Human monocytes differentiate into macrophages under the influence of human KPB-M15 conditioned medium

Mechanoregulation of Osteoclastogenesis-Inducing Potentials of Fibrosarcoma Cell Line by Substrate Stiffness

A micro-physiological system is generally fabricated using soft materials, such as polydimethylsiloxane silicone (PDMS), and seeks an inflammatory osteolysis model for osteoimmunological research as one of the development needs. Microenvironmental stiffness regulates various cellular functions via mechanotransduction. Controlling culture substrate stiffness may help spatially coordinate the supply of osteoclastogenesis-inducing factors from immortalized cell lines, such as mouse fibrosarcoma L929 cells, within the system. Herein, we aimed to determine the effects of substrate stiffness on the osteoclastogenesis-inducing potential of L929 cells via cellular mechanotransduction. L929 cells showed increased expression of osteoclastogenesis-inducing factors when cultured on type I collagen-coated PDMS substrates with soft stiffness, approximating that of soft tissue sarcomas, regardless of the addition of lipopolysaccharide to augment proinflammatory reactions. Supernatants of L929 cells cultured on soft PDMS substrates promoted osteoclast differentiation of the mouse osteoclast precursor RAW 264.7 by stimulating the expression of osteoclastogenesis-related gene markers and tartrate-resistant acid phosphatase activity. The soft PDMS substrate inhibited the nuclear translocation of YES-associated proteins in L929 cells without reducing cell attachment. However, the hard PDMS substrate hardly affected the cellular response of the L929 cells. Our results showed that PDMS substrate stiffness tuned the osteoclastogenesis-inducing potential of L929 cells via cellular mechanotransduction.

Vaccine-Mediated Inhibition of the Transporter Associated with Antigen Processing Is Insufficient To Induce Major Histocompatibility Complex E-Restricted CD8+ T Cells in Nonhuman Primates

Major histocompatibility complex E (MHC-E) is a highly conserved nonclassical MHC-Ib molecule that tightly binds peptides derived from leader sequences of classical MHC-Ia molecules for presentation to natural killer cells. However, MHC-E also binds diverse foreign and neoplastic self-peptide antigens for presentation to CD8+ T cells. Although the determinants of MHC-E-restricted T cell priming remain unknown, these cells are induced in humans infected with pathogens containing genes that inhibit the transporter associated with antigen processing (TAP). Indeed, mice vaccinated with TAP-inhibited autologous dendritic cells develop T cells restricted by the murine MHC-E homologue, Qa-1b. Here, we tested whether rhesus macaques (RM) vaccinated with viral constructs expressing a TAP inhibitor would develop insert-specific MHC-E-restricted CD8+ T cells. We generated viral constructs coexpressing SIVmac239 Gag in addition to one of three TAP inhibitors: herpes simplex virus 2 ICP47, bovine herpes virus 1 UL49.5, or rhesus cytomegalovirus Rh185. Each TAP inhibitor reduced surface expression of MHC-Ia molecules but did not reduce surface MHC-E expression. In agreement with modulation of surface MHC-Ia levels, TAP inhibition diminished presentation of MHC-Ia-restricted CD8+ T cell epitopes without impacting presentation of peptide antigen bound by MHC-E. Vaccination of macaques with vectors dually expressing SIVmac239 Gag with ICP47, UL49.5, or Rh185 generated Gag-specific CD8+ T cells classically restricted by MHC-Ia but not MHC-E. These data demonstrate that, in contrast to results in mice, TAP inhibition alone is insufficient for priming of MHC-E-restricted T cell responses in primates and suggest that additional unknown mechanisms govern the induction of CD8+ T cells recognizing MHC-E-bound antigen.IMPORTANCE Due to the near monomorphic nature of MHC-E in the human population and inability of many pathogens to inhibit MHC-E-mediated peptide presentation, MHC-E-restricted T cells have become an attractive vaccine target. However, little is known concerning how these cells are induced. Understanding the underlying mechanisms that induce these T cells would provide a powerful new vaccine strategy to an array of neoplasms and viral and bacterial pathogens. Recent studies have indicated a link between TAP inhibition and induction of MHC-E-restricted T cells. The significance of our research is in demonstrating that TAP inhibition alone does not prime MHC-E-restricted T cell generation and suggests that other, currently unknown mechanisms regulate their induction.

