Identification of flotillin-1 as an interacting protein for antisecretory factor

The role of endogenous Antisecretory Factor (AF) in the treatment of Ménière's Disease: A two-year follow-up study. Preliminary results

PURPOSE

To evaluate the effects of increased endogenous Antisecretory Factor (AF) synthesis using specially processed cereals (SPC) in a sample of patients with defined unilateral Meniere's disease (MD), compared to the results of a treatment protocol of intravenous glycerol and dexamethasone.

MATERIALS AND METHODS

Twenty-six patients with unilateral MD were divided in 2 groups and treated with SPC and with intravenous glycerol and dexamethasone for 24 months. Audio-vestibular evaluation was performed before (T0) and every six months. The number of vertigo spells were evaluated before and after therapy and the Efficacy Index (EI) was calculated. Questionnaires for hearing loss, tinnitus and quality of life were administered.

RESULTS

EI decreased in the SPC group after 18 (T18) (p = .0017) and 24 (T24) months of therapy (p = .0111). There was a significant reduction for tinnitus score in the SPC group at T24 (p = .0131). No significant differences were found between the two groups at T0 (p = .4723), while a significant difference was found at T24 (p = .0027). Quality of life showed a significant improvement in daily activities in the SPC group (p = .0033) compared to the infusion therapy group. No statistically significant changes in PTA thresholds were found in both groups between T0 and T24.

CONCLUSION

The preliminary results of our study show a significant reduction of vertigo spells and a positive effect on tinnitus severity and on quality of life in patients with unilateral MD treated with SPC and when compared to patients treated with intravenous glycerol and dexamethasone. No effects on hearing thresholds were noted in both groups.

Antisecretory Factor-Mediated Inhibition of Cell Volume Dynamics Produces Antitumor Activity in Glioblastoma

Interstitial fluid pressure (IFP) presents a barrier to drug uptake in solid tumors, including the aggressive primary brain tumor glioblastoma (GBM). It remains unclear how fluid dynamics impacts tumor progression and can be targeted therapeutically. To address this issue, a novel telemetry-based approach was developed to measure changes in IFP during progression of GBM xenografts. Antisecretory factor (AF) is an endogenous protein that displays antisecretory effects in animals and patients. Here, endogenous induction of AF protein or exogenous administration of AF peptide reduced IFP and increased drug uptake in GBM xenografts. AF inhibited cell volume regulation of GBM cells, an effect that was phenocopied in vitro by the sodium-potassium-chloride cotransporter 1 (SLC12A2/NKCC1) inhibitor bumetanide. As a result, AF induced apoptosis and increased survival in GBM models. In vitro, the ability of AF to reduce GBM cell proliferation was phenocopied by bumetanide and NKCC1 knockdown. Next, AF's ability to sensitize GBM cells to the alkylating agent temozolomide, standard of care in GBM patients, was evaluated. Importantly, combination of AF induction and temozolomide treatment blocked regrowth in GBM xenografts. Thus, AF-mediated inhibition of cell volume regulation represents a novel strategy to increase drug uptake and improve outcome in GBM. Mol Cancer Res; 16(5); 777-90. ©2018 AACR.

Antisecretory Factor Modulates GABAA Receptor Activity in Neurons

The antisecretory factor is an endogenous protein found in all mammalian tissues investigated so far. It acts by counteracting intestinal hypersecretion and various forms of inflammation, but the detailed mechanism of antisecretory factor (AF) action is unknown. We tested neuronal GABA_A receptors by means of AF-16, a potent AF peptide derived from amino acids 36-51 from the NH₂ part of AF. Cultured rat cerebellar granule cells were used, and the effects on the GABA-mediated chloride currents were determined by whole-cell patch clamp. Both the neurotransmitter GABA and AF-16 were added by perfusion of the experimental system. A 3-min AF-16 preincubation was more efficacious than 30 s in significantly elevating the rapidly desensitizing GABA-activated chloride current. No effect was found on the tonic, slowly desensitizing current. The GABA-activated current increase by AF-16 demonstrated a low k of 41 pM with a maximal increase of 37% persisting for some minutes after AF washout, independent from GABA concentration. This indicates an effect on the maximal stimulation (E%_Max) excluding an altered affinity between GABA and its receptor. An immunocytochemical fluorescence approach with anti γ2 subunit antibodies demonstrated an increased expression of GABA_A receptors. Thus, both the electrophysiological and the immunofluorescence approach indicate an increased appearance of GABA_A receptors on the neuronal membrane. The rationale of the experiments was to test the effect of AF on a defined neuronal population of GABA_A receptors. The implications of the results on the impact of AF on the enteric nervous system or on brain function are discussed.

