1,25-Dihydroxyvitamin D3 and phorbol esters (TPA) may induce select in vitro differentiation pathways in the HL60 promyelocytic cell line

Possible role of vitamin D in Covid-19 infection in pediatric population

PURPOSE

Covid-19 is a pandemic of unprecedented proportion, whose understanding and management is still under way. In the emergency setting new or available therapies to contrast the spread of COVID-19 are urgently needed. Elderly males, especially those affected by previous diseases or with comorbidities, are more prone to develop interstitial pneumonia that can deteriorate evolving to ARDS (acute respiratory distress syndrome) that require hospitalization in Intensive Care Units (ICUs). Even children and young patients are not spared by SARS-CoV 2 infection, yet they seem to develop a milder form of disease. In this setting the immunomodulatory role of Vitamin D, should be further investigated.

METHODS

We reviewed the literature about the immunomodulatory role of Vitamin D collecting data from the databases Medline and Embase.

RESULTS

Vitamin D proved to interact both with the innate immune system, by activating Toll-like receptors (TLRs) or increasing the levels of cathelicidins and β-defensins, and adaptive immune system, by reducing immunoglobulin secretion by plasma cells and pro-inflammatory cytokines production, thus modulating T cells function. Promising results have been extensively described as regards the supplementation of vitamin D in respiratory tract infections, autoimmune diseases and even pulmonary fibrosis.

CONCLUSIONS

In this review, we suggest that vitamin D supplementation might play a role in the prevention and/or treatment to SARS-CoV-2 infection disease, by modulating the immune response to the virus both in the adult and pediatric population.

Differential regulation of vitamin D receptor expression in distinct leukemic cell lines upon phorbol ester-induced growth arrest

A close correlation between vitamin D receptor (VDR) abundance and cell proliferation rate has been shown in NIH-3T3 fibroblasts, MCF-7 breast cancer and in HL-60 myeloblastic cells. We have now determined if this association occurs in other leukemic cell lines, U937 and K562, and if VDR content is related to c-myc expression, which is also linked to cell growth state. Upon phorbol myristate acetate (PMA) treatment, cells from the three lineages (HL-60, U937 and K562) differentiated and expressed specific surface antigens. All cell lines analyzed were growth inhibited by PMA and the doubling time was increased, mainly due to an increased fraction of cells in the G0/G1 phase, as determined by flow cytometry measurements of incorporated bromodeoxyuridine and cell DNA content. C-myc mRNA expression was down-regulated and closely correlated to cell growth arrest. However, VDR expression in leukemic cell lines, as determined by immunofluorescence and Northern blot assays, was not consistently changed upon inhibition of cell proliferation since VDR levels were down-regulated only in HL-60 cells. Our data suggest that VDR expression cannot be explained simply as a reflection of the leukemic cell growth state.

Comparison of immunological effects of Fullerene C60 and raw soot from Fullerene production on alveolar macrophages and macrophage like cells in vitro

Two carbon modifications, C60 and Raw Soot (RS) from fullerene production, were incubated with macrophages and macrophage-like cells. Their effects were compared both to DQ12 Quartz as a positive particle control known to damage BAM and HL60M, and LPS or zymosan as biological inducers of immunological reactions. C60 as well as RS are not cytotoxic as compared to DQ12. C60 seems to induce a lower chemotactic activity than RS and DQ12. Furthermore, C60 is of no or only very little influence on the formation of reactive oxygen species (ROS). RS itself is oxidatively active both with H2DFC-DA in in vitro cell culture and with KMB in a cell free incubation under the influence of light. It is not yet clear whether the in vitro effects of RS are caused by ROS formation by the cells and/or the oxidative activity due to light as indicated from the results with KMB.

Influence of salbutamol and isoproterenol on the production of TNF and reactive oxygen species by bovine alveolar macrophages and calcitriol differentiated HL-60 cells

The influence of the beta-adrenergic agonists Salbutamol and Isoproterenol on the release of reactive oxygen species and Tumor Necrosis Factor (TNF) was tested with bovine alveolar macrophages and HL-60 cells differentiated to macrophages by calcitriol. The production of reactive oxygen species was analyzed by a microplate assay using dichlorofluorescein-diacetate. It could be shown that this method almost exclusively measures superoxide anions. TNF was determined by a bioassay with WEHI cells. The superoxide anion production was stimulated by Zymosan, the TNF release by LPS. By incubation with 5 x 10(-6) and 5 x 10(-7) M Salbutamol or 5 x 10(-7) and 5 x 10(-8) M Isoproterenol prior to the stimulation, the production of superoxide anions as well as of TNF was inhibited to a significant degree. The inhibitory effects of the adrenergic agonists were completely or at least partially inhibited by the respective antagonists, ICI 118.551 and Propranolol, respectively.

