Dietary strategies can increase cloacal endotoxin levels and modulate the resident microbiota in broiler chickens

Endotoxins released from poultry feces have been associated with impaired human health. Because endotoxins are released from gram-negative intestinal bacteria, it was hypothesized that dietary strategies may influence endotoxin excretion via modulation of gut microbiota. We therefore tested dietary strategies that could potentially reduce cloacal endotoxin levels in broiler chickens. One-day-old male Ross 308 (N = 1,344) broilers were housed in 48 pens (N = 8 pens/treatment, 28 chickens per pen) and fed 1 of 6 diets for 35 days (d) in a 3-phase feeding program: a basic diet (CON) that served as the reference diet, or basic diet supplemented with butyrate (BUT), inulin (INU), medium-chain fatty acids (MCFA) or Original XPC™LS (XPC), or a high-fiber-low-protein (HF-LP) diet. A significant (P < 0.05) increase in cloacal endotoxin concentration at d 35 was observed in BUT as compared to CON. Analysis of cloacal microbiota showed a trend (P < 0.07) for a higher gram-negative/gram-positive ratio and for a higher relative abundance of gram-negative bacteria at d 35 (P ≤ 0.08) in BUT and HF-LP as compared to CON. A significant (P < 0.05) increase in average daily gain (ADG) and improved feed conversion ratio (P < 0.05) were observed in MCFA during the grower phase (d 14-28), and a significant (P < 0.05) increase in average daily feed intake (ADFI) was observed in MCFA during d 0 to 28. Broilers fed HF-LP had a significantly (P < 0.05) higher FCR and lower ADG throughout the rearing period. No treatment effects were found on footpad dermatitis, but BUT had worst hock burn scores at d 35 (P < 0.01) and MCFA had worst cleanliness scores at d 21 but not at d 35 (treatment*age P < 0.05), while INU had better cleanliness as compared to CON at d 35 (P < 0.05). In conclusion, especially BUT and HF-LP were able to modulate resident microbiota and BUT also increased cloacal endotoxin levels, which was opposite to our hypothesis. The present study indicates that cloacal endotoxin release can be affected by the diet but further study is needed to find dietary treatments that can reduce cloacal endotoxin release.

Gut Microbiome Signatures Are Predictive of Cognitive Impairment in Hypertension Patients—A Cohort Study

Growing evidence has demonstrated that hypertension was associated with dysbiosis of intestinal flora. Since intestinal microbes could critically regulate neurofunction via the intestinal–brain axis, the study aimed to reveal the role and prediction value of intestinal flora alteration in hypertension-associated cognitive impairment. A cohort of 97 participants included 63 hypertension patients and 34 healthy controls. The structure of intestinal flora was analyzed by V3–V4 16S rRNA amplicon sequencing. The cognitive function was assessed using the Montreal Cognitive Assessment (MoCA) scale, and 31 patients were considered to have cognitive impairment (MoCA &lt; 26). Patients with cognitive impairment had considerable alterations in intestinal flora structure, composition, and function compared with normal-cognitive patients. In particular, the abundance of LPS-containing taxa (Proteobacteria, Gammaproteobacteria, Enterobacterales, Enterobacteriaceae, and Escherichia–Shigella) and SCFA-producing taxon (Prevotella) significantly changed in cognition-impaired patients. Tax4Fun predication results showed downregulation of glycan biosynthesis and metabolism in hypertension patients with cognitive impairment. Additionally, the pathway was demonstrated to be significantly correlated with LPS-containing taxa (Proteobacteria, Gammaproteobacteria, Enterobacterales, Enterobacteriaceae, and Escherichia–Shigella) and SCFA-producing taxon Prevotella. Furthermore, the taxa-based multiple joint prediction model (9×) was demonstrated to have excellent diagnostic potential for cognitive impairment of hypertension patients (AUC = 0.944). The current study revealed the involvement of intestinal microbiota dysbiosis in cognition-impaired hypertension patients and provided an objective predictive index for this cognition disorder.

Pulmonary Retention of Adipose Stromal Cells Following Intravenous Delivery Is Markedly Altered in the Presence of ARDS

Transplantation of mesenchymal stromal cells (MSCs) has been shown to effectively prevent lung injury in several preclinical models of acute respiratory distress syndrome (ARDS). Since MSC therapy is tested in clinical trials for ARDS, there is an increased need to define the dynamics of cell trafficking and organ-specific accumulation. We examined how the presence of ARDS changes retention and organ-specific distribution of intravenously delivered MSCs isolated from subcutaneous adipose tissue [adipose-derived stem cells (ADSCs)]. This type of cell therapy was previously shown to ameliorate ARDS pathology. ARDS was triggered by lipopolysaccharide (LPS) aspiration, 4 h after which 300,000 murine CRE⁺ ADSCs were delivered intravenously. The distribution of ADSCs in the lungs and other organs was assessed by real-time polymerase chain reaction (PCR) of genomic DNA. As anticipated, the majority of delivered ADSCs accumulated in the lungs of both control and LPS-challenged mice, with minor amounts distributed to the liver, kidney, spleen, heart, and brain. Interestingly, within 2 h following ADSC administration, LPS-challenged lungs retained significantly lower levels of ADSCs compared to control lungs (∼7% vs. 15% of the original dose, respectively), whereas the liver, kidney, spleen, and brain of ARDS-affected animals retained significantly higher numbers of ADSCs compared to control animals. In contrast, 48 h later, only LPS-challenged lungs continued to retain ADSCs (∼3% of the original dose), whereas the lungs of control animals and nonpulmonary organs in either control or ARDS mice had no detectable levels of ADSCs. Our data suggest that the pulmonary microenvironment during ARDS may lessen the pulmonary capillary occlusion by MSCs immediately following cell delivery while facilitating pulmonary retention of the cells.

