Periarteriolar Lymphoid Sheath Research Articles

Response of lymphoid organs to immunization with Fc fragments of IgG carrying epitopes specific to regulatory rheumatoid factor

Previously, we identified a new factor of autoimmunity downregulation, called regulatory rheumatoid factor (regRF). The production of regRF was associated with the resistance of animals to the experimental autoimmune diseases or with the remission in animals that are sensitive to the autoimmune diseases. The action of regulatory rheumatoid factor is based on the killing of activated CD4 T lymphocytes expressing PD-1, which makes it possible to restrain the expansion of lymphocytes, including autoreactive ones. RegRF-specific epitopes (regRF epitopes) can be induced on IgG Fc fragments. Immunization of rats with homologous IgG Fc fragments bearing regRF epitopes suppresses symptoms, lymphocytic infiltration and target tissue damage in several experimental models of autoimmune diseases. An in vitro study of the mechanisms of regRF-producing lymphocytes activation by IgG Fc fragments carrying regRF epitopes showed that IgG Fc fragments carrying regRF epitopes are T cell-independent antigens type 2. The reactions of the immune system, in particular in lymphoid organs, to T cell-independent antigens type 2, especially having a protein nature, are poorly studied. The purpose of this work is to study the reactions of the spleen and lymph nodes of rats to immunization with IgG Fc fragments carrying regRF epitopes. Wistar rats were immunized subcutaneously with 500 μg of homologous IgG Fc fragments carrying regRF epitopes. Control animals received an injection of phosphate-buffered saline. Immunization with IgG Fc fragments carrying regRF epitopes caused a transient increase of regulatory rheumatoid factor blood level with a maximum on day 7 after immunization. It was found that immunization with IgG Fc fragments carrying regRF epitopes does not cause a reaction in the regional and distal lymph nodes of rats, but induces the development of secondary follicles in spleen that exist for at least 28 days. On day 49, the number of follicles with germinal centers in the spleen of rats immunized with IgG Fc fragments carrying regRF epitopes was lower than in control rats. Consequently, the reaction of splenic follicles in rats immunized with IgG Fc fragments carrying regRF epitopes is transient. No changes were detected in the periarteriolar lymphoid sheaths (splenic T cell zone) in rats immunized with IgG Fc fragments carrying regRF epitopes. Thus, IgG Fc fragments carrying regRF epitopes, being a T cell-independent antigens type 2, do not cause a reaction in the lymph nodes, but induce the development of germinal centers in the spleen that exist for several weeks.

Insights into microstructure and expression of markers of proliferation, apoptosis and T cells in the spleen of cattle egret (Bubulcus ibis)

AbstractThe spleen is the largest secondary lymphoid organ with significant roles in pathogen clearance. It is involved in several avian diseases. The cattle egret is a wild insectivorous bird of agricultural and socioeconomic importance. Data related to microstructural features of cattle egret spleen are lacking. The present study investigated the gross anatomical, histological and immunohistochemical characteristics of the cattle egret spleen. Proliferation (PCNA and PHH3), apoptosis (cleaved caspase 3, C.CASP3) and T‐cell (CD3 and CD8) markers were assessed. Grossly, the spleen appeared brownish red, oval‐shaped and located at the oesophago‐proventricular junction. Histologically, the spleen was surrounded by a thin capsule sending a number of trabeculae which contained branches of the splenic vessels. The white pulp consisted of the periarteriolar lymphoid sheath and periellipsoidal lymphatic sheath (PELS). The red pulp was formed of sinusoids and cords. The penicillar capillaries, which represent the terminal segments of the splenic arterial tree were highly branched, wrapped by prominent ellipsoids and directly connected to the splenic sinusoids, suggesting a closed type of circulation. Immunohistochemically, proliferating cell nuclear antigen (PCNA)‐expressing cells were distributed with high counts throughout the splenic parenchyma, being highest within the splenic cords and PELS. Both PHH3‐ and C.CASP3‐expressing cells revealed a similar pattern to that of PCNA, although with fewer counts. Large numbers of T cells were observed throughout the splenic parenchyma, mainly within the cords, as revealed by CD3 and CD8 immunoreaction. The present study provides a clear insight into the precise structure of the spleen in cattle egrets and thus improves our understanding about birds' immunity.

