The role of eosinophils in Angiostrongylus cantonensis infection

Angiostrongylus cantonensis is the causative agent of human eosinophilic meningoencephalitis in the Pacific Islands and Southeast Asia. Prominent eosinophilia in the cerebrospinal fluid (CSF) of the patients has been used as one of the diagnostic criteria for the disease but the role(s) of the CSF eosinophils has remained to be elucidated. In this article, Kentaro Yoshimura, Hiroko Sugaya and Kazuto Ishido discuss the involvement of CSF eosinophils in the killing of intracranial worms and the damage of the central nervous system of the hosts, and consider why eosinophils in A. cantonensis infection play a more important role in nonpermissive hosts (including humans) than in the permissive rat host.     

Eosinophil responses of permissive and nonpermissive hosts to the young adult worms of Angiostrongylus cantonensis

Blood and bone marrow eosinophilia was assessed in nonpermissive (guinea pigs) and permissive (rats) hosts following the pulmonary arterial transfers of live or dead young adult worms of Angiostrongylus cantonensis. Guinea pigs showed a marked eosinophilic response to live worms but only a slight response to dead worms. Neither IgE nor haemagglutinating antibodies correlated with the induction of this eosinophilia. In contrast, the rat responded to neither form of the young adult worm. When the guinea pig and the rat were injected with whole worm extract (WWE) of the young adult worms either by an osmotic mini-pump connected to the jugular vein or by intermittent intravenous injections, the former animal showed blood eosinophilia but the latter failed to do so. Guinea pigs also developed blood eosinophilia after continuous exposure to the excretory and secretory products of the young adult worms, administered by the mini-pump. Eosinophil responses to WWE could be induced both in athymic CD-1 (ICR) nude mice and in its heterozygous litter mates, suggesting that T cell-independent mechanism(s) could be involved in the induction of blood eosinophilia in the nonpermissive, mouse host. These data clearly indicate that the eosinophilia-inducing factor(s) and the mechanism of eosinophilia are different in permissive and nonpermissive hosts.     

Angiostrongylus cantonensis: Development following pulmonary arterial transfers into permissive and nonpermissive hosts

The survival, growth, and egg-laying capacity of young adult Angiostrongylus cantonensis, surgically transferred from intracranial sites into pulmonary arteries, were studied. A variety of experimental animals (rats, guinea pigs, mice, and mastomys) were chosen as donor animals and as recipient hosts (rats, guinea pigs, and rabbits). These species were specifically chosen to span the spectrum of host permissiveness relative to worm development in an attempt to understand the mechanisms which underlie species-dependent resistance. Recipient animals were monitored not only for the development of parasites per se but also for antibody production and histopathologic changes. The results indicated that these procedures were technically feasible, with good worm development following intra-rat transfers, as early as 15 days after initial exposure. Studies were performed to analyze the constraints of development both on initial, i.e., prelung and subsequent i.e., postlung development. When worms were obtained from permissive species such as rat or mastomys, transfer into rats resulted in good growth and development; however, worms which developed initially in exposed mice or guinea pigs developed less well in the rat. Conversely, worms which developed initially in permissive host such as the rat, when transferred into a variety of less permissive hosts such as the guinea pig and rabbit, apparently did not survive and caused significant morbidity and mortality within the nonpermissive host. Histopathologic evaluation revealed a strong eosinophilic perivascular and peribronchiolar infiltration as well as granulomatous reactions surrounding the worms in the lungs of recipient guinea pigs and rabbits, changes not observed in the lungs of permissive rat recipients. As reaginic antibody responses were also more prominent in nonpermissive than in permissive animals, it is possible that IgE responses may be more directly related to the phenomenon of morbidity and/or permissiveness than are other aspects of immune response. In support of this contention was the finding of nearly equivalent hemagglutinating antibody production between permissive rats and nonpermissive guinea pigs and rabbits.     

Biological activity of leukotriene B4 analogs: inhibition of guinea pig eosinophil migration in vitro by the 2,6-disubstituted pyridine analogs U-75,302 and U-75,485.

