Relationship between Numerous Mast Cells and Early Follicular Development in Neonatal MRL/MpJ Mouse Ovaries

In the neonatal mouse ovary, clusters of oocytes called nests break into smaller cysts and subsequently form individual follicles. During this period, we found numerous mast cells in the ovary of MRL/MpJ mice and investigated their appearance and morphology with follicular development. The ovarian mast cells, which were already present at postnatal day 0, tended to localize adjacent to the surface epithelium. Among 11 different mouse strains, MRL/MpJ mice possessed the greatest number of ovarian mast cells. Ovarian mast cells were also found in DBA/1, BALB/c, NZW, and DBA/2 mice but rarely in C57BL/6, NZB, AKR, C3H/He, CBA, and ICR mice. The ovarian mast cells expressed connective tissue mast cell markers, although mast cells around the surface epithelium also expressed a mucosal mast cell marker in MRL/MpJ mice. Some ovarian mast cells migrated into the oocyte nests and directly contacted the compressed and degenerated oocytes. In MRL/MpJ mice, the number of oocytes in the nest was significantly lower than in the other strains, and the number of oocytes showed a positive correlation with the number of ovarian mast cells. The gene expression of a mast cell marker also correlated with the expression of an oocyte nest marker, suggesting a link between the appearance of ovarian ? 4mast cells and early follicular development. Furthermore, the expression of follicle developmental markers was significantly higher in MRL/MpJ mice than in C57BL/6 mice. These results indicate that the appearance of ovarian mast cells is a unique phenotype of neonatal MRL/MpJ mice, and that ovarian mast cells participate in early follicular development, especially nest breakdown.     

Thymus involution in alloxan diabetes: analysis of mast cells

We previously reported that alloxan-induced diabetes results in reduction in the number and reactivity of mast cells at different body sites. In this study, the influence of diabetes on thymic mast cells was investigated. Thymuses from diabetic rats showed marked alterations including shrinkage, thymocyte depletion, and increase in the extracellular matrix network, as compared to those profiles seen in normal animals. Nevertheless, we noted that the number and reactivity of mast cells remained unchanged. These findings indicate that although diabetes leads to critical alterations in the thymus, the local mast cell population is refractory to its effect. This suggests that thymic mast cells are under a different regulation as compared to those located in other tissues.     

Collagen concentration and mast cell in perinatal murine uterus

Edema was found in the uterine tissue on the day of parturition. The number of mast cells was increased significantly on this day, indicating that the time of appearance of the edema is identical to the time of a significant increase in the number of mast cells. These results suggest that mast cells induce the high vascular permeability that permits passage of collagenase-activating proteases to the uterine tissue from the serum.     

The Lectin ArtinM Induces Recruitment of Rat Mast Cells from the Bone Marrow to the Peritoneal Cavity

Background

The D-mannose binding lectin ArtinM is known to recruit neutrophils, to degranulate mast cells and may have potential therapeutic applications. However, the effect of ArtinM on mast cell recruitment has not been investigated.

Methodology

Male Wistar rats were injected i.p. with ArtinM or ConA (control). The ability of the lectin to degranulate peritoneal and mesenteric mast cells was examined. Recruitment of mast cells to the peritoneal cavity and mesentery after ArtinM injection was examined with or without depletion of peritoneal mast cells by distilled water.

Results

ArtinM degranulated both peritoneal and mesentery mast cells in vitro. Three days after i.p. injection of the lectin there were reduced numbers of mast cells in the peritoneal lavage, while at 7 days post injection of ArtinM, the number of peritoneal mast cells was close to control values. Since immature mast cells are recruited from the bone marrow, the effect of the lectin on bone marrow mast cells was examined. Injection of ArtinM resulted in an increased number of mast cells in the bone marrow. To determine if degranulation of mast cells in the peritoneal cavity was required for the increase in bone marrow mast cells, the peritoneal cavity was depleted of mast cells with ultrapure water. Exposure to ArtinM increased the number of mast cells in the bone marrow of rats depleted of peritoneal mast cells.

