Human fecal alpha-glucosidase activity and its relationship with gut microbiota profiles and early stages of intestinal mucosa damage

OBJECTIVES

We investigated potential relationships among initial lesions of the intestinal mucosa, fecal enzymatic activities and microbiota profiles.

METHODS

Fecal samples from 54 volunteers were collected after recruitment among individuals participating in a colorectal cancer (CRC) screening program in our region (Northern Spain) or attending for consultation due to clinical symptoms; intestinal mucosa samples were resected during colonoscopy. Enzymatic activities were determined in fecal supernatants by a semi-quantitative method. The fecal microbiota composition was determined by 16S rRNA gene-based sequencing. The results were compared between samples from clinical diagnosis groups (controls and polyps), according with the type of polyp (hyperplastic polyps or conventional adenomas) and considering the grade of dysplasia for conventional adenomas (low and high grade dysplasia).

RESULTS

High levels of α-glucosidase activity were more frequent among samples from individuals diagnosed with intestinal polyps, reaching statistical significance for conventional adenomas and for low grade dysplasia adenomas when compared to controls. Regarding the microbiota profiles, higher abundance of Christensenellaceae_R-7 group and Oscillospiraceae_UCG-002 were found in fecal samples displaying low α-glucosidase activity as compared with those with higher activity as well as in controls with respect to conventional adenomas. A relationship was evidenced among intestinal mucosal lesions, gut glucosidase activities and intestinal microbiota profiles.

CONCLUSIONS

Our findings suggest a relationship among altered fecal α-glucosidase levels, the presence of intestinal mucosal lesions, which can be precursors of CRC, and shifts in defined microbial groups of the fecal microbiota.

Commensal Fecal Microbiota Profiles Associated with Initial Stages of Intestinal Mucosa Damage: A Pilot Study

Progressive intestinal mucosal damage occurs over years prior to colorectal cancer (CRC) development. The endoscopic screening of polyps and histopathological examination are used clinically to determine the risk and progression of mucosal lesions. We analyzed fecal microbiota compositions using 16S rRNA gene-based metataxonomic analyses and the levels of short-chain fatty acids (SCFAs) using gas chromatography in volunteers undergoing colonoscopy and histopathological analyses to determine the microbiota shifts occurring at the early stages of intestinal mucosa alterations. The results were compared between diagnosis groups (nonpathological controls and polyps), between samples from individuals with hyperplastic polyps or conventional adenomas, and between grades of dysplasia in conventional adenomas. Some microbial taxa from the Bacillota and Euryarchaeota phyla were the most affected when comparing the diagnosis and histopathological groups. Deeper microbiota alterations were found in the conventional adenomas than in the hyperplastic polyps. The Ruminococcus torques group was enriched in both the hyperplastic polyps and conventional adenomas, whereas the family Eggerthellaceae was enriched only in the hyperplastic polyps. The abundance of Prevotellaceae, Oscillospiraceae, Methanobacteriaceae, Streptococcaceae, Christensenellaceae, Erysipelotrichaceae, and Clostridiaceae shifted in conventional adenomas depending on the grade of dysplasia, without affecting the major SCFAs. Our results suggest a reorganization of microbial consortia involved in gut fermentative processes.

Severe vitamin D deficiency upon admission in critically ill patients is related to acute kidney injury and a poor prognosis

OBJECTIVES

To evaluate the prevalence of vitamin D deficiency in critically ill patients upon admission to an Intensive Care Unit (ICU) and its prognostic implications.

DESIGN

A single-center, prospective observational study was carried out from January to November 2015. Patients were followed-up on until death or hospital discharge.

SETTING

The department of Critical Care Medicine of a university hospital.

PATIENTS

All adults admitted to the ICU during the study period, without known factors capable of altering serum 25(OH)D concentration.

INTERVENTIONS

Determination of serum 25(OH)D levels within the first 24h following admission to the ICU.

MAIN VARIABLES OF INTEREST

Prevalence and mortality at 28 days.

RESULTS

The study included 135 patients, of which 74% presented deficient serum 25(OH)D levels upon admission to the ICU. Non-survivors showed significantly lower levels than survivors (8.14ng/ml [6.17-11.53] vs. 12ng/ml [7.1-20.30]; P=.04], and the serum 25(OH)D levels were independently associated to mortality (OR 2.86; 95% CI 1.05-7.86; P=.04]. The area under the ROC curve was 0.61 (95% CI 0.51-0.75), and the best cut-off point for predicting mortality was 10.9ng/ml. Patients with serum 25(OH)D<10.9ng/ml also showed higher acute kidney injury rates (13 vs. 29%; P=.02).

CONCLUSION

Vitamin D deficiency is highly prevalent upon admission to the ICU. Severe Vitamin D deficiency (25[OH]D<10.9ng/ml) upon admission to the ICU is associated to acute kidney injury and mortality.

