Alpha-lipoic acid, but not di-hydrolipoic acid, activates Nrf2 response in primary human umbilical-vein endothelial cells and protects against TNF-α induced endothelium dysfunction.

The antioxidants role in cell response regulation attracted great interest in the last decades and it is undergoing to a profound reconsideration. The mere concept of "biological antioxidant" has been frequently misconceived or misused, possibly leading to the misinterpretation of some experimental observation. Organosulfur compounds in general and α-lipoic acid, a dithiol molecule, can be considered a typical example of the kind. Reduced α-lipoic acid, dehydrolipoic acid has been in fact originally considered a bona fide, reducing, electron donor molecule. A more recent approach, according to stoichiometric and thermodynamic evidences, lead to a reinterpretation of the biochemical role of "antioxidants". The electrophilic nature of oxidized nucleophilic molecules, including α-lipoic acid, renders more plausible a mechanism based on the ability to activate Nrf2/EpRE mediated hormetic response. In this study, we demonstrate that nmolar concentrations of oxidized α-lipoic acid, but not dehydrolipoic acid, protect human umbilical primary endothelial cells (HUVEC) from TNF-α induced dysfunction, inhibit NF-κB activation and block apoptosis following the activation of Nrf2 transcription factor. Our observations corroborate the concept that the major, if not the unique, mechanism by which α-lipoic acid can non-enzymatically exert its reducing activity is related to the electrophilic nature of the oxidized form.

Growth performance, carcass quality, biochemical and haematological traits and immune response of growing rabbits as affected by different growth promoters.

The aim of the article was to study the effect of different growth promoters on growth performance, carcass quality, biochemical and haematological traits and immune response of growing rabbits. A total number of 105 male growing NZW rabbits during 35-91 days of age were randomly distributed among 7 groups fed the same basal diet and submitted to different dietary treatments: the first group was unsupplemented and used as control; the other groups were supplemented respectively with bee pollen and/or propolis at 200 mg/kg BW of each and inulin and/or mannanoligosaccharides (MOS) at 35 mg/kg BW of each. Body weight gain, daily feed intake, feed conversion ratio (FCR), biochemical and haematological blood parameters, carcass characteristics, histological studies of ileum and spleen and economical efficiency were measured. Bee pollen administered alone or with propolis significantly (p < 0.01) the body weight gain and improved FCR in respect of the control group. Inulin with MOS significantly improved just FCR than the control group. Bee pollen with propolis and MOS supplemented-groups resulted in significantly higher (7.96 and 8.41% respectively) white blood cells compared to the control group. Plasma total cholesterol was significantly higher for the MOS group in respect of the control, bee pollen, inulin and inulin with MOS supplemented-groups. Propolis resulted in significantly higher dressed carcass percentage than the control group and higher carcass index than only bee pollen with propolis supplemented-group. Bee pollen, in particular if in combination with propolis, could be used as a supplement in the growing rabbits during days 35-91 of age with positive effects on growth rate and feed conversion ratio.

Enhancement of D-chiro-inositol transport across intestinal cells by alpha-Lactalbumin peptides.

OBJECTIVE: This study aims to characterize in vitro D-chiro-inositol intestinal absorption and identify factors able to improve its bioavailability. D-chiro-inositol, one of the natural occurring stereoisomer of myo-inositol, acts as a second messenger in insulin-regulated glucose metabolism in complementary mode with myo-inositol. Because of their insulin-mimetic activities and safety, both myo-inositol and D-chiro-inositol are often employed as supplements in insulin-resistance treatment. MATERIALS AND METHODS: Trans-epithelial passage of D-chiro-inositol was evaluated in the human intestinal Caco-2 cell line differentiated on filter, a widely established in vitro model to study intestinal absorption. D-chiro-inositol transport was assayed in a concentration range corresponding to an estimated in vivo concentration following oral supplementation. α-Lactalbumin peptides, obtained by in vitro simulated gastrointestinal digestion, were tested as possible modulators of the intestinal permeability of D-chiro-inositol. RESULTS: The absorption of this stereoisomer was relatively low and presumably due to passive diffusion, while it was greatly enhanced by the presence of α-Lactalbumin digest. α-Lactalbumin peptides induced an increase in paracellular permeability that was completely reversible, indicating lack of cytotoxicity. This effect involved temporary rearrangement of F-actin apical cytoskeleton and of the tight junction protein ZO-1. CONCLUSIONS: Although further studies are required to identify and characterize the most effective peptides, the ability of α-Lactalbumin digest to act as absorption enhancers may have very interesting and promising applications in the fields of nutritional supplements and pharmacology.

