This nuclear translocation was associated with a 60% decrease in apoptosis in heat-stressed cells with THR. No antiapoptotic effect was observed with AIB.

CONCLUSIONS

This is the first demonstration that THR increases HSP70 and HSP 25 and protects cells from HS. THR's mechanism of protection may involve cytoskeletal stabilization, HSP up-regulation and nuclear translocation, and decreased apoptosis. THR's protection appears to involve both cell-swelling-dependent and -independent processes.

Abdominal contributions to cardiorenal dysfunction in congestive heart failure

Current pathophysiological models of congestive heart failure unsatisfactorily explain the detrimental link between congestion and cardiorenal function. Abdominal congestion (i.e., splanchnic venous and interstitial congestion) manifests in a substantial number of patients with advanced congestive heart failure, yet is poorly defined. Compromised capacitance function of the splanchnic vasculature and deficient abdominal lymph flow resulting in interstitial edema might both be implied in the occurrence of increased cardiac filling pressures and renal dysfunction. Indeed, increased intra-abdominal pressure, as an extreme marker of abdominal congestion, is correlated with renal dysfunction in advanced congestive heart failure. Intriguing findings provide preliminary evidence that alterations in the liver and spleen contribute to systemic congestion in heart failure. Finally, gut-derived hormones might influence sodium homeostasis, whereas entrance of bowel toxins into the circulatory system, as a result of impaired intestinal barrier function secondary to congestion, might further depress cardiac as well as renal function. Those toxins are mainly produced by micro-organisms in the gut lumen, with presumably important alterations in advanced heart failure, especially when renal function is depressed. Therefore, in this state-of-the-art review, we explore the crosstalk between the abdomen, heart, and kidneys in congestive heart failure. This might offer new diagnostic opportunities as well as treatment strategies to achieve decongestion in heart failure, especially when abdominal congestion is present. Among those currently under investigation are paracentesis, ultrafiltration, peritoneal dialysis, oral sodium binders, vasodilator therapy, renal sympathetic denervation and agents targeting the gut microbiota.

Cachexia in chronic heart failure: endocrine determinants and treatment perspectives

It is well documented in the current literature that chronic heart failure is often associated with cachexia, defined as involuntary weight loss of 5 % in 12 month or less. Clinical studies unraveled that the presence of cachexia decreases significantly mean survival of the patient. At the molecular level mainly myofibrillar proteins are degraded, although a reduced protein synthesis may also contribute to the loss of muscle mass. Endocrine factors clearly regulate muscle mass and function by influencing the normally precisely controlled balance between protein breakdown and protein synthesis The aim of the present article is to review the knowledge in the field with respect to the role of endocrine factors for the regulation of cachexia in patients with CHF and deduce treatment perspectives.

Role of the Toll Like receptor (TLR) radical cycle in chronic inflammation: possible treatments targeting the TLR4 pathway

Activation of the Toll-like receptor 4 (TLR4) complex, a receptor of the innate immune system, may underpin the pathophysiology of many human diseases, including asthma, cardiovascular disorder, diabetes, obesity, metabolic syndrome, autoimmune disorders, neuroinflammatory disorders, schizophrenia, bipolar disorder, autism, clinical depression, chronic fatigue syndrome, alcohol abuse, and toluene inhalation. TLRs are pattern recognition receptors that recognize damage-associated molecular patterns and pathogen-associated molecular patterns, including lipopolysaccharide (LPS) from gram-negative bacteria. Here we focus on the environmental factors, which are known to trigger TLR4, e.g., ozone, atmosphere particulate matter, long-lived reactive oxygen intermediate, pentachlorophenol, ionizing radiation, and toluene. Activation of the TLR4 pathways may cause chronic inflammation and increased production of reactive oxygen and nitrogen species (ROS/RNS) and oxidative and nitrosative stress and therefore TLR-related diseases. This implies that drugs or substances that modify these pathways may prevent or improve the abovementioned diseases. Here we review some of the most promising drugs and agents that have the potential to attenuate TLR-mediated inflammation, e.g., anti-LPS strategies that aim to neutralize LPS (synthetic anti-LPS peptides and recombinant factor C) and TLR4/MyD88 antagonists, including eritoran, CyP, EM-163, epigallocatechin-3-gallate, 6-shogaol, cinnamon extract, N-acetylcysteine, melatonin, and molecular hydrogen. The authors posit that activation of the TLR radical (ROS/RNS) cycle is a common pathway underpinning many "civilization" disorders and that targeting the TLR radical cycle may be an effective method to treat many inflammatory disorders.