Concomitant combination of active immunotherapy and carboplatin- or paclitaxel-based chemotherapy improves anti-tumor response

Recent preclinical evidence substantially supports the successful combination of chemotherapies and active immunotherapy for cancer treatment. These data sustain the effect of sequential combination schemes (vaccine plus chemotherapy or vice versa), which could be difficult to implement in clinical practice. Since chemotherapy is the standard treatment for most cancers, ethical issues forbid its delay and make difficult the evaluation of other treatments such as using an immunotherapeutic agent. Besides, vaccines must be applied as soon as possible to advanced cancer patients, in order to give them time to develop an effective immune response. Thus, a clinically attractive scenario is the concomitant application of treatments. However, little is known about the specific effect of different chemotherapeutic agents when combined with a cancer vaccine in such concomitant treatment. In this work, we analyze the influence of high-dose carboplatin or paclitaxel in the generation of a specific immune response when administered concomitantly with an OVA vaccine. Interestingly, neither carboplatin nor paclitaxel affects the humoral and CTL in vivo response generated by the vaccine. Moreover, an enhancement of the overall anti-tumor effect was observed in animals treated with OVA/CF vaccine combined with cytotoxic drugs. Moreover, the effect of the concomitant treatment was tested using a tumor-related antigen, the epidermal growth factor (EGF). Animals administered with EGF-P64k/Montanide and cytotoxic agents showed an antibody response similar to that from control animals. Therefore, our study suggests that carboplatin and paclitaxel can be concomitantly combined with active immunotherapies in the clinical practice of advanced cancer patients.

Anti-ganglioside anti-idiotypic monoclonal antibody-based cancer vaccine induces apoptosis and antiangiogenic effect in a metastatic lung carcinoma

Anti-idiotype monoclonal antibody (mAb) 1E10 was generated by immunizing BALB/c mice with an Ab1 mAb which recognizes NeuGc-containing gangliosides, sulfatides and some tumor antigens. 1E10 mAb induces therapeutic effects in a primary breast carcinoma and a melanoma model. However, the tumor immunity mechanisms have not been elucidated. Here we show that aluminum hydroxide-precipitated 1E10 mAb immunization induced anti-metastatic effect in the 3LL-D122 Lewis Lung carcinoma, a poorly immunogenic and highly metastatic model in C57BL/6 mice. The therapeutic effect was associated to the increment of T cells infiltrating metastases, the reduction of new blood vessels formation and the increase of apoptotic tumor cells in lung nodules. Interestingly, active immunization does not induce measurable antibodies to the 1E10 mAb, the NeuGc-GM3 or tumor cells, which may suggest a different mechanism which has to be elucidated. These findings may support the relevance of this target for cancer biotherapy.

Automatic identification of group I intron cores in genomic DNA sequences

Automatic identification of the ribozyme core of group I catalytic introns in genomic sequences is shown to be feasible in spite of the scarcity of strictly conserved features in the sequence and secondary structure of group I introns. An algorithm is described that successfully identified 132 out of the 143 currently reported group I cores with a false positive rate of only 10(-6) per nucleotide. The recognition process consists in generating and rating large sets of potential local solutions which are gradually combined into more complex structures until an entire core (six to seven pairings, six connecting segments, three terminal loops) has been assembled. The extent to which successful recognition may be prevented by sequencing errors is assessed. Also discussed are (1) possible relationships between scores allocated by the program and ability to self-splice in vitro and (2) the potential for objectively assessing the degree of relatedness to group I of structures claimed to resemble group I introns.

Differential effects of direct and indirectly acting cholinergic agonists on growth hormone release in man, and lack of effect on cortisol secretion

Abstract Acetylcholine plays a key role in the modulation of growth hormone secretion. In fact, growth hormone release after provocative stimuli is blocked by muscarinic cholinergic antagonists, and conversely, indirect cholinergic agonists potentiate growth hormone secretion. To further understand the mechanism by which cholinergic pathways exert their effects, we have compared the growth hormone and cortisol secretion elicited on normal volunteers by pyridostigmine and by RS-86 (2-ethyl-8-methyl-2,8-diazaspiro-((4,5))-decan-1,3-dion hydrobromide). The former acts by inhibiting acetylcholinesterase, thus being an indirect muscarinic agonist, while the latter is a muscarinic receptor agonist which binds directly to and stimulates cholinergic receptors. In six subjects, pyridostigmine (120 mg po) induced an increase of growth hormone of 11.0+/-2.4 mug/L at 90 min, significantly greater than following placebo administration (1.4 +/- 0.3 mug/L). In another group of five volunteers, RS-86 was administered in separate tests at a dose of 0.5, 1 and 2 mg po. Growth hormone levels were not altered by any RS-86 dose compared with placebo values. Neither pyridostigmine nor RS-86 altered cortisol values. These results suggest that the mechanism of action of the cholinergic agonists is of great importance for their growth hormone-releasing capabilities, and question the accepted view of a cholinergic regulation of cortisol secretion in man.