Vitamin D: a steroid hormone with progesterone-like activity.

OBJECTIVE: This review is aimed at demonstrating the progesterone-like activity exerted by the active form of vitamin D, or calcitriol (1,25(OH)2D). To achieve this outcome, we compared the effects in vivo and in vitro exerted by progesterone and vitamin D, with a special focus on the female reproductive system and pregnancy. MATERIALS AND METHODS: This is a literature review of the most important articles published in English on vitamin D as a hormone, mainly found by MEDLINE. Furthermore, a section of our review contains some unpublished data, concerning the analysis in silico of the similarities between the steric structure of progesterone and calcitriol, based on the availability of the experimental structures of progesterone and vitamin D3 receptors in complex with their physiological ligands in the RCSB Protein Data Bank. RESULTS: Vitamin D was shown to exert many physiological activities during the very early stages of gestation in perfect synchrony with progesterone. Both the molecules mutually help and reinforce the activity exerted by each one. A little bit later than progesterone is released, vitamin D secretion rises, but only if pregnancy occurs. Calcitriol contributes to prepare the endometrium to be receptive. Moreover, it supports the implantation process and the course of pregnancy through different but similar pathways to those used by progesterone, giving rise to a significant synergy of action. It is increasingly evident that vitamin D gives an essential support from the luteal phase onwards. CONCLUSIONS: Based on the evidence displayed in this review we may define appropriately vitamin D as a steroid hormone with progesterone-like activity.

Natural products - alpha-lipoic acid and acetyl-L-carnitine - in the treatment of chemotherapy-induced peripheral neuropathy.

OBJECTIVE: Cancer patients frequently experience Chemotherapy-Induced Peripheral Neuropathy (CIPN), as a typical side effect related to time of administration and dose of anticancer agents. Yet, CIPN pathophysiology is poorly understood, and there is a lack of well-tolerated pharmacological remedies helpful to prevent or treat it. Therefore, new safe and effective compounds are highly warranted, namely if based on an adequate understanding of the pathogenic mechanisms. MATERIAL AND METHODS: Herein we reviewed and discussed scientific data related to the beneficial role of some non-conventional treatments able to counteract CIPN, focusing our attention on alpha-lipoic acid (ALA) and L-acetyl-carnitine (LAC), two natural products that have been demonstrated to be promising preventive drugs. RESULTS: Although a growing body of in vitro and in vivo studies support ALA as a molecule able to counteract CIPN symptoms, mostly due to its antioxidant and anti-inflammatory properties, only two randomized clinical trials evaluated ALA usefulness in preventing chemotherapy-related neuropathy. Unfortunately, these studies were inconclusive and clinical outcomes showed to be highly dependent on the route of administration (oral versus or intravenous injection). LAC has demonstrated beneficial effects on both in vitro and in animal studies. Yet, some controversies aroused from randomized clinical trials. Indeed, while CIPN-patients treated with Taxane showed no benefit from LAC treatment, CIPN-patients treated with platinum compounds exhibit significant improvement of CIPN-related symptoms. Therefore, LAC treatment should be used, and thoroughly investigated only in patients treated with chemotherapy protocols Taxanes-free. CONCLUSIONS: Mechanisms of toxicity triggered by each single drug need to be deeply explored to better identify effective compounds to prevent or treat them. Moreover, additional experiments are mandatory to establish effective doses and length of treatment for each clinical situation in order to perform large and long-term randomized studies.

Safety of oral alpha-lipoic acid treatment in pregnant women: a retrospective observational study.

OBJECTIVE: Alpha-lipoic acid is a natural molecule, which directly or by means of its reduced form, dihydrolipoic acid, exerts antioxidant, anti-inflammatory and immunomodulatory activities, very helpful also in preventing miscarriage and preterm delivery. Used as dietary supplement alpha-lipoic acid was demonstrated to be safe for living organisms even when administered at high doses. However, no study was made so far to verify the safety of its continuous administration on a substantial number of pregnant women. The present investigation was performed to answer this issue. PATIENTS AND METHODS: An observational retrospective study was carried out analyzing 610 expectant mothers. They had been treated daily by oral route with 600 mg alpha-lipoic acid, for at least 7 weeks during gestation. The primary outcome was to verify alpha-lipoic acid safety in the mother and infant. Maternal safety was assessed by monitoring for adverse reactions, physical and clinical examination, including a morbidity assessment. Laboratory and clinical examinations were performed monthly. Neonatal safety was assessed by the evaluation of birth weight, gestational age, Apgar scores, neonatal death with the related cause of death. Data collected from the Birth Registry of Campania Region were used as control. RESULTS: This study provided a very clear and reassuring picture about the safety of alpha-lipoic acid oral treatment during pregnancy. No adverse effect was noticed in mothers or newborns. The two sets of monitored data, from treated and controls, were completely superimposable or, in some cases, better in alpha-lipoic acid group. CONCLUSIONS: Our results open a reassuring scenario regarding the administration of alpha-lipoic acid during pregnancy.

