Dexamethasone-induced apoptosis in immune cells from peripheral circulation and lymphomyeloid tissues of juvenile clearnose skates, Raja eglanteria

THE EFFECT OF DEXAMETHASONE ON HEMATOLOGIC PROFILES, HEMOSPORIDIAN INFECTION, AND SPLENIC HISTOLOGY IN HOUSE FINCHES (HAEMORHOUS MEXICANUS)

Research on host response to infectious disease often involves pharmacological induction of immunosuppression, frequently through administration of dexamethasone. Reports on the effect of dexamethasone in birds are largely restricted to poultry and pigeons. This study describes changes in white blood cell (WBC) differentials, hemoparasite counts, splenic histology, and splenic CD3 immunoreactivity in House Finches (Haemorhous mexicanus). Experimental group birds (n=9) were treated with a daily intramuscular injection of 25 µg of dexamethasone for 8 d; a control group (n=9) received daily saline solution. Smears were made with blood collected immediately before the first dose (day 0) and on d 4, 8, and 9, and stained with modified Wright. The WBC differential counts were performed by three blinded observers, parasite counts by two blinded observers, and histology by one blinded observer. Dexamethasone-treated birds experienced relative heterophilia and lymphopenia on d 4 (P=0.008); heterophilia was also present at d 8 (P=0.018). Hemosporidian counts were significantly increased in dexamethasone-treated birds on d 4 and 8 (P=0.048 and P=0.031, respectively). In contrast with control birds, all dexamethasone-treated birds lacked histologically apparent splenic lymphoid follicles (P<0.001). No significant difference was observed in splenic CD3 immunoreactivity between groups. Our results indicate that dexamethasone has an effect on the hematologic profile of House Finches and suggest that it may be a useful method to induce immunosuppression in this species.

Effects of dexamethasone and gamma globulin combined with prednisone on the therapeutic effect and immune function of Henoch-Schonlein purpura nephritis in children

Background

Henoch‐Schonlein purpura nephritis (HSPN) is a serious complication of Henoch‐Schonlein purpura (HSP), which is usually treated with immunosuppressant and glucocorticoid. This study was designed to explore the effect of dexamethasone and gamma globulin combined with prednisone in the treatment of pediatric HSPN.

Methods

According to the treatment plan, 60 children treated with dexamethasone and gamma globulin were included in the control group, and the rest 55 children treated with dexamethasone and gamma globulin combined with prednisone were selected as the research group. The clinical manifestations, therapeutic effect, immune function, serum inflammatory factors, blood coagulation function, urine routine, renal function, and adverse reactions were compared between the two groups.

Results

The clinical manifestations of children in the research group were significantly better than those in the control group after treatment (P < .05). The total effective rate in the research group (94.55%) was markedly higher than that in the control group (76.67%) (P < .05). CD3+, CD4+, CD8+, IL‐10, PT, and APTT increased while CD4+/CD8+, IgA, IL‐8, TNF‐α, FIB, urine protein, urine red blood cell, Scr, and BUN decreased in both groups after treatment, and the changes of all the above indexes in the research group were significant than those in the control group (P < .05). The incidence of adverse reactions in the research group was remarkably superior to that in the control group (P < .05).

Conclusion

Dexamethasone and gamma globulin combined with prednisone can improve the immune function of children with HSPN and promote the recovery of renal function.

In vivo phagocytosis and hematology in Astyanax altiparanae, a potential model for surrogate technology

Abstract Although the potential of surrogate propagation technology for aquaculture and conservation of Neotropical fish, the poor understanding of the host immune system may results in rejection and destruction of the donor material. Thus, it is necessary to study and to develop methods to evaluate the effects of immunosuppressive drugs employment and to evaluate the immunocompatibility between donor and receptor. Thus, the present study aimed to optimize a methodology to assess in vivo phagocytosis in Astyanax altiparanae using Saccharomyces cerevisiae and to evaluate their hematological response resultant from the inflammatory induction. To this, S. cerevisiae were labeled with Congo red and injected in the coelomic cavity of A. altiparanae at the concentration of 2.5 x 106 cells mL-1. A PBS solution and a non-injected group were kept as control. Fish blood was sampled and the phagocytic capacity and index were determined at 1, 2, 3 and 6 h post-injection (hpi). The yeast injection successfully stimulated phagocytosis, with the best result for phagocytosis assessment after 2 hpi. Moreover, it was achieved a high traceability of phagocytized and non-phagocytized yeast under optic microscopy analysis due to the Congo red labeling. The hematological profile was similar to usually observed in early infections, indicating lymphocyte migration to inflammatory site and increase in number of circulating phagocytes due to natural response to inflammatory stimulus. In conclusion, our method was efficient to assess in vivo phagocytosis in A. altiparanae and will be an important tool to evaluate the efficacy of immunosuppressive drugs in this species. Additionally, these results may serve as support for further studies in fish immunocompetence, both in laboratory and in field conditions.