Conclusions

The ArtinM induced recruitment of mast cells from the bone marrow to the peritoneal cavity may partially explain the therapeutic actions of ArtinM.     

Mast cells in human odontogenic cysts

Mast cells are granule-containing cells in mucosal and connective tissues that are known to play a central role in allergic and inflammatory responses owing to pro-inflammatory mediators. Cysts in jaws are among the most common expansive, benign and destructive bone lesions; at some stage they are associated with chronic inflammation. Earlier studies have identified mast cells in odontogenic cysts (OC). We investigated the presence and distribution of mast cells and compared their number in different types of radicular cysts (RC), dentigerous cysts (DC) and odontogenic keratocysts (OKC). Ten cases each of RC, DC and OKC diagnosed clinically and histopathologically were selected and stained with 1% toluidine blue. The greatest number of mast cells/mm(2) was found in RC. The fewest mast cells/mm(2) were found in OKC. The subepithelial zones of all cysts contained more mast cells than the deeper zones.     

Mast cells in human odontogenic cysts

Abstract

Mast cells are granule-containing cells in mucosal and connective tissues that are known to play a central role in allergic and inflammatory responses owing to pro-inflammatory mediators. Cysts in jaws are among the most common expansive, benign and destructive bone lesions; at some stage they are associated with chronic inflammation. Earlier studies have identified mast cells in odontogenic cysts (OC). We investigated the presence and distribution of mast cells and compared their number in different types of radicular cysts (RC), dentigerous cysts (DC) and odontogenic keratocysts (OKC). Ten cases each of RC, DC and OKC diagnosed clinically and histopathologically were selected and stained with 1% toluidine blue. The greatest number of mast cells/mm² was found in RC. The fewest mast cells/mm² were found in OKC. The subepithelial zones of all cysts contained more mast cells than the deeper zones.     

The role of mast cells in thioglycollate-induced inflammation

The possible role of mast cells in the initiation of inflammation was studied in genetically mast cell-deficient mice, WBB6F1-W/Wv. Inflammation was induced by i.p. injection of thioglycollate. The influx of neutrophils was markedly delayed in WBB6F1-W/Wv mice as compared to the WBB6F1-+/+, mice (congeneic controls). At the time (14 h) of maximum influx of neutrophils in WBB6F1-+/+ mice, thioglycollate caused a 3-fold increase in the total cell number in the peritoneal lavage fluid, and the neutrophil count was elevated 14-fold. At the same time point in W/Wv mice, the total cell number in the peritoneal lavage fluid was not increased significantly and the neutrophils were increased only three- to four-fold. Not only was the neutrophil influx in WBB6F1-W/Wv mice delayed, but the length of time during which the neutrophil count was elevated in the peritoneal fluid was significantly shortened. Transfer (i.p.) of mast cells cultured from the bone marrow of congeneic controls corrected the delay in the neutrophil influx. The magnitude of the neutrophil influx in WBB6F1-W/Wv mice was equivalent to that of congeneic controls 9 days after mast cell repletion. Histologic studies were performed to follow the migration and differentiation of mast cells after adoptive transfer into WBB6F1-W/Wv mice. No connective tissue mast cells could be identified on day 9 when the inflammatory reaction was restored. Migration of mast cells into the tissue, as studied in the cecum, progressed steadily. On day 9 after adoptive transfer, the mast cell number was 38% of congeneic controls. Therefore, the increase in thioglycollate-induced neutrophil influx in WBB6F1W/Wv mice after mast cell repletion seemed to be correlated, at least to some extent, with the migration of mast cells into tissues and not with differentiation into connective tissue mast cells. However, a certain maturation and differentiation may have occurred. These results suggest that mast cells play an important role, although they do not seem to be the only cell type responsible for the initiation of inflammation.     

