Durable Anti-SARS-CoV-2 Antibody Response after mRNA-1273 Booster in Peritoneal Dialysis Patients during the Omicron Wave.

Anti-SARS-CoV-2 vaccination of dialysis patients has been proven to be safe and effective to reduce COVID-19-related morbidity and mortality. However, data on the durability of anti-SARS-CoV-2 antibodies post-vaccination in peritoneal dialysis (PD) patients are scarce. In this prospective single-center cohort study we measured anti-SARS-CoV-2 RBD antibodies 3 and 6 months after the 3rd dose of the mRNA-1273 vaccine in 27 adult PD patients and recorded breakthrough infections. Furthermore, in a mixed model analysis, we analyzed potential factors influencing the humoral response following vaccination. Anti-SARS-CoV-2 RBD antibody levels declined from 21,424 BAU/mL at 1 month to 8397 BAU/mL at 3 months and to 5120 BAU/mL at 6 months after the 3rd dose, but remained higher than pre-3rd dose levels (212 BAU/mL). Eight patients (29.6%) were infected with SARS-CoV-2 within six months from the 3rd dose during the Omicron wave. Previous high antibody levels, high glomerular filtration rate (GFR) and low Davies Comorbidity Score were associated with higher anti-SARS-CoV-2 antibody levels after the booster. In conclusion, PD patients exhibited a robust and durable humoral response after a third dose of the mRNA-1273 vaccine. A high GFR and low comorbidity as well as previous high antibody levels predicted a better humoral response to vaccination.

Humoral Response to mRNA-1273 SARS-CoV-2 Vaccine in Peritoneal Dialysis Patients: Is Boostering After Six Months Adequate?

In dialysis patients the humoral response to anti-SARS-CoV-2 vaccines is attenuated and rapidly declines over time. However, data on the persistence of the immune response in peritoneal dialysis (PD) patients are scarce, particularly after a third (booster) dose with mRNA-1273 vaccine. In this prospective cohort study, we report anti-SARS-CoV-2 antibody levels in PD patients before and after the third dose of mRNA-1273 vaccine. Six months after the second dose, anti-SARS-CoV-2 antibodies were detected in all patients (n = 34). However, within this time period antibodies substantially declined in 31 of 34 patients (4.5-fold, median = 192 BAU/mL, p = 1.27 × 10-9) and increased in three patients. In accordance with government regulations, a third dose of mRNA-1273 vaccine (50 µg) was given to 27 PD patients 6 months after the second dose which induced a significant increase of anti-SARS-CoV-2 antibody titers (58.6-fold, median = 19405 BAU/mL, p = 1.24 × 10-29). A mixed model analysis showed that a lower Davies Comorbidity Score and a higher GFR were associated with higher antibody titers (p = 0.03 and p = 0.02). The most common adverse events after the third dose were pain at the injection site (77.8%) and fatigue (51.9%). No hospitalizations were reported. In conclusion, 6 months after the second dose of mRNA-1273 vaccine, anti-SARS-CoV-2 antibodies substantially decreased in PD patients, whereas a well-tolerated third dose induced a robust humoral response. Our data suggest that the administration of a booster dose within a shorter interval than 6 months should be considered in PD patients in order to maintain high anti-SARS-CoV-2 antibody levels and assure protection from severe COVID-19 disease.

Antibody Response and Safety After mRNA-1273 SARS-CoV-2 Vaccination in Peritoneal Dialysis Patients - the Vienna Cohort.

