Table 1.
Impact of monocytic myeloid-derived suppressor cells (M-MDSC) on infectious disease outcome and their immunosuppressive effects.
| Microbial organism | Context of M-MDSC investigation | Major outcome; immunosuppressive effect | Reference |
|---|---|---|---|
| Viruses | |||
| Immunodeficiency virus [human immunodeficiency viruse (HIV), simian immunodeficiency virus, LP-BM5] | M-MDSC and total MDSC | Host detrimental; suppress T-cell and B-cell responses, express inducible nitric oxide synthase (iNOS), and produce reactive oxygen species (ROS), ARG-1, IL-10, induce Treg | Gama et al. (26); Vollbrecht et al. (49); Qin et al. (24); Green et al. (93); Garg and Spector (23); Sui et al. (94); Wang et al. (54); O’Connor et al. (95); du Plessis et al. (28); Sui et al. (25); Garg et al. (96); Dross et al. (97) |
| Cytomegalovirus (CMV) | M-MDSC-like | Host detrimental; impair T-cell expansion, slowing viral clearance | Daley-Bauer et al. (70) |
| Hepatitis C virus (HCV) | M-MDSC and total MDSC | Host detrimental; suppress CD4 T-cell and NK cell function, increase Treg | Tacke et al. (21); Salem et al. (98); Zeng et al. (99); Nonnenman et al. (100); Ning et al. (101); Goh et al. (102); Ren et al. (22); Lei et al. (103); Pang et al. (19); Ren et al. (104) |
| Hepatitis B virus (HBV) | M-MDSC and total MDSC | Host detrimental; express IL-10, suppress T-cell function, promote disease chronicity | Chen et al. (45); Huang et al. (105); Kondo et al. (106) |
| Viral coinfection (HIV/CMV, HCV/HIV) | Host detrimental; impair T-cell function, accelerate disease progression | Lei et al. (103); Garg et al. (96); Tumino et al. (107) | |
| Bacteria | |||
| Staphylococcus aureus | M-MDSC and PMN-MDSC | Host detrimental; suppress T-cell function, express ARG-1, iNOS, IL-10, exacerbate disease, promote disease chronicity | Skabytska et al. (32); Heim et al. (108); Heim et al. (47, 48); Tebartz et al. (33); Peng et al. (31) |
| Francisella tularensis | Total MDSC | Host detrimental; reduced phagocytosis, reduced survival | Periasamy et al. (42) |
| Mycobacteria spp. | M-MDSC and total MDSC | Host beneficial/detrimental; suppress T-cell function; express ARG-1 and iNOS, impaired pathogen killing; TNF-dependent suppression of CD4 T cells | Dietlin et al. (109); Martino et al. (65); Obregón-Henao et al. (41); Knaul et al. (30); Tsiganov et al. (50); Yang et al. (110); du Plessis et al. (28); Chavez-Galan et al. (80) |
| Klebsiella pneumoniae | M-MDSC and PMN-MDSC | Host beneficial/detrimental; pro-resolving, express ARG-1, IL-10/impair phagocytosis/killing | Poe et al. (35); Ahn et al. (3); Chakraborty et al. (4) |
| Helicobacter pylori | M-MDSC | Host detrimental; suppress protective TH1 development. | Zhuang et al. (111) |
| Polymicrobial sepsis | M-MDSC and total MDSC | Host beneficial/detrimental; suppress T-cell function, express nitric oxide and pro-inflammatory cytokines (early) and ARG-1, IL-10, and TGF-β (late) | Delano et al. (55); Sander et al. (112); Brudecki et al. (75); McPeak et al. (76, 77) |
| Escherichia coli | M-MDSC | Host detrimental; suppress T-cell activation, innate immunity, impair bacterial uptake and increase disease severity, infection susceptibility | Bernsmeier et al. (52) |
| Protozoa | |||
| Leishmania spp. | M-MDSC and total MDSC | Host beneficial/detrimental; species-specificity, suppress CD4 T-cell proliferation, improved killing of parasites | Pereira et al. (73); Schmid et al. (74); Ribeiro-Gomes et al. (113); Bandyopadhyay et al. (114); Hammami et al. (115) |
| Trypanosoma cruzi | M-MDSC and PMN-MDSC | Host beneficial/detrimental; dependent on MDSC subset, express ROS, NO, suppress CD8 T-cell proliferation | Goni et al. (116); Cuervo et al. (117); Arocena et al. (118) |
| Toxoplasma gondii | Total MDSC | Host protective; express NO, control parasite replication | Voisin et al. (119); Dunay et al. (120) |
| Helminths | |||
| Schistosoma spp. | Total MDSC | Not evaluated; express ROS, suppress T-cell responses | Yang et al. (121) |
| Echinnococcus granulosus | Total MDSC | Not evaluated; association with increased Treg and impaired T-cell L-selectin | Pan et al. (122) |
| Nippostrongylus brasiliensis | M-MDSC and PMN-MDSC | Host beneficial/detrimental; dependent on MDSC subset, express TH2 cytokines, reduce parasite burden (PMN-MDSC) | Saleem et al. (123) |
| Heligmosomoides polygyrus bakeri | Total MDSC | Host detrimental; suppress CD4 T-cell proliferation, increase parasite burden, and promote chronic infection | Valanparambil et al. (124, 125) |
M-MDSC are studied as a purified cell population or as part of the total MDSC population to measure their impact on the host control of infectious pathogens.