Decades Long Involvement of THP-1 Cells as a Model for Macrophage Research: A Comprehensive Review

Over the years, researchers have endeavored to identify dependable and reproducible in vitro models for examining macrophage behavior under controlled conditions. The THP-1 cell line has become a significant and widely employed tool in macrophage research within these models. Originating from the peripheral blood of individuals with acute monocytic leukemia, this human monocytic cell line can undergo transformation into macrophage-like cells, closely mirroring primary human macrophages when exposed to stimulants. Macrophages play a vital role in the innate immune system, actively regulating inflammation, responding to infections, and maintaining tissue homeostasis. A comprehensive understanding of macrophage biology and function is crucial for gaining insights into immunological responses, tissue healing, and the pathogenesis of diseases such as viral infections, autoimmune disorders, and neoplastic conditions. This review aims to thoroughly evaluate and emphasize the extensive history of THP-1 cells as a model for macrophage research. Additionally, it will delve into the significance of THP-1 cells in advancing our comprehension of macrophage biology and their invaluable contributions to diverse scientific domains.

Human and mouse neutrophils share core transcriptional programs in both homeostatic and inflamed contexts

Neutrophils are frequently studied in mouse models, but the extent to which findings translate to humans remains poorly defined. In an integrative analysis of 11 mouse and 13 human datasets, we find a strong correlation of neutrophil gene expression across species. In inflammation, neutrophils display substantial transcriptional diversity but share a core inflammation program. This program includes genes encoding IL-1 family members, CD14, IL-4R, CD69, and PD-L1. Chromatin accessibility of core inflammation genes increases in blood compared to bone marrow and further in tissue. Transcription factor enrichment analysis implicates members of the NF-κB family and AP-1 complex as important drivers, and HoxB8 neutrophils with JunB knockout show a reduced expression of core inflammation genes in resting and activated cells. In independent single-cell validation data, neutrophil activation by type I or type II interferon, G-CSF, and E. coli leads to upregulation in core inflammation genes. In COVID-19 patients, higher expression of core inflammation genes in neutrophils is associated with more severe disease. In vitro treatment with GM-CSF, LPS, and type II interferon induces surface protein upregulation of core inflammation members. Together, we demonstrate transcriptional conservation in neutrophils in homeostasis and identify a core inflammation program shared across heterogeneous inflammatory conditions.

β-defensinas como posibles indicadores de la actividad inflamatoria en la enfermedad periodontal

Periodontal disease (gingivitis and periodontitis) is an inflam-matory process caused by the activity of pathogenic bacteria and their products on the gingival sulcus, with the consequent activation of the immune response. Saliva and crevicular fluid contain a wide variety of enzymes and antimicrobial factors that are in contact with the supragingival and subgingival region, in-cluding β-defensins (hBDs). hHBDs are non-glycosylated, cysteine-rich cationic peptides produced by epithelial cells with antimicrobial and immunoregulatory effects, thus contributing to maintaining homeostasis in periodontal tissues. The changes in the microbiota and the immune response from a healthy peri-odontium to gingivitis and, finally, to periodontitis are complex. Their sever-ity depends on a dynamic balance between bacteria associated with plaque, genetic and environmental factors. Recent advances have made it possible to understand the implication of hBDs in the detection, diagnosis, and therapy of periodontal disease and the relationship between periodontitis and other inflammatory conditions. This review aims to describe the effect of hBDs on the immune response and its use as a possible marker of the inflammatory activity of the periodontal disease.

From infection to repair: Understanding the workings of our innate immune cells

In a world filled with microbes, some posing a threat to our body, our immune system is key to living a healthy life. The innate immune system is made of various cell types that act to guard our bodies. Unlike the adaptive immune system that has a specific response, our innate immune system encompasses cells that elicit unspecific immune responses, triggered whenever the right signals are detected. Our understanding of immunity started with the concept of our immune system only responding to "nonself" like the pathogens that invade our body. However, over the past few decades, we have learned that the immune system is more than an on/off switch that recognizes nonself. The innate immune system regularly patrols our bodies for pathogens and tissue damage. Our innate immune system not only seeks to resolve infection but also repair tissue injury, through phagocytosing debris and initiating the release of growth factors. Recently, we are starting to see that it is not just recognizing danger, our innate immune system plays a crucial role in repair. Innate immune cells phenotypically change during repair. In the context of severe injury or trauma, our innate immune system is modified quite drastically to help repair, resulting in reduced infection control. Moreover, these changes in immune cell function can be modified by sex as a biological variable. From past to present, in this overview, we provide a summary of the innate immune cells and pathways in infection and tissue repair. This article is categorized under: Immune System Diseases > Molecular and Cellular Physiology.