Background: Dialysis patients are at high risk for a severe clinical course after infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Safety and early immune responses after mRNA-based vaccination have been reported mostly in patients on hemodialysis (HD), whereas reports of peritoneal dialysis (PD) patients remain rare. Methods: In this retrospective observational study, 39 PD patients had received two doses of the mRNA-1273 Moderna® vaccine. We analyzed SARS-CoV-2 Spike (S) antibody titers 4 weeks after each dose of mRNA-1273 and report local and systemic side effects in PD patients that occurred within one week after each mRNA-1273 dose. Using a quantile regression model we examined factors that might influence SARS-CoV-2 S antibody levels in PD patients. Results: Four weeks after the first dose of mRNA-1273 vaccine 33 of 39 (84.6%) PD patients seroconverted and presented with 6.62 U/mL (median; IQR 1.57-22.5) anti-SARS-CoV-2 S antibody titers. After the second dose, 38 of 39 (97.4%) PD patients developed anti-SARS-CoV-2 S antibodies and titers increased significantly (median 968 U/mL; IQR 422.5-2500). Pain at the injection site was the most common local adverse event (AE) (71%). Systemic AEs occurring after the first dose were mostly fatigue (33%) and headache (20%). No severe systemic AEs were reported after the first injection. After the second dose the incidence and the severity of the systemic AEs increased. The most common systemic AEs were: fatigue (40.5%), headache (22.5%), joint pain (20%), myalgia (17.5%) and fever (13%). Lower Davies Comorbidity Score (p=0.04) and shorter dialysis vintage (p=0.017) were associated with higher antibody titers after the first dose. Patients with higher antibody titers after the first dose tended to have higher antibody titers after the second dose (p=1.53x10-05). Conclusions: Peritoneal dialysis patients in this cohort had a high seroconversion rate of 97.4%, showed high antibody titers after full vaccination and tolerated the anti-SARS-CoV-2 mRNA-1273 vaccine well without serious adverse events.

Comparison of Iron Dosing Strategies in Patients Undergoing Long-Term Hemodialysis: A Randomized Controlled Trial.

BACKGROUND AND OBJECTIVES: Whether iron supplementation in patients on hemodialysis could be delivered by less frequent but higher single doses compared with the currently more common higher-frequency schedules of lower single iron doses is unknown. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: We carried out an open-label, randomized, controlled noninferiority trial over 40 weeks in patients on prevalent hemodialysis (n=142). We administered in total 2 g iron as 100 mg iron sucrose biweekly in a continuous (20 × 100 mg) fashion or 500 mg ferric carboxymaltose every 10 weeks in a periodic (4 × 500 mg) fashion. The primary end point was the change in hemoglobin at week 40 from baseline with a noninferiority margin of -0.8 g/dl. Secondary end points were changes in ferritin, transferrin, transferrin saturation, and erythropoiesis-stimulating agent use. RESULTS: In total, 108 patients completed the study. At 40 weeks, hemoglobin changed by -0.27 g/dl (95% confidence interval, -0.64 to 0.09) in the iron sucrose arm and by -0.74 g/dl (95% confidence interval, -1.1 to -0.39) in the ferric carboxymaltose arm compared with baseline. Noninferiority was not established in the per-protocol population as hemoglobin changes compared with baseline differed by -0.47 g/dl (95% confidence interval, -0.95 to 0.01) in the ferric carboxymaltose arm compared with the iron sucrose arm. Proportional changes from baseline to week 40 differed by -31% (98.3% confidence interval, -52 to -0.1) for ferritin, by 1% (98.3% confidence interval, -7 to 10) for transferrin, and by -27% (98.3% confidence interval, -39 to -13) for transferrin saturation in the ferric carboxymaltose arm compared with the iron sucrose arm. Erythropoiesis-stimulating agent dosing did not differ between groups. The overall number of adverse events was similar; however, more infections were observed in the iron sucrose arm. CONCLUSIONS: An equal cumulative dose of ferric carboxymaltose administered less frequently did not meet noninferiority for maintaining hemoglobin levels compared with iron sucrose administered more frequently. CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER: Comparison Study of Two Iron Compounds for Treatment of Anemia in Hemodialysis Patients (COPEFER), NCT02198495.

Electrolyte disorders in stable renal allograft recipients.

BACKGROUND: Acid base and electrolyte disorders are frequently reported in the early period after renal transplantation. No comprehensive data exist on the prevalence and patterns of, and contributing factors to, electrolyte disturbances in patients with stable long-term allograft function. METHODS: We analysed 576 renal transplant recipients (serum creatinine level <2.0 mg/dl) in a cross-sectional study to evaluate the prevalence of electrolyte disorders and the risk factors associated with their occurrence. RESULTS: A total of 369 patients (64%) of all allograft recipients (n = 576) showed at least one electrolyte and acid base disorder. The most abundant disorder was hypomagnesaemia (25%, n = 143), followed by hyperkalaemia (12.8%, n = 74), hypercalcaemia (12%, n = 69), hypophosphataemia (11.6%, n = 67), metabolic acidosis (11.1%, n = 61) and hyponatraemia (9%, n = 52). All other electrolyte disorders were rare (<6%). In most cases the electrolyte disorders could be classified as mild. Forty percent of the cases had a combined disorder, but without a preferential pattern of combinations. In a multivariate logistic regression analysis, the most important factors contributing significantly to the occurrence of electrolyte disorders were renal function and concomitant medications. CONCLUSION: Acid base and electrolyte disorders are frequently observed in stable renal allograft recipients, but are usually mild. A combination of two or more electrolyte abnormalities often occurs, although no predominant pattern of a unique combination of electrolyte disorder is recognizable.  .