Can high levels of D-chiro-inositol in follicular fluid exert detrimental effects on blastocyst quality?

OBJECTIVE: It was previously shown that higher concentrations of myo-inositol in human follicular fluid improve oocyte and embryo quality, whereas D-chiro-inositol seems to worsen oocyte quality and ovarian response in polycystic ovary syndrome patients. Our study was the first one aiming to test whether different myo-inositol and D-chiro-inositol concentration in follicular fluids correlate with blastocyst quality in healthy young women. PATIENTS AND METHODS: Eight egg donors and eleven couples undergoing in vitro fertilization, were involved in a prospective observational study. Myo-inositol/D-chiro-inositol ratio was calculated in the follicular fluids and associated with different blastocyst grades. Donors were homogeneous and followed the same standard stimulation protocol. RESULTS: The ratio between myo-inositol and D-chiro-inositol was significantly higher in the specimens rated as good quality blastocysts, compared to those rated as poor-quality blastocysts. In this study, almost all the transferred blastocysts were graded as good quality and were correlated to lower D-chiro-inositol content in the follicular fluid; the implantation rate and pregnancy rate were satisfying. Our data suggest that the reduction of such ratio in follicular fluid seems to play a negative role in follicular development. CONCLUSIONS: We found a correlation between myo-inositol/D-chiro-inositol ratio in follicular fluid and blastocyst quality. The value of this ratio may represent a new biomarker for estimating the good features of blastocysts, and a prognostic factor of embryo implantation and pregnancy success. Moreover, the pre-treatment with myo-inositol in women undergoing in vitro fertilization (IVF) may improve oocyte quality and ART outcome. CLINICAL TRIAL REGISTRATION NUMBER: NCT03055442 (ClinicalTrials.gov registry).

[Epidemiology of hospital loads in patients with multiple hospitalizations due to diabetes]. / Epidemiologia dei carichi assistenziali ospedalieri in pazienti con ricoveri ripetuti per diabete.

This study describes the results of a retrospective study carried out to evaluate the hospitalizations of patients with type 2 diabetes admitted from January to June 2001 in the teaching hospital "SS. Annunziata" of Chieti. This research evaluates the generic appropriateness using the PRUO manual and the specific appropriateness using the guidelines approved by Italian Diabetes Association, Italian Diabetes Society and Italian College of General Practitioners. A sample of 196 medical charts was examined. The percentage of inappropriate admission was 21.9%. The "critical" clinical conditions of patients were responsible for only 23.7% of inappropriate admissions. The first reason of the inappropriateness of the admission was the execution of diagnostic examinations (60.5%), followed by the execution of medical therapy (23.2%) and waiting for surgical intervention (16.3%). 46.5% of inappropriate hospitalization was prescribed by specialists. Concerning specific appropriateness, 42.3% of hospitalization was inappropriate. These findings suggest that a system for the assessment of disease management of diabetes should be started up in the Abruzzo region. Moreover, guidelines utilization should be implemented in order to get a more correct utilization of acute hospital by specialists and GPs.

Phosphatidylserine, a putative inhibitor of tumor necrosis factor, prevents autoimmune demyelination.

We tested the effect of bovine cortex phosphatidylserine (BC-PS), a membrane phospholipid known to inhibit the release of the cytokine tumor necrosis factor (TNF), in SJL/J mice sensitized for adoptively transferred experimental autoimmune encephalomyelitis (EAE). Control, sensitized mice developed severe clinical and histologic EAE within 6 to 9 days, whereas only 20% of mice given BC-PS displayed clinical signs that were much less severe and minimal CNS pathology. Cessation of BC-PS treatment after 15 to 40 days led to disease within 1 to 2 weeks, but when treatment was more prolonged, animals remained healthy after cessation. Serial transfer of spleen cells (SC) from BC-PS-treated and control animals into naive recipients resulted in acute EAE within 6 to 7 days with cells from either donor type. Animals treated late with BC-PS failed to relapse and generally remained healthier than controls did over a 40-day period of observation. Cultures of lymph node cells or SC from BC-PS-treated and control animals showed an 80 to 90% reduction in TNF production in the BC-PS-treated group. Thus, we demonstrate that PS can abrogate or significantly reduce the severity of EAE without permanently inhibiting effector T cells. The approach might be considered a candidate for future therapies of relevance to MS.