Spleen white pulp structural and cellular composition in experimental furosemide-­induced hypomagnesemia

Relevance. Magnesium deficiency in the blood (hypomagnesemia) is due to many reasons, among which loop diuretics (furosemide) occupy acertain place. The role of the spleen in this process has not been determined. The aim of the work was to elucidate the effect of furosemide-­induced hypomagnesemia on the immune structures of the white pulp of rat spleen. Materials and Methods. Furosemide (Lasix® Aventis Pharma Ltd, India) was injected daily intraperitoneally at adose of 30 mg/kg to the experimental group of white outbred rats for 6 days, animals of the control group received an injection of 0.9% NaCl. Investigated: blood serum for the content of magnesium, calcium, sodium and iron; serial sections of the white pulp of the spleen after staining with hematoxylin and eosin to assess the structure and azure-­II-eosin to assess the cellular composition. With amicroscope magnification of 280 times, the ratio (in%) of primary (PLNS) and secondary lymphoid nodules of the spleen (SLNS) was calculated, the following were measured (µm): the diameter of the germinal center (GC), the width of the mantle and marginal zone, the diameter of the periarteriolar lymphoid sheath (PALS). In GC, the peripheral zone of lymphoid nodules, PALS at amagnification of 1500 times per field of view (100 μm2) was counted and presented as apercentage of the number of lymphocytes; macrophages; cells, mitotic and apoptotic elements. Morphometric analysis was carried out using Image ProPlus6.0 software (Media Cybernetics, USA). Statistical processing was carried out using the Statistica 10.0 software package with the determination of the arithmetic mean (M) and its error (m). Results and Discussion. The administration of furosemide led to adecrease in magnesium in the blood serum by 1.6 times (p0.05). In the white pulp of the spleen of animals of the experimental group, the proportion of SLNS decreased by 18.14%, the number of SLNS increased by 42.5% (p0.05). The diameter of SLNS increased insignificantly, the diameter of GC and the width of the marginal zone significantly increased by 27.1 and 24.8%, respectively. The proportion of macrophages increased by 20.6% in GC SLNS, and by 17.0% in PALS. The highest increase in the proportion of cells with signs of apoptosis was found in the periarteriolar lymphoid sheath of experimental animals - 34.6% (p0.05). Conclusion. Furosemide loading causes the development of dyselementosis, with the most significant loss of magnesium (hypomagnesemia) and has apronounced effect on the immune parameters of the spleen, represented by white pulp structures. Therefore, correction of the elemental status and monitoring of the state of the spleen in hypomagnesemia caused by the use of loop diuretics is anecessary element in the prevention of complications associated with the use of diuretic drugs.

EFFECT OF CYPHENOTHRIN-INDUCED SPLENIC DAMAGE AND HEMATOLOGICAL ALTERATIONS IN MALE WISTAR RATS (RATTUS NORVEGICUS)

Objective: Cyphenothrin is a major insecticide causing toxicological implications in mammals. Several studies estimated the consequences posed by this insecticide. The present study was designed to investigate the possible pyrethroid effects of cyphenothrin-induced hematological alterations and splenic damage in male Wistar albino rats. Methods: The rats were subjected to 60 d of exposure to a sublethal concentration of cyhenothrin. Hematological analyses revealed alterations in blood indices including red blood cells, white blood cells, hematocrit, hemoglobin, and platelet count. However, increased cyphenothrin level in treated rat groups was significant in the present study. This might be attributed to cyphenothrin enhancing stress of animal physiology. Results: Histological examination of spleen resulted in rarefication of white pulp, damaged marginal zone, decreased periarteriolar lymphoid sheath (PALS) 35.33 mg/Kg BW high dose, and number of lymphoid follicles in the high concentration of cyphenothrin group. However, the treatment of cyphenothrin significantly affected the low-concentration cyphenothrin-treated group more than the high-concentration-treated group 63.6 mg/Kg BW low dose compared to the control. Conclusion: This indicates the effective property of toxicity on the immunomodulatory effects of cyphenothrin. Results of the present study suggest that the Cyphenothrin effect has a potentially key role in hematological and immunomodulatory processes that might be implemented.