Vitamin E succinate induction of HL-60 cell adhesion: a role for fibronectin and a 72-kDa fibronectin-binding molecule

HL-60 cells, growing as single cells in suspension, exhibit marked cell-cell adhesion when treated for 24 hours with 10 micrograms/ml RRR-alpha-tocopheryl succinate, also called vitamin E succinate (VES). VES-induced cell-cell adhesion is dependent on divalent cations and a functional cytoskeleton and is protein mediated. Cell adhesion molecules CD11a/CD18, CD11b/CD18, CD29, and CD54 do not appear to be mediating VES-induced cell adhesion. HL-60 cells treated with VES adhere to fibronectin-coated plastic and secrete elevated levels of fibronectin. A 72-kDa fibronectin-binding membrane molecule was detected on VES-treated HL-60 cells, and antibodies to fibronectin were shown to inhibit VES-induced cell aggregation. VES induction of HL-60 cell-cell adhesion is proposed to result from increased amounts of extracellular fibronectin binding to VES-induced cell surface fibronectin-binding molecules.

CD14: cell surface receptor and differentiation marker

In the past, CD14 has been viewed simply as a useful marker molecule for monocytes and macrophages. Now, new findings on its role in binding of LPS-LBP complexes and in signal transduction have engendered renewed interest in the properties of CD14. Here, CD14 function, its expression in different cell types and the regulation of expression, including the generation of soluble CD14, are described, and the diagnostic value of CD14 in various diseases is discussed.

Multiparametric flow cytometric analysis of the kinetics of surface molecule expression after polyclonal activation of human peripheral blood T lymphocytes

In this report we have analysed the kinetics of modulation of human peripheral blood T lymphocyte membrane molecules upon activation with optimal amounts of phytohaemagglutinin (PHA) and concanavalin A (ConA). The following activation-related and differentiation/adhesion molecules were selectively and concomitantly investigated on CD4+ and CD8+ subsets by dual colour flow cytometry: CD69, CD25 and CD71; CD2, CD45RA and L-selectin. Cultures were assayed after 24, 48, 72, 120 and 168 h of incubation with PHA and ConA. This approach allowed a comprehensive evaluation of membrane phenomena occurring during activation of normal resting human T lymphocytes. Data show that the kinetics of expression of these molecules follows a precise and consistent time-course with no major differences between CD4 and CD8 subsets. CD69 expression peaked at 24 h, whereas CD25 and CD71 expression peaked at 48/72 h with some differences between PHA and ConA activation. L-selectin expression started an evident decrease in step with culture time whose magnitude was dependent on the lectin used, being higher with PHA than with ConA. Conversely, the expression of CD45RA remained stable for 72 h and then briskly decreased with no major differences between PHA and ConA activation. CD2 molecules increased with time in number and density, although the percentage of positive cells remained essentially constant (greater than 85%). After 48/72 h of stimulation about 10% of cells co-expressed CD4 and CD8 molecules. To ascertain whether the phenomenon was restricted to cells in a particular activation state, the phenotype of cells in the diverse phases of the cell cycle was established. Results obtained show that only actively proliferating cells, that is cells in S and G2-M phases, co-expressed the two molecules, suggesting that such a phenomenon reflects a momentary dysregulation of the normal sequence of gene expression. The present data are also discussed in the light of the dynamic role of T lymphocyte activation and adhesion molecules in regulating cell-cell interactions, tissue localization and eventual immunological function.