Modular Acid-Activatable Acetone-Based Ketal-Linked Nanomedicine by Dexamethasone Prodrugs for Enhanced Anti-Rheumatoid Arthritis with Low Side Effects

Given the physically encapsulated payloads with drug burst release and/or low drug loading, it is critical to initiate an innovative prodrug strategy to optimize the design of modular nanomedicines. Here, we designed modular pH-sensitive acetone-based ketal-linked prodrugs of dexamethasone (AKP-dexs) and formulated them as nanoparticles. We comprehensively studied the relationships between AKP-dex structure and properties, and we selected two types of AKP-dex-loaded nanoparticles for in vivo studies on the basis of their size, drug loading, and colloidal stability. In a collagen-induced arthritis rat model, these AKP-dex-loaded nanoparticles showed higher accumulation in inflamed joints and better therapeutic efficacy than free dexamethasone phosphate with less-severe side effects. AKP-dex-loaded nanoparticles may be useful for treating other inflammatory diseases and thus have great translational potential. Our findings represent an important step toward the development of practical applications for acetone-based ketal-linked prodrugs and are useful in the design of modular nanomedicines.

Potential Human Health Applications from Marine Biomedical Research with Elasmobranch Fishes

Members of the subclass of fishes collectively known as elasmobranchs (Class Chondrichthyes, Subclass Elasmobranchii) include sharks, skates, rays, guitarfish, and sawfish. Having diverged from the main line of vertebrate evolution some 400 million years ago, these fishes have continued to be successful in our ever-changing oceans. Much of their success must be attributed to their uncanny ability to remain healthy. Based on decades of basic research, some of their secrets may be very close to benefitting man. In this short review, some of the molecular and cellular biological areas that show promise for potential human applications are presented. With a brief background and current status of relevant research, these topics include development of new antibiotics and novel treatments for cancer, macular degeneration, viral pathogens, and Parkinson’s disease; potentially useful genomic information from shark transcriptomes; shark antibody-derived drug delivery systems; and immune cell-derived compounds as potential cancer therapeutic agents.

High‐dose, short‐term, anti‐inflammatory treatment with dexamethasone reduces growth and augments the effects of 5‐fluorouracil on dimethyl‐α‐benzanthracene‐induced mammary tumors in rats

OBJECTIVE

To evaluate the effects of dexamethasone (DXM) alone or in combination with 5-fluorouracil (5-FU) on dimethyl-alpha-benzanthracene (DMBA)-induced mammary tumors in rats.

MATERIAL AND METHODS

Female Sprague-Dawley rats were divided into 4 groups receiving: 1) saline (controls), 2) DXM (3 mg/kg), 3) 5-FU (1.5 mg/kg) and 4) DXM and 5-FU combined. The drugs were given i.p. every day for 4 days. Interstitial fluid pressure (Pif) and tumor growth were determined in all tumors on days 1, 5 and 7 using the "wick-in-the needle" technique and by external size measurements, respectively. Vessel density and inflammatory cell infiltration of tumor tissue were analyzed by immunohistochemistry.

RESULTS

DXM treatment significantly retarded tumor growth and reduced Pif. Treatment with a combination of DXM and 5-FU reduced tumor size significantly more than any of the agents alone (p<0.01-0.001). Enhanced uptake of 5-FU by DXM treatment was demonstrated by microdialysis. There were no differences in the density of CD31-positive vessels after DXM or 5-FU treatment, but inflammatory cell infiltration of tumor tissue was significantly reduced after DXM treatment.

CONCLUSIONS

Our data suggest that DXM may be beneficial as an adjuvant to chemotherapy in the treatment of mammary cancer by increasing the uptake of 5-FU in the tumor.