Реакция нейроэндокринных клеток и макрофагов селезенки на развитие опухоли в толстой кишке

Introduction. High cancer incidence requires finding new ways for comprehensive studying car-cinogenesis. Therefore, it is crucial to understand immune organ cell response and cell interaction in tumor development. The aim of the research was to study Synaptophysin+-, CD68+-cells, and biogenic amines in rat spleens during tumor development in the colon during dysplasia stages and adenocarcinoma formation. Materials and methods. Spleen histological slides of 110 mature male rats were studied 1 and 4 months after 1,2-dimethylhydrazine carcinogen administration using immunohistochemical, morphometric, and luminescent histochemical methods. Results. We found imbalanced production of biogenic amines (serotonin, histamine, and catecholamines) in the spleen and, therefore, a decrease in the cellular activity of the germinal centers of the lymphoid nodules. We also observed activation of periarteriolar lymphoid sheath (PALS) and red pulp in rats with precancerous colon lesions (1 month after carcinogen administration). At the same time, there was an increase in the number of CD68+ macrophages and Synaptophysin+ cells in the red pulp. In animals with adenocarcinoma (4 months after carcinogen introduction), the level of catecholamines in the luminescent granular cells of the PALS and the functional activity of these cells increased significantly. Simultaneously, the number of macrophages decreased in all the studied spleen compartments. Amid the decreased level of all biogenic amines in the red pulp, the quantity of Synaptophysin+ cells grew even more. Conclusion. The cells of all spleen compartments react to colon carcinogenesis, with reactivity of PALS cells and the red pulp being the most pronounced. The population of spleen macrophages undergoes rapid changes: their number increases in the red pulp in animals with precancerous lesions, while it decreases in all the splenic structures of rats with adenocarcinoma. Synaptophysin+ neuroendocrine cells of the red pulp play an important role in the reaction of the spleen to tumor development, and the number of these cells rises over time. Biogenic amines participate in the interaction of spleen cells with each other and with tumor-associated cells. Keywords: spleen, biogenic amines, neuroendocrine cells, synaptophysin, carcinogenesis

γδ Tcells license immature B cells to produce a broad range of polyreactive antibodies.

Immature autoreactive B cells are present in all healthy individuals, but it is unclear which signals are required for their maturation into antibody-producing cells. Inducible depletion of γδ Tcells show that direct interaction between γδ Tcells and immature B cells in the spleen support an "innate" transition to mature B cells with a broad range of antigen specificities. IL-4 production of γδ Tcells and cell-to-cell contact via CD30L support B cell maturation and induce genes of the unfolded protein response and mTORC1 signaling. Eight days after invivo depletion of γδ Tcells, increased numbers of B cells are already stuck in the transitional phase and express increased levels of IgD and CD21. Absence of γδ Tcells leads also to reduced levels of serum anti-nuclear autoantibodies, making γδ Tcells an attractive target to treat autoimmunity.

The effects of edible bird’s nest on T-lymphocyte proliferation, secondary lymphoid organs, and interleukin-2 production

• Edible bird’s nest (EBN) specifically promotes the expansion of T-cells both in vitro and in vivo studies. • EBN treatments can maintain the homeostasis of T-cells under the immunosuppressive condition. • The level of serum IL-2 has predominantly increased in response to the administration of EBN treatments. • The changes of secondary lymphoid organs (Peyer’s patches and spleen) have been affected by EBN treatments. This study aimed to investigate the immunomodulatory effect of edible bird’s nest (EBN) in vitro and in vivo studies. EBN-treated peripheral blood mononuclear cells showed that EBN specifically enhanced the expansion of CD3 + T-cells. The restoration of lymphocyte subpopulations under the influence of immunosuppressive drug has been successfully recovered in CD3 + T-cells, not CD45RA + B-cells and CD335 + NK-cells. In addition, oral administration of EBNs in Sprague-Dawley rats revealed their potential to increase the number of peripheral blood T-cells. Our study also demonstrated that EBN treatments affected the numbers of the Peyer’s patches, spleen weight and length, and cellularity of the periarteriolar lymphoid sheath. Interestingly, we observed that elevation of serum interleukin-2 (IL-2) had been correlated with the proliferation of T-cells in the animal model. Therefore, these results are essential for developing therapeutic strategies in improving immunity, particularly T-cell homeostasis, under immunosuppressive therapy.

