Macrophage populations and self-renewal: Changing the paradigm

The origin of macrophages has been considered since several decades to be a continuum from bone marrow (BM) to tissue via monocytes as precursors. The development of new tools such as genetic lineage tracing, parabiosis and BM chimeras changed the paradigm of macrophage origin. In steady state, most resident macrophages are of embryonic origin, whereas a monocyte origin remains prominent in pathological conditions. The findings of a proliferation of mature macrophages will oblige us to reappraise the relationship between proliferation and differentiation in macrophages. This review is based on the recent explosion of high impact articles on macrophage biology. It summarizes new data on the origin of macrophages and their self-renewal potential in steady states. While monocytes are required for intestinal macrophage development, the microglia is independent of monocyte influx and skin macrophages provide an excellent model of the balance between monocyte input and self-renewal. In addition, macrophage proliferation requires intrinsic and extrinsic factors including growth factors and cytokines. It also analyzes the impact of this new paradigm in human diseases such as athrosclerosis, cancer, infectious diseases and neurodegenerative diseases. In atherosclerosis, the finding of macrophage proliferation within the lesions will change our understanding of disease pathophysiology, this new paradigm may have therapeutical impact in the future.

New insights on chitinases immunologic activities

Mammalian chitinases and the related chilectins (ChiLs) belong to the GH18 family, which hydrolyse the glycosidic bond of chitin by a substrate-assisted mechanism. Chitin the fundamental component in the coating of numerous living species is the most abundant natural biopolymer. Mounting evidence suggest that the function of the majority of the mammalian chitinases is not exclusive to catalyze the hydrolysis of chitin producing pathogens, but include crucial role specific in the immunologic activities. The chitinases and chitinase-like proteins are expressed in response to different proinflammatory cues in various tissues by activated macrophages, neutrophils and in different monocyte-derived cell lines. The mechanism and molecular interaction of chitinases in relation to immune regulation embrace bacterial infection, inflammation, dismetabolic and degenerative disease. The aim of this review is to update the reader with regard to the role of chitinases proposed in the recent innate and adaptive immunity literature. The deep scrutiny of this family of enzymes could be a useful base for further studies addressed to the development of potential procedure directing these molecules as diagnostic and prognostic markers for numerous immune and inflammatory diseases.

PICOT promotes T lymphocyte proliferation by down-regulating cyclin D2 expression

The mammalian protein kinase C-interacting cousin of thioredoxin (PICOT; also termed glutaredoxin 3) is a multi-domain monothiol glutaredoxin that is involved in a wide variety of signaling pathways and biological processes. PICOT is required for normal and transformed cell growth and is critical for embryonic development. Recent studies in T lymphocytes demonstrated that PICOT can translocate to the nucleus and interact with embryonic ectoderm development, a polycomb group protein and a core component of the polycomb repressive complex 2, which contributes to the maintenance of transcriptional repression and chromatin remodeling. Furthermore, PICOT was found to interact with chromatin-bound embryonic ectoderm development and alter the extent of histone 3 lysine 27 trimethylation at the promoter region of selected polycomb repressive complex 2 target genes. PICOT knockdown in Jurkat T cells led to increased histone 3 lysine 27 trimethylation at the promoter region of CCND2, a cell cycle-regulating gene which encodes the cyclin D2 protein. As a result, the expression levels of CCND2 mRNA and protein levels were reduced, concomitantly with inhibition of the cell growth rate. Analysis of multiple data sets from the Cancer Genome Atlas revealed that a high expression of PICOT correlated with a low expression of CCND2 in a large number of human cancers. In addition, this parameter correlated with poor patient survival, suggesting that the ratio between PICOT/CCND2 mRNA levels might serve as a predictor of patient survival in selected types of human cancer.