Mast cells in the rat brain synthesize gonadotropin-releasing hormone

Mast cells occur in the brain and their number changes with reproductive status. While it has been suggested that brain mast cells contain the mammalian hypothalamic form of gonadotropin-releasing hormone (GnRH-I), it is not known whether mast cells synthesize GnRH-I de novo. In the present study, mast cells in the rat thalamus were immunoreactive to antisera generated against GnRH-I and the GnRH-I associated peptide (GAP); mast cell identity was confirmed by the presence of heparin, a molecule specific to mast cells, or serotonin. To test whether mast cells synthesize GnRH-I mRNA, in situ hybridization was performed using a GnRH-I cRNA probe, and the signal was identified as being within mast cells by the binding of avidin to heparin. GnRH-I mRNA was also found, using RT-PCR, in mast cells isolated from the peritoneal cavity. Given the function of GnRH-I in the regulation of reproduction, changes in the population of brain GnRH-I mast cells were investigated. While housing males with sexually receptive females for 2 h or 5 days resulted in a significant increase in the number of brain mast cells, the proportion of mast cells positive for GnRH-I was similar to that in males housed with a familiar male. These findings represent the first report showing that mast cells synthesize GnRH-I and that the mast cell increase seen in a reproductive context is the result of a parallel increase in GnRH-I positive and non-GnRH-I positive mast cells.     

Light microscopic radioautographic study of the localization of an anti-allergic agent, Tranilast, in rat mast cells

In order to demonstrate the localization of an anti-allergic agent, Tranilast, in the mast cells, light microscopic radioautography was performed. The mast cells collected from rat peritoneal cavity were incubated for 0 to 60 min in a medium containing 3H-Tranilast. After the incubation, they were fixed, embedded and processed for light microscopic radioautography. The radioautographic silver grains were frequently localized around and over the cytoplasmic granules and their number increased according to the prolongation of incubation time. From the results obtained at present it was demonstrated that Tranilast was rapidly taken into the cytoplasm of mast cells. This phenomenon may suggest an important role of this agent in the inhibition of allergic reactions of mast cells.     

Submucosal mast cells in the gastrointestinal tract are a target of staphylococcal enterotoxin type A

Staphylococcal enterotoxin A (SEA) is a leading causative toxin of staphylococcal food poisoning. However, it remains unclear how this toxin induces emesis in humans, primates, and certain experimental animals. To understand the mechanism of SEA-induced emesis, we investigated the behavior of SEA in the gastrointestinal (GI) tract in vivo using the house musk shrew (Suncus murinus). Immunofluorescence of GI sections showed that perorally administered SEA translocated from the lumen to the interior tissues of the GI tract and rapidly accumulated in certain submucosa cells. These SEA-binding cells in the submucosa were both tryptase- and FcεRIα-positive, suggesting these SEA-binding cells were mast cells. These SEA-binding mast cells were 5-hydroxytryptamine (5-HT)-positive, but the intensity of the 5-HT signal decreased over time compared to that of mast cells in the negative control. Furthermore, toluidine blue staining showed the number of metachromatic mast cells was decreased in the duodenal submucosa, suggesting that SEA binding induced degranulation and release of 5-HT from submucosal mast cells. These observations suggest that the target cells of SEA are submucosal mast cells in the GI tract and that 5-HT released from submucosal mast cells plays an important role in SEA-induced emesis.     

HISTAMINE AND MAST CELLS IN DEVELOPING RAT BRAIN

The number and distribution of mast cells in rat brain were determined at different postnatal ages. The number of brain mast cells was found to change during ontogenic development following the same pattern as brain histamine (HA) levels. The calculated HA content of brain mast cells was close to the HA content of the crude nuclear fraction at every age studied. Since most of the brain HA in the newborn sediments with the crude nuclear fraction, these results suggest that the developmental pattern of brain HA reflects changes in the number of brain mast cells, that is, in the size of the mast cell HA pool. The HA content of the supernatant of the crude nuclear fraction corrected for mast cell HA contamination, on the other hand, follows a developmental pattern similar to that of other known neurotransmitters.     