The intestinal microbiota, a leaky gut, and abnormal immunity in kidney disease

Chronic kidney disease (CKD) and end-stage renal disease (ESRD) are associated with systemic inflammation and acquired immunodeficiency, which promote cardiovascular disease, body wasting, and infections as leading causes of death. This phenomenon persists despite dialysis-related triggers of immune deregulation having been largely eliminated. Here we propose a potential immunoregulatory role of the intestinal microbiota in CKD/ESRD. We discuss how the metabolic alterations of uremia favor pathogen overgrowth (dysbiosis) in the gut and an increased translocation of living bacteria and bacterial components. This process has the potential to activate innate immunity and systemic inflammation. Persistent innate immune activation involves the induction of immunoregulatory mediators that suppress innate and adaptive immunity, similar to the concept of 'endotoxin tolerance' or 'immune paralysis' in advanced sepsis or chronic infections. Renal science has largely neglected the gut as a source of triggers for CKD/ESRD-related immune derangements and complications and lags behind on the evolving microbiota research. Interdisciplinary research activities at all levels are needed to unravel the pathogenic role of the intestinal microbiota in kidney disease and to evaluate if therapeutic interventions that manipulate the microbiota, such as pre- or probiotics, have a therapeutic potential to correct CKD/ESRD-related immune deregulation and to prevent the associated complications.

Intestinal barrier dysfunction links metabolic and inflammatory markers of aging to death in Drosophila

Aging is characterized by a growing risk of disease and death, yet the underlying pathophysiology is poorly understood. Indeed, little is known about how the functional decline of individual organ systems relates to the integrative physiology of aging and probability of death of the organism. Here we show that intestinal barrier dysfunction is correlated with lifespan across a range of Drosophila genotypes and environmental conditions, including mitochondrial dysfunction and dietary restriction. Regardless of chronological age, intestinal barrier dysfunction predicts impending death in individual flies. Activation of inflammatory pathways has been linked to aging and age-related diseases in humans, and an age-related increase in immunity-related gene expression has been reported in Drosophila. We show that the age-related increase in expression of antimicrobial peptides is tightly linked to intestinal barrier dysfunction. Indeed, increased antimicrobial peptide expression during aging can be used to identify individual flies exhibiting intestinal barrier dysfunction. Similarly, intestinal barrier dysfunction is more accurate than chronological age in identifying individual flies with systemic metabolic defects previously linked to aging, including impaired insulin/insulin-like growth factor signaling, as evidenced by a reduction in Akt activation and up-regulation of dFOXO target genes. Thus, the age-dependent loss of intestinal integrity is associated with altered metabolic and immune signaling and, critically, is a harbinger of death. Our findings suggest that intestinal barrier dysfunction may be an important factor in the pathophysiology of aging in other species as well, including humans.

Increased IgA and IgM responses against gut commensals in chronic depression: further evidence for increased bacterial translocation or leaky gut

BACKGROUND

Recently, we discovered that depression is accompanied by increased IgM and IgA responses directed against gram negative gut commensals. The aim of this study was to replicate these findings in a larger study group of depressed patients and to examine the associations between the IgA and IgM responses to gut commensals and staging of depression as well as the fatigue and somatic (F&S) symptoms of depression.

METHODS

We measured serum concentrations of IgM and IgA against the LPS of gram-negative enterobacteria, i.e. Hafnia alvei, Pseudomonas aeruginosa, Morganella morganii, Pseudomonas putida, Citrobacter koseri, and Klebsiella pneumoniae in 112 depressed patients and 28 normal controls. The severity of F&S symptoms was measured using the Fibromyalgia and Chronic Fatigue Syndrome Rating Scale.

