Macrophage‐fibroblast circuits in the spleen

Abstract

Located in the abdominal cavity between the diaphragm and the fundus of the stomach, the spleen is the largest secondary lymphoid organ in the body. It acts mainly as a blood filter that selectively removes immune complexes, circulating pathogens and senescent, dysfunctional, or infected red blood cells. 1 As a result, splenectomy is associated with an increased susceptibility to severe bacterial infections (Streptococcus pneumoniae, Haemophilus influenzae, and Neisseria meningitidis…) and a major risk of overwhelming sepsis. 2,3 Besides its immune function, the spleen is involved in other important physiological processes such as iron homeostasis. Senescent or ruptured red blood cells are trapped in the spleen and their hemoglobin content is metabolized into free iron, which supplies most of the iron needed for erythropoiesis. 4,5 The adult spleen is also a prominent site for extramedullary hematopoiesis. In conditions of infection, anemia and genetic blood disorders or during pregnancy, hematopoietic stem cells (HSC) mobilized from the bone marrow

Toxic Effects of Metallic Nanoparticles on Rat’s Spleen; a Review

“…Additionally, the spleen is the biggest secondary lymphoid organ in the body [16,17] comprising approximately one-fourth of all the lymphocytes in the body and being responsible for the initiation of immunological responses to blood-borne antigens. The white pulp that surrounds the central arterioles is responsible for performing this job.…”

“…[18,19]. Extra medullary hematopoiesis occurs extensively in the adult spleen as well [17]. When the bone marrow needs to produce more blood cells due to an infection, anaemia, or a hereditary blood problem, or because of pregnancy, hematopoietic stem cells (HSC) move into splenic niches and begin differentiating into blood cells [20].…”

Regulated contribution of local and systemic immunity to new bone regeneration by modulating B/Sr concentration of bioactive borosilicate glass

“…It's generally believed that macrophages originate from monocytes, which is produced in bone marrow, and circulate in blood, bone marrow and spleen [ 9 ]. Spleen, a large secondary lymphoid organ with high metabolic activity, serves as a critical reservoir of monocytes and myeloid progenitors to filter the blood and regulate immunity [ [10] , [11] , [12] ]. As reported, when heart gets inflammation, the monocytes cycled to the injured part is more than in the blood, indicating that the monocytes move from the storages to the part.…”

Plasmodium vivax Protein PvTRAg23 Triggers Spleen Fibroblasts for Inflammatory Profile and Reduces Type I Collagen Secretion via NF-κBp65 Pathway

“…The spleen serves several important roles during Plasmodium infection, ranging from induction of adaptive immune responses, production of erythrocytes, and selective filtration of aging and infected red blood cells (iRBCs) ( 6 ). Of note, splenic fibroblasts (SFs) are one of the main components supporting the structure and function of the spleen ( 7 ); which are widely distributed in connective tissues and help to deposit structural proteins such as collagen and elastin fibers into the extracellular matrix (ECM) ( 8 , 9 ). Type I collagen (collagen I) is the major component of ECM secreted by fibroblasts and is crucial to create a microenvironment conducive to the development of immune responses in lymphoid organs ( 10 ).…”