Short communication: Ex-situ conservation in hatcheries is associated with spleen development in Lepidochelys olivacea turtle hatchlings

Ex-situ conservation in hatcheries is a successful strategy for the recovery of sea turtle populations. However, it alters the ontogenesis of the brain and gonads, as well as body size and locomotor performance at nest emergence. Relocation to hatcheries may alter immune system development, since this depends highly on the nest environment. We hypothesized that ex-situ brooding would negatively associate with immune traits of Lepidochelys olivacea. Splenic cytoarchitecture and leukocyte quantification were used as proxies for the immune configuration. Body size, gonadal sex and sand temperature during incubation were determined. Additionally, the success of nest hatching and emergence was quantified. Linear mixed models of splenic cytoarchitecture, leucocyte proportions and body size, using sex and nest type as explanatory variables, evaluated the effects of ex-situ brooding. Generalized linear mixed models using quasibinomial distributions (log link) analyzed effects on hatching and emergence success. Hatchlings from ex-situ nests were heavier, larger and showed a greater spleen-somatic index. They showed more and better defined splenic periarteriolar lymphoid sheaths, as well as a higher proportion of heterophils but less monocytes. Moreover, ex-situ brooding increased hatching and emergence success. Sand temperatures in hatcheries favored male sex determination, while the opposite occurred for in-situ incubation. Interestingly, the immune configuration and body size were independent of sex but associated with ex-situ conservation. Greater body size promotes early hatchling survival, while better spleen development is related to a greater antibody production and a better immune response to pathogens. Altogether, the results suggest that ex-situ incubation is associated with a better immune configuration and higher survival success.

Splenic Transcriptional Responses in Severe Visceral Leishmaniasis: Impaired Leukocyte Chemotaxis and Cell Cycle Arrest.

Structural changes in the spleen have been reported in several infectious diseases. In visceral leishmaniasis (VL), a severe parasitic disease caused by Leishmania spp., the loss of white pulp accompanies a severe clinical presentation. Hamster model reproduces aspects of human VL progression. In the early stages, a transcriptomic signature of leukocyte recruitment was associated with white pulp hyperplasia. Subsequently, impaired leukocyte chemotaxis with loss of T lymphocytes in the periarteriolar lymphoid sheath occurred. This differential gene expression was subsequently corroborated by transcriptomic profiling of spleens in severe human VL. At the latest stage, spleen disorganization was associated with increasing clinical signs of VL. White pulp disruption was accompanied by decreased DLK1 expression. The expression of CXCL13, CCR5, CCL19, CCR6, CCR7 and LTA decreased, likely regulated by CDKN2A overexpression. Our findings enlighten a pathway implying cell cycle arrest and decreased gene expression involved in spleen organization.

Abstract 529: Characterization of a humanized TLR8 mouse model and its application in immuno-oncology drug development

Abstract Background: TLR8 belongs to the Toll-like receptor family, serving as endosomal sensors of uridine rich single strand viral or endogenous RNA and several types of small molecule agonist. In humans, TLR8 is primarily expressed on monocytes, macrophages and myeloid dendritic cells (DCs), while in murine it was originally reported that TLR8 has no function due to the lack of five amino acids that recognize the endogenous RNA ligand. Increasing evidence suggests that mouse TLR8 may function differently from its human counterpart, including ligand binding and signaling through pathways other than NK-κB. Therefore, a humanized TLR8 mouse model is pivotal for mechanistically understanding TLR8 innate immune regulation and pharmacologically targeting TLR8 in various malignancies and inflammatory diseases. Methods: Exon 3 of mouse Tlr8 was replaced with the corresponding human region to generate humanized TLR8 knock-in mice. hTLR8+/- mice (n=5) and age matched naïve C57BL/6 mice were maintained until 27 weeks of age. Liver, spleen, kidney and pancreas were collected for pathological characterization. Serum cytokines levels were analyzed by MSD, and hTLR8 expression pattern and immune cells were analyzed in the spleen by flow cytometry. Comparisons of anti-PD-1 response in TLR8 knock-in mice and naïve C57BL/6 mice bearing various syngeneic tumors were also conducted. Results: We systemically characterized the phenotypic changes between age-matched 27-week-old C57BL/6 and hTLR8 mice. A high percentage of hTLR8 expression was detected on CD11b+ F4/80+ macrophages, CD11b+Gr-1+ myeloid cells and CD11c+ DCs. Hepatomegaly, splenomegaly, and nephromegaly were observed in aged hTLR8 mice. Histology analysis revealed a prominent portal inflammation with fibrosis and bile duct hyperplasia in liver; a decreased cellularity in periarteriolar lymphoid sheath and increase of histiocytes in the red pulp of spleen; and inflammatory immune cell infiltration in the kidneys. Analysis of serum cytokines showed a significant increase of KC/GRO (CXLCL1), TNF-α and IL-10 in the peripheral blood of the aged hTLR8 mice. PBMC from hTLR8 mice responded to a specific RNA-ligand based human TLR8 agonist (ORN-8L) in vitro. We are now profiling different syngeneic and genetically engineered murine tumor models to fully characterize the potential adjuvant-like function of hTLR8 in different tumor models. Conclusion: Expression of humanized TLR8 leads to auto-activation of TLR8 signaling in mice. This pivotal model system enables us to study the function of human TLR8 and pharmacology of its agonists and antagonists in vivo. These knock-in mice may also serve as an interesting host strain for syngeneic tumor studies, potentiating immune responses to therapies. Citation Format: Hongjuan Zhang, Ruilin Sun, Annie X. An, Henry Q.x Li, Davy Xuesong Ouyang. Characterization of a humanized TLR8 mouse model and its application in immuno-oncology drug development [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 529.