A "late phase" antigen-induced bronchoalveolar eosinophilia has been demonstrated in ovalbumin sensitized guinea pigs (1,2). This in vivo response to antigen inhalation can be inhibited by a 2,6-disubstituted pyridine analog of LTB4, U-75,302(2) (3). In the present study, the mechanism of the drug action was studied by assessing the activity of U-75,302 and a second analog, U-75,485 to displace [3H]-leukotriene B4 binding at the guinea pig eosinophil membrane, as well as their action as chemoattractants or inhibitors of the directional migration of guinea pig eosinophils in vitro. Radioligand competition experiments demonstrated that both analogs interacted strongly with the high affinity LTB4 binding sites on guinea pig eosinophil membrane. Both analogs are powerful chemoattractants for guinea pig eosinophils since they induced directional migration of guinea pig eosinophils when administered alone. In addition, when the cells were treated with either analog and their chemotaxis response was measured in response to a natural chemoattractant, both U-75,302 and U-75,485 at concentrations of 0.1 to 100 microM dose dependently inhibited the LTB4 induced chemotaxis response. The EC50s obtained for U-75,302 and U-75,485 as inhibitors of LTB4 induced guinea pig eosinophil chemotaxis were estimated to be 11.5 +/- 5.5 microM and 5.4 +/- 2.5 microM respectively. Under the same conditions, they had no significant effect upon eosinophil migration induced by zymosan activated plasma at concentrations below 100 microM. We suggest that the inhibition of antigen-induced eosinophil infiltration in guinea pig airway in vivo by U-75,302 or U-75,485 may be a result of partial antagonism or desensitization at the LTB4 receptor level of guinea pig eosinophils.     

Surface antigens of Angiostrongylus cantonensis developing in permissive and non-permissive hosts

The immunofluorescent antibody test and immunocytochemical method were employed to study the surface antigens of Angiostrongylus cantonensis obtained from infected rats, mice and guinea pigs. Positive results with intense fluorescence and brownish peroxidase staining were observed on the cuticular surface of A. cantonensis recovered from rats 22 days (late cerebral phase) and 34 days (lung phase) post-infection when tested with antisera against host (normal rat serum) antigens as well as crude extracts of A. cantonensis. However, host antigens were not observed on the surface of the nematode recovered from the brain of mice and guinea pigs 15 days post-infection.     

In vivo airway eosinophil accumulation does not enhance antigen- or propranolol-induced bronchoconstriction in guinea pigs

BACKGROUND: Chronic airway eosinophil accumulation is characteristic of asthma. However, it remains unclear whether airway eosinophils enhance or reduce release of chemical mediators and/or action of the released mediators in the airways in vivo, because previous investigators have indicated that eosinophil-derived factors such as histaminase and arylsulfatase may alter the allergic reaction by metabolizing chemical mediators. Recently, we have developed a guinea pig model of propranolol-induced bronchoconstriction (PIB), which is mediated by lipid mediators such as thromboxane A2 (TxA2), cysteinyl leukotrienes (cLTs) and platelet activation factor (PAF). This study was conducted to explain the influence of airway eosinophil accumulation on antigen-induced bronchoconstriction and the following PIB, both of which are mediated by lipid mediators. METHODS: Guinea pigs were transnasally treated with 75 microg/kg of polymyxin-B or vehicle twice a week for a total of 3 weeks. Guinea pigs were anesthetized and treated with diphenhydramine hydrochloride, and then artificially ventilated 24 h after the last administration of polymyxin-B or vehicle followed by passive sensitization. Propranolol at a concentration of 10 mg/ml was inhaled 20 min after an aerosolized antigen challenge. RESULTS: The proportion of eosinophils in bronchoalveolar lavage fluid obtained 15 min after the propranolol inhalation was significantly increased in guinea pigs treated with polymyxin-B compared with the vehicle. The polymyxin-B treatment did not affect antigen-induced bronchoconstriction or the following PIB. CONCLUSIONS: We conclude that eosinophils accumulated in the airways by polymyxin-B does not affect release of chemical mediators induced by antigen or propranolol inhalation, or action of released mediators in vivo.     

