Reversal of Global CD4+ Subset Dysfunction Is Associated with Spontaneous Clinical Resolution of Pulmonary Sarcoidosis

Abstract

Sarcoidosis pathogenesis is characterized by peripheral anergy and an exaggerated, pulmonary CD4+ Th1 response. In this study, we demonstrate that CD4+ anergic responses to polyclonal TCR stimulation are present peripherally and within the lungs of sarcoid patients. Consistent with prior observations, spontaneous release of IL-2 was noted in sarcoidosis bronchoalveolar lavage CD4+ T cells. However, in contrast to spontaneous hyperactive responses reported previously, the cells displayed anergic responses to polyclonal TCR stimulation. The anergic responses correlated with diminished expression of the Src kinase Lck, PKC-θ and NF-κB, key mediators of IL-2 transcription. Although Tregs were increased in sarcoid patients, Treg depletion from the CD4+ T cell population of sarcoidosis patients did not rescue IL-2 and IFN-γ production; whereas, restoration of the IL-2 signaling cascade, via PKC-θ overexpression, did. Furthermore, sarcoidosis Tregs displayed poor suppressive capacity indicating that T cell dysfunction was a global CD4+ manifestation. Analyses of patients with spontaneous clinical resolution revealed that restoration of CD4+ Th1 and Treg cell function was associated with resolution. Conversely, disease progression exhibited decreased Th1 cytokine secretion and proliferative capacity, and reduced Lck expression. These findings implicate normalized CD4+ T cell function as a potential therapeutic target for sarcoidosis resolution.

Longitudinal analysis of sarcoidosis blood transcriptomic signatures and disease outcomes

“…Our analyses were adjusted for lymphocyte counts, as lymphopenia may be seen in sarcoidosis [2]. In future studies, we propose to perform cell sorting analyses of T-cell subsets to ascertain whether these findings stemmed from peripheral changes in differential subsets of lymphocytes in sarcoidosis; however, a recent study by OSWALD-RICHTER et al [35] showed that sarcoidosis peripheral and BAL sorted CD4 + T-cells exhibited decreases in the TCR-responsive genes LCK and PKCQ, both of which were also shown to be downregulated in our Ingenuity TCR signalling pathway analyses. Our results add to their study by demonstrating that the degree of TCR downregulation has important clinical correlations longitudinally.…”

Programmed Death-1 Inhibition of Phosphatidylinositol 3-Kinase/AKT/Mechanistic Target of Rapamycin Signaling Impairs Sarcoidosis CD4+ T Cell Proliferation

“…1 T cells exhibit reduced proliferative capacity upon TCR stimulation, compared with healthy controls (1,2). It was also noted that blockade of the PD-1 pathway restored proliferative capacity in sarcoidosis CD4 1 T cells (1).…”

“…This cut off was based upon prior publications demonstrating proliferative capacities of less than 50% with sarcoidosis disease severity (1,2). Participant demographics are outlined in Table 1.…”

“…Total cellular RNA was extracted from purified, resting CD4 1 T cells or after 5-day TCR stimulation, then cDNA was generated as previously described (2). Quantitative RT-PCR amplification was performed in triplicate using 23 TaqMan Universal PCR Mastermix (Applied Biosystems/Life Technologies, Foster City, Lysates, SDS-PAGE, and Western Blotting CD4 1 T cells were TCR stimulated and lysed as described previously (9).…”

“…Sarcoidosis is a granulomatous disease characterized by spontaneous secretion of Th1 cytokines, but reduced cytokine expression and proliferative capacity after T cell receptor (TCR) stimulation among subjects experiencing disease progression (1,2).…”