The Role of Mononuclear Phagocytes in the Testes and Epididymis

Features, functions, and associated diseases of visceral and ectopic fat: a comprehensive review

Obesity is a complex, chronic, and recurrent disease marked by abnormal or excessive fat accumulation that poses significant health risks. The distribution of body fat, especially ectopic fat deposition, plays a crucial role in the development of chronic metabolic diseases. Under normal conditions, fatty acids are primarily stored in subcutaneous adipose tissue; however, excessive intake can lead to fat accumulation in visceral adipose tissue and ectopic sites, including the pancreas, heart, and muscle. This redistribution is associated with disruptions in energy metabolism, inflammation, and insulin resistance, impairing organ function and raising the risk of cardiovascular disease, diabetes, and fatty liver. This review explores the roles of visceral and ectopic fat in the development of insulin resistance and related diseases such as type 2 diabetes and metabolic dysfunction-associated steatotic liver disease. Specifically, we examine the structure and characteristics of different fat types, their associations with disease, and the underlying pathogenic mechanisms. Future strategies for managing obesity-related diseases may include lifestyle modifications, surgical interventions, and emerging medications that target lipid metabolism and energy regulation, aiming to improve patient outcomes.

The immunoregulatory effects of scoparone on immune-mediated inflammatory diseases

Scoparone (SCO), also known as 6,7-Dimethoxycoumarin, is a naturally occurring bioactive ingredient originally derived from Chinese herb Artemisiae Scopariae Herba (Yin-Chen-Hao). Previous studies have shown that it is effective in treating some of the liver diseases. Beyond its hepatoprotective effects, an expanding body of research has underscored the immunoregulatory properties of SCO, indicating its potential therapeutic benefits for autoimmune and other inflammatory diseases. Over the past decade, significant advances have been made in understanding the mechanistic insights into its effects on immune-mediated diseases as well as liver diseases. SCO has an impact on various immune cells, including mast cells, monocytes, macrophages, neutrophils and T cells, and affects a broad range of intracellular signaling pathways, including TLR4/Myd88/NFκB, TGFβR/Smad3 and JNK/Sab/SHP-1 etc. Therefore, this review not only summarizes the immunomodulatory and therapeutic effects of SCO on immune-based inflammatory diseases (IMIDs), such as inflammatory bowel disease, osteoarthritis, allergic rhinitis, acute lung injury, type 1 diabetes and neuroinflammatory diseases etc., but also provides a comprehensive summary of its therapeutic effects on hepatic diseases, including non-alcoholic steatohepatitis, fulminant hepatic failure and hepatic fibrosis. In this review, we also include the broad impacts of SCO on intracellular signaling pathways, such as TLR4/Myd88/NFκB, TGFβR/Smad3, Nrf2/P38, JAK2/STAT3 and JNK/Sab/SHP-1 etc. Further researches on SCO may help understand its in-depth mechanisms of action and pave the way for the development of novel drugs to prevent and treat various immune-mediated inflammatory disorders as well as hepatic diseases, thereby significantly advancing its innovations and pharmaceutical applications.

Innate Antiviral Defense of the Male Reproductive System

The male reproductive system (MRS) is a complex system, considering its isolated anatomical locations and special microenvironments. The major organs of the MRS, including the testis, epididymis, seminal vesicle, and prostate, are relatively separated and have distinct immune status for protecting male germ cells from adverse immune responses and counteracting microbial infection for conducting their functions. A large spectrum of viruses has tropism for the MRS and may impair male fertility. To defend against invading viruses, the MRS has developed a local innate antiviral environment to reduce virus-impaired male fertility. All major tissue cells are well equipped with innate antiviral machinery. Both tissue-specific cells and immune cells are involved in the antiviral defense against viral infection of the MRS. Understanding the mechanisms underlying local innate antiviral responses in the MRS can aid in the development of preventive and therapeutic strategies for viral diseases. This chapter focuses on pattern recognition receptor-mediated innate antiviral responses in the major cells of the testis, epididymis, seminal vesicle, and prostate.

