Bacterial Lymphatic Metastasis in Infection and Immunity

Abstract

Lymphatic vessels permeate tissues around the body, returning fluid from interstitial spaces back to the blood after passage through the lymph nodes, which are important sites for adaptive responses to all types of pathogens. Involvement of the lymphatics in the pathogenesis of bacterial infections is not well studied. Despite offering an obvious conduit for pathogen spread, the lymphatic system has long been regarded to bar the onward progression of most bacteria. There is little direct data on live virulent bacteria, instead understanding is largely inferred from studies investigating immune responses to viruses or antigens in lymph nodes. Recently, we have demonstrated that extracellular bacterial lymphatic metastasis of virulent strains of Streptococcus pyogenes drives systemic infection. Accordingly, it is timely to reconsider the role of lymph nodes as absolute barriers to bacterial dissemination in the lymphatics. Here, we summarise the routes and mechanisms by which an increasing variety of bacteria are acknowledged to transit through the lymphatic system, including those that do not necessarily require internalisation by host cells. We discuss the anatomy of the lymphatics and other factors that influence bacterial dissemination, as well as the consequences of underappreciated bacterial lymphatic metastasis on disease and immunity.

Colic due to dorsally located perirectal abscesses: A retrospective case series of six horses

“…In five young horses, the perirectal abscesses were suspected to be due to anorectal lymphadenopathy, as mainly lymphocytes were found in the fine‐needle aspirate of three of these horses (Magee et al, 1997). Following haematogenous or lymphatic spread of pyogenic bacteria into a lymph node, a suppurative lymphadenitis can result in lymph node abscess formation (Fraser, 2009; Siggins & Sriskandan, 2022). Whether the young horses presented here also suffered from an abscessed lymph node remains unclear, as neither fine‐needle aspirates nor biopsies of the altered tissue were taken.…”

C-Reactive Protein: Pathophysiology, Diagnosis, False Test Results and a Novel Diagnostic Algorithm for Clinicians

“…It is already known that a high percentage of the immune system is located in the gut, thus there are higher possibilities for such colonies to be transformed. Importantly, it has been demonstrated that the extracellular bacterial lymphatic metastasis of the virulent strains of certain streptococci drives systemic infection, and there have also been illustrated multifarious routes and mechanisms by which an increasing variety of bacteria are acknowledged to transit through the lymphatic system, including those that do not necessarily require internalization by host cells [ 1224 ]. Therefore, one can already have organ inflammation and possible subsequent other system inflammation (i.e., nervous system inflammation) due to systemic inflammation, and realize it after being symptomatic for any system (i.e., muscle symptoms and underlying systemic acidosis) by random or due to genetic factors.…”

Immunomodulatory properties of the lymphatic endothelium in the tumor microenvironment

“…In the context of inflammatory processes, the lymphatic vascular network appears to be expanded due to lymphatic hyperplasia and abnormal lymphangiogenesis ( 6 ), as shown in both mouse models and patient samples of inflammatory diseases, such as arthritis ( 7 ), atopic dermatitis ( 8 ), psoriasis ( 9 ), and inflammatory bowel disease ( 10 ). Distorted function of LVs has been also associated with cardiometabolic diseases ( 11 ), infection diseases ( 12 ), and more recently, neurodegenerative pathologies ( 13 ).…”