Characterization of Conventional Dendritic Cells and Macrophages in the Spleen Using the CSF1R-Reporter Transgenic Chickens

The spleen is a major site for the immunological responses to blood-borne antigens that is coordinated by cells of the mononuclear phagocyte system (MPS). The chicken spleen is populated with a number of different macrophages while the presence of conventional dendritic cells (cDC) has been described. However, a detailed characterization of the phenotype and function of different macrophage subsets and cDC in the chicken spleen is limited. Using theCSF1R-reporter transgenic chickens (CSF1R-tg), in which cells of the MPS express a transgene under the control elements of the chickenCSF1R, we carried out an in-depth characterization of these cells in the spleen. Immunohistological analysis demonstrated differential expression of MRC1L-B by periarteriolar lymphoid sheaths (PALS)-associatedCSF1R-tg+cells. In the chicken's equivalent of the mammalian marginal zone, the peri-ellipsoid white-pulp (PWP), we identified high expression of putative CD11c by ellipsoid-associated cells compared to ellipsoid-associated macrophages. In addition, we identified a novel ellipsoid macrophage subset that expressed MHCII, CD11c, MRC1L-B, and CSF1R but not theCSF1R-tg. In flow cytometric analysis, diverse expression of theCSF1R-tg and MHCII was observed leading to the categorization ofCSF1R-tg cells intoCSF1R-tgdimMHCIIinter−hi,CSF1R-tghiMHCIIhi, andCSF1R-tghiMHCIIintersubpopulations. Low levels of CD80, CD40, MHCI, CD44, and Ch74.2 were expressed by theCSF1R-tghiMHCIIintercells. Functionally,in vivofluorescent bead uptake was significantly higher in theCSF1R-tghiMHCIIhiMRC1L-B+cells compared to theCSF1R-tgdimandCSF1R-tghiMHCIIinterMRC1L-B+subpopulations while LPS enhanced phagocytosis by theCSF1R-tghiMHCIIintersubpopulation. The analysis of bead localization in the spleen suggests the presence of ellipsoid-associated macrophage subsets. In addition, we demonstrated the functionality ofex vivoderivedCSF1R-tg+MRC1L-BnegcDC. Finally, RNA-seq analysis of theCSF1R-tg subpopulations demonstrated that separating theCSF1R-tghisubpopulation into CD11chiand CD11cdimcells enriched for cDC and macrophage lineages, respectively, while theCSF1R-tghiMHCIIintersubpopulation was enriched for red pulp macrophages. However, our analysis could not define the cell lineage of the heterogeneousCSF1R-tgdimsubpopulation. This detailed overview of the MPS in the chicken spleen will contribute to future research on their role in antigen uptake and presentation.

Structure of the Eurasian moorhen spleen: A comprehensive study using gross anatomy, light, and transmission electron microscopy.