Ozone-induced hyperresponsiveness and blockade of M2 muscarinic receptors by eosinophil major basic protein.

Control of airway smooth muscle is provided by parasympathetic nerves that release acetylcholine onto M(3) muscarinic receptors. Acetylcholine release is limited by inhibitory M(2) muscarinic receptors. In antigen-challenged guinea pigs, hyperresponsiveness is due to blockade of neuronal M(2) receptors by eosinophil major basic protein (MBP). Because exposure of guinea pigs to ozone also causes M(2) dysfunction and airway hyperresponsiveness, the role of eosinophils in ozone-induced hyperresponsiveness was tested. Animals were exposed to filtered air or to 2 parts/million ozone for 4 h. Twenty-four hours later, the muscarinic agonist pilocarpine no longer inhibited vagally induced bronchoconstriction in ozone-exposed animals, indicating M(2) dysfunction. M(2) receptor function in ozone-exposed animals was protected by depletion of eosinophils with antibody to interleukin-5 and by pretreatment with antibody to guinea pig MBP. M(2) function was acutely restored by removal of MBP with heparin. Ozone-induced hyperreactivity was also prevented by antibody to MBP and was reversed by heparin. These data show that loss of neuronal M(2) receptor function after ozone is due to release of eosinophil MBP.     

Bronchoalveolar eosinophilia in guinea pigs harboring inapparent infections of Paraspidodera uncinata

During the course of experiments examining the changes in cell populations in bronchoalveolar lavage (BAL) fluid in 3-11-wk-old guinea pigs, a marked increase in the numbers of eosinophils was observed in BAL fluid in untreated control animals from historical levels (observations made over the previous 2 yr) of 8.8 +/- 1.5% to levels greater than 16% and up to 44%. Repeated occurrence of this phenomenon in several different groups of guinea pigs that appeared clinically normal and the impact on our experimental studies led us to attempt to identify the cause of increased inflammatory cell numbers in these guinea pigs. Examination in 2 groups of animals of whole blood and lung tissue for the presence of bacteria or fungi revealed minor bacterial infections in one group but not the other, whereas both exhibited elevated eosinophil numbers. At necropsy, 41.7% and 60% of the animals in the 2 groups harbored the nematode Paraspidodera uncinata. Guinea pigs exhibiting eosinophil numbers in BAL fluid comparable to our historical levels were then inoculated with approximately 100 embryonated eggs of P. uncinata and developed elevated eosinophilia in BAL fluid compared to sham-inoculated animals (significant at 2 of the 3 examination times postinoculation). These findings suggest that P. uncinata is capable of causing changes in inflammatory cell populations in the lungs of guinea pigs and illustrate the importance of subclinical or inapparent infections in experimental design and interpretation.     

Curcumin alleviates eosinophilic meningitis through reduction of eosinophil count following albendazole treatment against Angiostrongylus cantonensis in mice

Angiostrongylus cantonensis (A. cantonensis) is the most common cause of parasitic eosinophilic meningitis worldwide. By using an animal model of BALB/c mice infected with A. cantonensis, previous studies indicated that the anthelmintic drug, albendazole, could kill A. cantonensis larvae and prevent further infection. However, the dead larvae will induce severe immune responses targeting at brain tissues. To alleviate the detrimental effects caused by the dead larvae, we administered curcumin, a traditional anti-inflammatory agent, as a complementary treatment in addition to albendazole therapy, to determine whether curcumin could be beneficial for treatment. The results showed that although curcumin treatment alone did not reduce worm number, combined treatment by albendazole and curcumin helped to reduce eosinophil count in the cerebrospinal fluid, better than using albendazole alone. This alleviating effect did not affect albendazole treatment alone, since histological analysis showed similar worm eradication with or without addition of curcumin. Nevertheless, curcumin treatment alone and combined albendazole-curcumin treatment did not inhibit MMP-9 expression in the brain tissue. In conclusion, curcumin, when used as a complementary treatment to albendazole, could help to alleviate eosinophilic meningitis through suppression of eosinophil count in the cerebrospinal fluid.     