Helicobacter pylori vs immune system or antibiotics

Helicobacter pylori (H. pylori) infection has often no clinical signs and is one of the most common bacterial infections. All infected subjects have histology of active chronic gastritis. In some cases patients develop peptic ulcer and minority of them develop gastric cancer. Gastric cancer is multifactorial disease, thus various progressions of H. pylori infection and disease are dependent on the host genetic factors, the characteristics of the individual’s immune response, environmental factors, and different bacterial virulence factors of the individual bacterial strains. Eradication of the bacteria plays a crucial role in the treatment of these cases however antibiotic therapy does not always help. Bacteria often develop resistance to antibiotics so we recommend that not only screening for H. pylori also the strain determination should have some diagnostic value, especially in the patients who already developed gastritis. Furthermore, for such patients assessment of disease progression (atrophic or metaplastic gastritis) could be followed by polymorphism determination. Until now we cannot predict the disease based only on single polymorphism. Bacteria successfully neutralize the responses of the immune systems using different enzymes or even components of the host immune response. However, the influence of immune system and its components could represent new ways of treatments and could help to eradicate the infection.

GM3-containing nanoparticles in immunosuppressed hosts: Effect on myeloid-derived suppressor cells

Cancer vaccines to date have not broadly achieved a significant impact on the overall survival of patients. The negative effect on the immune system of the tumor itself and conventional anti-tumor treatments such as chemotherapy is, undoubtedly, a key reason for these disappointing results. Myeloid-derived suppressor cells (MDSCs) are considered a central node of the immunosuppressive network associated with tumors. These cells inhibit the effector function of natural killer and CD8⁺ T cells, expand regulatory T cells and can differentiate into tumor-associated macrophages within the tumor microenvironment. Thus, overcoming the suppressive effects of MDSCs is likely to be critical for cancer immunotherapy to generate effective anti-tumor immune responses. However, the capacity of cancer vaccines and particularly their adjuvants to overcome this inhibitory population has not been well characterized. Very small size proteoliposomes (VSSP) is a nanoparticulated adjuvant specifically designed to be formulated with vaccines used in the treatment of immunocompromised patients. This adjuvant contains immunostimulatory bacterial signals together with GM3 ganglioside. VSSP promotes dendritic cell maturation, antigen cross-presentation to CD8⁺ T cells, Th1 polarization, and enhances CD8⁺ T cell response in tumor-free mice. Currently, four cancer vaccines using VSSP as the adjuvant are in Phase I and II clinical trials. In this review, we summarize our work characterizing the unique ability of VSSP to stimulate antigen-specific CD8⁺ T cell responses in two immunocompromised scenarios; in tumor-bearing mice and during chemotherapy-induced leukopenia. Particular emphasis has been placed on the interaction of these nanoparticles with MDSCs, as well as comparison with other cancer vaccine adjuvants currently in preclinical or clinical studies.

Immunological aspects of drug-induced liver injury

Drug induced liver injury (DILI) is a common condition of increasing incidence. Many environmental and genetic factors are involved in its pathogenesis, and immunological mechanisms are also thought to contribute to the development and severity of DILI. This review summarizes current understanding of the immunological pathogenesis of DILI and discusses the perspective for clinical applications.

Role of tumor associated macrophages in regulating pancreatic cancer progression

Pancreatic cancer has an overall 5-year survival rate of less than 5%. Unfortunately, patient survival has not substantially improved in the last couple of decades despite advances in treatment modalities that have been successful in other cancer types. The poor response of pancreatic cancer to therapy is a major obstacle faced by clinicians. Increasing attention is being paid to how tumor cells and non-tumor cells influence each other in the pancreatic tumor microenvironment. Tumor-associated macrophages (TAMs) are a highlight in this field because of their vast presence in the tumor microenvironment. TAMs promote angiogenesis, metastasis, and suppress the anti-tumor immune response. Here we review the current understanding of the role of TAMs in regulating the progression of pancreatic cancer.