RESULTS

The prevalences and median values of serum IgM and IgA against LPS of these commensals were significantly higher in depressed patients than in controls. The IgM levels directed against the LPS of these commensal bacteria were significantly higher in patients with chronic depression than in those without. The immune responses directed against LPS were not associated with melancholia or recurrent depression. There was a significant correlation between the IgA response directed against LPS and gastro-intestinal symptoms.

DISCUSSION

The results indicate that increased bacterial translocation with immune responses to the LPS of commensal bacteria may play a role in the pathophysiology of depression, particularly chronic depression. Bacterial translocation may a) occur secondary to systemic inflammation in depression and intensify and perpetuate the primary inflammatory response once the commensals are translocated; or b) be a primary trigger factor associated with the onset of depression in some vulnerable individuals. The findings suggest that "translocated" gut commensal bacteria activate immune cells to elicit IgA and IgM responses and that this phenomenon may play a role in the pathophysiology of (chronic) depression by causing progressive amplifications of immune pathways.

Cardiorenal syndrome type 1: pathophysiological crosstalk leading to combined heart and kidney dysfunction in the setting of acutely decompensated heart failure

Cardiorenal syndrome (CRS) type 1 is characterized as the development of acute kidney injury (AKI) and dysfunction in the patient with acute cardiac illness, most commonly acute decompensated heart failure (ADHF). There is evidence in the literature supporting multiple pathophysiological mechanisms operating simultaneously and sequentially to result in the clinical syndrome characterized by a rise in serum creatinine, oliguria, diuretic resistance, and in many cases, worsening of ADHF symptoms. The milieu of chronic kidney disease has associated factors including obesity, cachexia, hypertension, diabetes, proteinuria, uremic solute retention, anemia, and repeated subclinical AKI events all work to escalate individual risk of CRS in the setting of ADHF. All of these conditions have been linked to cardiac and renal fibrosis. In the hospitalized patient, hemodynamic changes leading to venous renal congestion, neurohormonal activation, hypothalamic-pituitary stress reaction, inflammation and immune cell signaling, systemic endotoxemic exposure from the gut, superimposed infection, and iatrogenesis all contribute to CRS type 1. The final common pathway of bidirectional organ injury appears to be cellular, tissue, and systemic oxidative stress that exacerbate organ function. This review explores in detail the pathophysiological pathways that put a patient at risk and then effectuate the vicious cycle now recognized as CRS type 1.

Increased intestinal permeability and Parkinson disease patients: chicken or egg?

Gastrointestinal involvement is a frequent and early event in the course of Parkinson Disease (PD), and may have a prominent role in the early pathophysiology of the disease. On the other hand, derangement in intestinal permeability could also result from the involvement of the gastrointestinal tract over the course of the disease.

PATIENTS AND METHODS

The intestinal permeability of 12 non-selected PD patients was studied using a validated, non-invasive test; these results were compared to predefined age-adjusted reference values.

RESULTS

4/12 PD patients had abnormal gastrointestinal permeability; two had both an abnormal lactulose/mannitol ratio and an abnormal sucrose concentration, and two an isolated abnormal result. An increased lactulose/mannitol ratio is consistent with defect of either the enterocytes or the tight junctions between them.

CONCLUSION

Intestinal permeability is increased in a significant proportion of unselected PD patients with minimal gastrointestinal symptoms. The significance of this finding needs to be further evaluated.

The differential effects of recombinant brain natriuretic peptide, nitroglycerine and dihydralazine on systemic oxygen delivery and gastric mucosal microvascular oxygenation in dogs

Brain natriuretic peptide has vasodilatory properties and may thus increase splanchnic perfusion and oxygenation. We compared the effects of recombinant brain natriuretic peptide on gastric mucosal microvascular haemoglobin oxygenation (reflectance spectrophotometry) and systemic variables with those of equi-hypotensive doses of two other vasodilators (nitroglycerine and dihydralazine). Chronically instrumented, healthy dogs were randomly allocated to receive on different days, one of the three drugs (nitroglycerine and dihydralazine doses titrated to reduce mean arterial pressure by ∼20%). Brain natriuretic peptide significantly increased gastric mucosal microvascular haemoglobin oxygenation selectively, i.e. without concomitant haemodynamic effects. In contrast, the other vasodilators either did not increase gastric mucosal microvascular haemoglobin oxygenation at all (nitroglycerine), or did so only with marked increases in other systemic haemodynamic variables (dihydralazine). Our data suggest a potential role of recombinant brain natriuretic peptide selectively for increasing microvascular mucosal oxygenation. Studies are required to extend these findings to the clinical setting.