Beta-endorphin concentrations in brain areas and peritoneal macrophages in rats susceptible and resistant to experimental allergic encephalomyelitis: a possible relationship between tumor necrosis factor alpha and opioids in the disease.

Since the central nervous system and neuropeptides modulate immune functions, we investigated whether the different susceptibility of Lewis and Brown Norway rats to experimental allergic encephalomyelitis could also reflect differences in beta-endorphin and substance P concentrations in brain areas and macrophages during the development of the disease. We show that beta-endorphin concentrations increase much more in the hypothalamus and macrophages of Lewis rats during the development of the disease, while the increase is much lower or absent in Brown Norway rats. Tumor necrosis factor-alpha seems to play an important role in this difference. The administration of the opiate receptor antagonist naltrexone worsens the development of the disease, suggesting that the increase of the opioid beta-endorphin might represent a mechanism to downregulate the immune response. In both strains, the concentrations of substance P do not change.

Protection from experimental autoimmune encephalomyelitis (EAE): non-depleting anti-CD4 mAb treatment induces peripheral T-cell tolerance to MBP in PL/J mice.

Following pre-treatment with a non-depleting anti-CD4 mAb (H129.19) that produces long-lasting receptor saturation, PL/J mice were fully protected from experimental auto-immune encephalomyelitis (EAE) induced by injection of myelin basic protein (MBP). These mice did not develop EAE following MBP re-challenge 5-10 weeks later when the CD4+ cells were no longer coated by the mAb and their lymph node cells were specifically unresponsive to MBP stimulation in vitro. Moreover, superantigen staphylococcal enterotoxin B (SEB) inoculation, which re-induces EAE in MBP immunized mice, failed to activate encephalitogenic T-cells in anti-CD4 + MBP treated mice, even after MBP re-challenge, indicating that tolerance in the peripheral T-cell compartment was achieved. However, MBP re-challenge 16 weeks later, but not SEB, produced an acute episode of EAE in these mice, while it failed to induce disease in a parallel group of adult thymectomized mice. These results indicate that no memory of the first priming exists at this time and that new MBP-specific T-cell precursors are peripheralized and produce EAE after MBP recognition.

Beta-adrenergic receptors mediate in vivo the adrenaline inhibition of lipopolysaccharide-induced tumor necrosis factor release.

Adrenaline has been shown to inhibit the release of tumor necrosis factor (TNF) elicited by lipopolysaccharide (LPS) when tested in vitro on cultured human blood cells and rat macrophages. In this report we have examined the effect of the in vivo administration of adrenaline on TNF serum levels induced by LPS. In agreement with in vitro data, adrenaline (0.1 mg/kg, s.c.) was found to inhibit in the mouse the LPS-induced TNF release. The beta-adrenergic antagonist propranolol administered 1 h before adrenaline completely blocked the adrenaline activity, whereas the alpha-adrenergic antagonist phentolamine was ineffective. These data demonstrate that: (i) adrenaline is an effective antagonist of LPS-induced TNF release in vivo, and (ii) its effect is mediated by beta-adrenergic receptors.

Cloricromene, a semi-synthetic coumarin derivative, inhibits tumor necrosis factor-alpha production at a pre-transcriptional level.

Cloricromene decreases myocardial infarct size after ischemic-reperfusion injury in vivo, and it has been suggested that this is due to inhibition of tumor necrosis factor-alpha (TNF-alpha). The purpose of this work was to characterize the mechanism of cloricromene-induced inhibition of TNF-alpha in rat macrophages. Cloricromene inhibited lipopolysaccharide-induced TNF-alpha release in a dose-dependent manner (IC(50)=5.9 +/- 0.8 microM). This was not due to cytotoxicity, as cloricromene was well tolerated up to 500 microM. Cloricromene inhibited lipopolysaccharide-induced expression of TNF-alpha mRNA, which suggests a pre-transcriptional effect. We then investigated the early signal transduction pathway triggered by lipopolysaccharide. The binding of lipopolysaccharide to its receptor CD14 activates protein kinase C and nuclear factor-kappaB (NF-kappaB). Cloricromene inhibited NF-kappaB activation in a dose-dependent manner, but affected protein kinase C translocation only slightly. We then established that cloricromene inhibited lipopolysaccharide-induced cellular oxidative activity, which is important for NF-kappaB activation. Our results show that cloricromene interferes with the early signal transduction pathway triggered by lipopolysaccharide.

