Systemic inflammatory and immune pathways – indirect paracrine modulation, no direct molecular target

This entry describes a broad physiological mechanism rather than a specific molecular target. It refers to the systemic modulation of inflammatory and immune pathways through indirect paracrine signaling, a process where therapeutic agents—most notably mesenchymal stem cells (MSCs)—exert their effects by secreting a complex 'secretome' of bioactive molecules (Caplan & Correa, 2011). These factors interact with multiple signaling networks in the host to resolve inflammation and promote tissue homeostasis without relying on a single, direct drug-receptor interaction (Galipeau & Sensébé, 2018). This approach is particularly relevant for treating multi-factorial conditions such as sepsis, graft-versus-host disease (GvHD), and acute respiratory distress syndrome (ARDS), where the immune response is dysregulated across several pathways (Levy et al., 2020). Because there is no discrete molecular target, this mechanism represents a holistic therapeutic strategy that adapts to the patient's specific inflammatory milieu. However, the lack of a single target presents significant challenges for traditional pharmacological characterization and regulatory standardization (Bernardo & Fibbe, 2013).

Other names

Indirect paracrine modulationSystemic immune modulationParacrine signaling pathwaysCell-mediated immunomodulationSecretome-mediated signaling

The mechanism involves the indirect modulation of systemic immune and inflammatory responses through the secretion of a broad spectrum of paracrine factors, including cytokines, chemokines, growth factors, and extracellular vesicles (Galipeau & Sensébé, 2018). Rather than binding to a single primary molecular target, the therapeutic agent (often a cell therapy) responds to the local inflammatory environment by releasing bioactive molecules that shift the phenotype of surrounding immune cells, such as macrophages and T-cells, from pro-inflammatory to anti-inflammatory states (Bernardo & Fibbe, 2013; Caplan & Correa, 2011).