Evolution of hormone signaling in elasmobranchs by exploitation of promiscuous receptors

Specific interactions among proteins, nucleic acids, and metabolites drive virtually all cellular functions and underlie phenotypic complexity and diversity. Despite the fundamental importance of interactions, the mechanisms and dynamics by which they evolve are poorly understood. Here we describe novel interactions between a lineage-specific hormone and its receptors in elasmobranchs, a subclass of cartilaginous fishes, and infer how these associations evolved using phylogenetic and protein structural analyses. The hormone 1alpha-hydroxycorticosterone (1alpha-B) is a physiologically important steroid synthesized only in elasmobranchs. We show that 1alpha-B modulates gene expression in vitro by activating two paralogous intracellular transcription factors, the mineralocorticoid receptor (MR) and glucocorticoid receptor (GR), in the little skate Leucoraja erinacea; MR serves as a high-sensitivity and GR as a low-sensitivity receptor. Using functional analysis of extant and resurrected ancestral proteins, we show that receptor sensitivity to 1alpha-B evolved millions of years before the hormone itself evolved. The 1alpha-B differs from more ancient corticosteroids only by the addition of a hydroxyl group; the three-dimensional structure of the ancestral receptor shows that the ligand pocket contained ample unoccupied space to accommodate this moiety. Our findings indicate that the interactions between 1alpha-B and elasmobranch GR and MR proteins evolved by molecular exploitation: a novel hormone recruited into new functional partnerships two ancient receptors that had previously interacted with other ligands. The ancestral receptor's promiscuous capacity to fortuitously bind compounds that are slight structural variants of its original ligands set the stage for the evolution of this new interaction.

Influence of reproductive activity, sex steroids, and seasonality on epigonal organ cellular proliferation in the skate (Leucoraja erinacea)

In elasmobranchs, the epigonal organ, a unique leukopoietic immune tissue, is associated with the gonads. As the ovaries increase in size during reproductive activity, the overall mass of the epigonal organ does not change. However, immunohistochemistry (proliferating cell nuclear antigen Ab) demonstrated more proliferative activity and extravasation of epigonal leukocytes from blood vessels in reproductively active (RA) skates (Leucoraja erinacea) than in non-reproductively active (NRA) skates. In addition, [(3)H]thymidine incorporation was greater in epigonal leukocytes from RA skates than in leukocytes from NRA skates. Plasma from RA skates, but not from NRA skates, increased proliferation of epigonal leukocytes in vitro, an effect that was not seen using steroid-free plasma. In contrast to the stimulatory effect of plasma on leukocyte proliferation, addition of steroids (estrogen, progesterone, testosterone, and dexamethasone) in vitro decreased [(3)H]thymidine incorporation. While the inhibitory response to steroids was seasonally variable, (3)[H]thymidine incorporation was always highest in RA animals, in which plasma steroid levels were also consistently highest. These studies suggest functional interactions between reproductive and immune tissues in the skate, and that cellular turnover in epigonal tissue may be influenced by gonadal activity.

Nitric oxide production by nurse shark (Ginglymostoma cirratum) and clearnose skate (Raja eglanteria) peripheral blood leucocytes

Reactive nitrogen intermediates, such as nitric oxide (NO), are important immunomodulators in vertebrate immune systems, but have yet to be identified as mediators of host defence in any member of class Chondrichthyes, the cartilaginous fishes. In the present study, production of NO by nurse shark (Ginglymostoma cirratum) peripheral blood leucocytes (PBL) stimulated with bacterial cell wall lipopolysaccharide (LPS) was investigated. PBL were cultured for 24 to 96 h following stimulation with LPS at concentrations ranging from 0 to 25 microg ml(-1), in both serum-supplemented and serum-free culture conditions. Production of NO was measured indirectly using the Griess reaction, with maximal NO production occurring after 72 h using 10% FBS and 10 microg LPS ml(-1). Application of these culture conditions to PBL from another cartilaginous fish (clearnose skate, Raja eglanteria) resulted in a similar NO response. Addition of a specific inhibitor of inducible nitric oxide synthase (iNOS), L-N(6)-(1-iminoethyl)lysine (L-NIL), resulted in a significant decrease in the production of NO by PBL from both species.

Evidence of apoptotic effects of 2,4-D and butachlor on walking catfish, Clarias batrachus, by transmission electron microscopy and DNA degradation studies

Apoptosis or programmed cell death is characterized morphologically by chromatin condensation, cell shrinkage, fragmentation of the nucleus and cytoplasm, and consequently formation of apoptotic bodies. It has also been best characterized by the cleavage of DNA into nucleosomal size fragments of 180-200 bp or multiples of the same. Contrary to this, under extreme conditions, the cells were found to show adaptive response to apoptosis and unable to regulate their own death; necrosis is therefore predominantly observed. In the present study, we showed induction of apoptosis in Clarias batrachus due to sublethal concentration of 2,4-D and butachlor at multiple exposure time. The first phase of the study involved light microscopy (LM) and transmission electron microscopy (TEM) for ultrastructural abnormalities of the germinal tissues. While, in the second phase of the study, DNA degradation of blood and hepatic tissue was resolved on agarose gel electrophoresis. In histopathological studies, large numbers of stage II oocytes were noted for nuclear blebbing irrespective of the test chemical. Some of the butachlor-exposed oocytes showed vacuolation and electron dense cytoplasm along with thickened nuclear envelope, having close association with the lysosomes on the cytoplasmic side. Some oocytes undergo nuclear blebbing having inner dense core and translucent cytoplasm. Leydig cells were slightly hypertrophied and few appeared pycnotic, a process involving necrotic changes in which the cell nuclei were characterized by rounding up and condensation resulting in hyperchromatic staining or pycnosis. In testicular tissue, spermatogonial nuclei had irregular large clumps of heterochromatin adjoining the nuclear membrane indicating initial stage of apoptotic cell death. Electrophoretic separation resulted in a ladder pattern of blood DNA and smear like pattern of hepatic DNA. These results indicate that the above herbicides are able to induce apoptosis both at molecular as well as cytological level. A reference dose or safety factor approach to calculate risk of human exposure to both chemicals is still awaited.