Cultured human monocytes release proinflammatory cytokines in response to myelin basic protein.

In human cultured monocytes we examined the ability of myelin basic protein (MBP) to induce the production of proinflammatory cytokines potentially involved in inflammatory demyelination. Northern blots and specific immunoassays demonstrated that monocytes incubated with optimal doses of MBP showed increased mRNA expression and release of tumor necrosis factor (TNF-alpha), interleukin-1beta (IL-1beta), interleukin-6 (IL-6), interleukin-8 (IL-8) but not of interleukin-12/p40 (IL-12/p40). We also showed that cytokine production by MBP-stimulated monocytes was abrogated by incubation with Dexamethasone. These data suggest that interaction of mononuclear phagocytes with MBP may participate in the regulatory process of cytokine production during inflammatory demyelination and support the beneficial role of corticosteroids therapy in aberrant immune responses to the myelin sheath.

Adrenalectomy abolishes phosphatidylserine inhibition of lipopolysaccharide-induced tumor necrosis factor release.

The treatment with phosphatidylserine (PS) has recently been shown to inhibit in vivo the lipopolysaccharide (LPS)-induced release of tumor necrosis factor (TNF) (Monastra and Bruni, 1992, Lymphokine Cytokine Res. 11:39). The aim of the present work was to investigate the mechanism(s) involved in the inhibition by PS. No in vitro inhibition of LPS-induced TNF release was observed when PS was used in vitro with human whole blood cells. The opposite was observed, in vitro PS enhanced TNF release. Previous work has shown that PS induces histamine release by mast cells and it is known that histamine inhibits TNF release. PS treatment of W/WV mice lacking mast cells, which are therefore unable to release histamine, resulted in inhibition of LPS-induced TNF release; thus excluding a major role of histamine in mediating PS inhibition. However, in adrenalectomized mice PS treatment failed to inhibit the LPS-induced TNF release, while the effect of PS was evident in sham-operated mice. PS treatment in adrenalectomized mice was associated with an increase in TNF serum levels when compared to untreated animals. Overall these results suggest that PS inhibition of LPS-induced TNF release is dependent on adrenal hormones, while PS, in the absence of adrenal hormones, seems to have a priming effect on the cells that produce TNF after LPS stimulus.

Effect of dietary amounts of inorganic and organic zinc on productive and physiological traits of White Pekin ducks.

The effects of different dietary amounts of organic and inorganic Zn were studied in male White Pekin ducks (WPD) from 1 to 56 days of age. The control diet (26 ppm of Zn from raw ingredients) was supplemented with 30, 60 and 120 ppm of Zn from both inorganic and organic sources, for a total of seven treatment groups, each containing five replicates of nine 1-day-old ducklings each. BW, feed intake and feed conversion ratio (FCR) were recorded at 1, 28 and 56 days of age. At 56 days of age, five birds per group were used in a digestibility trial to measure Zn retention and excretion. At the end of the trial, five birds per treatment were slaughtered and carcass traits as well as Zn content in tibia and liver were measured. Samples of blood from five birds per treatment were used to measure plasma concentration of Zn and Cu. BW gain during the entire period of the trial increased (P < 0.001) by 30 and 60 ppm of Zn. Increasing Zn contents progressively increased (P < 0.001) the tibia and the liver Zn contents as well as the plasma Zn and Cu contents. The concentration of 120 ppm of Zn increased (P < 0.001) tibia ash and decreased (P < 0.001) abdominal fat in the carcasses. In the period 1 to 56 days, Zn oxide increased (P < 0.001) growth rate and improved (P < 0.03) FCR compared with organic Zn, whereas organic Zn increased (P < 0.003) the dressed carcass percentage. Organic Zinc increased (P < 0.001) Zn and Cu concentration in the plasma. A level of 30 ppm of Zn from an inorganic source was adequate for male WPD during 1 to 56 days of age, based on positive effects of growth rate and Zn excretion.

Decreased serum level of tumor necrosis factor in animals treated with lipopolysaccharide and liposomes containing phosphatidylserine.