The spleen is the largest secondary lymphoid organ with major roles in the removal of blood-borne antigens. The Eurasian moorhen is a wild aquatic bird that revealed the adaptation to harsh environmental conditions. Information regarding the structural features of moorhen's spleen is lacking. The present study aimed to describe the composition of moorhen's spleen using anatomical dissection, histology, histochemistry, immunohistochemistry, and transmission electron microscopy. The spleen appeared as a brownish red sickle-shaped organ close to the proventriculus and gizzard. The splenic capsule was very thin, and the trabeculae were poorly developed. The white pulp formed of the periarteriolar lymphoid sheath, lymphoid follicles, and periellipsoidal lymphatic sheath. The red pulp composed of sinusoids and cords and contained various types of blood cells. Blood vessels were observed within the splenic capsule and inside the parenchyma. Notably, penicillar capillaries (PCs) appeared branched and surrounded by well-developed ellipsoids. Direct connections were observed between PCs and splenic sinusoids suggesting a closed type of circulation. Ultrastructurally, intercellular spaces and vascular channels were evident in the wall of PCs. Ellipsoid-associated cells, lymphocytes, monocytes, and heterophils were observed within splenic ellipsoids. Ellipsoids were thus suggested as a crucial component of moorhen's spleen. Numerous MafB-immunoreactive (IR) macrophages were seen within the red pulp. Splenic cords contained the highest number of PHH3-IR cells, while CCASP3-IR cells were exclusive to follicles of the white pulp. In conclusion, the structure of moorhen's spleen revealed species-specific features. The findings of the present study could help to improve the immunity of domestic birds.

Histopathological investigation of the effects of a combination of parenteral nutrition and hunger on rabbit splenic tissue

Aim: Parenteral nutrition (PN) is a life-saving practice when the use of the gastrointestinal tract is not possible. However, PN can cause a variety of complications despite its many benefits. In this study, we examined the histopathological effects of PN combined with hunger in the splenic tissue of rabbits.Materials and Methods: The rabbits were divided into four groups. The hunger + PN (PNH) group was completely starved and received the daily energy requirement with PN via an intravenous central catheter. The second group received enteral nutrition + PN (PNEN), wherein half of the required daily calories were provided through enteral nutrition, and the other half, through PN. A third group comprised semi-hungry (SH) rabbits that were provided only half the required daily calories by oral feeding.They did not receive PN. The last group was the control group. After 10 days, the rabbits were euthanized, and splenic tissue samples were collected from all the groups and examined histopathologically.Results: The histopathological examination for the PNH group revealed damage in the form of germinal center effacement, reduction of white pulp, congestion of red pulp, and decreased cellularity in the periarteriolar lymphoid sheath. Immunohistochemical examination revealed a significant increase in the apoptotic activity of the splenic tissues of this group. The corresponding findings were mild in the PNEN group, and no signs of damage were found in the other two groups.Conclusion: PN combined with hunger appears to cause damaging effects on splenic tissue in rabbits. Adding enteral nutrition to PN may reduce these effects.

Human splenic polymorphonuclear myeloid-derived suppressor cells (PMN-MDSC) are strategically located immune regulatory cells in cancer.

In contrast to the mouse, functional assets of polymorphonuclear myeloid-derived suppressor cells (PMN-MDSC) in the human spleen remain to be better elucidated. Here, we report that the spleen in gastric and pancreatic cancer adopts an immune regulatory character, harbors excessive amount of PMN-MDSC, and anatomically enables their interaction with T cells. Compared to the peripheral blood, the spleen from cancer patients contained significantly higher levels of low-density PMN-MDSC, but not early-stage MDSC (e-MDSC) and monocytic-MDSC (M-MDSC). Low-density fraction of polymorphonuclear (PMN) cells was enriched in immature myeloid cells and displayed higher levels of CD10, CD16, and ROS than their blood-derived counterparts. They were also positive for PD-L1, LOX-1, and pSTAT3. The white pulp and periarteriolar lymphoid sheath (PALS) were strategically surrounded by PMN cells that were in contact with T cells. Unlike those from the blood, both low-density and normal-density PMN cells from the human spleen suppressed T cell proliferation and IFN-γ production. Independent of clinical grade, high PMN-MDSC percentages were associated with decreased survival in gastric cancer. In summary, our results outline the immune regulatory role of the spleen in cancer where neutrophils acquire MDSC functions and feasibly interact with T cells.