Antigen inhalation induces mast cells and eosinophils infiltration in the guinea pig esophageal epithelium involving histamine-mediated pathway

Antigen challenge in sensitized guinea pig esophagus in vitro induces mast cell degranulation and histamine release. This study tests the hypothesis that antigen inhalation in vivo induces infiltration of the esophageal epithelium by mast cells and eosinophils via a histamine pathway. Actively sensitized guinea pigs were exposed to inhaled 0.1% ovalbumin. One or 24 h after inhalation exposure, the esophagus was processed for immunofluorescent staining of mast cell tryptase and eosinophil major basic protein (MBP). Additional animals were pretreated with thioperamide, a histamine H4/H3 receptor antagonist. Total tryptase- and MBP-labeled cells and percent of positive cells in the epithelial layer were counted. The total number of mast cells was unchanged after inhalation challenge, but the percentage in the epithelium increased 1 h after challenge. The total number of eosinophils increased 1 h after challenge, and the percentage migrating to the epithelium increased by 24 h after challenge. Mast cell migration into the mucosal epithelium preceded that of eosinophils. Thioperamide inhibited mast cell and eosinophil migration. In conclusion, antigen inhalation in sensitized animals induces mast cells and eosinophils to infiltrate in the esophageal epithelium via histamine-mediated mechanism.     

Leukocyte differential analysis in multiple laboratory species by a laser multi-angle polarized light scattering separation method.

Leukocyte differential analysis was performed in various species, particularly laboratory animals, by the laser multi-angle polarized light scattering separation method. Venous blood specimens were drawn from the following subjects: healthy adult men and women ("humans"); cynomolgus monkeys ("monkeys"); common marmosets ("marmosets"); beagle dogs ("dogs"); miniature potbelly pigs ("swine"); Japanese white rabbits ("rabbits"); Hartley guinea pigs ("guinea pigs"); and Sprague-Dawley rats ("rats"). 90 degrees/10 degrees scatter plot: Basophils and mononuclear-polymorphonuclear cells were separated in all subjects, but individual 10 degrees and 90 degrees scatter plots overlapped in dogs and guinea pigs, respectively. 90 degrees depolarized /90 degrees scatter plot: Neutrophils and eosinophils were clearly separated in human, monkey, guinea pig, swine and rat subjects. The eosinophil cluster was not clearly plotted in marmoset, dog, or rabbit. 0 degree/10 degrees scatter plot: Regarding this plot for monocytes and lymphocytes, cells were plotted in the following order in all subjects: lymphocytes < basophils < or = monocytes in the 0 degree (size) scatter; and lymphocytes [symbol: see text] monocytes < or = basophils in the 10 degrees (complexity) scatter. Compared to other species, the rat scatter showed a tendency to overlapping plots in both the 0 degree and 10 degrees scatters in the monocyte and lymphocyte clusters. In both dog and guinea pig, the monocyte and neutrophil plots overlapped in the 0 degree and 10 degrees scatters. Basobox: In the human and rabbit subjects, the basophil cluster was plotted within the established basobox, but no clear cell cluster was plotted in the other subjects. As a result of comparing the percentage values for leukocytes in various species obtained by using the CD3500 apparatus versus the corresponding values obtained manually, good correspondence was found in the monkey, and eosinophils in the marmoset were lower with CD3500 than manually. In the rabbit, the mean measured value for basophils matched in the manual and CD3500 findings. In the guinea pig, the CD3500 values were lower than the manual values for lymphocytes, but higher for monocytes and neutrophils. The above findings suggest that the laser multi-angle polarized light scattering separation method is indeed capable of analyzing leukocytes from various species based on cell size and cell complexity, i.e., the presence or absence of nuclei, granules and cell enclosures.     