Food-induced changes of lipids in rat neuronal tissue visualized by ToF-SIMS imaging

Time of flight secondary ion mass spectrometry (ToF-SIMS) was used to image the lipid localization in brain tissue sections from rats fed specially processed cereals (SPC). An IonTof 5 instrument equipped with a Bi cluster ion gun was used to analyze the tissue sections. Data from 15 brain samples from control and cereal-fed rats were recorded and exported to principal components analysis (PCA). The data clearly show changes of certain lipids in the brain following cereal feeding. PCA score plots show a good separation in lipid distribution between the control and the SPC-fed group. The loadings plot reveal that the groups separated mainly due to changes in cholesterol, vitamin E and c18:2, c16:0 fatty acid distribution as well as some short chain monocarboxylic fatty acid compositions. These insights relate to the working mechanism of SPC as a dietary supplement. SPC is thought to activate antisecretory factor (AF), an endogenous protein with regulatory function for inflammation and fluid secretion. These data provide insights into lipid content in brain following SPC feeding and suggest a relation to activating AF.

Enhanced cellular uptake of antisecretory peptide AF-16 through proteoglycan binding

Peptide AF-16, which includes the active site of Antisecretory Factor protein, has antisecretory and anti-inflammatory properties, making it a potent drug candidate for treatment of secretory and inflammatory diseases such as diarrhea, inflammatory bowel diseases, and intracranial hypertension. Despite remarkable physiological effects and great pharmaceutical need for drug discovery, very little is yet understood about AF-16 mechanism of action. In order to address interaction mechanisms, we investigated the binding of AF-16 to sulfated glycosaminoglycan, heparin, with focus on the effect of pH and ionic strength, and studied the influence of cell-surface proteoglycans on cellular uptake efficiency. Confocal laser scanning microscopy and flow cytometry experiments on wild type and proteoglycan-deficient Chinese hamster ovary cells reveal an endocytotic nature of AF-16 cellular uptake that is, however, less efficient for the cells lacking cell-surface proteoglycans. Isothermal titration calorimetry provides quantitative thermodynamic data and evidence for that the peptide affinity to heparin increases at lower pH and ionic strength. Experimental data, supported by theoretical modeling, of peptide-glycosaminoglycan interaction indicate that it has a large electrostatic contribution, which will be enhanced in diseases accompanied by decreased pH and ionic strength. These observations show that cell-surface proteoglycans are of general and crucial importance for the antisecretory and anti-inflammatory activities of AF-16.

Antisecretory factor effectively and safely stops childhood diarrhoea: a placebo-controlled, randomised study

AIM

We studied the response to high doses of egg yolk containing antisecretory factor (B221® , Salovum®) in young children with acute diarrhoea, presenting to the Children's Hospital, Lahore, Pakistan.

METHODS

In a randomised, placebo-controlled trial, 36 children aged 7 to 60 months with acute diarrhoea of unknown aetiology, with mild-to-moderate dehydration, were randomised to the Salovum® or placebo groups. Initially, 16 grams of Salovum® or ordinary egg yolk (placebo) mixed in oral rehydration salts was given, followed by 8 g every 5 h until recovery. The number and consistency of stools were recorded.

RESULTS

The two groups were comparable in age, gender, duration of diarrhoea, hydration and nutritional status, although the proportion with watery stools was higher in the Salovum® group (p = 0.04). Reduction in the frequency of stools was seen at 7 versus 18 h (p < 0.0001) and normalising of stool consistency was 10 versus 18 h, p < 0.03) in the Salovum® and placebo groups. The overall effect was 35 versus 70 h in the two groups (p = 0.001). No side effects were reported.