Free fatty acids block growth hormone (GH) releasing hormone-stimulated GH secretion in man directly at the pituitary

Increases in plasma FFA levels inhibit GH responses to a variety of pharmacological and physiological stimuli. To gain further insight into the mechanism by which FFA exert their effect, we studied the plasma GH responses to GHRH-(1-44) (1 microgram/kg, iv) in normal subjects in whom plasma FFA levels were raised by a lipid-heparin infusion (250 mL 10% Intralipid plus 2500 U heparin). Paired tests were performed in 10 normal subjects, with and without lipid-heparin pretreatment. Lipid-heparin infusion from -30 to 120 min increased mean FFA levels from 0.41 +/- 0.03 (+/- SEM) to 3.12 +/- 0.40 mmol/L at 120 min. The mean plasma GH levels after GHRH administration were lower at all times; however, the values were significantly different (P less than 0.05) only at the later times (45, 60, and 90 min). When considered individually, an all or none pattern was observed; 5 subjects had no plasma GH response to GHRH, and 5 had no reduction. To investigate the time relationships between the FFA peak and subsequent GH blockade, a different protocol of paired tests was performed with GHRH with or without a different lipid-heparin infusion protocol. Lipid-heparin was infused from -90 to 0 min, with an additional heparin pulse at -15 min, to obtain a higher and earlier (0 min) FFA increase. FFA increased from 1.06 +/- 0.19 to 11.61 +/- 0.83 mmol/L at zero time. The GHRH-induced GH secretory peak (15.8 +/- 3.5 ng/ml) at 15 min was completely blocked (0.9 +/- 0.2 ng/ml), and the mean plasma GH levels were also lower at 30, 45, and 60 min. To determine whether the FFA-induced blockade of GH secretion was exerted in the pituitary, a series of in vitro studies was conducted using monolayer cultures of rat anterior pituitary glands, with GHRH concentrations of both 10(-10) and 10(-8) M and 10(-5) M forskolin to stimulate GH release. Both caprylic and oleic acid inhibited basal GH release and GHRH- or forskolin-induced GH release. PRL release was not altered, nor were toxic actions noted on the cells. In conclusion, FFA are able to block GH secretion directly at the pituitary level.

Atropine selectively blocks GHRH-induced GH secretion without altering LH, FSH, TSH, PRL and ACTH/cortisol secretion elicited by their specific hypothalamic releasing factors

The role of acetylcholine in the regulation of the hypothalamo-pituitary system in man was assessed using atropine, which selectively blocks cholinergic muscarinic receptors. Paired tests were performed in 10 normal men using either GHRH (1 microgram/kg i.v.), or TRH (300 micrograms i.v.) plus LHRH (100 micrograms i.v.) plus corticotrophin releasing hormone (CRH) (1 microgram/kg i.v.) with or without atropine given 30 min previously (1 mg i.m.). The GHRH-induced GH secretory peak (17.8 +/- 3.0 ng/ml) was completely blocked by atropine administration (2.8 +/- 0.6 ng/ml) (P less than 0.05). Atropine did not, however, modify TRH-induced TSH and PRL secretion, nor FSH and LH release induced by the LHRH pulse. ACTH/cortisol secretion elicited by CRH was also unaffected by atropine. These results suggest that atropine blockade of GHRH-induced GH secretion is highly specific, and constitutes an indication of the importance of cholinergic control of GH function. Furthermore, atropine's lack of action on the other pituitary hormones rules out the possibility that it acts non-specifically, i.e. via blood flow changes or toxic effects.

Atropine blockade of growth hormone (GH)-releasing hormone-induced GH secretion in man is not exerted at pituitary level

The role of acetylcholine (Ach) in the regulation of human GH secretion was assessed using atropine, which selectively blocks cholinergic muscarinic receptors. Paired tests were performed in seven normal subjects using GH-releasing hormone (GHRH) 1-44 (1 microgram/kg iv), with and without atropine pretreatment (1 mg im). The GHRH 1-44-induced GH secretory peak [20.7 +/- 4.5 (SEM) ng/ml] was completely blocked by atropine administration (2.3 +/- 0.6 ng/ml) (P less than 0.01). To determine whether this atropine blockade was at the pituitary level, a series of in vitro studies were conducted using monolayer cultures of cells from bovine anterior pituitary glands. GHRH 1-44 (10(-8) M) stimulated bovine GH release (11.1 +/- 1.5 micrograms/ml) as compared to control values (5.1 +/- 0.4 microgram/ml) (P less than 0.01). This response was not altered by 10(-6) M atropine (14.9 +/- 0.9 microgram/ml). Similar results were obtained with GHRH, 10(-9) M, with or without atropine, 10(-7) M. Addition of 10(-6) M Ach to the incubation medium significantly increased bovine GH release (12.7 +/- 1.2 microgram/ml) and the effect of 10(-6) M Ach and 10(-8) M GHRH was additive (20.9 +/- 2.1 micrograms/ml) (P less than 0.01). Similar results were obtained with Ach, 10(-5) M, and GHRH, 10(-9) M. Atropine or eserine alone did not alter basal GH secretion, and atropine blocked Ach-stimulating activity. In conclusion, atropine blockade of GHRH-induced GH secretion appears to be exerted at a site other than pituitary.