Cytokine/Chemokine Release Patterns and Transcriptomic Profiles of LPS/IFNγ-Activated Human Macrophages Differentiated with Heat-Killed Mycobacterium obuense, M-CSF, or GM-CSF

Abstract

Macrophages (Mφs) are instrumental regulators of the immune response whereby they acquire diverse functional phenotypes following their exposure to microenvironmental cues that govern their differentiation from monocytes and their activation. The complexity and diversity of the mycobacterial cell wall have empowered mycobacteria with potent immunomodulatory capacities. A heat-killed (HK) whole-cell preparation of Mycobacterium obuense (M. obuense) has shown promise as an adjunctive immunotherapeutic agent for the treatment of cancer. Moreover, HK M. obuense has been shown to trigger the differentiation of human monocytes into a monocyte-derived macrophage (MDM) type named Mob-MDM. However, the transcriptomic profile and functional properties of Mob-MDMs remain undefined during an activation state. Here, we characterized cytokine/chemokine release patterns and transcriptomic profiles of lipopolysaccharide (LPS)/interferon γ (IFNγ)-activated human MDMs that were differentiated with HK M. obuense (Mob-MDM(LPS/IFNγ)), macrophage colony-stimulating factor M-MDM(LPS/IFNγ)), or granulocyte/macrophage colony-stimulating factor (GM-MDM(LPS/IFNγ)). Mob-MDM(LPS/IFNγ) demonstrated a unique cytokine/chemokine release pattern (interleukin (IL)-10low, IL-12/23p40low, IL-23p19/p40low, chemokine (C-x-C) motif ligand (CXCL)9low) that was distinct from those of M-MDM(LPS/IFNγ) and GM-MDM(LPS/IFNγ). Furthermore, M-MDM(LPS/IFNγ) maintained IL-10 production at significantly higher levels compared to GM-MDM(LPS/IFNγ) and Mob-MDM(LPS/IFNγ) despite being activated with M1-Mφ-activating stimuli. Comparative RNA sequencing analysis pointed to a distinct transcriptome profile for Mob-MDM(LPS/IFNγ) relative to both M-MDM(LPS/IFNγ) and GM-MDM(LPS/IFNγ) that comprised 417 transcripts. Functional gene-set enrichment analysis revealed significant overrepresentation of signaling pathways and biological processes that were uniquely related to Mob-MDM(LPS/IFNγ). Our findings lay a foundation for the potential integration of HK M. obuense in specific cell-based immunotherapeutic modalities such as adoptive transfer of Mφs (Mob-MDM(LPS/IFNγ)) for cancer treatment.

Macrophage Polarization: Learning to Manage It

“…Indeed, activated Mφs (M1-subtype) can defend against tumors by directing tumor cytotoxicity and by secreting cytokines, whereas an increased number of M2-phenotype is associated with poor prognosis as, for example, in primary breast cancer. One interesting paper in the Special Issue focused on the use of heat-killing preparation of Mycobacterium obuense (M. obuense) as an adjunctive immunotherapeutic agent for the treatment of cancer, since it may trigger the differentiation of human monocytes into a monocyte-derived macrophage (MDM) with the potential to induce the antitumor activity of macrophages [8] (Figure 2D). Another paper of the Special Issue investigated the ameliorative effects of protease inhibitors (PI) extracted from Avena sativa (A. sativa) on dampening chronic inflammation contributing to the development of a tolerogenic phenotype of macrophages [9] (Figure 2E).…”

“…(C) ERAP2 short form caused an inhibition of anti-inflammatory ativity of Renin Angiotensin System[7]. (D)Anti-tumor ativity is increased with the addition of adjuvant M. obuense[8]. (E) A. sativa induced a tolerogenic Mφ phenotype[9].…”