Pulmonary arterial hypertension (ascites syndrome) in broilers: a review

Pulmonary arterial hypertension (PAH) syndrome in broilers (also known as ascites syndrome and pulmonary hypertension syndrome) can be attributed to imbalances between cardiac output and the anatomical capacity of the pulmonary vasculature to accommodate ever-increasing rates of blood flow, as well as to an inappropriately elevated tone (degree of constriction) maintained by the pulmonary arterioles. Comparisons of PAH-susceptible and PAH-resistant broilers do not consistently reveal differences in cardiac output, but PAH-susceptible broilers consistently have higher pulmonary arterial pressures and pulmonary vascular resistances compared with PAH-resistant broilers. Efforts clarify the causes of excessive pulmonary vascular resistance have focused on evaluating the roles of chemical mediators of vasoconstriction and vasodilation, as well as on pathological (structural) changes occurring within the pulmonary arterioles (e.g., vascular remodeling and pathology) during the pathogenesis of PAH. The objectives of this review are to (1) summarize the pathophysiological progression initiated by the onset of pulmonary hypertension and culminating in terminal ascites; (2) review recent information regarding the factors contributing to excessively elevated resistance to blood flow through the lungs; (3) assess the role of the immune system during the pathogenesis of PAH; and (4) present new insights into the genetic basis of PAH. The cumulative evidence attributes the elevated pulmonary vascular resistance in PAH-susceptible broilers to an anatomically inadequate pulmonary vascular capacity, to excessive vascular tone reflecting the dominance of pulmonary vasoconstrictors over vasodilators, and to vascular pathology elicited by excessive hemodynamic stress. Emerging evidence also demonstrates that the pathogenesis of PAH includes characteristics of an inflammatory/autoimmune disease involving multifactorial genetic, environmental, and immune system components. Pulmonary arterial hypertension susceptibility appears to be multigenic and may be manifested in aberrant stress sensitivity, function, and regulation of pulmonary vascular tissue components, as well as aberrant activities of innate and adaptive immune system components. Major genetic influences and high heritabilities for PAH susceptibility have been demonstrated by numerous investigators. Selection pressures rigorously focused to challenge the pulmonary vascular capacity readily expose the genetic basis for spontaneous PAH in broilers. Chromosomal mapping continues to identify regions associated with ascites susceptibility, and candidate genes have been identified. Ongoing immunological and genomic investigations are likely to continue generating important new knowledge regarding the fundamental biological bases for the PAH/ascites syndrome.

Broiler pulmonary hypertensive responses during lipopolysaccharide-induced tolerance and cyclooxygenase inhibition

Bacterial lipopolysaccharide (LPS, endotoxin) triggers pulmonary hypertension (PH) characterized by an increase in pulmonary arterial pressure (PAP) that reaches a peak value within 20 to 25 min and then gradually subsides within 60 min. As the PAP subsides PH cannot be reinitiated, signifying the onset of a period of tolerance (refractoriness) to repeated LPS exposure. The present study was conducted to determine the duration of this tolerance, and to evaluate key mediators thought to contribute to LPS-mediated PH in broilers. Tolerance was shown to persist for 4 to 5 d after the initial exposure to LPS. In tolerant broilers supramaximal i.v. injections of LPS did not reinitiate PH, nor was a significant modulatory role for nitric oxide demonstrated. The pulmonary vasculature of tolerant broilers remains responsive to the thromboxane A(2) (TxA(2)) mimetic U44069, 5-hydroxytryptamine (5-HT, serotonin), and constitutive nitric oxide. Meclofenamate successfully blocked the conversion of arachidonic acid to vasoconstrictive eicosanoids such as TxA(2); nevertheless, meclofenamate failed to inhibit PH in response to LPS. Therefore, TxA(2) does not appear to be the primary vasoconstrictor involved in the PH response to LPS and neither does 5-HT. Broilers emerging from tolerance 5 d after the initial exposure to LPS exhibited interindividual variation in their PH responsiveness to a second LPS injection, ranging from zero response (individuals that remain fully tolerant) to large increases in PAP (post-tolerant individuals). Tolerance might be an important compensatory or protective mechanism for broilers whose pulmonary vascular capacity is marginally adequate under optimal conditions, and whose respiratory systems are chronically challenged with LPS in commercial production facilities. The key vasoconstrictors responsible for the PH elicited by LPS remain to be determined.