Presence of a blastocyst and mast cell depletion of the mouse uterus

The mast cell population has been studied during early decidualization of the mouse uterus. The number increases in early pregnancy until the attachment phase when a sharp depletion is noticed. This fall has been correlated with stimuli of maternal origin, but at the same time the presence of a blastocyst at the presumptive implantation sites seems to exert a significant effect on the depletion of mast cells. A relationship between the number of mast cells in the uterus and the physiological state of the organ has definitely been established [Harvey, 1964; Likar and Likar, 1964; Gibbons and Chang, 1972; Brandon and Evans, 1983]. The number of mast cells in the pregnant uterus is known to decrease around the time of implantation in the rat [Shelesnyak, 1960; De Feo, 1967; Brandon and Bibby, 1979]. Several workers believe that the mast cell population and histamine content decrease as a result of a rise in circulating estrogen [Westin, 1955; Gibbons and Chang, 1972; Spaziani, 1975]. In the present communication the possibility of a relationship between the decrease in mast cell population and the presence of a blastocyst, whose estrogenic role has been reported [Dickmann and Dey, 1973; Dickmann et al., 1975; Sengupta et al., 1977], in the uterine horn has been discussed.     

Prostaglandin D2 generation after activation of rat and human mast cells with anti-IgE

Anti-IgE-dependent activation of rat and human mast cells resulted in the preferential generation of the cyclooxygenase products prostaglandin D2 (PGD2) and prostaglandin I2 (PGI2) in the rat and PGD2 in the human. The average net generation of PGD2, determined by gas chromatography-mass spectrometry, was 13.1 ng/10(6) purified rat mast cells and 39.5 ng/10(6) dispersed, enriched human mast cells. After IgE-dependent activation, there was a linear relationship between the net quantities of PGD2 generated and of histamine secreted from dispersed human pulmonary cells when the number of mast cells was varied but the total number of cells was held constant, indicating that it is the number of mast cells participating in IgE-dependent activation, rather than total mast cell number, that determines PGD2 generation. A linear relationship was also shown between PGD2 generation, determined by radioimmunoassay, and the release of the granule marker beta-hexosaminidase from purified rat mast cells on the dose-response portion of the plot of their response to anti-IgE challenge. With higher concentrations of anti-IgE, PGD2 generation from rat mast cells plateaued, whereas net percent beta-hexosaminidase release increased further. In kinetic studies of rat mast cells activated with anti-IgE, the onset (1 to 2 min) and time of maximum generation (5 to 10 min) for PGD2 were delayed relative to the onset (15 to 30 sec) and completion (1 to 2 min) of beta-hexosaminidase release. Thus, the extracellular appearance of PGD2 during IgE-dependent mast cell activation represents a response additional to the secretion of granule-associated mediators.     

High levels of filamentous actin and apoptosis correlate with mast cell refractoriness under alloxan-evoked diabetes

Mast cell number and reactivity were shown to be down-regulated under diabetic conditions. Since the balance between globular and filamentous actin plays a pivotal role in the activity of secretory cells, we investigated whether an imbalance in that system could underlie the hyporesponsiveness of mast cells in diabetes. The apoptotic state was also evaluated. By means of rhodamine/phalloidine staining of F-actin, we noted that diabetic mast cells exhibited an increase in fluorescence intensity and reduction in cellular size, when compared with cells from normal animals, in parallel with elevation in the percentage of cells developing apoptosis. The levels of Bax, a pro-apoptotic member of Bcl-2 family, appeared increased at baseline in mast cells from diabetic rats compared with normal cells. These phenomena correlated with reduction in histamine and PGD2 release following antigen challenge in vitro. The steroid antagonist RU 486 abolished the reduction of histamine secretion from diabetic mast cells. We conclude that hyporesponsiveness of mast cells noted in diabetes may be accounted for by reduction in actin filament plasticity, in clear association with the rise in the percentage of cells undergoing apoptosis. In addition, the refractoriness of diabetic mast cells to antigen in vitro seems to be dependent on glucocorticoids.     

