Group 2 innate lymphocytes at the interface between innate and adaptive immunity.

Group 2 innate lymphoid cells (ILC2) are innate immune cells that respond rapidly to their environment through soluble inflammatory mediators and cell-to-cell interactions. As tissue-resident sentinels, ILC2 help orchestrate localized type 2 immune responses. These ILC2-driven type 2 responses are now recognized in diverse immune processes, different anatomical locations, and homeostatic or pathological settings. ILC2-derived cytokines and cell surface signaling molecules function as key regulators of innate and adaptive immunity. Conversely, ILC2 are governed by their environment. As such, ILC2 form an important nexus of the immune system and may present an attractive target for immune modulation in disease

Cross-talk between ILC2 and Gata3^high T_regs locally constrains adaptive type 2 immunity

Regulatory T cells (Tregs) control adaptive immunity and restrain type 2 inflammation in allergic disease. Interleukin-33 promotes the expansion of tissue-resident Tregs and group 2 innate lymphoid cells (ILC2s); however, how Tregs locally coordinate their function within the inflammatory niche is not understood. Here, we show that ILC2s are critical orchestrators of Treg function. Using spatial, cellular, and molecular profiling of the type 2 inflamed niche, we found that ILC2s and Tregs engage in a direct (OX40L-OX40) and chemotaxis-dependent (CCL1-CCR8) cellular dialogue that enforces the local accumulation of Gata3high Tregs, which are transcriptionally and functionally adapted to the type 2 environment. Genetic interruption of ILC2-Treg communication resulted in uncontrolled type 2 lung inflammation after allergen exposure. Mechanistically, we found that Gata3high Tregs can modulate the local bioavailability of the costimulatory molecule OX40L, which subsequently controlled effector memory T helper 2 cell numbers. Hence, ILC2-Treg interactions represent a critical feedback mechanism to control adaptive type 2 immunity

Early Neutrophilia Marked by Aerobic Glycolysis Sustains Host Metabolism and Delays Cancer Cachexia.

An elevated neutrophil-lymphocyte ratio negatively predicts the outcome of patients with cancer and is associated with cachexia, the terminal wasting syndrome. Here, using murine model systems of colorectal and pancreatic cancer we show that neutrophilia in the circulation and multiple organs, accompanied by extramedullary hematopoiesis, is an early event during cancer progression. Transcriptomic and metabolic assessment reveals that neutrophils in tumor-bearing animals utilize aerobic glycolysis, similar to cancer cells. Although pharmacological inhibition of aerobic glycolysis slows down tumor growth in C26 tumor-bearing mice, it precipitates cachexia, thereby shortening the overall survival. This negative effect may be explained by our observation that acute depletion of neutrophils in pre-cachectic mice impairs systemic glucose homeostasis secondary to altered hepatic lipid processing. Thus, changes in neutrophil number, distribution, and metabolism play an adaptive role in host metabolic homeostasis during cancer progression. Our findings provide insight into early events during cancer progression to cachexia, with implications for therapy

AvCystatin treatment in primary RSV infection.

<p>A) Schematic of the primary RSV model with AvCystatin treatment regimen: i.p. intraperitoneal; i.n. intranasal application. Neutrophil influx in the BAL was shown (B). RSV L gene copy numbers in the lungs (C) and viral load (D) measured 4 days post RSV/mock challenge. RSV-specific IgG2a detected in serum 8 days post infection (E). IFN-γ, TNFα, IL-6, CCL3, and CCL5 cytokine and chemokine production (F). Naïve (dark grey bars): mock infected and mock treated with PBS, RSV challenged day 0 (black bars); AvCystatin/RSV; AvCystatin treatment i.n. or i.p. on day -1 (white bars or light grey bars, respectively). Representative data of at least 2 independent experiments, 5 mice per group. Error bars indicate SEM. <i>P</i> values reflect Mann-Whitney t-test: * p<0.05, **p<0.01.</p

IL-10⁺ CD4⁺ T cell induction by AvCystatin conditioned macrophages.

