A role for TNF-α in alveolar macrophage damage-associated molecular pattern release
Morgan K. Collins, Abigail M. Shotland, Morgan F. Wade, Shaikh M. Atif, Denay K. Richards, Manolo Torres-Llompart, Douglas G. Mack, Allison K. Martin, Andrew P. Fontenot, Amy S. McKee
Morgan K. Collins, Abigail M. Shotland, Morgan F. Wade, Shaikh M. Atif, Denay K. Richards, Manolo Torres-Llompart, Douglas G. Mack, Allison K. Martin, Andrew P. Fontenot, Amy S. McKee
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Research Article Immunology

A role for TNF-α in alveolar macrophage damage-associated molecular pattern release

Abstract

Chronic beryllium disease (CBD) is a metal hypersensitivity/autoimmune disease in which damage-associated molecular patterns (DAMPs) promote a break in T cell tolerance and expansion of Be2+/self-peptide–reactive CD4+ T cells. In this study, we investigated the mechanism of cell death induced by beryllium particles in alveolar macrophages (AMs) and its impact on DAMP release. We found that phagocytosis of Be led to AM cell death independent of caspase, receptor-interacting protein kinases 1 and 3, or ROS activity. Before cell death, Be-exposed AMs secreted TNF-α that boosted intracellular stores of IL-1α followed by caspase-8–dependent fragmentation of DNA. IL-1α and nucleosomal DNA were subsequently released from AMs upon loss of plasma membrane integrity. In contrast, necrotic AMs released only unfragmented DNA and necroptotic AMs released only IL-1α. In mice exposed to Be, TNF-α promoted release of DAMPs and was required for the mobilization of immunogenic DCs, the expansion of Be-reactive CD4+ T cells, and pulmonary inflammation in a mouse model of CBD. Thus, early autocrine effects of particle-induced TNF-α on AMs led to a break in peripheral tolerance. This potentially novel mechanism may underlie the known relationship between fine particle inhalation, TNF-α, and loss of peripheral tolerance in T cell–mediated autoimmune disease and hypersensitivities.

Authors

Morgan K. Collins, Abigail M. Shotland, Morgan F. Wade, Shaikh M. Atif, Denay K. Richards, Manolo Torres-Llompart, Douglas G. Mack, Allison K. Martin, Andrew P. Fontenot, Amy S. McKee

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Figure 8

cDCs and MyD88-dependent signaling are required for expansion of Be2+/self-peptide–specific CD4+ T cell responses in a mouse model of CBD.

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cDCs and MyD88-dependent signaling are required for expansion of Be2+/se...
(A and B) cDCs in zDC-DTR DP2 bone marrow chimeras were depleted in some mice by i.p. injection of diphtheria toxin (DT) every 3 days. Control and cDC-depleted mice were exposed i.t. to PBS or 50 μg Be and LDLNs were analyzed 12 days later. (A) Total cDCs/LDLN and (B) IL-2 spot-forming units (SFU) per 5 × 105 LDLN cells are shown. (C) Lethally irradiated B6 (WT or MyD88-KO) mice were reconstituted with B6 (WT or MyD88-KO) bone marrow. Chimeric mice were exposed i.t. to PBS or 50 μg Be and accumulation of cDCs in the LDLNs determined 48 hours later as described in Figure 6. Chimeras with indicated WT or MyD88-KO hematopoietic cells (HCs) and stromal cell (SCs) are indicated. (D and E) FVB/N (WT) DP2 recipients were lethally irradiated and reconstituted with bone marrow from FVB/N DP2 Myd88+/+ (WT DP2) or Myd88–/– (MyD88-KO DP2) littermates. Chimeric mice were exposed i.t. to PBS or 50 μg Be on day 0, challenged on day 14 with BeO, and sacrificed on day 21. (D) Total numbers of Be2+/self-peptide–specific IFN-γ+ CD4+ cells detected by ELISPOT in the LDLNs and lungs are shown. (E) H&E-stained lung sections (original magnification, ×4, top) and indicated areas of lymphocyte infiltration (original magnification, ×40, bottom) are shown. (F) The percentage of bronchioles in each lung with 1 or more peribronchovascular infiltrates is shown. (G) The diameter/infiltrate calculated as described in Supplemental Methods is shown. Data in A–D are combined from 2 independent experiments (n = 12 mice per group), symbols on graphs are values from individual mice, and bars indicate means ± SEM (cDC graphs) or medians (ELISPOT data). Data in E and G are representative data of 2 independent experiments. Data in F are combined from 2 independent experiments (n = 3 mice/group); bars indicate mean ± SEM. One-way ANOVA or Kruskal-Wallis tests were used to test for differences between multiple groups of data with a normal (DC data) or skewed (ELISPOT data) distribution, respectively. An unpaired 2-tailed t test was used in F and G. Statistical P values for selected comparisons are indicated as *P < 0.05; **P < 0.01; ***P < 0.001.