ABCG1 regulates mouse adipose tissue macrophage cholesterol levels and ratio of M1 to M2 cells in obesity and caloric restriction

In addition to triacylglycerols, adipocytes contain a large reserve of unesterified cholesterol. During adipocyte lipolysis and cell death seen during severe obesity and weight loss, free fatty acids and cholesterol become available for uptake and processing by adipose tissue macrophages (ATMs). We hypothesize that ATMs become cholesterol enriched and participate in cholesterol clearance from adipose tissue. We previously showed that ABCG1 is robustly upregulated in ATMs taken from obese mice and further enhanced by caloric restriction. Here, we found that ATMs taken from obese and calorie-restricted mice derived from transplantation of WT or Abcg1-deficient bone marrow are cholesterol enriched. ABCG1 levels regulate the ratio of classically activated (M1) to alternatively activated (M2) ATMs and their cellular cholesterol content. Using WT and Abcg1(-/-) cultured macrophages, we found that Abcg1 is most highly expressed by M2 macrophages and that ABCG1 deficiency is sufficient to retard macrophage chemotaxis. However, changes in myeloid expression of Abcg1 did not protect mice from obesity or impaired glucose homeostasis. Overall, ABCG1 modulates ATM cholesterol content in obesity and weight loss regimes leading to an alteration in M1 to M2 ratio that we suggest is due to the extent of macrophage egress from adipose tissue.

An increase of CD83+ dendritic cells ex vivo correlates with increased regulatory T cells in patients with active eosinophilic granulomatosis and polyangiitis

BACKGROUND

Eosinophilic granulomatosis with polyangiitis (EGPA) is a rare disease characterized by the presence of allergic granulomatosis and necrotizing vasculitis with eosinophilic infiltration. The etiology of EGPA is unknown. Dendritic cells (DCs) are not only critical for the induction of primary immune responses; they may also be important for the induction of immunological tolerance and the regulation of the type of T-cell-mediated immune response. To investigate whether DC maturation is associated with EGPA disease status, we examined the relationship between the maturation of DCs and the differentiation of regulatory T (Treg) cells in EGPA patients. We exposed the CD14+ blood monocytes of 19 patients with EGPA in remission or relapse to stimulation with GM-CSF and IL-4 for 6 d and lipopolysaccharide for 24 h to obtain mature CD83+ DCs and immature CD206+ DCs. Using immunohistochemistry, we examined four patients for the presence of CD83+ and CD206+ DCs in the lung at the onset of EGPA.

RESULTS

The percentage of CD83+ cells among DCs differentiated from CD14+ monocytes was lower for EGPA patients in relapse than in remission. The percentage of CD83+ DCs was inversely correlated with the percentage of CD206+ DCs and was significantly correlated with the numbers of naturally occurring CD4+ regulatory Treg (nTreg; FOXP3+CD4+) cells and inducible Treg (iTreg; CD4+CD25+ T cells producing IL-10 or TGF-β) cells but not the number of eosinophils. The percentage of CD206+ DCs was significantly inversely correlated with the percentages of nTreg and iTreg cells but not the number of eosinophils. Immunohistochemistry revealed both CD206+ DCs and CD83+ DCs in alveoli and interstitial spaces at the onset of EGPA.

CONCLUSION

The maturation of DCs from monocytes was related to disease activity in patients with EGPA. Increased CD83+ DCs in EGPA patients may induce the differentiation of iTreg and nTreg cells, thereby suppressing inflammation and disease activity.