SNEV(Prp19/PSO4) deficiency increases PUVA-induced senescence in mouse skin.

Senescent cells accumulate during ageing in various tissues and contribute to organismal ageing. However, factors that are involved in the induction of senescence in vivo are still not well understood. SNEV(P) (rp19/) (PSO) (4) is a multifaceted protein, known to be involved in DNA damage repair and senescence, albeit only in vitro. In this study, we used heterozygous SNEV(+/-) mice (SNEV-knockout results in early embryonic lethality) and wild-type littermate controls as a model to elucidate the role of SNEV(P) (rp19/) (PSO) (4) in DNA damage repair and senescence in vivo. We performed PUVA treatment as model system for potently inducing cellular senescence, consisting of 8-methoxypsoralen in combination with UVA on mouse skin to induce DNA damage and premature skin ageing. We show that SNEV(P) (rp19/) (PSO) (4) expression decreases during organismal ageing, while p16, a marker of ageing in vivo, increases. In response to PUVA treatment, we observed in the skin of both SNEV(P) (rp19/) (PSO) (4) and wild-type mice an increase in γ-H2AX levels, a DNA damage marker. In old SNEV(P) (rp19/) (PSO) (4) mice, this increase is accompanied by reduced epidermis thickening and increase in p16 and collagenase levels. Thus, the DNA damage response occurring in the mouse skin upon PUVA treatment is dependent on SNEV(P) (rp19/) (PSO) (4) expression and lower levels of SNEV(P) (rp19/) (PSO) (4) , as in old SNEV(+/-) mice, result in increase in cellular senescence and acceleration of premature skin ageing.

MicroRNAs differentially present in the plasma of HIV elite controllers reduce HIV infection in vitro.

Elite controllers maintain HIV-1 viral loads below the limit of detection. The mechanisms responsible for this phenomenon are poorly understood. As microRNAs (miRNAs) are regulators of gene expression and some of them modulate HIV infection, we have studied the miRNA profile in plasma from HIV elite controllers and chronically infected individuals and compared against healthy donors. Several miRNAs correlate with CD4+ T cell count or with the known time of infection. No significant differences were observed between elite controllers and healthy donors; however, 16 miRNAs were different in the plasma of chronic infected versus healthy donors. In addition, levels of hsa-miR-29b-3p, hsa-miR-33a-5p and hsa-miR-146a-5p were higher in plasma from elite controllers than chronic infected and hsa-miR-29b-3p and hsa-miR-33a-5p overexpression significantly reduced the viral production in MT2 and primary T CD4+ cells. Therefore, levels of circulating miRNAs might be of diagnostic and/or prognostic value for HIV infection, and hsa-miR-29b-3p and miR-33a-5p may contribute to the design of new anti-HIV drugs.

Identification of microRNA-mRNA functional interactions in UVB-induced senescence of human diploid fibroblasts.

BACKGROUND: Cellular senescence can be induced by a variety of extrinsic stimuli, and sustained exposure to sunlight is a key factor in photoaging of the skin. Accordingly, irradiation of skin fibroblasts by UVB light triggers cellular senescence, which is thought to contribute to extrinsic skin aging, although molecular mechanisms are incompletely understood. Here, we addressed molecular mechanisms underlying UVB induced senescence of human diploid fibroblasts. RESULTS: We observed a parallel activation of the p53/p21(WAF1) and p16(INK4a)/pRb pathways. Using genome-wide transcriptome analysis, we identified a transcriptional signature of UVB-induced senescence that was conserved in three independent strains of human diploid fibroblasts (HDF) from skin. In parallel, a comprehensive screen for microRNAs regulated during UVB-induced senescence was performed which identified five microRNAs that are significantly regulated during the process. Bioinformatic analysis of miRNA-mRNA networks was performed to identify new functional mRNA targets with high confidence for miR-15a, miR-20a, miR-20b, miR-93, and miR-101. Already known targets of these miRNAs were identified in each case, validating the approach. Several new targets were identified for all of these miRNAs, with the potential to provide new insight in the process of UVB-induced senescence at a genome-wide level. Subsequent analysis was focused on miR-101 and its putative target gene Ezh2. We confirmed that Ezh2 is regulated by miR-101 in human fibroblasts, and found that both overexpression of miR-101 and downregulation of Ezh2 independently induce senescence in the absence of UVB irradiation. However, the downregulation of miR-101 was not sufficient to block the phenotype of UVB-induced senescence, suggesting that other UVB-induced processes induce the senescence response in a pathway redundant with upregulation of miR-101. CONCLUSION: We performed a comprehensive screen for UVB-regulated microRNAs in human diploid fibroblasts, and identified a network of miRNA-mRNA interactions mediating UVB-induced senescence. In addition, miR-101 and Ezh2 were identified as key players in UVB-induced senescence of HDF.