Marker profile, enzyme activity, and function of a human myelomonocytic leukemia cell line

Morphological and functional characteristics of a permanent human leukemia cell line (DD) that possesses myelomonocytic features were investigated. The cells bear a second type Fc gamma receptor and form rosettes with sheep erythrocytes sensitized with rabbit IgG (EA). However, the surface-bound EA is not internalized. The cell line lacks the surface markers CD2, CD19, CD14, HLA-DR, Fc gamma receptor I, Fc gamma receptor III, and CR3. alpha 1-Antitrypsin, lysozyme, Factor XIII a subunit of blood coagulation, and acid phosphatase reactions were negative. A terminal differentiation of the DD cell line was observed when the expression of CD14, CR3, Fc gamma receptor I, and Fc gamma receptor III was induced. The DD cells induced with 12-O-tetradecanoylphorbol-13-acetate or Escherichia coli lipopolysaccharide can internalize EA via Fc gamma receptor II and complement-coated yeast in the function of the inducers. The phagocytic ability appears to be parallel with the appearance of enzymes which participate in phagocytosis.

RRR-alpha-tocopheryl succinate modulation of human promyelocytic leukemia (HL-60) cell proliferation and differentiation

HL-60 human promyelocytic leukemia cells can be induced to differentiate to granulocytes by retinoic acid and dimethyl sulfoxide or monocyte-macrophages by phorbol esters and 1,25-dihydroxyvitamin D3. These studies show that RRR-alpha-tocopheryl succinate (TS) inhibits HL-60 cell proliferation and induces the HL-60 cells to differentiate toward a functionally deficient macrophage-like cell. TS at (15 micrograms/ml) was found to suppress HL-60 cell proliferation by 63% and 89% at 24 and 48 hours, respectively. This suppression of proliferation, however, is not permanent and requires the presence of TS. HL-60 cells treated for 48 hours with TS (15 micrograms/ml) were found to be blocked in the G2/M phase of the cell cycle. HL-60 cells blocked in the G2/M cell cycle phase by TS expressed normal levels of the transferrin receptor. TS-treated HL-60 cells exhibited binucleated morphological appearance; however, the cells did not exhibit chemotaxis, phagocytosis, or changes in the expression of the cell surface markers, CD11a and CD18. However, HL-60 cells treated for 48 hours with TS (15 micrograms/ml) could be stimulated to produce superoxide radicals and exhibited nonspecific esterase activity, two characteristics of macrophages. These results suggest a role for TS as an antitumor proliferative agent and as a modifier of human leukemia cell differentiation.

Human alpha-fetoprotein (AFP) causes a selective down regulation of monocyte MHC class II molecules without altering other induced or noninduced monocyte markers or functions in monocytoid cell lines

Human alpha-fetoprotein (AFP) purified from human amniotic fluid was investigated for its effect on human monocytoid cell lines, including U 937 cells with established subclones. The impact of AFP on the expression of surface markers (MHC class I and II, CD4, CD18, CD45, Fc receptors for IgG) was analyzed using known inducers of monocyte-macrophage differentiation such as phorbol esters and IFN-gamma. Furthermore we investigated the effect of AFP on the induction of macrophage antibody-dependent cell-mediated cytolytic activity (ADCC). AFP did selectively induce a rapid down regulation of surface MHC class II expression. No evidence of alterations was found in the endogenous or differentiation-induced expression of other markers on the surface on monocytes, nor did AFP affect the functional maturation of surface Fc receptors or the ability to express ADCC.

Transforming growth factor-beta 1 modulates the effect of 1 alpha, 25-dihydroxyvitamin D3 on leukemic cells

The human leukemic cells HL-60, U937, KG-1 and THP-1 incubated with transforming growth factor-beta 1 (TGF-beta 1) were studied by examining cell surface antigens and macrophage-specific activities. The addition of 0.5 ng/ml (20 pM) of TGF-beta 1 with 1 alpha, 25-dihydroxyvitamin D3 [1 alpha, 25(OH)2D3] induced more Leu-M3 (CD14)-positive cells (approximately 80%) than 5 X 10(-8) M 1 alpha, 25(OH)2D3 alone did (30 to 50%), although original HL-60 cells did not express any Leu-M3 antigen at all. Tumor necrosis factor-alpha (TNF-alpha) with TGF-beta 1 and 1 alpha, 25(OH)2D3 was found to potentiate the expression of these surface antigens. Furthermore, the phagocytic activity was also induced strongly. The expression of CR3 (CD11b) antigen was also increased, and all Leu-M3-positive cells were found CR3-positive when HL-60, U937, and THP-1 cells were treated with these stimulants. In contrast, CR3 but not Leu-M3 was induced in KG-1 cells after the same treatment. This may indicate that the responsiveness of leukemic cells to TGF-beta 1 and 1 alpha, 25(OH)2D3 might vary depending on a differentiation stage of the target cells. Furthermore, K562 cells originated from a more undifferentiated precursor, were not able to respond to these two inducers. These results suggested that some of TGF-beta superfamily proteins might represent potent modulators in hematopoiesis, especially in the development of monocytes-macrophages or their precursors.

