In this issue, Mehrpouya-Bahrami et al. uncover a key role for STAT4 in multiple neutrophil functions and innate immune responses. The cover art depicts the production of neutrophiI extracellular traps. Image credit: Cristina Risi.
The NR4A family of orphan nuclear receptors (Nr4a1-3) plays redundant roles to establish and maintain Treg identity; deletion of multiple family members in the thymus results in Treg deficiency and a severe inflammatory disease. Consequently, it has been challenging to unmask redundant functions of the NR4A family in other immune cells. Here we use a competitive bone marrow chimera strategy, coupled with conditional genetic tools, to rescue Treg homeostasis and unmask such functions. Unexpectedly, chimeras harboring Nr4a1–/– Nr4a3–/– (DKO) bone marrow develop autoantibodies and a systemic inflammatory disease despite a replete Treg compartment of largely wild-type origin. This disease differs qualitatively from that seen with Treg-deficiency and is B cell-extrinsic. Negative selection of DKO thymocytes is profoundly impaired in a cell-intrinsic manner. Consistent with escape of self-reactive T cells into the periphery, DKO T cells with functional, phenotypic, and transcriptional features of anergy accumulate in chimeric mice. Nevertheless, we observe upregulation of genes encoding inflammatory mediators in anergic DKO T cells, and DKO T cells exhibit enhanced capacity for IL-2 production. These studies reveal cell-intrinsic roles for the NR4A family in both central and peripheral T cell tolerance, and demonstrate that each is essential to preserve immune homeostasis.
Ryosuke Hiwa, Hailyn V. Nielsen, James L. Mueller, Ravi Mandla, Julie Zikherman
G protein-coupled receptors (GPCRs) are highly desirable drug targets for human disease. Although GPCR dysfunction drives development and progression of many tumors, including breast cancer (BC), targeting individual GPCRs has limited efficacy as a cancer therapy because numerous GPCRs are activated. Here, we sought a new way of blocking GPCR activation in HER2+-BC by targeting a subgroup of GPCRs that couple to Gi/o proteins (Gi/o-GPCRs). In mammary epithelial cells of transgenic mouse models, and BC cell lines, HER2 hyperactivation altered GPCR expression, particularly, Gi/o-GPCRs. Gi/o-GPCR stimulation transactivated EGFR and HER2 and activated the PI3K/AKT and Src pathways. If we uncoupled Gi/o-GPCRs from their cognate Gi/o proteins by pertussis toxin (PTx), then BC cell proliferation and migration was inhibited in vitro and HER2-driven tumor formation and metastasis suppressed in vivo. Moreover, targeting Gi/o-GPCR signaling via PTx, PI3K, or Src inhibitors enhanced HER2-targeted therapy. These results indicate that, in BC cells, HER2 hyperactivation drives aberrant Gi/o-GPCR signaling, and Gi/o-GPCR signals converge on PI3K/AKT and Src signaling pathways to promote cancer progression and resistance to HER2-targeted therapy. Our findings point to a new way to pharmacologically deactivate GPCR signaling to block tumor growth and enhance therapeutic efficacy.
Cancan Lyu, Yuanchao Ye, Maddison M. Lensing, Kay-Uwe Wagner, Ronald J. Weigel, Songhai Chen
BACKGROUND. A previous Phase I study showed that the infusion of autologous Treg cells expanded ex-vivo into recent onset Type 1 Diabetes (T1D) patients had an excellent safety profile, however, the majority of the infused Tregs could no longer be detected in the peripheral blood three months post-infusion (NCT01210664-Treg-T1D Trial). Interleukin-2 (IL-2) has been shown to enhance human Treg cell survival and expansion at low doses in vivo. Therefore, we conducted a Phase 1 study (NCT02772679-TILT trial) combining polyclonal Treg and low-dose IL-2 and assessed the impact over time on Tregs populations and other immune cells. METHODS. T1D Patients were treated with a single infusion of autologous polyclonal Tregs, expanded ex vivo, followed by one or two 5-day courses of recombinant human low dose IL-2 (ld-IL-2) at 0.3 x 106 to 1 x 106 units/dose. Fluorescence-based flow cytometry, Cytometry by Time Of Flight (CyTOF) and 10X Genomics single cell RNAseq were used to follow the distinct immune cell populations phenotypes over time following immunotherapy. RESULTS. Multiparametric analysis revealed that the combination therapy led to an increase in the number of infused and endogenous Tregs but also resulted in a significant increase from baseline in a subset of activated NK, Mucosal-Associated Invariant T (MAIT) cells and clonal CD8+ T populations. CONCLUSIONS. These data support the hypothesis that Id-IL-2 expands exogenously administered Tregs but also can expand cytotoxic cells. These results have important implications for the use of a combination of ld-IL-2 and Tregs for the treatment of autoimmune diseases with pre-existing active immunity. TRIAL REGISTRATION. ClinicalTrials.gov NCT01210664 (Treg-T1D Trial), NCT02772679 (TILTtrial). FUNDING. Sean N. Parker Autoimmunity Research Laboratory Fund, National Center for Research Resources.