Noncanonical intercellular communication in immune response

The classical view of signaling between cells of immune system includes two major routes of intercellular communication: Through the release of extracellular molecules or a direct interaction between membrane bound receptor and its membrane bound ligand, which initiate a cascade of signaling in target cell. However, recent studies indicate that besides these canonical modes of signaling there are also noncanonical routs of intercellular communications through membrane stripping/membrane exchange/trogocytosis, extracellular traps, exosomes and ectososmes/microparticles. In this review we discuss what are the components of noncanonical pathways of signaling and what role they play in immune cells interactions.

Maillard reaction and immunogenicity of protein therapeutics

The recombinant DNA technology enabled the production of a variety of human therapeutic proteins. Accumulated clinical experience, however, indicates that the formation of antibodies against such proteins is a general phenomenon rather than an exception. The immunogenicity of therapeutic proteins results in inefficient therapy and in the development of undesired, sometimes life-threatening, side reactions. The human proteins, designed for clinical application, usually have the same amino acid sequence as their native prototypes and it is not yet fully clear what the reasons for their immunogenicity are. In previous studies we have demonstrated for the first time that interferon-β (IFN-β) pharmaceuticals, used for treatment of patients with multiple sclerosis, do contain advanced glycation end products (AGEs) that contribute to IFN-β immunogenicity. AGEs are the final products of a chemical reaction known as the Maillard reaction or glycation, which implication in protein drugs’ immunogenicity has been overlooked so far. Therefore, the aim of the present article is to provide a comprehensive overview on the Maillard reaction with emphasis on experimental data and theoretical consideration telling us why the Maillard reaction warrants special attention in the context of the well-documented protein drugs’ immunogenicity.

CD28/CTLA-4/B7 and CD40/CD40L costimulation and activation of regulatory T cells

Costimulatory signals are crucial for T cell activation. Attempts to block costimulatory pathways have been effective in preventing unwanted immune reactions. In particular, blocking the CD28/cytotoxic T lymphocyte antigen (CTLA)-4/B7 interaction (using CTLA-4Ig) and the CD40/CD40L interaction (using anti-CD40L antibodies) prevents T cell mediated autoimmune diseases, transplant rejection and graft vs host disease in experimental models. Moreover, CTLA-4Ig is in clinical use to treat rheumatoid arthritis (abatacept) and to prevent rejection of renal transplants (belatacept). Under certain experimental conditions, this treatment can even result in tolerance. Surprisingly, the underlying mechanisms of immune modulation are still not completely understood. We here discuss the evidence that costimulation blockade differentially affects effector T cells (Teff) and regulatory T cells (Treg). The latter are required to control inappropriate and unwanted immune responses, and their activity often contributes to tolerance induction and maintenance. Unfortunately, our knowledge on the costimulatory requirements of Treg cells is very limited. We therefore summarize the current understanding of the costimulatory requirements of Treg cells, and elaborate on the effect of anti-CD40L antibody and CTLA-4Ig treatment on Treg cell activity. In this context, we point out that the outcome of a treatment aiming at blocking the CD28/CTLA-4/B7 costimulatory interaction can vary with dosing, timing and underlying immunopathology.

Apoptotic signaling through reactive oxygen species in cancer cells

Reactive oxygen species (ROS) take part in diverse biological processes like cell growth, programmed cell death, cell senescence, and maintenance of the transformed state through regulation of signal transduction. Cancer cells adapt to new higher ROS circumstance. Sometimes, ROS induce cancer cell proliferation. Meanwhile, elevated ROS render cancer cells vulnerable to oxidative stress-induced cell death. However, this prominent character of cancer cells allows acquiring a resistance to oxidative stress conditions relative to normal cells. Activated signaling pathways that increase the level of intracellular ROS in cancer cells not only render up-regulation of several genes involved in cellular proliferation and evasion of apoptosis but also cause cancer cells and cancer stem cells to develop a high metabolic rate. In over the past several decades, many studies have indicated that ROS play a critical role as the secondary messenger of tumorigenesis and metastasis in cancer from both in vitro and in vivo. Here we summarize the role of ROS and anti-oxidants in contributing to or preventing cancer. In addition, we review the activated signaling pathways that make cancer cells susceptible to death.