New, simple flow cytometry technique to discriminate between internalized and membrane-bound particles in phagocytosis

This report describes a new flow cytometry technique to measure phagocytic activity and discriminate simultaneously between internalized and membrane-bound particles. Fluorescein-conjugated heat-killed Candida albicans (F-Ca) are opsonized with purified antibodies or normal human serum and used as targets for human polymorphonuclear granulocytes (PMN). The procedure is based on the observation that F-Ca lose their green fluorescence and acquire red fluorescence upon incubation with ethidium bromide (EB) through the resonance energy-transfer phenomenon occurring between the two fluorochromes. PMN are incubated with opsonized F-Ca particles for 20 min at 37 degrees C or, as a control, at 4 degrees C and in the presence of cytochalasin B, an inhibitor of the phagocytic process that does not affect membrane binding of F-Ca. EB is added, and green and red fluorescence associated with PMN is evaluated using a mercury-lamp-powered instrument. Because EB does not penetrate intact cell membranes, internalized particles are not affected by EB and remain green, whereas membrane-bound particles assume an intense red stain. By means of contour plot analysis, the number of PMN containing and/or binding F-Ca particles can be readily assessed. The method described here allows precise quantitative analysis of the phagocytic process on the part of human PMN in a single, one-step assay that does not require sophisticated instrumentation or reagents and should prove to become a test suitable for clinical purposes.

Anti-endothelial cell antibodies: detection and characterization in sera from patients with autoimmune hypoparathyroidism

In a previous report, we described antibodies in autoimmune hypoparathyroidism (AHP) that are cytotoxic for cultured bovine parathyroid cells. In the present study, we show that sera from six AHP patients, but not from 26 patients with other autoimmune diseases or from 7 healthy subjects, react with bovine endothelial cells in culture (by flow cytometry and fluorescence microscopy) and in tissue sections (by immunohistology). We found uniformly that the immunoglobulin class reacting is IgM. Adsorption experiments showed that the antigenic determinants reacting with AHP sera were similar on bovine cultured endothelial cell membranes and in tissue sections of bovine parathyroid glands. The AHP sera also reacted with endothelial cells cultured from bovine adrenal medulla and pulmonary artery. Immunoblot analysis showed antibody binding to two major bands of 200 and 130 kDa solubilized from the membrane fraction of bovine parathyroid endothelial cells. Only one AHP serum consistently recognized endothelium-related structures on frozen sections of three different human parathyroid adenomas; two other sera reacted with one adenoma each; and three did not react with human adenomas. This indicates that human material is less suitable than bovine in detecting endothelium-related immune phenomena in AHP sera. The anti-endothelium IgM antibodies appear to be disease-specific but are not organ- or species-specific. The identification of endothelial cells as the target for antibodies in AHP raises the possibility that the endothelium subserves an important local function for endocrine epithelium.

In human monocytes a strong correlation exists between expression of the M3 antigen, Fc-mediated phagocytic activity and failure to participate in extracellular antibody-dependent cytotoxicity

Human fresh blood monocytes can phagocytize and lyse antibody-coated target cells by contact with membrane Fc receptors. Recently, the monocyte differentiation antigen Leu M3 has been described to be associated with monocyte/macrophage maturation pathway and to be linked to functionally distinct monocyte subsets. In the present study peripheral blood monocytes were separated into M3+ and M3- subsets, and evaluated for their ability to mediate antibody-driven effector functions. A clear cut functional difference could be demonstrated. M3+ monocytes phagocytize antibody-coated sheep red cells but do not carry out contact-mediated extracellular lysis. In contrast, M3- monocytes have exactly the opposite functional features and they mediate cytolysis without exhibiting any phagocytic activity. By using phenotypically defined clones of the U937 histiocytic cell line, the segregation of different lytic abilities and their linkage of the M3 phenotype have been confirmed.