In vivo exposure of clearnose skates, Raja eglanteria, to ionizing X-radiation: acute effects on the thymus

To investigate for the first time the effects of ionizing radiation on thymus of a representative cartilaginous fish, juvenile clearnose skates, Raja eglanteria, were exposed to 0-75 Gy of X-radiation and sacrificed after 12 days. Morphometrics (weight, disc width and total length) and thymus and thymic cyst area were compared to controls using ANOVA. Thymus area declined logarithmically and medullary cysts increased as a function of dose (P < or = 0.05). To assess thymic recovery, skates were exposed to 0, 9, 13.5 or 18 Gy of X-radiation and sacrificed when moribund or on days 10, 20, 30 and 40 post-irradiation. Complete restoration of the thymus was not achieved during the 40-day observation period, although repopulation with pro-thymocytes and partial recovery of thymic architecture were evident histologically. The observed high radiosensitivity of R. eglanteria thymocytes was similar to responses of other vertebrates, but recovery time was prolonged.

Evolutionary origins of lymphocytes: ensembles of T cell and B cell transcriptional regulators in a cartilaginous fish

The evolutionary origins of lymphocytes can be traced by phylogenetic comparisons of key features. Homologs of rearranging TCR and Ig (B cell receptor) genes are present in jawed vertebrates, but have not been identified in other animal groups. In contrast, most of the transcription factors that are essential for the development of mammalian T and B lymphocytes belong to multigene families that are represented by members in the majority of the metazoans, providing a potential bridge to prevertebrate ancestral roles. This work investigates the structure and regulation of homologs of specific transcription factors known to regulate mammalian T and B cell development in a representative of the earliest diverging jawed vertebrates, the clearnose skate (Raja eglanteria). Skate orthologs of mammalian GATA-3, GATA-1, EBF-1, Pax-5, Pax-6, Runx2, and Runx3 have been characterized. GATA-3, Pax-5, Runx3, EBF-1, Spi-C, and most members of the Ikaros family are shown throughout ontogeny to be 1) coregulated with TCR or Ig expression, and 2) coexpressed with each other in combinations that for the most part correspond to known mouse T and B cell patterns, supporting conservation of function. These results indicate that multiple components of the gene regulatory networks that operate in mammalian T cell and B cell development were present in the common ancestor of the mammals and the cartilaginous fish. However, certain factors relevant to the B lineage differ in their tissue-specific expression patterns from their mouse counterparts, suggesting expanded or divergent B lineage characteristics or tissue specificity in these animals.

Effects of 17alpha-ethinylestradiol on immune parameters in the lizard Sceloporus occidentalis

We examined the effect of 17alpha-ethinylestradiol on immunity of the Western fence lizard, Sceloporus occidentalis. Injection of 17alpha-ethinylestradiol resulted in dose-dependent suppression of peripheral blood leukocyte levels as determined by cell counts, whereas total spleen cell levels were decreased only at higher doses of 17alpha-ethinylestradiol. In contrast, spleen cell proliferation was enhanced by 17alpha-ethinylestradiol as measured by reduction of MTT to formazan following a two-way mixed lymphocyte reaction. Antibody responses were unaffected. Effects on peripheral blood leukocyte levels and spleen cell proliferation similar to those observed in response to injection of 17alpha-ethinylestradiol were observed following injection of a single dose of hydrocortisone. However, injection of lizards with 17alpha-ethinylestradiol did not result in a significant increase in serum cortisol. Results of this study suggest that exposure of Western fence lizards to 17alpha-ethinylestradiol leads to decreased numbers of circulating leukocytes and total spleen cell numbers and the enhancement of spleen cell proliferation in a two-way mixed lymphocyte reaction. These effects probably involve mechanisms other than or in addition to the induction of cortisol release.