Cardio-renal cachexia syndromes (CRCS): pathophysiological foundations of a vicious pathological circle

Cardio-renal syndromes (CRS) are defined as disorders of the heart and kidney whereby acute or chronic dysfunction in one organ may induce acute or chronic dysfunction of the other. CRS have been classified into five categories, where types 2 and 4 represent respectively chronic cardio-renal and chronic reno-cardiac syndromes. In these conditions, the chronic disorder of either the heart or kidney has been shown to induce some degree of cachexia. At the same time, cachexia has been proposed as a possible mechanism contributing to the worsening of such pathological organ cross talk. Common pathogenetic mechanisms underlie body wasting in cachectic states of different chronic heart and kidney diseases. In these circumstances, a vicious circle could arise, in which cachexia associated with either heart failure or chronic kidney disease may contribute to further damage of the other organ. In chronic CRS, activation of the immune and neuroendocrine systems contributes to the genesis of cachexia, which in turn can negatively affect the heart and kidney function. In patients with cardiac sustained activation of the immune and neuroendocrine systems and oxidative stress, renal vascular resistance can increase and therefore impair renal perfusion, leading to worsening kidney function. Similarly, in renal cachexia, increased levels of pro-inflammatory cytokines can cause progressive left ventricular systolic dysfunction, myocardial cell death, endothelial dysfunction and increased myocardial fibrosis, with consequent impairment of the chronic reno-cardiac syndrome type 4. Thus, we speculate that the occurrence of different types of chronic CRS could represent a fundamental step in the genesis of cachexia, being renal and cardiac dysfunction closely related to the occurrence of systemic disorders leading to a final common pathway. Therefore, the heart and kidney and cachexia represent a triad causing a vicious circle that increases mortality and morbidity: In such circumstances, we may plausibly talk about cardio-renal cachexia syndrome. Complex interrelations may explain the transition from CRS to cachexia and from cachexia to CRS. Identification of the exact mechanisms occurring in these conditions could potentially help in preventing and treating this deadly combination.

Obesity and the gut microbiota: does up-regulating colonic fermentation protect against obesity and metabolic disease?

Obesity is now considered a major public health concern globally as it predisposes to a number of chronic human diseases. Most developed countries have experienced a dramatic and significant rise in obesity since the 1980s, with obesity apparently accompanying, hand in hand, the adoption of "Western"-style diets and low-energy expenditure lifestyles around the world. Recent studies report an aberrant gut microbiota in obese subjects and that gut microbial metabolic activities, especially carbohydrate fermentation and bile acid metabolism, can impact on a number of mammalian physiological functions linked to obesity. The aim of this review is to present the evidence for a characteristic "obese-type" gut microbiota and to discuss studies linking microbial metabolic activities with mammalian regulation of lipid and glucose metabolism, thermogenesis, satiety, and chronic systemic inflammation. We focus in particular on short-chain fatty acids (SCFA) produced upon fiber fermentation in the colon. Although SCFA are reported to be elevated in the feces of obese individuals, they are also, in contradiction, identified as key metabolic regulators of the physiological checks and controls mammals rely upon to regulate energy metabolism. Most studies suggest that the gut microbiota differs in composition between lean and obese individuals and that diet, especially the high-fat low-fiber Western-style diet, dramatically impacts on the gut microbiota. There is currently no consensus as to whether the gut microbiota plays a causative role in obesity or is modulated in response to the obese state itself or the diet in obesity. Further studies, especially on the regulatory role of SCFA in human energy homeostasis, are needed to clarify the physiological consequences of an "obese-style" microbiota and any putative dietary modulation of associated disease risk.