High levels of oncomiR-21 contribute to the senescence-induced growth arrest in normal human cells and its knock-down increases the replicative lifespan.

Cellular senescence of normal human cells has by now far exceeded its initial role as a model system for aging research. Many reports show the accumulation of senescent cells in vivo, their effect on their microenvironment and its double-edged role as tumour suppressor and promoter. Importantly, removal of senescent cells delays the onset of age-associated diseases in mouse model systems. To characterize the role of miRNAs in cellular senescence of endothelial cells, we performed miRNA arrays from HUVECs of five different donors. Twelve miRNAs, comprising hsa-miR-23a, hsa-miR-23b, hsa-miR-24, hsa-miR-27a, hsa-miR-29a, hsa-miR-31, hsa-miR-100, hsa-miR-193a, hsa-miR-221, hsa-miR-222 and hsa-let-7i are consistently up-regulated in replicatively senescent cells. Surprisingly, also miR-21 was found up-regulated by replicative and stress-induced senescence, despite being described as oncogenic. Transfection of early passage endothelial cells with miR-21 resulted in lower angiogenesis, and less cell proliferation mirrored by up-regulation of p21(CIP1) and down-regulation of CDK2. These two cell-cycle regulators are indirectly regulated by miR-21 via its validated direct targets NFIB (Nuclear factor 1 B-type), a transcriptional inhibitor of p21(CIP) (1) , and CDC25A, which regulates CDK2 activity by dephosphorylation. Knock-down of either NFIB or CDC25A shows a phenocopy of over-expressing miR-21 in regard to cell-cycle arrest. Finally, miR-21 over-epxression reduces the replicative lifespan, while stable knock-down by sponges extends the replicative lifespan of endothelial cells. Therefore, we propose that miR-21 is the first miRNA that upon its knock-down extends the replicative lifespan of normal human cells.

Mast cell population in the frog brain: distribution and influence of thyroid status.

In the developing frog brain, the majority of mast cells (MC) are distributed in the pia mater, and some immature MC are located adjacent to the blood capillaries in and around the neuropil. In the adult brain, MC are more numerous than in pre- and pro-metamorphic tadpoles; they are mainly located within the pia mater and are particularly numerous in the choroid plexuses. Many MC are found within the brain ventricles juxtaposed to the ependymal lining. MC are rarely observed in the brain parenchyma. In the adult brain, MC number is much higher than in the brain of post-metamorphic froglets. In the latter, MC number is nearly 2-fold over that found in the pre-metamorphic brain. Treatment of pre- and pro-metamorphic tadpoles with 3,5,3'-triiodothyronine (T(3)) and thyroxine (T(4)) stimulates overall larval development but does not induce a significant change in MC population within the brain. By contrast, treatment with 6-n-propyl-2-thiouracil (PTU) delays larval development and leads to a significant numerical increase of brain MC. In the adult, PTU treatment also has a similar effect whereas hypophysectomy causes a drastic decrease of MC population. The negative effects of hypophysectomy are successfully counteracted by a two-week replacement therapy with homologous pars distalis homogenate. In the adult frog, MC population seems to be refractory to thyroid hormone treatment. The present study on frog brain suggests that pituitary-thyroid axis may be involved in the regulation of MC frequency.

Mast cells in the amphibian brain during development.