Effect of L-tryptophan supplementation on eosinophils and eotaxin in guinea pigs

Eosinophilia Myalgia Syndrome is a hypereosinophilic disorder that appears to result from the ingestion of the dietary supplement L-tryptophan by susceptible individuals. It is unclear if this disease results from tryptophan, contaminants found in tryptophan, individual predisposition (such as immune status and allergies), or some combination of effects. To evaluate effects of L-tryptophan on eosinophil migration, guinea pigs were compared with or without supplemental tryptophan (0.4 g/kg/day), with or without immune sensitization, and with or without immune challenge. Eosinophil counts were obtained from bone marrow, blood, lung, and bronchial alveolar lavage fluid (BAL). Lung cells were obtained to measure eotaxin concentrations in supernates and lysates with or without antigen and calcium ionophore challenge using direct ELISA. Skin biopsies were taken from both non-injected and antigen injection sites. The tryptophan supplemented, antigen-sensitized/antigen-challenged guinea pigs showed a significant decrease in blood eosinophils, compared to control (cellulose) supplemented antigen-sensitized/antigen-challenged guinea pigs [(0.086 +/- 0.023) x 10(6) vs (0.147 +/- 0.021) x 10(6) eosinophils/ml recovered, respectively] with a significant increase in BAL eosinophils [(0.052 +/- 0.008) x 10(6) vs (0.033 +/- 0.005) x 10(6) eosinophils/ml recovered, respectively]. Unchallenged lung cell lysates from tryptophan-supplemented guinea pigs contained significantly less eotaxin compared to cellulose-supplemented guinea pigs regardless of whether they were sensitized (0.006 +/- 0.002 vs 0.027 +/- 0.008 ng/10(6) cells, respectively). No differences were observed in skin biopsies between cellulose and tryptophan groups. These results suggest that L-tryptophan-supplemented guinea pigs have altered eotaxin regulation, a potential mechanism by which human overconsumption of tryptophan dietary supplements could lead to hypereosinophilic disorders in susceptible individuals.     

Effects of lactation on Trichostrongylus colubriformis infections in the guinea pig

Effects of lactation on Trichostrongylus colubriformis infections in the guinea pig. International journal for Parasitology, 4: 177–181. An increase in parasite egg output occurred in lactating guinea pigs infected with Trichostrongylus colubriformis, compared with that of either non-lactating or nulliparous females similarly infected. The lactating animals carried more parasites than either of the other two groups both as fourth stage larvae 9 days after infection and as adults at the peak of egg output 19 days after infection. Both the nulliparous and the non-lactating female guinea pigs had more mast cells and eosinophils in the small intestinal mucosa than did the lactating females.The behaviour of T. colubriformis in the lactating guinea pig is considered to be substantially the same as that of the various nematodes which have been studied in the lactating ewe.     

Ixodes dammini: Induced skin lesions in guinea pigs and rabbits compared to erythema chronicum migrans in patients with lyme arthritis

Erythematous skin lesions occurred in rabbits 2 days after being fed upon by larvae or nymphs of the tick, Ixodes dammini. Similar lesions occurred in guinea pigs 7 days after a primary infestation with either larvae or nymphs. Host resistance to secondary feeding by larvae was demonstrated in guinea pigs and rabbits. Host resistance to secondary feeding by nymphs was seen in guinea pigs, but not in rabbits. Guinea pigs developed resistance to nymphs after being previously fed upon twice by larvae. All skin lesions in resistant guinea pigs contained large accumulations of basophils (49–76% of cells) with smaller (20–33%), but significant, numbers of eosinophils. These responses were characteristic of strong cutaneous basophil hypersensitivity reactions. Primary and secondary lesions in rabbits fed upon by larvae contained mostly mononuclear cells (46–52%) and moderate numbers (16–30%) of basophils and eosinophils. Primary and secondary lesions in rabbits fed upon by nymphs had few (3–11%) basophils and eosinophils and were dominated by mononuclear cells (73–86%). Thus, acquired resistance in guinea pigs and rabbits was associated with cutaneous basophil and eosinophil responses and the lack of resistance of rabbits to nymphs was associated with erythematous lesions dominated by mononuclear cells. The mononuclear nature of rabbit lesions induced by nymphal feeding was similar to that seen in erythema chronicum migrans in Lyme arthritis patients who are thought to have been fed upon by I. dammini nymphs. This study confirms the cutaneous basophil hypersensitivity characteristics of lesions in guinea pigs resistant to ticks and demonstrates a relationship between the mononuclear cell response of rabbits to nymphal I. dammini and the cellular response seen in patients with erythema chronicum migrans and Lyme arthritis.     