Syphilis testing algorithms: A review

The methods and strategies used to screen for syphilis and to confirm initially reactive results can vary significantly across clinical laboratories. While the performance characteristics of these different approaches have been evaluated by multiple studies, there is not, as of yet, a single, universally recommended algorithm for syphilis testing. To clarify the currently available options for syphilis testing, this update will summarize the clinical challenges to diagnosis, review the specific performance characteristics of treponemal and non-treponemal tests, and finally, summarize select studies published over the past decade which have evaluated these approaches. Specifically, this review will discuss the traditional and reverse sequence syphilis screening algorithms commonly used in the United States, alongside a discussion of the European Centre for Disease Prevention and Control syphilis algorithm. Ultimately, in the United States, the decision of which algorithm to use is largely dependent on laboratory resources, the local incidence of syphilis and patient demographics.

Circulating immune cell activation and diet: A review on human trials

Protein energy malnutrition is the main cause of immunodeficiency and, secondarily, of several infections. However, immune cell activation is involved in several pathophysiological processes that play a crucial role in the appearance of cardiovascular disease (CVD) or cancer. The aim of this review is to update the knowledge of the modulation of immune cell activation by different dietary patterns and its components focusing on CVD or cancer. While a westernized high-saturated fat high-carbohydrate diet is positively associated with low-grade inflammation, vegetable- and fruit-based diets rich in monounsaturated fatty acids, polyunsaturated fatty acids and polyphenols, key nutrients of Mediterranean diet, decrease the levels of cellular and circulating inflammatory biomarkers thereby reducing the risk of related chronic diseases.

Biologic response modifiers in retinal vasculitis

Intraocular inflammation is an important cause of blindness both in the developing and developed world. Corticosteroids play a pivotal role in the treatment of intraocular inflammation. Lately, therapy by immunosuppression has taken the center stage for patients with severe intraocular inflammation. However, the side effects of immunosuppressive drugs are oncogenic, infectious, and hematological. Recently, biologic response modifiers specifically targeting suppression of the immune effector responses have revolutionized the treatment of intraocular inflammation. Anti-tumour necrosis factor agents are etanercept, infliximab, and adalimumab. Newer drugs include certolizumab and golimumab. Infliximab has been found to be superior to corticosteroids in treating retinal vasculitis. Anti-interlenkin therapies include rituximab, daclizumab, anakinra, tocilizumab and secukinumab. Rituximab has been proven to be quite effective. Other biologics used are interferons and abatacept. However, there are several limitations and side effects associated with their use.

Aberrant expression of CD56 by circulating Sézary syndrome malignant T lymphocytes

Sézary syndrome (SS) is an aggressive variant of cutaneous T cell lymphoma characterized by the presence of malignant T cells in the skin, peripheral blood and lymph nodes. The tumoral population typically displays a CD3⁺ CD4⁺ CD45RO⁺ memory T cell phenotype. We report a case of SS with an aberrant CD56⁺ immunophenotype. This patient presented with a generalized erythroderma and palpable small axillary lymph nodes. SS (stage IVA) was diagnosed on histological criteria and by the detection of a major T cell clone in skin and blood, an elevated CD4/CD8 T cell ratio and Sézary cells count > 1000/mm³. Beside the Sézary cell marker KIR3DL2, immunostainings revealed that two third of the malignant cells expressed CD56 but no other natural killer (NK) cell marker such as CD16, CD160 or NKp46. This atypical expression was not linked to an activation-dependent process and remained stable during the time course of the disease. No loss of the pan T-cell markers CD2, CD3 or CD4 was detected while a complete down-modulation of CD26 was observed. Despite several lines of treatment, no durable amelioration was observed and patient died after 10 mo of follow-up. Because this CD4⁺ CD56⁺ SS case is the only one reported so far, the functional significance of CD56 expression remained difficult to assess in terms of aggressiveness and prognosis.

Intracellular localisation of Mycobacterium marinum in mast cells

AIM: To study the bacteriocidal or bacteriostatic role of mast cells during infection with Mycobacterium.