Gastrointestinal lymphatics in health and disease

Lymphatics perform essential transport and immune regulatory functions to maintain homeostasis in the gastrointestinal (GI) system. Although blood and lymphatic vessels function as parallel and integrated systems, our understanding of lymphatic structure, regulation and functioning lags far behind that of the blood vascular system. This chapter reviews lymphatic flow, differences in lymphangiogenic and hemangiogenic factors, lymphatic fate determinants and structural features, and examines how altered molecular signaling influences lymphatic function in organs of the GI system. Innate errors in lymphatic development frequently disturb GI functioning and physiology. Expansion of lymphatics, a prominent feature of GI inflammation, may also play an important role in tissue restitution following injury. Destruction or dysregulation of lymphatics, following injury, surgery or chronic inflammation also exacerbates GI disease activity. Understanding the physiological roles played by GI lymphatics is essential to elucidating their underlying contributions to forms of congenital and acquired forms of GI pathology, and will provide novel approaches for therapy.

Multiple aberrations in shared inflammatory and oxidative & nitrosative stress (IO&NS) pathways explain the co-association of depression and cardiovascular disorder (CVD), and the increased risk for CVD and due mortality in depressed patients

There is evidence that there is a bidirectional relationship between major depression and cardiovascular disorder (CVD): depressed patients are a population at risk for increased cardiac morbidity and mortality, and depression is more frequent in patients who suffer from CVD. There is also evidence that inflammatory and oxidative and nitrosative stress (IO&NS) pathways underpin the common pathophysiology of both CVD and major depression. Activation of these pathways may increase risk for both disorders and contribute to shared risk. The shared IO&NS pathways that may contribute to CVD and depression comprise the following: increased levels of pro-inflammatory cytokines, like interleukin-1β (IL-1β), IL-2, IL-6, IL-8, IL-12, tumor necrosis factor-α, and interferon-γ; T cell activation; increased acute phase proteins, like C-reactive protein, haptoglobin, fibrinogen and α1-antitrypsin; complement factors; increased LPS load through bacterial translocation and subsequent gut-derived inflammation; induction of indoleamine 2,3-dioxygenase with increased levels of tryptophan catabolites; decreased levels of antioxidants, like coenzyme Q10, zinc, vitamin E, glutathione and glutathione peroxidase; increased O&NS characterized by oxidative damage to low density lipoprotein (LDL) and phospholipid inositol, increased malondialdehyde, and damage to DNA and mitochondria; increased nitrosative stress; and decreased ω3 polyunsaturated fatty acids (PUFAs). The complex interplay between the abovementioned IO&NS pathways in depression results in pro-atherogenic effects and should be regarded as a risk factor to future clinical CVD and due mortality. We suggest that major depression should be added as a risk factor to the Charlson "comorbidity" index. It is advised that patients with (sub)chronic or recurrent major depression should routinely be assessed by serology tests to predict if they have an increased risk to cardiovascular disorders.

Correction of iron deficiency in the cardiorenal syndrome

Impaired energy metabolism is a feature of Congestive Heart Failure (CHF). Iron deficiency has been shown to reduce energy production in the cell in animals and humans. Iron deficiency is common in both Chronic Kidney Disease (CKD) and in CHF. Recent studies suggest that iron deficiency is an independent risk factor for mortality in CHF. Studies of correction of the anemia with intravenous (IV) iron in both CKD and CHF have shown an improvement in the anemia and, in some cases, in the renal function as well. Some CHF studies of correction of the iron deficiency have shown an improvement in cardiac function and structure as well as in exercise capacity and quality of life. This occurred independent of whether or not they had anemia, suggesting that the iron deficiency itself may be independently contributing to the worsening of the CHF and CKD. If future long-term studies confirm the safety and efficacy of IV iron in the treatment of iron deficiency in CKD and CHF, this will become a new addition to the therapeutic armamentarium of the cardiorenal syndrome, and parameters of iron deficiency will become part of the routine measurements performed in both CKD and CHF whether or not the patient is anemic.