The rise in serum level of tumor necrosis factor (TNF), produced by lipopolysaccharide, has been measured in mice and rabbits treated with phospholipid liposomes. After 3 daily ip injection (mice) or 5 daily i.v. injections (rabbits) of 30 mg/kg of a phospholipid mixture enriched in phosphatidylserine, the action of lipopolysaccharide was 80-90% reduced. The phospholipid effect is dose dependent, requires a minimum of two daily injections before the administration of lipopolysaccharide, and is still manifest 2 days after the last phospholipid dose. Among individual purified phospholipids, phosphatidylserine and phosphatidylethanolamine were effective whereas phosphatidylinositol, phosphatidylglycerol, and phosphatidylcholine did not show significant activity. The data indicate that the parenteral administration of liposomes containing the aminophospholipids phosphatidylserine, and phosphatidylethanolamine is an efficient mode to reduce the endotoxin-induced production of TNF. As suggested by liposome pharmacokinetics, this effect may be related to phospholipid accumulation in the mononuclear phagocyte system of liver and spleen.

Autacoid properties of lysophosphatidylserine.

The hypothesis of this study is summarized in Fig. 6. Phosphatidylserine due to distribution in the internal side of plasma membrane is prevented to react with the extracellular environment. When injury to cell occurs, phospholipid asymmetry is lost and the exposed phosphatidylserine becomes a signal of cell damage. Phosphatidylserine may activate defense reactions while it is still anchored to plasma membrane (Zwaal, 1978; Tanaka and Schroit, 1983). Alternatively, the soluble lysophosphatidylserine is generated, ready to diffuse and transmit the information of tissue damage to other cells. In this sequence of events, lysophosphatidylserine becomes an autacoid, originated from a membrane phospholipid. In rodents, lysophosphatidylserine seems specifically devoted to activate mast cells. The role of these cells in the regulation of the immune reactions and in tissue repair has been advocated (Dexter et al., 1981). The lysophosphatidylserine-induced mast cell activation has been shown in vivo and in vitro in a variety of rodent species (mouse, rat, gerbil, hamster). It may occur through a direct effect or through the participation of synergistic endogenous compounds. Structure-activity relationships in the action of lysophosphatidylserine show that the effect on mast cells is linked to a definite molecular organization. Determinants of the mast cell activation are the free amino group and the carboxyl group of the serine. Support to the general hypothesis of this study originates from the observation that active lysophosphatidylserine is generated within a population of leukocytes, the cells migrating in areas of wounded tissue (Mietto et al., 1987). Production of lysophosphatidylserine can be anticipated in pathological situations associated with extensive cell death (tumor growth, graft rejection, burns). At present, the observations on lysophosphatidylserine are confined to rodent mast cells. Other histamine-secreting cells (e.g., the human basophil) are unresponsive to this phospholipid (Kolster et al., 1987). Among the endogenous compounds interacting with lysophosphatidylserine, nerve growth factor seems of particular interest (Bruni et al., 1982). The synergism with lysophosphatidylserine has been confirmed in other laboratories (Sugiyama et al., 1985; Pearce and Thompson, 1986; Mazurek et al., 1986). The concerted effects by these two compounds on mast cells is in line with current opinion on the participation of nerve growth factor in the regulation of inflammatory and immune reactions (Mietto et al., 1987; Weskamp and Otten, 1987).(ABSTRACT TRUNCATED AT 400 WORDS)

Lysophosphatidylserine-induced activation of mast cells in mice.

Intravenous injection of lysophosphatidylserine (2.5-25 mg/kg) increases the blood histamine level in mice. Lysophosphatidyl-D-serine, alkyl-lysophosphatidylserine and glycerophosphorylserine show little or no activity. As shown by the similar efficacy of the analogue lacking the OH group in the C-2 position of glycerol conversion into phosphatidylserine is not required. The age of mice influences the activity of lysophosphatidylserine. Thus, the increase in blood histamine is greater in adult mice (8-10 weeks) than in young mice (4-6 weeks). In old mice (50-60 weeks) the tolerance to lysophosphatidylserine is reduced. Repeated parenteral administrations induce depletion of histamine stores with concomitant desensitization to lysophosphatidylserine. Well-perfused organs containing connective tissue mast cells (tongue) are more affected. When [3H] histidine is injected into lysophosphatidylserine-treated mice, the highly radioactive histamine detected in the tongue indicates the preservation of histidine decarboxylase activity after degranulation. The data suggest that lysophosphatidylserine specifically activates connective tissue mast cells in mice.