Mast cells in the rat brain synthesize gonadotropin‐releasing hormone

Mast cells occur in the brain and their number changes with reproductive status. While it has been suggested that brain mast cells contain the mammalian hypothalamic form of gonadotropin‐releasing hormone (GnRH‐I), it is not known whether mast cells synthesize GnRH‐I de novo. In the present study, mast cells in the rat thalamus were immunoreactive to antisera generated against GnRH‐I and the GnRH‐I associated peptide (GAP); mast cell identity was confirmed by the presence of heparin, a molecule specific to mast cells, or serotonin. To test whether mast cells synthesize GnRH‐I mRNA, in situ hybridization was performed using a GnRH‐I cRNA probe, and the signal was identified as being within mast cells by the binding of avidin to heparin. GnRH‐I mRNA was also found, using RT‐PCR, in mast cells isolated from the peritoneal cavity. Given the function of GnRH‐I in the regulation of reproduction, changes in the population of brain GnRH‐I mast cells were investigated. While housing males with sexually receptive females for 2 h or 5 days resulted in a significant increase in the number of brain mast cells, the proportion of mast cells positive for GnRH‐I was similar to that in males housed with a familiar male. These findings represent the first report showing that mast cells synthesize GnRH‐I and that the mast cell increase seen in a reproductive context is the result of a parallel increase in GnRH‐I positive and non‐GnRH‐I positive mast cells. © 2003 Wiley Periodicals, Inc. J Neurobiol 56: 113–124, 2003     

Compartmentalized mast cell degranulations in the ovarian hilum, fat pad, bursa and blood vessel regions of the cyclic hamster: relationships to ovarian histamine and blood flow.

Ovaries from hamsters on each day of the oestrous cycle at 09.00 h were observed for the number of mast cells, the pattern of mast cell degranulation, histamine concentration and blood flow. On day 4 (pro-oestrus), ovaries were also observed at 9.00, 15.00 and 21.00 h. Mast cell degranulation was evaluated by 3 criteria: (1) no degranulation = less than 5 granules dispersed from the cell; (2) moderate degranulation = 5 or more granules dispersed but less than 15, and (3) extensive degranulation = 15 or more granules released. Blood flow was determined using radio-active microspheres in anaesthetized animals. Mast cells were observed in fat pad (beyond 2 mm of the bursal mesothelium), bursa (within 2 mm of the bursal mesothelium), hilum and near ovarian blood vessels (these 4 regions are collectively called the ovarian complex). The distribution of ovarian mast cells was not uniform. Most mast cells were near ovarian blood vessels (42.2%) and in the fat pad (37.2%). A moderate number of cells were in the bursal wall (20%) and only a few cells were observed in the hilum (0.64%). Mast cell number remained unchanged on days 1-4 of the cycle in each ovarian compartment. However, summation of the number of mast cells in the entire ovarian complex revealed a significant decline in number at 15.00 h on pro-oestrus. Alterations in mast cell degranulation were primarily restricted to 2 periods of the cycle (pro-oestrus and di-oestrus). An increase in moderate but not extensive degranulation was observed in only the fat pad and bursa on day 2 when compared with day 1 values. In most ovarian compartments on pro-oestrus, degranulation was higher than on any other day of the cycle. At 15.00 h on pro-oestrus, extensive degranulation in bursa, fat pad and blood vessel regions (but not hilum) coincided with an increase in ovarian histamine and decline in number of mast cells; ovarian blood flow also increased at the time but remained unchanged the remainder of the cycle.(ABSTRACT TRUNCATED AT 250 WORDS)     

Estrogen-induced increase in eosinophil number and peroxidase activity in uterus of genetically mast cell-deficient W/Wv mice

The role of mast cells in induction of uterine eosinophilia was investigated by using genetically mast cell-deficient (WB X C57BL/6)F1-W/Wv (hereafter called WBB6F1-W/Wv) mice. The injection of estradiol-17 beta (0.16 micrograms/g body weight) increased the peroxidase activity and eosinophil number in the uteri of castrated WBB6F1-W/Wv and WBB6F1-+/+ mice. Since no significant differences were detectable between these two type of mice, mast cells did not seem to be essential for the estrogen-induced uterine eosinophilia, at least in mice.     