Innate immunity and remodelling

A wide variety of cardiac disease states can induce remodelling and lead to the functional consequence of heart failure. These complex disease states involve a plethora of parallel signal transduction events, which may be associated with tissue injury or tissue repair. Innate immunity is activated in hearts injured in different ways, evident as cytokine release from the heart, activation of toll-like receptors involved in recognizing danger, and activation of the transcription factor nuclear factor kappa B. Nuclear factor kappa B regulates gene programmes involved in inflammation as well as the resolution of inflammation. The impact of this is an enigma; while cytokines, toll-like receptors, and nuclear factor kappa B appear to elicit myocardial protection in studies of preconditioning, the literature strongly indicates a detrimental role for activation of innate immunity in studies of acute ischaemia–reperfusion injury. The impact of activation of cardiac innate immunity on the long-term outcome in in vivo models of hypertrophy and remodelling is less clear, with conflicting results as to whether it is beneficial or detrimental. More research using genetically engineered mice as tools, different models of evoking remodelling, and long-term follow-up is required for us to conclude whether activation of the innate immune system is good, bad, or unimportant in chronic injury models.

TNFα in myocardial ischemia/reperfusion, remodeling and heart failure

TNFα is crucially involved in the pathogenesis and progression of myocardial ischemia/reperfusion injury and heart failure. The formation and release of TNFα and its downstream signal transduction cascade following activation of its two receptor subtypes are characterized. Myocardial TNFα and TNF receptor activation have an ambivalent role in myocardial ischemia/reperfusion injury and protection from it. Excessive TNFα expression and subsequent cardiomyocyte TNF receptor type 1 stimulation induce contractile dysfunction, hypertrophy, fibrosis and cell death, while a lower TNFα concentration and subsequent cardiomyocyte TNF receptor type 2 stimulation are protective. Apart from its concentration and receptor subtype, the myocardial action of TNFα depends on the duration of its exposure and its localization. While detrimental during sustained ischemia, TNFα contributes to ischemic preconditioning protection, no matter whether it is the first, second or third window of protection, and both TNF receptors are involved in the protective signal transduction cascade. Finally, the available clinical attempts to antagonize TNFα in cardiovascular disease, notably heart failure, are critically discussed.

The difficult patient: drug interaction and the influence of concomitant diseases on the treatment of hypothyroidism

Although most hypothyroid patients do well with one single tablet of thyroxine daily, approximately 10% are dissatisfied and another important group of patients is difficult to control. We reviewed the most common causes for frequent-dose adjustment or high-dose requirement, including poor compliance with therapy and inadequate medication. Since these two causes have been ruled out, drug interaction and other concomitant diseases need to be investigated. Requirements of thyroxine increase in all conditions characterized by impaired gastric acid secretion. Proton-pump inhibitors, antacids and a long list of drugs may decrease thyroxine absorption. In addition, a series of diseases including celiac disease and chronic inflammatory intestinal diseases, as well as nutritional habits may be important in patient control. Finally, we mention the effects of a growing list of drugs and thyroid disruptors that may also affect thyroid hormone metabolism at many levels.

Human schistosomiasis is associated with endotoxemia and Toll-like receptor 2- and 4-bearing B cells

Schistosomiasis is caused by parasitic trematodes. Individuals can accumulate hundreds of intravascular worms, which secrete a myriad of antigenic molecules into the bloodstream. Some of these molecules suppress immunity to microbial Toll-like receptor (TLR) ligands, such as lipopolysaccharides, which may increase host susceptibility to coinfecting pathogens. We show that schistosomiasis is associated with extremely high levels of endotoxemia as well as high mobility group 1, an endogenous inflammatory TLR ligand, in the absence of other coinfected pathogens. Circulating B cells express surface TLR2 and TLR4, reflecting systemic exposure to microbial ligands. Bacterial translocation may occur with schistosomal egg movement from the vascular to the gut and other routes, such as the skin during infection. Our report suggests that immunosuppressive schistosome antigens may have evolved to curb inflammatory responses to the high antigenic burden of translocated bacteria products and endogenous TLR ligands that arise during parasite exposure and inflammation.