This is the first descriptive study of ontogenesis and anatomical distribution of mast cells in the developing brain of three different amphibian species. In the toad and the green frog, mast cells are preferentially located in: (i) the meningeal lining (pia mater), (ii) the choroid plexuses, both anterior and posterior, and (iii) the neuropil, in close association with the epithelial cell lining of blood vessels. It is only in the perennially aquatic African clawed frog that mast cells never appear inside brain ventricles and within the neuropil. Mast cells first become identifiable in brain of different species in different stages of development. While there are differences in the number of mast cells in different species at different stages of development, the number nearly doubles in all three species during the transition from pro-metamorphic stage of larval development to the peak of metamorphic climax. Furthermore, the number of mast cells is comparatively higher in the toad and remarkably lower in the fully aquatic Xenopus laevis, in which species the first appearance of identifiable mast cells during larval development occurs much later than in equivalent stages of development of the toad and the green frog. The secretory nature of mast cells can be assumed by the presence of cytoplasmic granules, which may show species-specific texture. Further experimental analyses are required to unveil the usefulness of mast cells in the amphibian brain.

Thyroid status can influence brain mast cell population.

Neuroanatomical mapping as well as the influence of thyroid status on brain mast cell distribution and detectable mast cell number in adult Rana esculenta is studied. Treatment with tizoxin (T4) does not modify number or activational state of brain mast cells, whereas administration of the antithyroid agent 6-n-propyl-2-thiouracil induces a significant increase (up to 40%) in the mast cell number within the telencephalon and diencephalon. Hypophysectomy induces a significant decrease (up to 65%) of mast cells in all brain regions, whereas the pituitary homogenate augments their number. The results suggest that the pituitary-thyroid axis may be involved in the regulation of brain mast cell population.

D-Aspartate affects secretory activity in rat Harderian gland: molecular mechanism and functional significance.

In this paper, the role of D-aspartate in the rat Harderian gland (HG) was investigated by histochemical, ultrastructural, and biochemical analyses. In this gland, substantial amounts of endogenous D-Asp were detected, along with aspartate racemases that convert D-Asp to L-Asp and vice versa. We found that the gland was capable of uptaking and accumulating exogenously administered D-Asp. D-Asp acute treatment markedly increased lipid and porphyrin secretion and induced a powerful hyperaemia in inter-acinar interstitial tissue. Since D-Asp is known to be recognized by NMDA receptors, the expression of such receptors in rat HG led us to the hypothesis that D-Asp acute treatment induced the activation of the extracellular signal-regulated protein kinase (ERK) and nitric oxide synthase (NOS) pathways mediated by NMDA. Interestingly, as a result of enhanced oxidative stress due to increased porphyrin secretion, the revealed activation of the stress-activated protein kinase/c-jun N-terminal kinase (SAPK/JNK) pro-apoptotic pathway was probably triggered by the gland itself to preserve its cellular integrity.

Morphological and biochemical changes in the Harderian gland of hypothyroid rats.

The secretory activity of the Harderian gland (HG) is influenced by both exogenous (such as light and temperature) and endogenous (such as prolactin, thyroid hormones and steroid hormones) factors, which vary among species. In the present study, the effects of hypothyroidism on the rat HG were examined at morphological and biochemical levels. The decrease in cytoplasmic lipoproteic vacuoles and the increase in mucosubstance secretion in the acinar lumina were the most notable histological effects elicited by hypothyroidism. The release of all granules with nuclei and cellular debris suggested the occurrence of holocrine secretion. Electron microscopy revealed in the glandular cells of hypothyroid rat an increased condensation of chromatin in the nuclei, mitochondria with decreased cristae and vacuolisation, decreased glycogen granules, autophagic vacuoles, and lipofuscins in the cytoplasm. TUNEL reaction indicated DNA fragmentation in hypothyroid HG, indicative of an underlying apoptotic process. Translocation of cytochrome c from mitochondria to cytosol strongly supported this hypothesis. In conclusion, these findings indicate that thyroid hormones play a pivotal role in preserving the structural integrity of the rat HG and, hence, its secretory activity.

Dimorphic expression of uncoupling protein-3 in golden hamster harderian gland: effects of castration and testosterone administration.

