Immunomodulatory effects of β-defensin 2 on macrophages induced immuno-upregulation and their antitumor function in breast cancer

Host-directed therapies modulating innate immunity against infection in hematologic malignancies

Patients with hematologic malignancies (HM) are highly susceptible to bloodstream infection (BSI), particularly those undergoing treatments such as chemotherapy. A common and debilitating side effect of chemotherapy is oral and intestinal mucositis. These Patients are also at high risk of developing sepsis, which can arise from mucosal barrier injuries and significantly increases mortality in these patients. While conventional antibiotics are effective, their use can lead to antimicrobial resistance (AMR) and disrupt the gut microbiota (dysbiosis). In this review, we discuss utilizing host defense peptides (HDPs), key components of the innate immune system, and immune system inducers (ISIs) to maintain mucosal barrier integrity against infection, an underexplored host-directed therapy (HDT) approach to prevent BSI and sepsis. We advocate for the discovery of potent and safe ISIs for clinical use and call for further research into the mechanisms by which these ISIs induce HDPs and strengthen mucosal barriers.

Defensins: Exploring Their Opposing Roles in Colorectal Cancer Progression

Colorectal cancer (CRC) represents a significant global healthcare burden, with a particularly concerning rising incidence among younger adults. This trend may highlight potential links between diet, gut microbiome, and CRC risk. Novel therapeutic options have been increasingly based on the understanding of molecular mechanisms and pathways. The PI3K/AKT/mTOR pathway, a crucial cell growth regulator, offers a promising target for CRC therapy. mTOR, a key component within this pathway, controls cell growth, survival, and metabolism. Understanding the specific roles of defensins, particularly human β-Defensin 1 (HBD-1), in CRC is crucial. HBD-1 exhibits potent antimicrobial activity and may influence CRC development. Deciphering defensin expression patterns in CRC holds the promise of improved understanding of tumorigenesis, which may pave the way for improved diagnostics and therapies. This article reviews recent advances in understanding regarding how HBD-1 influences CRC initiation and progression, highlighting the molecular mechanisms by which it impacts CRC. Further, we describe the interaction between defensins and mTOR pathway in CRC.

Defensins regulate cell cycle: Insights of defensins on cellular proliferation and division

Defensins are a class of small antimicrobial peptides that play a crucial role against pathogens. However, recent research has highlighted defensins exhibit the ability to influence cell cycle checkpoints, promoting or inhibiting specific phases such as G1 arrest or S/M transition. By regulating the cell cycle, defensins impact the proliferation of normal and cancerous cells, with implications for cancer development and progression. Dysregulation of defensin expression can disrupt the delicate balance of cell cycle regulation, leading to uncontrolled cell growth and an increased risk of tumor formation. Defensins contribute to the resolution of inflammation, stimulate angiogenesis, and enhance the migration and proliferation of cells involved in tissue repair. Furthermore, The ability of defensins to respond to microenvironmental changes further demonstrates the significance of these peptides in host defense mechanisms and immune function. By adjusting their expression, defensins continue to combat pathogens effectively and maintain homeostasis within the body. This review highlights the multifaceted role of defensins in regulating the cell cycle and their broader implications in cancer progression, tissue repair, and microenvironmental response.

Silver nanoparticles induces apoptosis of cancer stem cells in head and neck cancer

Background

Several nano formulations of silver nanoparticles with bioconjugates, herbal extracts and anti-cancerous drug coating have been vividly studied to target cancer. Despite of such extensive studies, AgNPs (silver nanoparticles) have not reached the stage of clinical use. Out of all possible reasons for this failure, the unexplored effect on Cancer Stem Cell (CSC) population and mechanism of action of AgNPs, are the most plausible ones and are worked upon in this study.

Methods

AgNPs were synthesized by chemical reduction method using sodium citrate and characterized by UV, FTIR, XRD and electron microscopy. CSC population was isolated from Cal33 cell line by MACS technique. MTT assay, trypan blue exclusion assay, Annexin V and PI based apoptosis assay and cell cycle assay were performed.