In vivo immunostimulatory effect of the amoebocyte lysate and plasma of Asian horseshoe crab, Tachypleus gigas in a piscine model

Antimicrobial proteins/peptides are becoming a new generation of immunostimulants for prevention and disease control in human and animals, including aquatic animals. As the haemolymph of horseshoe crabs (Tachypleus) contains broad ranges of bioactive compounds, we have explored the in vivo immunostimulating potential of amoebocyte lysate and plasma using a fish model. Indian major carp, Labeo rohita, yearlings were injected intraperitoneally with two doses of lysate and plasma at 50 and 100 µg protein per fish. No abnormalities and/or mortalities were recorded in any group. L. rohita injected with 50 µg lysate and 100 µg plasma protein showed significant enhancement (P < 0.01) of various haematological and immunological parameters. There was a significant rise in the total protein and globulin content, myeloperoxidase and respiratory burst activity following injection with 50 µg lysate and 100 µg plasma protein. The agglutinating and haemagglutinating activities were increased albeit not significantly (P > 0.01) in any groups. On the contrary, a significantly high hemolysin titre was recorded in fish that received 100 µg plasma protein. Following challenge with Aeromonas hydrophila, both lysate and plasma protein(s) cross protected the fish after 30 days. The highest survival (50%) was recorded in group injected with 50 µg lysate protein, followed by 45% in both 100 µg lysate and plasma protein injected groups.

Neutrophils and Influenza: A Thin Line between Helpful and Harmful

Influenza viruses are one of the most prevalent respiratory pathogens known to humans and pose a significant threat to global public health each year. Annual influenza epidemics are responsible for 3-5 million infections worldwide and approximately 500,000 deaths. Presently, yearly vaccinations represent the most effective means of combating these viruses. In humans, influenza viruses infect respiratory epithelial cells and typically cause localized infections of mild to moderate severity. Neutrophils are the first innate cells to be recruited to the site of the infection and possess a wide range of effector functions to eliminate viruses. Some well-described effector functions include phagocytosis, degranulation, the production of reactive oxygen species (ROS), and the formation of neutrophil extracellular traps (NETs). However, while these mechanisms can promote infection resolution, they can also contribute to the pathology of severe disease. Thus, the role of neutrophils in influenza viral infection is nuanced, and the threshold at which protective functions give way to immunopathology is not well understood. Moreover, notable differences between human and murine neutrophils underscore the need to exercise caution when applying murine findings to human physiology. This review aims to provide an overview of neutrophil characteristics, their classic effector functions, as well as more recently described antibody-mediated effector functions. Finally, we discuss the controversial role these cells play in the context of influenza virus infections and how our knowledge of this cell type can be leveraged in the design of universal influenza virus vaccines.

Cysteine-rich antimicrobial peptides from plants: The future of antimicrobial therapy

There has been a spurt in the spread of microbial resistance to antibiotics due to indiscriminate use of antimicrobial agents in human medicine, agriculture, and animal husbandry. It has been realized that conventional antibiotic therapy would be less effective in the coming decades and more emphasis should be given for the development of novel antiinfective therapies. Cysteine rich peptides (CRPs) are broad-spectrum antimicrobial agents that modulate the innate immune system of different life forms such as bacteria, protozoans, fungi, plants, insects, and animals. These are also expressed in several plant tissues in response to invasion by pathogens, and play a crucial role in the regulation of plant growth and development. The present work explores the importance of CRPs as potent antimicrobial agents, which can supplement and/or replace the conventional antibiotics. Different plant parts of diverse plant species showed the presence of antimicrobial peptides (AMPs), which had significant structural and functional diversity. The plant-derived AMPs exhibited potent activity toward a range of plant and animal pathogens, protozoans, insects, and even against cancer cells. The cysteine-rich AMPs have opened new avenues for the use of plants as biofactories for the production of antimicrobials and can be considered as promising antimicrobial drugs in biotherapeutics.