Phenotypic characterization of leukocytes in prenatal human dermis

The adult human skin harbors a variety of leukocytes providing immune surveillance and host defense, but knowledge about their ontogeny is scarce. In this study we investigated the number and phenotype of leukocytes in prenatal human skin (dermal dendritic cells (DDCs), macrophages, T cells (including FoxP3⁺ regulatory T cells), and mast cells) to unravel their derivation and to get a clue as to their putative function in utero. By flow cytometry and immunofluorescence, we found a distinction between CD206⁺CD1c⁺CD11c⁺ DDCs and CD206⁺CD209⁺CD1c⁻ skin macrophages by 9 weeks estimated gestational age (EGA). T cells appear at the end of the first trimester, expressing CD3 intracytoplasmatically. During midgestation, CD3⁺FoxP3⁻ and CD3⁺FoxP3⁺ cells can exclusively be found in the dermis. Similarly, other leukocytes such as CD117⁺ (c-kit) mast cells were not identified before 12–14 weeks EGA and only slowly acquire a mature phenotype during gestation. Our data show at which time point during gestation antigen-presenting cells, T cells, and mast cells populate the human dermis and provide a step forward to a better understanding of the development of the human skin immune system.

Primary human mDC1, mDC2, and pDC dendritic cells are differentially infected and activated by respiratory syncytial virus

Respiratory syncytial virus (RSV) causes recurrent infections throughout life. Vaccine development may depend upon understanding the molecular basis for induction of ineffective immunity. Because dendritic cells (DCs) are critically involved in early responses to infection, their interaction with RSV may determine the immunological outcome of RSV infection. Therefore, we investigated the ability of RSV to infect and activate primary mDCs and pDCs using recombinant RSV expressing green fluorescent protein (GFP). At a multiplicity of infection of 5, initial studies demonstrated ∼6.8% of mDC1 and ∼0.9% pDCs were infected. We extended these studies to include CD1c⁻CD141⁺ mDC2, finding mDC2 infected at similar frequencies as mDC1. Both infected and uninfected cells upregulated phenotypic markers of maturation. Divalent cations were required for infection and maturation, but maturation did not require viral replication. There is evidence that attachment and entry/replication processes exert distinct effects on DC activation. Cell-specific patterns of RSV-induced maturation and cytokine production were detected in mDC1, mDC2, and pDC. We also demonstrate for the first time that RSV induces significant TIMP-2 production in all DC subsets. Defining the influence of RSV on the function of selected DC subsets may improve the likelihood of achieving protective vaccine-induced immunity.

Phagocytic activity of macrophages against liposomes with conjugates of oxidized dextrans and isonicotinic acid hydrazide during modeling of phagocytosis disturbances in vitro

We studied phagocytic activity of macrophages against molecular-liposome hybrid compositions consisting of liposomes (diameter 200-450 nm) containing oxidized dextrans with a molecular weight of 35 or 60 kDa conjugated with the basic antituberculosis preparation isonicotinic acid hydrazide (dextrazides) during modeling of various disturbances of endocytosis function of phagocytic cells in vitro. Preincubation of macrophages with trypsin, colchicine, or sodium azide did not change the parameters of adhesion of molecular-liposome hybrid compositions to macrophages. It was found that preincubation of cells with colchicine or sodium azide reduced parameters of phagocytosis of the molecular-liposome hybrid compositions; this reduction did not depend on the molecular weight of dextrans entering the composition of the molecular-liposome hybrid compositions.

Gag- and Nef-specific CD4+ T cells recognize and inhibit SIV replication in infected macrophages early after infection

The precise immunological role played by CD4(+) T cells in retroviral infections is poorly defined. Here, we describe a new function of these cells, the elimination of retrovirus-infected macrophages. After experimental CD8(+) cell depletion, elite controlling macaques with set-point viral loads < or = 500 viral RNA copies/mL mounted robust Gag- and Nef-specific CD4(+) T cell responses during reestablishment of control with > or = 54% of all virus-specific CD4(+) T cells targeting these 2 proteins. Ex vivo, these simian immunodeficiency virus (SIV)-specific CD4(+) T cells neither recognized nor suppressed viral replication in SIV-infected CD4(+) T cells. In contrast, they recognized SIV-infected macrophages as early as 2 h postinfection because of presentation of epitopes derived from virion-associated Gag and Nef proteins. Furthermore, virus-specific CD4(+) T cells displayed direct effector function and eliminated SIV-infected macrophages. These results suggest that retrovirus-specific CD4(+) T cells may contribute directly to elite control by inhibiting viral replication in macrophages.