The effects of levosimendan and glibenclamide on circulatory and metabolic variables in a canine model of acute hypoxia

PURPOSE

To study the effects of pretreatment with levosimendan (LEVO, a Ca²(+)-sensitizer and K (ATP) (+) channel opener) and/or the K (ATP) (+) channel antagonist glibenclamide (GLIB) on systemic hemodynamics, metabolism, and regional gastromucosal oxygenation during hypoxic hypoxemia.

METHODS

Chronically instrumented, healthy dogs (24-32 kg, n = 6 per group, randomized cross-over design) were repeatedly sedated, mechanically ventilated (FiO₂ ~0.3) and subjected to the following interventions: no pretreatment, LEVO pretreatment, GLIB pretreatment, or combined LEVO + GLIB pretreatment, each followed by hypoxic hypoxemia (FiO₂ ~0.1). We measured cardiac output (CO, ultrasonic flow probes), oxygen consumption (VO₂, indirect calorimetry), and gastromucosal microvascular hemoglobin oxygenation (μHbO₂, spectrophotometry).

STATISTICS

data are presented as mean ± SEM and compared by one-way ANOVA (direct drug effects within group) and two-way ANOVA (between all hypoxic conditions) both with Bonferroni corrections; p < 0.05.

RESULTS

In LEVO-pretreated hypoxemia, CO was significantly higher compared to unpretreated hypoxemia. The increased CO was neither associated with an increased VO₂ nor with markers of aggravated anaerobiosis (pH, BE, lactate). In addition, LEVO pretreatment did not further compromise gastromucosal μHbO₂ in hypoxemia. After combined LEVO + GLIB pretreatment, systemic effects of GLIB were apparent, however, CO was significantly higher than during unpretreated and GLIB-pretreated hypoxemia, but equal to LEVO-pretreated hypoxemia, indicating that GLIB did not prevent the increased CO in LEVO-pretreated hypoxia.

CONCLUSIONS

LEVO pretreatment resulted in improved systemic circulation (CO) during hypoxemia without fueling systemic VO₂, without aggravating systemic anaerobiosis markers, and without further compromising microvascular gastromucosal oxygenation. Thus, LEVO pretreatment may be an option to support the systemic circulation during hypoxia.

Lactobacillus plantarum MB452 enhances the function of the intestinal barrier by increasing the expression levels of genes involved in tight junction formation

Background

Intestinal barrier function is important for preserving health, as a compromised barrier allows antigen entry and can induce inflammatory diseases. Probiotic bacteria can play a role in enhancing intestinal barrier function; however, the mechanisms are not fully understood. Existing studies have focused on the ability of probiotics to prevent alterations to tight junctions in disease models, and have been restricted to a few tight junction bridging proteins. No studies have previously investigated the effect of probiotic bacteria on healthy intestinal epithelial cell genes involved in the whole tight junction signalling pathway, including those encoding for bridging, plaque and dual location tight junction proteins. Alteration of tight junction signalling in healthy humans is a potential mechanism that could lead to the strengthening of the intestinal barrier, resulting in limiting the ability of antigens to enter the body and potentially triggering undesirable immune responses.

Results

The effect of Lactobacillus plantarum MB452 on tight junction integrity was determined by measuring trans-epithelial electrical resistance (TEER) across Caco-2 cell layers. L. plantarum MB452 caused a dose-dependent TEER increase across Caco-2 cell monolayers compared to control medium. Gene expression was compared in Caco-2 cells untreated or treated with L. plantarum MB452 for 10 hours. Caco-2 cell RNA was hybridised to human oligonucleotide arrays. Data was analysed using linear models and differently expressed genes were examined using pathway analysis tools. Nineteen tight junction-related genes had altered expression levels in response to L. plantarum MB452 (modified-P < 0.05, fold-change > 1.2), including those encoding occludin and its associated plaque proteins that anchor it to the cytoskeleton. L. plantarum MB452 also caused changes in tubulin and proteasome gene expression levels which may be linked to intestinal barrier function. Caco-2 tight junctions were visualised by fluorescent microscopy of immuno-stained occludin, zona occludens (ZO)-1, ZO-2 and cingulin. Caco-2 cells treated with L. plantarum MB452 had higher intensity fluorescence of each of the four tight junction proteins compared to untreated controls.