Shen Dong, Kamir J. Hiam-Galvez, Cody T. Mowery, Kevan C. Herold, Stephen E. Gitelman, Jonathan H. Esensten, Weihong Liu, Angela P. Lares, Ashley S. Leinbach, Michael Lee, Vinh Nguyen, Stanley J. Tamaki, Whitney Tamaki, Courtney M. Tamaki, Morvarid Mehdizadeh, Amy L. Putnam, Matthew H. Spitzer, C. Jimmie Ye, Qizhi Tang, Jeffrey A. Bluestone
cGMP-dependent protein kinase 1α (PKG1α) promotes left ventricle (LV) compensation to pressure overload. PKG1-activating drugs improve heart failure (HF) outcomes but are limited by vasodilation-induced hypotension. Signaling molecules which mediate PKG1α cardiac therapeutic effects but do not promote PKG1α-induced hypotension could therefore represent improved therapeutic targets. We investigated roles of mixed lineage kinase 3 (MLK3) in mediating PKG1α effects on LV function after pressure overload, and in regulating blood pressure (BP). In a transaortic constriction HF model PKG activation with sildenafil preserved LV function in MLK3+/+, but not MLK3-/- littermates. MLK3 co-immunoprecipitated with PKG1α. MLK3-PKG1α co-interaction decreased in failing LVs. PKG1a phosphorylated MLK3 on Thr-277/Ser-281 sites required for kinase activation. MLK3-/- mice displayed hypertension and increased arterial stiffness, though PKG stimulation with sildenafil or the sGC stimulator BAY41-2272 still reduced BP in MLK3-/- mice. MLK3 kinase inhibition with URMC-099 did not affect BP, but induced LV dysfunction in mice. These data reveal MLK3 as a PKG1α substrate mediating PKG1α preservation of LV function but not acute PKG1α BP effects. Mechanistically, MLK3 kinase-dependent effects preserve LV function, while MLK3 kinase-independent signaling regulates BP. These findings suggest augmenting MLK3 kinase activity could preserve LV function in HF but avoid hypotension from PKG1α activation.
Timothy D. Calamaras, Suchita Pande, Robert A.U. Baumgartner, Seung Kyum Kim, Joseph C. McCarthy, Gregory L. Martin, Kelly Tam, Angela L. McLaughlin, Guang-rong Wang, Mark J. Aronovitz, Weiyu Lin, Jonathan I. Aguirre, Paulina Baca, Peiwen Liu, Daniel A. Richards, Roger J. Davis, Richard H. Karas, Iris Z. Jaffe, Robert M. Blanton
Cardiac inflammation and fibrosis contribute significantly to hypertension-related adverse cardiac remodeling. IκB kinase β (IKKβ), a central coordinator of inﬂammation through activation of NF-κB, has been demonstrated as a key molecular link between inflammation and cardiovascular disease. However, the cell-specific contribution of IKKβ signaling towards adverse cardiac remodeling remains elusive. Cardiac fibroblasts are one of the most populous non-myocyte cell types in the heart that play a key role in mediating cardiac fibrosis and remodeling. To investigate the function of fibroblast IKKβ, we generated inducible fibroblast-specific IKKβ-deficient mice. Here we report an important role of IKKβ in the regulation of fibroblast functions and cardiac remodeling. Fibroblast-specific IKKβ deficient male mice were protected from angiotensin II (Ang II)-induced cardiac hypertrophy, fibrosis, and macrophage infiltration. Ablation of fibroblast IKKβ inhibited Ang II-stimulated fibroblast proinflammatory and profibrogenic responses, leading to ameliorated cardiac remodeling and improved cardiac function in IKKβ-deficient mice. Findings from this study establish fibroblast IKKβ as a key factor regulating cardiac fibrosis and function in hypertension-related cardiac remodeling.
Weiwei Lu, Zhaojie Meng, Rebecca Hernandez, Changcheng Zhou
JCI This Month is a digest of the research, reviews, and other features published each month.