The linkage of innate and adaptive immune response during granulomatous development

Abstract

Granulomas represent a spectrum of inflammatory sequestration responses that may be initiated by a variety of agents, including non-infectious environmental factors and infectious microbial pathogens. Although this reaction is designed to be protective, the associated tissue injury is often responsible for a profound degree of pathology. While many of the mechanisms that sustain the development of the granuloma are enigmatic, it is accepted that the maintenance of this inflammatory process is dependent upon dynamic interactions between an inciting agent, inflammatory mediators, various immune and inflammatory cells, and structural cells of the involved tissue. The best studied of the host-dependent processes during granuloma development is the innate and adaptive immune response. The innate immune response by antigen-presenting cells [APCs; dendritic cells (DCs) and macrophages] is initiated quickly to protect from overwhelming pathogens, but with time, can also activate the adaptive immune response. APCs, essential regulators of the innate immune response, can respond to microbial ligands through Toll-like receptors (TLRs), which function in the recognition of microbial components and play an important role to link the innate and adaptive immune responses. CD4+ T helper (Th) cells are essential regulators of adaptive immune responses and inflammatory diseases. Recently, the Notch system has been shown to be an important bridge between APCs and T cell communication circuits. In the present review, we discuss recent findings that explore the mechanisms in the linkage of innate and adaptive immunity, including granulomatous formation though TLRs and Notch activation.

Identifying mechanisms driving formation of granuloma-associated fibrosis during Mycobacterium tuberculosis infection

“…Granulomas are extremely heterogeneous, with variable abilities to kill Mtb, even in the same host. These structures are composed of macrophages of different types (4), T and B cells (2, 5, 6), and other immune cells. Granulomas can be categorized by size, shape, cellular organization, number of bacteria (colony forming units, CFU), or morphology (3, 4, 7–12) (Figure 1).…”

Time-dependent degenerative transformations in the lipidome of chalazia

“…the first mechanism described above. Indeed, a typical granulomatous response, such as chalazion, contains a large population of inflammatory cells, predominantly macrophages (Ito et al, 2013). We also observed a pronounced infiltration of macrophages in the chalazia.…”

Granulomatous responses in larval taeniid infections

“…Nonimmunological granulomas are mostly composed of macrophages. In contrast, immunological granulomas additionally contain lymphocytes and further cell types …”

“…Among a host of functions, TNF‐α stimulates the secretion of chemokines that attract inflammatory cells. In terms of T‐cell polarization, Th1, Th2 and Th17 cells, and combinations thereof, can participate in immunological granulomas . Prototypical Th1 granulomas are those elicited by mycobacteria, whereas the most studied Th2 granulomas are those elicited by Schistosoma eggs.…”

“…Macrophages, being highly plastic cells, tend to polarize in granulomas in parallel with T cells. In terms of granulocytes, Th1 granulomas tend to contain neutrophils, whereas Th2 granulomas tend to contain eosinophils …”