TRH-like immunoreactivity in endocrine cells and neurons in the gastro-intestinal tract of the rat and guinea pig

Summary By use of the indirect immunofluorescence technique, the cellular localization of thyrotropin-releasing hormone (TRH) was studied in the gastrointestinal tract of rats and guinea pigs of different ages. TRH-like immunoreactivity (LI) was observed in many pancreatic islet cells of young rats and guinea pigs but only in single cells of 6-month-old rats. In aged guinea pigs, a reduction in the number of TRH-positive cells was evident; however, numerous strongly fluorescent cells were still present. In the guinea pig, TRH-LI was in addition observed in gastrin cells in the stomach. TRH-positive nerve fibers occurred in the myenteric plexus of the oesophagus, stomach and intestine of the rat, and in the muscle layers of the guinea pig. These results suggest a functional role of TRH both as hormone and neuroactive compound in various portions and sites of the gastro-intestinal tract of the rat and guinea pig     

Species heterogeneity of hepatic alpha 1-adrenoceptors: alpha 1A-, alpha 1B- and alpha 1C-subtypes.

alpha 1-Adrenergic activation stimulated phosphorylase and phosphoinositide turnover in hepatocytes from guinea pigs, rats and rabbits. Chlorethylclonidine inhibited these effects in rat and rabbit cells but not in guinea pig hepatocytes; low concentrations of 5-methyl urapidil blocked the alpha 1 actions in guinea pig and rabbit liver cells, but not in rat hepatocytes. Binding competition experiments also showed high affinity for 5-methyl urapidil in liver membranes from guinea pigs and rabbits and low affinity in those from rats. The data indicated that guinea pig hepatocytes express alpha 1A-, rat hepatocytes alpha 1B- and rabbit hepatocytes alpha 1C- adrenoceptors. This was confirmed by Northern analysis using receptor subtype-selective probes.     

Reactivity of rabbit antiserum to guinea pig eosinophils.

Although the eosinophil has been recognized as a distinctive cell type for almost 100 years, the major functions of these cells remain unknown. As an approach to defining these functions we have treated guinea pigs with rabbit antiserum to eosinophils (AES) in an attempt to ablate these cells from tissues. Rabbits were immunized thrice with purified eosinophils and the antisera were absorbed with peripheral blood cells from guinea pigs made eosinopenic with methyprednisolone to remove antibodies reactive with serum proteins and erythrocytes. The resulting sera reacted strongly with eosinophils in cytotoxicity tests and had weak or no reactivity with neutrophils. However, absorption of AES with purified neutrophils removed antieosinophil activity. Intraperitoneal injection of potent AES into guinea pigs resulted in complete absence of eosinophils from the peripheral blood and from the peritoneal cavity with only transient or no reduction in circulating neutrophils. Eosinophils were also reduced in bone marrow, spleen, and intestine. The ability of neutrophils to absorb AES activity in spite of weak reactivity in cytotoxicity tests may reflect a quantitative difference in antigenic determinants between eosinophils and neutrophils.     

Characterization of eosinophil cell activation by peptides. Differential effects of substance P, melittin, and FMET-Leu-Phe.