Hamster (Mesocricetus auratus) harderian gland (HG) is a dimorphic orbital gland producing a copious lipid secretion. Two cell-types are present in hamster HG, type I in both sexes, type II only in males. In hamster HGs, we found a marked sexual dichotomy in the expression of uncoupling protein-3 (UCP3), a mitochondrial protein carrier, that probably exports fatty acid anions and fatty acid peroxides from the mitochondrial matrix. Following castration and/or testosterone treatment: (1) UCP3 levels correlated with the type II-cell percentage, not with testosterone levels, (2) in male HGs, UCP3 was comparable to female levels at 30 days post-castration (when the type II-cell percentage had fallen from 50 to 5%), although testosterone was already near zero at 15 days (when neither the type II-cell percentage nor the UCP3 level had fallen), and testosterone-replacement therapy prevented these changes. Testosterone-treated females possessed type II cells and a UCP3 level about twofold higher than in control females. Males displayed more intense UCP3 immunohistochemical positivity in type I HG cells than females. Hence, testosterone may indirectly control UCP3 expression by regulating the gland's morphological and lipid dimorphism. Straight-chain fatty acids [found in alkyl diacylglycerols (ADGs) in males] are oxidized predominantly in mitochondria, branched-chain fatty acids (abundant in ADGs in females) predominantly in peroxisomes, so we speculate that the higher UCP3 expression in males reflects greater fatty acid flux in HG mitochondria. This is supported by our finding that in female (not male) HGs, the peroxisome-rich fraction contained alpha-methylacyl-CoA racemase (AMACR), an enzyme important in the beta-oxidation of branched-chain fatty acids.

Mast cell-derived TNF contributes to airway hyperreactivity, inflammation, and TH2 cytokine production in an asthma model in mice.

BACKGROUND: Mast cells, IgE, and TNF, which have been implicated in human atopic asthma, contribute significantly to the allergic airway inflammation induced by ovalbumin (OVA) challenge in mice sensitized with OVA without alum. However, it is not clear to what extent mast cells represent a significant source of TNF in this mouse model. OBJECTIVE: We investigated the importance of mast cell-derived TNF in a mast cell-dependent model of OVA-induced airway hyperreactivity (AHR) and allergic airway inflammation. METHODS: Features of this model of airway inflammation were analyzed in C57BL/6J-wild-type mice, mast cell-deficient C57BL/6J-Kit(W-sh)(/W-sh) mice, and C57BL/6J Kit(W-sh/W-sh) mice that had been systemically engrafted with bone marrow-derived cultured mast cells from C57BL/6J-wild-type or C57BL/6J-TNF(-/-) mice. RESULTS: Ovalbumin-induced AHR and airway inflammation were significantly reduced in mast cell-deficient Kit(W-sh/W-sh) mice versus wild-type mice. By contrast, Kit(W-sh/W-sh) mice that had been engrafted with wild-type but not with TNF(-/-) bone marrow-derived cultured mast cells exhibited responses very similar to those observed in wild-type mice. Mast cells and mast cell-derived TNF were not required for induction of OVA-specific memory T cells in the sensitization phase, but significantly enhanced lymphocyte recruitment and T(H)2 cytokine production in the challenge phase. CONCLUSION: Mast cell-derived TNF contributes significantly to the pathogenesis of mast cell-dependent and IgE-dependent, OVA-induced allergic inflammation and AHR in mice, perhaps in part by enhancing lymphocyte recruitment and T(H)2 cytokine production. CLINICAL IMPLICATIONS: Our findings in mice support the hypothesis that mast cell-derived TNF can promote allergic inflammation and AHR in asthma.

Mast cell-derived tumor necrosis factor can promote nerve fiber elongation in the skin during contact hypersensitivity in mice.

In humans, lesions of contact eczema or atopic dermatitis can exhibit increases in epidermal nerves, but the mechanism resulting in such nerve elongation are not fully understood. We found that contact hypersensitivity reactions to oxazolone in mice were associated with significant increases in the length of nerves in the epidermis and dermis. Using genetically mast cell-deficient c-kit mutant mice selectively repaired of their dermal mast cell deficiency with either wild-type or tumor necrosis factor (TNF)-deficient mast cells, we found that mast cells, and mast cell-derived TNF, significantly contributed to the elongation of epidermal and dermal PGP 9.5+ nerves and dermal CGRP+ nerves, as well as to the inflammation observed at sites of contact hypersensitivity in response to oxazolone. Moreover, the percentage of mast cells in close proximity to dermal PGP 9.5+ nerve fibers was significantly higher in wild-type mice and in c-kit mutant mice repaired of their dermal mast cell deficiency by the adoptive transfer of wild-type mast cells than in TNF-deficient mice or in TNF-/- mast cell-engrafted c-kit mutant mice. These observations show that mast cells, and mast cell-derived TNF, can promote the elongation of cutaneous nerve fibers during contact hypersensitivity in the mouse.