Cutaneous mast cell depletion results from topical corticosteroid usage

The effect of long-term topical application of corticosteroids on human cutaneous mast cells was examined. Two potent corticosteroids, clobetasol-17-propionate and fluocinonide, produced a greater than 85% decrease in histamine content over a 6-wk treatment period, whereas betamethasone valerate, a less potent corticosteroid, produced a 66% decrease. Electron microscopic examination of the biopsies taken from sites after 6 wk of treatment indicate that the reduced levels of histamine were caused by the depletion of mast cells, as evidenced by: the inability to identify any cells representative of mast cells by detailed electron microscopy of the biopsies; and the marked acellularity around the vasculature where mast cells are certain to be detected. Histamine levels did not begin to decline until after 3 wk of corticosteroid treatment, indicating that corticosteroids are not immediately harmful to mast cells. Electron microscopic examination of biopsies taken at the beginning of treatment and 1 wk later showed normal-appearing mast cells, whereas at 3 wk, a small population of mast cells was detected with features usually associated with degenerating or dying cells. These observations suggest that protracted application of corticosteroids to skin is toxic to mast cells. After discontinuation of treatment, the drug-related atrophy associated with chronic application of potent corticosteroids to skin is rapidly reversed, and skin structure returns to near normal by 14 days. Over this time period, however, histamine levels did not increase and mature mast cells could not be observed by electron microscopy. At 14 days post-steroid treatment, the first signs of cells containing sparse amounts of granules having the characteristics of mast cell granules were seen. We interpret this to represent new mast cells beginning to mature in the skin. By 3 mo, histamine levels returned to normal, demonstrating the reversibility of the steroid-induced mast cell depletion. The studies presented here establish the deleterious effects of long-term topical corticosteroid treatment on cutaneous mast cells, and begin to establish a system in which the development of mast cells in tissue can be investigated.     

Chronic allergen challenge induces bronchial mast cell accumulation in BALB/c but not C57BL/6 mice and is independent of IL-9

As genetically engineered mutant mice deficient in single genes are usually generated on a C57BL/6 background, to study mast cell trafficking in mutant mice, we initially investigated whether mast cells accumulated in bronchi in C57BL/6 mice challenged with OVA allergen acutely or chronically for 1 to 3 months. The total number of bronchial mast cells were quantitated using toluidine blue staining in airways of different sizes, i.e. , small (<90 μm), medium (90–155 μm), or large (>150 μm) airways. Non-OVA challenged and acute OVA challenged mice (C57BL/6 and BALB/c) had no detectable bronchial mast cells. Chronic OVA challenge in BALB/c mice for 1 or 3 months induced a significant increase in the number of bronchial mast cells in small-, medium-, and large-sized airways but minimal change in the number of bronchial mast cells in C57BL/6 mice. Both BALB/c and C57BL/6 mice developed significant lung eosinophilia following acute or chronic OVA challenge. Studies of IL-9-deficient mice on a BALB/c background demonstrated a significant increase in the number of bronchial mast cells in IL-9-deficient mice suggesting that IL-9 was not required for the bronchial accumulation of mast cells. Overall, these studies demonstrate that the chronic OVA challenge protocol we have utilized in BALB/c mice provides a model to study the mechanism of bronchial mast cell accumulation and that bronchial mast cell accumulation in chronic OVA challenged mice is independent of IL-9 in this model.     

Ultrastructural circadian variation of mast cells in the pinna of the mouse

It has been found previously under the light microscope that there was a circadian variation in mast cell number in the pinna of mice. The mast cell number was increased at 18.00 h and decreased at 06.00 h. In the current study, 5 mice of each group were synchronized for 4 weeks with a standard lighting regimen (light: 06.00-20.00 h; dark: 20.00-06.00 h). Both pinnas of every mouse of each group were removed at 06.00, 12.00, 18.00 and 24.00 h, respectively. Under the electron microscope, it was observed that more degranulated mast cells were found at 06.00 h and more intact mast cells were visible at 18.00 h. It appeared that the mast cell numbers, decreased and increased under the light microscope, were due to mast cell degradation and regranulation. This finding suggests that a functional circadian variation exists in the mast cell under physiological conditions.