Conclusions

This research indicates that enhancing the expression of genes involved in tight junction signalling is a possible mechanism by which L. plantarum MB452 improves intestinal barrier function.

Lactobacillus plantarum DSM 2648 is a potential probiotic that enhances intestinal barrier function

The aim of this research was to identify bacterial isolates having the potential to improve intestinal barrier function. Lactobacillus plantarum strains and human oral isolates were screened for their ability to enhance tight junction integrity as measured by the transepithelial electrical resistance (TEER) assay. Eight commercially used probiotics were compared to determine which had the greatest positive effect on TEER, and the best-performing probiotic strain, Lactobacillus rhamnosus HN001, was used as a benchmark to evaluate the isolates. One isolate, L. plantarum DSM 2648, was selected for further study because it increased TEER 135% more than L. rhamnosus HN001. The ability of L. plantarum DSM 2648 to tolerate gastrointestinal conditions and adhere to intestinal cells was determined, and L. plantarum DSM 2648 performed better than L. rhamnosus HN001 in all the assays. Lactobacillus plantarum DSM 2648 was able to reduce the negative effect of Escherichia coli [enteropathogenic E. coli (EPEC)] O127:H6 (E2348/69) on TEER and adherence by as much as 98.75% and 80.18%, respectively, during simultaneous or prior coculture compared with EPEC incubation alone. As yet, the precise mechanism associated with the positive effects exerted by L. plantarum DSM 2648 are unknown, and may influence its use to improve human health and wellness.

Nutrition in heart failure: an update

PURPOSE OF REVIEW

Chronic heart failure (CHF) is increasingly recognized as a multisystem disease with important comorbidities such as anemia, insulin resistance, autonomic dysbalance, or cardiac cachexia.

RECENT FINDINGS

Apart from these perturbations, increasing evidence points to alterations in intestinal morphology, permeability, and absorption function in patients with CHF. This review provides an overview of the sonographic, histological, and functional abnormalities of different gastrointestinal regions. This intestinal dysfunction and disturbed intestinal barrier may lead to both the chronic inflammatory state and catabolic/anabolic imbalance as seen in cardiac cachexia, as a terminal stage of CHF, which carries a particularly poor prognosis. This review highlights the current knowledge of nutritional abnormalities that may occur in CHF, including fat, carbohydrates, proteins, water, and micronutrients. The regulation of feeding is discussed, as are nutritional strategies with potentially anti-inflammatory effects in the treatment of CHF.

SUMMARY

The gut and its role for inflammation and dietary interventions in heart failure patients are a crucial target of further heart failure research.

Recent insights on chronic heart failure, cachexia and nutrition

PURPOSE OF REVIEW

To provide recent observations on the interrelation between chronic heart failure (CHF), cachexia and human nutrition and updating epidemiological issues in CHF.

RECENT FINDINGS

Present evidence suggests that impairment in cardiac muscle energetics plays an important role in the pathogenesis of heart failure. New concepts such as microRNA expression are emerging as potential agents in heart failure. Recent research suggests mechanisms by which inflammatory catabolic states may persist in the presence of adequate growth factors and nutrition. A consensus panel has recently designed a definition for general cachexia and its stratification. Together with classicals, new nutrients and substrates are showing efficacies in the malnutrition associated with CHF. Although still promising, ghrelin, growth factors and other biological compounds maintain emergent therapeutical positions for heart failure or associated catabolic states or both.

SUMMARY

Altered intestinal function as an agent for CHF is rising in evidence. New techniques to well diagnose and stratify malnutrition and cardiac cachexia in CHF are needed. Treatment of cachexia in CHF appears to be a combination of different approaches, in which metabolic, nutritional, immunological and hormonal strategies may play an important role. Although the current experimental research is of great help, well designed randomized controlled trials are needed to test these hypothesis and generate clinical evidence.