Thyroid hormone affects secretory activity and uncoupling protein-3 expression in rat harderian gland.

The effects of T(3) administration on the rat Harderian gland were examined at morphological, biochemical, and molecular levels. T(3) induced hypertrophy of the two cell types (A and B) present in the glandular epithelium. In type A cells, the hypertrophy was mainly due to an increase in the size of the lipid compartment. The acinar lumina were filled with lipoproteic substances, and the cells often showed an olocrine secretory pattern. In type B cells, the hypertrophy largely consisted of a marked proliferation of mitochondria endowed with tightly packed cristae, the mitochondrial number being nearly doubled (from 62 to 101/100 microm(2)). Although the average area of individual mitochondria decreased by about 50%, the total area of the mitochondrial compartment increased by about 80% (from 11 to 19/100 microm(2)). This could be ascribed to T(3)-induced mitochondrial proliferation. The morphological and morphometric data correlated well with our biochemical results, which indicated that mitochondrial respiratory activity is increased in hyperthyroid rats. T(3), by influencing the metabolic function of the mitochondrial compartment, induces lipogenesis and the release of secretory product by type A cells. Mitochondrial uncoupling proteins 2 and 3 were expressed at both mRNA and protein levels in the euthyroid rat Harderian gland. T(3) treatment increased the mRNA levels of both uncoupling protein 2 (UCP2) and UCP3, but the protein level only of UCP3. A possible role for these proteins in the Harderian gland is discussed.

Androgen and estrogen receptors expression in the rat exorbital lacrimal gland in relation to "harderianization".

The rat exorbital lacrimal glands (ELG) are particularly interesting for their biochemical and morphological sexual differences. Our histochemical and ultrastuctural observations confirm a phenomenon termed "harderianization" that occurs in the ELG of males and females at three months of age. The "harderianization" consists of the appearance of lipid foci in the ELG; this effect increases at six months of age only in the male glands, while it is not detectable in those of females. Histochemical tests for mucosubstances and proteins evidenced that while the secretory granules of male ELG are prevalently composed of sulphate substances, those of the female are composed of acid substances, and only a few cells positive to proteins were seen in the acinar epithelium of the glands. Moreover, we demonstrated by RT-PCR the presence of androgen and estrogen receptors in the rat ELG of both sexes. Androgen receptor transcript is always present in male and female ELG while the expression of estrogen receptor is not more detectable in the ELG of males at six months of life. In conclusion, our results suggest that estradiol may prevent the further lipid degeneration of the female ELG at six months of life. In addition, the disappearance of both the "harderian lipid" foci in the female gland and of estrogen receptor in the male gland indicates a probable involvement of estrogens in the phenomenon of "harderianization."

Induced maturation of frog mast cells by nerve growth factor during ontogenesis.

The effect of nerve growth factor (NGF) on ontogenesis of frog mast cells was investigated in vivo by histochemical, morphometric, and ultrastructural analysis. Three groups of tadpoles at various stages of development were used. In the first group, the larvae received i.p. injections of 1 ng NGF/g; the second group received 10 ng NGF/g, while the control group received only the vehicle. The first recognizable mast cells arose symmetrically in the tongue at stage 26 of Witschi's standard table. At stages 26 and 29, the mast cell number in the NGF-injected tadpoles was significantly higher than the control group. From stage 29 onward, the mast cell number rapidly increased in all groups. No significant differences in mast cell number were observed between the control group and the NGF-injected groups at stages 31 and 33. Electron microscopy revealed that at metamorphic climax (stage 33), the mast cells in the NGF-treated groups were more mature than those in the control group. Therefore, nerve growth factor at early stages of tadpole development is likely to induce differentiation of mast cell precursors, while at later stages it is likely to induce maturation of immature mast cells. The close anatomical association between mast cells and perineurium, observed during nerve development, is intriguing. Already in the early stages of nerve development, the mast cells form a network around Schwann cell-axon complexes, together with the perineurial cells. At climax, the mast cells are located between the perineurial layers, suggesting that they may play a role in the tissue-nerve barrier of the perineurium. Nerve growth factor also seems to induce perineurial cell maturation.