METHODS: Mycobacterium marinum (M. marinum) (BAA-535/M strain) was investigated for its ability to grow at a temperature relevant to the mammalian host. Primary mast cells were differentiated from bone marrows of mice, a human mast cell line (HMC-1) and a human monocytic cell line (MonoMac6) were maintained in culture. Mice were stimulated by intraperitoneal injection of heat-killed M. marinum to study cytochemically the degranulation of peritoneal mast cells. HMC-1 cells were stimulated with M. marinum to analyse mRNA expression for inflammatory reactant genes, while HMC-1 and primary mouse mast cells were infected with M. marinum to establish in parallel cell viability (lactate dehydrogenase release and cell counts) and viable mycobacterial counts. Flow cytometry was used to assess intracellular presence of fluorescein isothiocyanate labelled M. marinum after trypan blue quenching and to measure the extent of infection-induced apoptosis or necrosis in HMC-1. A GFP expressing recombinant M. marinum strain was used to assess intracellular location by fluorescence microscopy. Light microscopy of osmium tetroxide and Gram Twort stained sections of 0.5 μm and transmission electron microscopy were undertaken as sensitive methods.

RESULTS: Since its isolation, M. marinum has adapted to grow at 37 °C. This study found that M. marinum infects HMC-1 cells and primary murine mast cells, where they survive, replicate, and cause dose dependent cell damage over the analysis period of up to 120 h. Amikacin was an effective aminoglycoside antibiotic to eliminate extracellular or membrane attached M. marinum in order to adequately quantify the intracellular bacterial loads. In vivo, intraperitoneal injection of heat-killed M. marinum led to the release of mast cell granules in mice. HMC-1 cells stimulated with M. marinum showed a biphasic pattern of increased mRNA expression for LL-37 and COX-2/TNF-α during 24 h of stimulation. In HMC-1, M. marinum localised to the cytoplasm whereas in primary mast cells, M. marinum were found in vacuoles.

CONCLUSION: The effector role of mast cells in infection with M. marinum can be studied in vitro and in vivo.

Stem and immune cells in colorectal primary tumour: Number and function of subsets may diagnose metastasis

An important percentage of colorectal cancer (CRC) patients will develop metastasis, mainly in the liver, even after a successful curative resection. This leads to a very high mortality rate if metastasis is not detected early on. Disseminated cancer cells develop from metastatic stem cells (MetSCs). Recent knowledge has accumulated about these cells particularly in CRC, so they may now be tracked from the removed primary tumour. This approach could be especially important in prognosis of metastasis because it is becoming clear that metastasis does not particularly rely on testable driver mutations. Among the many traits supporting an epigenetic amplification of cell survival and self-renewal mechanisms of MetSCs, the role of many immune cell populations present in tumour tissues is becoming clear. The amount of tumour-infiltrating lymphocytes (T, B and natural killer cells), dendritic cells and some regulatory populations have already shown prognostic value or to be correlated with disease-free survival time, mainly in immunohistochemistry studies of unique cell populations. Parallel analyses of these immune cell populations together with MetSCs in the primary tumour of patients, with later follow-up data of the patients, will define the usefulness of specific combinations of both immune and MetSCs cell populations. It is expected that these combinations, together to different biomarkers in the form of an immune score, may predict future tumour recurrences, metastases and/or mortality in CRC. It will also support the future design of improved immunotherapeutic approaches against metastasis.