Single-cell transcriptome analysis of liver immune microenvironment changes induced by microplastics in mice with non-alcoholic fatty liver

Recent studies have discovered that tiny particles of microplastics (MPs) at the nano-scale level can enter the body of organisms from the environment, potentially causing metabolic ailments. However, further investigation is required to understand the alterations in the immune microenvironment associated with non-alcoholic fatty liver disease (NAFLD) occurrence following exposure to MPs. Experiments were performed using mice, which were given a normal chow or high-fat diet (NCD or HFD, respectively) plus free drinking of sterile water with or without MPs, respectively. Employing an impartial technique known as unbiased single-cell RNA-sequencing (scRNA-seq), the cellular (single-cell) pathology landscape of NAFLD and related changes in the identified immune cell populations induced following MPs plus HFD treatment were assessed. The results showed that mice in the HFD groups had remarkably greater NAFLD activity scores than those from the NCD groups. Moreover, administration of MPs plus HFD further worsened the histopathological changes in the mice's liver, leading to hepatic steatosis, inflammatory cell infiltrations and ballooning degeneration. Following the construction of a sing-cell resolution transcriptomic atlas of 43,480 cells in the mice's livers of the indicated groups, clear cellular heterogeneity and potential cell-to-cell cross-talk could be observed. Specifically, we observed that MPs exacerbated the pro-inflammatory response and influenced the stemness of hepatocytes during HFD feeding. Importantly, treatment with MPs significantly increase the infiltration of the infiltrating liver-protecting Vsig4+ macrophages in the liver of the NAFLD mouse model while remarkably decreasing the angiogenic S100A6+ macrophage subpopulation. Furthermore, mice treated with MPs plus HFD exhibited significantly increased recruitment of CD4+ cells and heightened exhaustion of CD8+ T cells than those from the control group, characteristics typically associated with the dysregulation of immune homeostasis and severe inflammatory damage. Overall, this study offers valuable perspectives into comprehending the potential underlying cellular mechanisms and regulatory aspects of the microenvironment regarding MPs in the development of NAFLD.

Special Issue "Molecular Immunology of the Male Reproductive System"

The immunological aspects of male infertility have gradually become the focus of both basic and clinical research [...].

Do macrophages play a role in the adverse effects of endocrine disrupting chemicals (EDCs) on testicular functions?

During the past decades, several endocrine disrupting chemicals (EDCs) have been confirmed to affect male reproductive function and fertility in animal studies. EDCs are suspected to exert similar effects in humans, based on strong associations between levels of antiandrogenic EDCs in pregnant women and adverse reproductive effects in infants. Testicular macrophages (tMΦ) play a vital role in modulating immunological privilege and maintaining normal testicular homeostasis as well as fetal development. Although tMΦ were not historically studied in the context of endocrine disruption, they have emerged as potential targets to consider due to their critical role in regulating cells such as spermatogonial stem cells (SSCs) and Leydig cells. Few studies have examined the impact of EDCs on the ability of testicular cells to communicate and regulate each other's functions. In this review, we recapitulate what is known about tMΦ functions and interactions with other cell types in the testis that support spermatogenesis and steroidogenesis. We also surveyed the literature for reports on the effects of the EDCs genistein and DEHP on tMΦ, SSCs, Sertoli and Leydig cells. Our goal is to explore the possibility that EDC disruption of tMΦ interactions with other cell types may play a role in their adverse effects on testicular developmental programming and functions. This approach will highlight gaps of knowledge, which, once resolved, should improve the risk assessment of EDC exposure and the development of safeguards to protect male reproductive functions.

Macrophages and stem/progenitor cells interplay in adipose tissue and skeletal muscle: a review

Like all immune cells, macrophages do not act autonomously but in unison with other immune cells, surrounding tissues, and the niche they occupy. Constant exchange of information between cellular and noncellular participants within a tissue allows for preserving homeostasis and defining responses in a pathologic environment. Although molecular mechanisms and pathways involved in reciprocal signaling between macrophages and other immune cells have been known for decades, much less is known about interactions between macrophages and stem/progenitor cells. Based on the time when stem cells form, there are two stem cell types: embryonic stem cells existing only in an early embryo, which are pluripotent and can differentiate into any cell type present in an adult, and somatic (adult) stem cells formed in fetus and persisting for whole adult life. Tissues and organs have their own (tissue-specific and organ-specific) adult stem cells, which serve as a reserve for tissue homeostasis and regeneration after injury. It is still uncertain whether organ- and tissue-specific stem cells are actual stem cells or just progenitor cells. The important question is how stem/progenitor cells can sculpt macrophage phenotype and functions. Even less is known if or how macrophages can shape stem/progenitor cell functions, their divisions, and fate. We describe here examples from recent studies of how stem/progenitor cells can affect macrophages and how macrophages can influence stem/progenitor cell properties, functions, and destiny.