Results

The results showed that synthesized AgNPs have cytotoxic activity on all cancer cell lines tested with the IC50 value of a wide range (1.5-49.21 µg/ml for cell lines and 0.0643-0.1211 µg/ml for splenocytes and thymocytes). CSCs Cal33 showed higher resistance to AgNP treatment and arrest in G1/G0 phase upon cell cycle analysis.

Conclusion

AgNPs as an anti-cancer agent although have great potential but is limited by its off-target effects on normal cells and less effective on cancer stem cells at lower concentrations.

Mechanisms and regulation of defensins in host defense

As a family of cationic host defense peptides, defensins are mainly synthesized by Paneth cells, neutrophils, and epithelial cells, contributing to host defense. Their biological functions in innate immunity, as well as their structure and activity relationships, along with their mechanisms of action and therapeutic potential, have been of great interest in recent years. To highlight the key research into the role of defensins in human and animal health, we first describe their research history, structural features, evolution, and antimicrobial mechanisms. Next, we cover the role of defensins in immune homeostasis, chemotaxis, mucosal barrier function, gut microbiota regulation, intestinal development and regulation of cell death. Further, we discuss their clinical relevance and therapeutic potential in various diseases, including infectious disease, inflammatory bowel disease, diabetes and obesity, chronic inflammatory lung disease, periodontitis and cancer. Finally, we summarize the current knowledge regarding the nutrient-dependent regulation of defensins, including fatty acids, amino acids, microelements, plant extracts, and probiotics, while considering the clinical application of such regulation. Together, the review summarizes the various biological functions, mechanism of actions and potential clinical significance of defensins, along with the challenges in developing defensins-based therapy, thus providing crucial insights into their biology and potential clinical utility.

Role of Defensins in Tumor Biology

Defensins have long been considered as merely antimicrobial peptides. Throughout the years, more immune-related functions have been discovered for both the α-defensin and β-defensin subfamily. This review provides insights into the role of defensins in tumor immunity. Since defensins are present and differentially expressed in certain cancer types, researchers started to unravel their role in the tumor microenvironment. The human neutrophil peptides have been demonstrated to be directly oncolytic by permealizing the cell membrane. Further, defensins can inflict DNA damage and induce apoptosis of tumor cells. In the tumor microenvironment, defensins can act as chemoattractants for subsets of immune cells, such as T cells, immature dendritic cells, monocytes and mast cells. Additionally, by activating the targeted leukocytes, defensins generate pro-inflammatory signals. Moreover, immuno-adjuvant effects have been reported in a variety of models. Therefore, the action of defensins reaches beyond their direct antimicrobial effect, i.e., the lysis of microbes invading the mucosal surfaces. By causing an increase in pro-inflammatory signaling events, cell lysis (generating antigens) and attraction and activation of antigen presenting cells, defensins could have a relevant role in activating the adaptive immune system and generating anti-tumor immunity, and could thus contribute to the success of immune therapy.

Immunity in Sea Turtles: Review of a Host-Pathogen Arms Race Millions of Years in the Running

The immune system of sea turtles is not completely understood. Sea turtles (as reptiles) bridge a unique evolutionary gap, being ectothermic vertebrates like fish and amphibians and amniotes like birds and mammals. Turtles are ectotherms; thus, their immune system is influenced by environmental conditions like temperature and season. We aim to review the turtle immune system and note what studies have investigated sea turtles and the effect of the environment on the immune response. Turtles rely heavily on the nonspecific innate response rather than the specific adaptive response. Turtles' innate immune effectors include antimicrobial peptides, complement, and nonspecific leukocytes. The antiviral defense is understudied in terms of the diversity of pathogen receptors and interferon function. Turtles also mount adaptive responses to pathogens. Lymphoid structures responsible for lymphocyte activation and maturation are either missing in reptiles or function is affected by season. Turtles are a marker of health for their marine environment, and their immune system is commonly dysregulated because of disease or contaminants. Fibropapillomatosis (FP) is a tumorous disease that afflicts sea turtles and is thought to be caused by a virus and an environmental factor. We aim, by exploring the current understanding of the immune system in turtles, to aid the investigation of environmental factors that contribute to the pathogenesis of this disease and provide options for immunotherapy.