Distribution of nerve fibers and nerve-immune cell association in mouse spleen revealed by immunofluorescent staining

The central nervous system regulates the immune system through the secretion of hormones from the pituitary gland and other endocrine organs, while the peripheral nervous system (PNS) communicates with the immune system through local nerve-immune cell interactions, including sympathetic/parasympathetic (efferent) and sensory (afferent) innervation to lymphoid tissue/organs. However, the precise mechanisms of this bi-directional crosstalk of the PNS and immune system remain mysterious. To study this kind of bi-directional crosstalk, we performed immunofluorescent staining of neurofilament and confocal microscopy to reveal the distribution of nerve fibers and nerve-immune cell associations inside mouse spleen. Our study demonstrates (i) extensive nerve fibers in all splenic compartments including the splenic nodules, periarteriolar lymphoid sheath, marginal zones, trabeculae, and red pulp; (ii) close associations of nerve fibers with blood vessels (including central arteries, marginal sinuses, penicillar arterioles, and splenic sinuses); (iii) close associations of nerve fibers with various subsets of dendritic cells, macrophages (Mac1+ and F4/80+), and lymphocytes (B cells, T helper cells, and cytotoxic T cells). Our data concerning the extensive splenic innervation and nerve-immune cell communication will enrich our knowledge of the mechanisms through which the PNS affects the cellular- and humoral-mediated immune responses in healthy and infectious/non-infectious states.

Phenotypical Characterization of Spleen Remodeling in Murine Experimental Visceral Leishmaniasis.

Background: Visceral leishmaniasis (VL) is caused by Leishmania infantum or L. donovani infection. One of the main problems related to this disease is the emergence of severe clinical forms with a lethality of 5–20%, even while under specific treatment. In humans and other species susceptible to fatal VL, such as dogs and hamsters, the disruption of splenic white pulp (WP) is accompanied by disease progression. Control of VL progression is seen in BALB/c mice, as evidenced by a mild clinical presentation and controlled parasite replication in the liver and spleen. In this study, we investigated the features involved in the morphological remodeling of splenic compartments associated with the control of VL progression to death.Methods: We evaluated cohorts of BALB/c mice after 30, 60, and 90 days of infection by L. infantum. Spleen morphology, cell population subsets and cytokine production were studied in the spleen using flow- and histo-cytometry.Results: Intraperitoneal infection with 108 promastigotes of L. infantum led to progressive increases in spleen size at 60 and 90 days after infection. Splenomegaly was the only clinical sign of disease observed. At 30 days after infection, hyperplasia in the WP and decreased numbers of plasmacytoid dendritic cells were observed. The WP hyperplasia subsided at 60 days post-infection. However, the splenomegaly remained in association with increased numbers of macrophages, B and T lymphocytes and plasma cells. An increased number of lymphoid tissue inducer (LTi) cells was observed; these were distributed around the periarteriolar lymphoid sheath in control mice and scattered throughout the red pulp in the Leishmania-infected mice. After 90 days of infection, increased IL-6 and IFN-γ production was seen in the spleen, as well as higher frequencies of follicular and plasmacytoid dendritic cells.Conclusion: The data presented herein emphasizes the potential role of spleen remodeling in the control of severe forms of VL and highlights features potentially involved in this process.

Evaluation of the splenic injury following exposure of mice to bisphenol S: A mass spectrometry-based lipidomics and imaging analysis

BackgroundThe widespread use of bisphenol A (BPA) substitutes has aroused great attention towards their toxicological evaluation in vivo and in vitro. Considering the intimate correlation between BPA and metabolic diseases, we explored whether bisphenol S (BPS), a major substitute to BPA, could cause the splenic toxicity by disturbing the lipid metabolism in mouse model. MethodsWe investigated the splenic injury by combing the mass spectrometry (MS)-based lipidomics and imaging analysis, as well as molecular biological methods. Mice were divided into three groups (control-olive oil, 10 and 100 μg-BPS/kg body weight/day group) and treated by BPS in 56 days. ResultsTwo of BPS-treated concentrations induced the splenic morphological alterations and inflammation, including the decreased numbers and cellularity in the periarteriolar lymphoid sheath (T cell zone) and paucicellular primary lymphoid follicles (B cell zone) in splenic white pulp. Lipidome profiling of spleen after BPS treatment was also changed with up-regulated sphingosine [So], neutral glycosphingolipids [CerG], cholesteryl ester [ChE], diacylglycerols [DAG], lysophosphatidylcholine [LPC], lysophosphatidylethanolamine [LPE], phosphatidylglycerols [PG], phosphatidylinositols [PI] and phosphatidylserine [PS] as well as down-regulated ceramide [Cer], phosphatidylethanolamines [PE] and sphingomyelin [SM] compared to the control group. More importantly, significant different lipids in abundance and spatial distribution also implicated that white pulp were more sensitive to BPS treatment than other splenic sub-structures. Signaling lipids such as So (d18:0), Cer (d18:1/24:0), Cer (d18:1/22:0), SM (d18:1/22:1) and SM (d18:1/24:2) associated with inflammation were remarkable changed and co-localized in the splenic white pulp. ConclusionsOur finding indicated that BPS exposure promoted the splenomegaly, pro-inflammatory activation and morphological alterations, as well as induced the lipidome perturbation in the immune cells of white pulp, which might be expected to contribute a new perspective of bisphenol-induced organ injury.