The ability of three different peptides, substance P (SP), FMLP and melittin, to activate eosinophils purified from the peritoneal cavity of human serum-treated guinea pigs was investigated. Degranulation (eosinophil peroxidase, EPO), oxidative burst (O2-), [Ca2+]i mobilization, and arachidonic acid metabolism (thromboxane B2, TXB2) were used as indices of eosinophil activation. SP (100 nM to 100 microM), FMLP (1 to 100 microM) and melittin (10 nM to 100 microM) induced EPO release but only FMLP (1 to 100 microM) led to an elevation of [Ca2+]i. The melittin- and SP-induced EPO secretion occurred at both cytotoxic and noncytotoxic concentrations as assessed by lactate dehydrogenase release. In addition, the effect of SP was not inhibited by the SP analogue (D-Pro4, D-Trp7,9,10)SP(4-11) and SP failed to promote the generation and subsequent release of TXA2. In contrast, FMLP (10 to 100 microM) stimulated the release of TXB2 from guinea pig eosinophils that was selectively inhibited by pretreatment of the cells with BOC-FMLP. On an equimolar basis (1 microM), melittin was approximately fivefold more active at promoting TXB2 release than FMLP. The results indicate that eosinophils respond to the three peptides, SP, melittin, and FMLP in differential fashion. We conclude that activation of guinea pig eosinophils by FMLP is likely to be receptor-mediated whereas the actions of SP and melittin may act through nonspecific peptide-membrane phospholipid interactions.     

In vivo PAF-induced airway eosinophil accumulation reduces bronchial responsiveness to inhaled histamine

Chronic eosinophilic bronchitis and bronchial hyperresponsiveness have been considered to be the fundamental features of bronchial asthma. However, the role of airway eosinophils in bronchial responsiveness in vivo has not been fully discussed. The aim of this study was to investigate the direct effect of airway eosinophil accumulation on bronchial responsiveness in vivo. Guinea pigs were transnasally treated with platelet activating factor (PAF) or vehicle twice a week for a total of 3 weeks. Anesthetized guinea pigs were surgically cannulated and artificially ventilated 48 h after the last administration of PAF or vehicle. Ten minutes after the installation of artificial ventilation, ascending doses of histamine were inhaled. In a subsequent study, selective inhibitors of diamine oxidase and histamine N-methyltransferase were intravenously administered before the histamine inhalation in the PAF-treated animals. Next study was conducted 20 min after treatment with indomethacin in this study line. Finally, ascending doses of methacholine were inhaled in our animal model. Proportion of eosinophils and the number of nuclear segmentation in bronchoalveolar lavage fluid significantly increased in guinea pigs treated with PAF compared with vehicle and this finding was confirmed histologically. Nevertheless, bronchial responsiveness to inhaled histamine, but not methacholine, was significantly decreased by the PAF treatment. This bronchoprotective effect induced by PAF remained following aminoguanidine and histamine N-methyltransferase administration, but abolished by treatment of indomethacin. These results suggest that in vivo airway eosinophils may reduce nonspecific bronchial responsiveness through production of inhibitory or bronchoprotective prostanoids, but not through histaminase production.     

Orally administrated Lactobacillus gasseri TMC0356 and Lactobacillus GG alleviated nasal blockage of guinea pig with allergic rhinitis

Lactobacillus GG (LGG) and L. gasseri TMC0356 (TMC0356) were investigated for their ability to alleviate nasal blockage associated with allergic rhinitis using a guinea pig model. The increases in sRaw at 10 min and 5 hr after the exposure of the nasal mucosa to OVA were significantly alleviated in the guinea pigs orally administrated with LGG and TMC0356 compared with those of the control (P<0.05 and P<0.01). The total numbers of leukocytes, particularly eosinophils and neutrophils from the nasal cavity lavage fluid, and the OVA-specific IgE concentration in the serum were also decreased in the guinea pigs orally administrated with LGG and TMC0356, although the decreases were not statistically significant. These results suggest that LGG and TMC0356 can alleviate antigen-induced nasal blockage in earlyphase and late-phase inflammatory responses associated with allergic rhinitis.