Holistic paradigm in carcinogenesis: Genetics, epigenetics, immunity, inflammation and oral infections

Recent debate among the experts of cancer research regarding the main causes of carcinogenesis encouraged us to review the etiology of cancer pathogenesis. The somatic mutation theory attributes carcinogenesis to random errors in DNA multiplication while the tissue organization field theory ascribes causation to environmental factors. We recognize complexity in cancer pathogenesis and accept the premise of both DNA multiplication errors and environmental factors in cancer development. Furthermore, it should also be noted that the combination of these factors and the relative importance of the each differ in various types of cancers. For example, in some cancers, genetics plays a prominent role while in others environment such as obesity plays a much stronger role. Additionally, the cancer mitigating factors should also be considered. The balance of cancer-enhancing and cancer-suppressing forces determines the cancer incidence. Ultimately, identifying the lifestyle factors that revise somatic mutations or epigenetic alterations will lead to a clear understanding of pathogenic mechanisms of cancer and to the optimal preventive strategies. This narrative review evaluates the published evidence on carcinogenesis pertaining to the whole organism (thus, holistic) incorporating genetics, epigenetics, immunology, inflammation and infections with emphasis on oral infections.

Role of host immune responses in sequence variability of HIV-1 Vpu

Viral protein U (Vpu) is an accessory protein associated with two main functions important in human immunodeficiency virus type 1 (HIV-1) replication and dissemination; these are down-regulation of CD4 receptor through mediating its proteasomal degradation and enhancement of virion release by antagonizing tetherin/BST2. It is also well established that Vpu is one of the most highly variable proteins in the HIV-1 proteome. However it is still unclear what drives Vpu sequence variability, whether Vpu acquires polymorphisms as a means of immune escape, functional advantage, or otherwise. It is assumed that the host-pathogen interaction is a cause of polymorphic phenotype of Vpu and that the resulting functional heterogeneity of Vpu may have critical significance in vivo. In order to comprehensively understand Vpu variability, it is important to integrate at the population level the genetic association approaches to identify specific amino acid residues and the immune escape kinetics which may impose Vpu functional constraints in vivo. This review will focus on HIV-1 accessory protein Vpu in the context of its sequence variability at population level and also bring forward evidence on the role of the host immune responses in driving Vpu sequence variability; we will also highlight the recent findings that illustrate Vpu functional implication in HIV-1 pathogenesis.

Cigarette smoking and innate immune responses to influenza infection

Cigarette smoking (CS) suppresses the immune system, and smoking is a well-known major risk factor for respiratory tract infections, including influenza infection. Both smoking cigarettes and passive smoking alter a wide range of immunological functions, including innate and adaptive immune responses. Past reviews on CS and innate immunity have been focused on the effects of CS on structural changes of the lung, as well as the effects on the function of alveolar macrophages, leukocytes, natural killer cells and dendritic cells. The study of innate immunity has developed rapidly in the last decade with the discovery of new receptors for virus recognition and interferon responses. This review aims to give a brief summary of recent findings on the suppressive effects of CS on the innate response to influenza virus, especially as it pertains to suppression of the function of pattern recognition receptors for influenza virus.

Targeting TLR4/MAPKs signaling pathway: A better option for therapeutic inhibition of atherosclerosis

Cardiovascular diseases, especially atherosclerosis, found to be the dreadful diseases worldwide. There are diverse pathways associated with the progression of atherosclerosis. One of the important signaling pathways to target atherosclerotic plaque rupture is toll-like receptor 4 (TLR4) Pathway. Several studies are available for illustrating the role of TLR4 in health and diseases. Different types of immune cell are activated in atherosclerosis but primary cells that are activated by the TLR4 signaling are macrophages and endothelial cells. Mechanisms by which macrophages uptake lipids are diverse and it is very important to target signaling pathway responsible for controlling foam cell formation. The process of macrophages transformed foam cell formation is the critical event in progression of atherosclerotic lesion and TLR4 found to have actively participate in the event through mitogen activated protein kinases (MAPKs) activation. The activation of MAPKs signaling pathway leads to the accumulation of cholesterol in the macrophages and also contribute to the dissociation of IκB and the nuclear translocation of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) p65 subunit, thereby activating key inflammatory cascade activation by MAPKs/NF-κB signaling pathway to induce toxicity by activating different inflammatory parameters. Hence, the review focussed on exploring the role of TLR4/MAPKs signaling pathway for the therapeutic inhibition of atherosclerosis.