Rat liver and kidney post-mitochondrial dysfunction by addition of chronic mixed metal intoxication and hepatorenal wellness mediated by phenolic components from Croton zambiscus leaves

Chronic exposure of mixed-metal intoxication has been associated with prolonged oxidative stress and severe hepatorenal damage. This present study demonstrates the hepatoprotective and renoprotective activity of Croton zambesicus (C-ZAMB) leaves, naturally occurring phenolic compounds against chronic mixed-metal (EOMABRSL) induced toxicity. 0.5 ml of EOMABRSL via oral route induced chronic hepatoxicity and nephrotoxicity on exposure for 98 days (non-withdrawal) and 70 days (withdrawal) by abnormal alteration in the levels of endogenous antioxidants. Moreover, EOMABRSL induced hepatorenal damage by increasing the markers of liver toxicity (ALT, AST, ALP, GGT and bilirubin) and kidney failure (creatinine, urea, uric acid, and renal electrolytes-Na+ and K+). Both non-withdrawal and withdrawal approaches of EOMABRSL-exposed animals exhibited hepatorenal dysfunctions by increasing the activity of eco-51-nucleotidase (51ENT) followed by the decreased in the activity of lactate dehydrogenase (LDH)-index of cellular ATP. These results were further supported by the histopathological examination of nephritic cells, hepatocytes and splenocytes, manifested by hepatocellular necrosis, swelling or degeneration of tubular kidney epithelial cells as well as coalescing splenic periarteriolar lymphoid sheaths (PALSs) and lymphoid haemosiderin. The chronic EOMABRSL intoxication was ameliorated by administration of phenolic antioxidants from C-ZAMB leaves. Therefore, our study supports the view that phenolic C-ZAMB leaves may mediate hepatorenal wellness on chronic exposure to mixed-metal intoxication

Histotopography of α-Gustdusin- and T2R3-Expressing Lymphocytes in Mouse Spleen.

Histotopography of lymphocytes expressing bitter taste receptors of T2R family and α-gustducin (receptor-associated subunit of the G-protein complex) in mouse spleen in the norm and in 48 h after intraperitoneal administration of LPS was studied by the immunohistochemical method. Two populations of immunopositive lymphocytes expressing the above proteins were detected in the spleen; they were located in the marginal zones of lymphoid follicles and periarteriolar lymphoid sheaths. In most α-gustducin-positive lymphocytes, co-expression of α-gustducin and CD19 (B-cell marker) was found. Intraperitoneal administration of LPS significantly increased the number of gustducinergic lymphocytes in periarteriolar lymphoid sheaths. We hypothesize that spleen lymphocytes with gustducin signaling are involved in T-dependent immune response to the blood bacterial polysaccharides.

The spleen morphophysiology of fruit bats.

Spleen is one of the important lymphoid organs with wide variations of morphological and physiological functions according to species. Morphology and function of the spleen in bats, which are hosts to several viral strains without exhibiting clinical symptoms, remain to be fully elucidated. This study aims to examine the spleen morphology of fruit bats associated with their physiological functions. Spleen histological observations were performed in three fruit bats species: Cynopterus titthaecheilus (n = 9), Rousettus leschenaultii (n = 3) and Pteropus vampyrus (n = 3). The spleens of these fruit bats were surrounded by a thin capsule. Red pulp consisted of splenic cord and wide vascular space filled with blood. Ellipsoids in all three studied species were found numerously and adjacent to one another forming macrophages aggregates. White pulp consisted of periarteriolar lymphoid sheaths (PALS), lymphoid follicles and marginal zone. The lymphoid follicle contained a germinal centre and a tingible body macrophage that might reflect an active immune system. The marginal zone was prominent and well developed. This study reports some differences in spleen structure of fruit bats compared to other bat species previously reported and discusses possible physiological implications of the spleen based on its morphology.