A helminth cathelicidin-like protein suppresses antigen processing and presentation in macrophages via inhibition of lysosomal vATPase

We previously reported the identification of a novel family of immunomodulatory proteins, termed helminth defense molecules (HDMs), that are secreted by medically important trematode parasites. Since HDMs share biochemical, structural, and functional characteristics with mammalian cathelicidin-like host defense peptides (HDPs), we proposed that HDMs modulate the immune response via molecular mimicry of host molecules. In the present study, we report the mechanism by which HDMs influence the function of macrophages. We show that the HDM secreted by Fasciola hepatica (FhHDM-1) binds to macrophage plasma membrane lipid rafts via selective interaction with phospholipids and/or cholesterol before being internalized by endocytosis. Following internalization, FhHDM-1 is rapidly processed by lysosomal cathepsin L to release a short C-terminal peptide (containing a conserved amphipathic helix that is a key to HDM function), which then prevents the acidification of the endolysosomal compartments by inhibiting vacuolar ATPase activity. The resulting endolysosomal alkalization impedes macrophage antigen processing and prevents the transport of peptides to the cell surface in conjunction with MHC class II for presentation to CD4(+) T cells. Thus, we have elucidated a novel mechanism by which helminth pathogens alter innate immune cell function to assist their survival in the host.

Isolation and characterization of an extracellular antimicrobial protein from Aspergillus oryzae

A 17 kDa antimicrobial protein was isolated from growth medium containing the filamentous fungus Aspergillus oryzae by extracting the supernatants from the culture media, ion exchange chromatography on CM-sepharose, and C18 reverse-phase high-performance liquid chromatography. This antimicrobial protein, which we considered to be an extracellular antimicrobial protein from A. oryzae (exAP-AO17), possessed antimicrobial activity but lacked hemolytic activity. The exAP-AO17 protein strongly inhibited pathogenic microbial strains, including pathogenic fungi, Fusarium moniliform var. subglutinans and Colletotrichum coccodes, and showed antibacterial activity against bacteria, including E. coli O157 and Staphylococcus aureus. To confirm that the protein acts as a regulation factor for extracellular secretion, we examined growth under varying conditions of N sources, C sources, ions, ambient pH, and stress. Various culture conditions were found to induce characteristic changes in the expression of protein synthesis as analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Highly basic polypeptides were regulated by suppressing the ambient pH under acidic conditions and strongly induced under alkaline conditions, thus confirming that pH regulation is physiologically relevant. The expression of exAP-AO17 was upregulated by heat shock upon growth in the presence of NaCl. Automated Edman degradation showed that the N-terminal sequence of exAP-AO17 was NH 2-GLPGPAGAVGFAGKDQNM-. ExAP-AO17 showed partial sequence homology with a collagen belonging to the animal source. These results suggest that exAP-AO17 is an excellent candidate as a lead compound for the development of novel oral or other types of anti-infective agents.

Antibacterial peptides in hemocytes and hematopoietic tissue from freshwater crayfish Pacifastacus leniusculus: characterization and expression pattern

A 14 amino acid residues proline/arginine-rich antibacterial peptide designated as astacidin 2 was purified and characterized from hemocytes of the freshwater crayfish, Pacifastacus leniusculus. Astacidin 2 has a broad range of antibacterial activity against both Gram-positive and Gram-negative bacteria. The primary sequence of astacidin 2 is RPRPNYRPRPIYRP with an amidated C-terminal and the molecular mass is 1838Da determined by mass spectrometry. Furthermore, the cDNA of three different crustin antibacterial homologs were isolated from a crayfish hemocyte EST library. RT-PCR was used to analyze the expression of the genes coding for astacidin 2 and P. leniusculus crustins (Plcrustin) 1-3 after bacterial challenge. The expression of Plcrustin1 was upregulated in both hemocytes and hematopoietic tissue after challenge with Gram-negative Escherichia coli or Acinetobacter ssp. non pathogenic bacteria as well as by a Gram negative crayfish pathogenic bacterium (Aeromonas hydrophila). The PlCrustin3 transcript was only upregulated after inoculation with the non-pathogenic Acinetobacter ssp. while there was no change in expression of Plcrustin2 or astacidin 2 following a bacterial challenge.

Biologically active proteins from natural product extracts

The term "biologically active proteins" is almost redundant. All proteins produced by living creatures are, by their very nature, biologically active to some extent in their homologous species. In this review, a subset of these proteins will be discussed that are biologically active in heterologous systems. The isolation and characterization of novel proteins from natural product extracts including those derived from microorganisms, plants, insects, terrestrial vertebrates, and marine organisms will be reviewed and grouped into several distinct classes based on their biological activity and their structure.