CONCLUSION

High doses of AF in the form of Salovum® effectively and safely reduce childhood diarrhoea of a likely broad aetiology.

Antisecretory factor as a potential health-promoting molecule in man and animals

Antisecretory factor (AF) is a protein secreted in plasma and other tissue fluids in mammals with proven antisecretory and anti-inflammatory activity; its immunohistological distribution suggests a role in the immune system. The expression level and the distribution of AF protein are altered during an immunological response. Exposure to bacterial toxins induces secretion of AF in plasma, probably reflecting a natural defence mechanism to agents causing diarrhoea, thereby contributing to a favourable clinical outcome and disease termination. An increase of AF levels in plasma by dietary means, such as specially processed cereals (SPC), has been demonstrated in human subjects and animals. Administration of SPC to patients affected by inflammatory bowel disease, gastroenteritis and Ménière's disease relieved symptoms and improved quality of life. A recent study showed the positive effect of SPC diet supplementation on prevention of the effects of exposure to low levels of blast overpressure in rats, reducing the extent of intracranial pressure increase and cognitive function impairment. AF-rich egg yolk powder improved health status in children suffering acute and chronic diarrhoea, reducing the frequency and increasing the consistency of stools. This kind of functional food could be used for prophylaxis in populations exposed to a high risk of morbidity and mortality caused by diarrhoea and as a complementary therapy in patients affected by chronic intestinal inflammatory disease to improve well-being. In pig husbandry AF-inducing diets, owing to their antisecretory activity and anti-inflammatory action, are a suitable option as an alternative to antibiotic growth promoters to counteract post-weaning diarrhoea.

Antisecretory factor-inducing therapy improves the clinical outcome in patients with Ménière's disease

CONCLUSION

Intake of antisecretory factor (AF)-inducing SPC-flakes significantly reduced vertigo in patients suffering from Ménière's disease (MD). The positive effect may be due to a modulation of the transport of water and ions in the endolymphatic space.

OBJECTIVE

To evaluate the effects of a 3-month treatment period with SPC-flakes in patients suffering from MD.

PATIENTS AND METHODS

A prospective, double-blind, placebo-controlled study was performed. A total of 51 adult patients with MD were included in the study: 27 subjects treated with SPC-flakes and 24 subjects with control cereals. The patients received SPC-flakes or control cereals (1 g per kg body weight per 24 h in two servings) for 3 months. Otoneurological examinations were carried out before and after this period.

RESULTS

The severity of MD was classified according to the American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) grading system. Fourteen of the 27 patients randomized to intake of the AF-inducing SPC-flakes reported decreased vertigo, compared with 2 of 24 in the control group (p < 0.001). No consistent change in the otoneurological examinations could be demonstrated in any of the groups of patients.

Development of monoclonal antibodies for detection of Antisecretory Factor activity in human plasma

Antisecretory Factor (AF) is expressed in most tissues and can be demonstrated in plasma and other body fluids. Most of the AF in plasma is in an inactive form and activation of AF occurs after exposure to bacterial toxins or after intake of various dietary components. Patients with chronic diseases involving disturbances in inflammatory and secretory processes may benefit from an AF-inducing diet. The aim of the present study was to develop an in vitro assay for the analysis of AF-activity in human plasma. Monoclonal antibodies were raised against a native form of AF prepared from human placenta. Nine clones of the monoclonal antibodies recognizing AF and AF peptides were identified. With the aid of these antibodies, we developed a sensitive ELISA method for direct detection of AF-activity in human plasma. The AF activity in plasma from five healthy volunteers was low, 0.112+/-0.022 (absorbance at 405 nm), before intake of the AF-inducing diet with the SPC-Flakes, and increased significantly (p<0.05) to 0.444+/-0.068 after >or=6 weeks on the diet. A comparison of the plasma-AF values, obtained by the bioassay and the immunogenic assay (indirect ELISA), shows that there is a significant correlation (r=0.85) between the values from the two methods. The results indicate that the ELISA measures AF-activity and has the potential to be an important tool for the analysis of AF-activity in further clinical studies on AF-therapy.