<p>Lung and BAL CD4⁺ T cells detected by flow cytometry (A and D). Total number of IL-10 producing T cells determined by intracellular staining for IL-10 after restimulation with PMA/ionomycin for 3h in Lung and BAL (B and E). Number of CD4⁺ T cells positive for FoxP3 in lung (C) and BAL (F). Percentage of F4/80⁺CD11b⁺ cells infiltrating the lungs 24h post RSV challenge (G) and total cell number (H). Total cell number of CD4⁺ IL-10⁺ T cells infiltrating the BAL, 8 days post PEC transfer (I). Naïve (dark grey bars): mock infected and mock treated with PBS, RSV challenged day 0 (black bars); AvCystatin/RSV; AvCystatin treatment i.n. or i.p. on day -1 (white bars or light grey bars, respectively). Representative data of 2 experiments, 5 mice per group. Error bars indicate SEM. <i>P</i> values reflect Mann-Whitney t-test: * p<0.05, **p<0.01.</p

AvCystatin treatment reduced RSV-induced immunopathology in Th2-based models of viral lung eosinophilia.

<p>A) Schematic of the vvG RSV model: e.d. epidermabrasive; i.p. intraperitoneal; i.n. intranasal application. B) Weight loss in vvG RSV over an eight day period C) Eosinophil, neutrophil, and macrophage influx into BAL: total numbers in vvG RSV. D) RSV-specific serum immunoglobulin levels. E) L gene copy numbers in lungs, d4 after RSV/mock challenge. Naïve (light grey bars): mock infected and mock treated with PBS; vvG/RSV (black bars): scarified with vvG and challenged with RSV; vvG/AvCystatin/RSV (white bars): vvG/RSV plus intraperitoneal (d -14 and -7) and intranasal (d -2 and -1) injection of AvCystatin. Representative data from 2 independent experiments, 5 mice per group. Error bars indicate SEM. <i>P</i> values reflect Mann-Whitney t-test: * p<0.05, **p<0.01.</p

AvCystatin induced IL-10 production by CD4⁺ T cells in airways and lungs.

<p>Total CD4⁺ T cell counts in lungs (A) and BAL (B). CD4⁺ T cells were stimulated with PMA/ionomycin for 3h, IL-10⁺ and IFN-γ⁺ cells were gated in lung (B+C) and BAL (E+F). Ratios of IL-10⁺ versus IFN-γ⁺ CD4⁺ T cells in lung and BAL (G). Naïve (light grey): mock infected and mock treated with PBS; vvG/RSV (black bars): scarified with vvG (d-14) and challenged with RSV (d0); vvG/Av17/RSV (white bars): model plus injection of AvCystatin (d-14 and -7 i.p., d-2 and -1 i.n.). (A) Combined data from 2 independent experiments, (B-G) Representative data from 2 independent experiments, 5 mice per group. Error bars indicate SEM. <i>P</i> values reflect Mann-Whitney t-test: * p<0.05, **p<0.01.</p

AvCystatin reduced chemokine and cytokine release in the airways.

<p>A) IL-4, B) IL-13, C) CCL11/Eotaxin, D) CCL5 / RANTES, E) TNF- α, F) IFN-γ, G) CCL3 / MIP-1α, Detection limit: 0.3pg/ml; 7.8pg/ml; 2.2pg/ml; 5.2pg/ml; 3.4pg/ml; 1.8pg/ml; 12.5pg/ml, respectively). Day 4 post RSV/mock challenge. Naïve (light grey bars): mock infected and mock treated with PBS; vvG/RSV (black bars): scarified with vvG and challenged with RSV; FI-RSV/AvCystatin/RSV (white bars). Representative data from 2 experiments, 5 mice per group. Error bars indicate SEM. <i>P</i> values reflect Mann-Whitney t-test: * p<0.05, **p<0.01, ***p<0.001.</p

Blocking IL-10R signalling increases cellular influx into the lungs and delays recovery during RSV infection.

<p>BALB/c mice were infected with 10⁶ PFU RSV i.n. (day 0). Where indicated, mice were injected with anti-IL-10R antibody on day -1 (i.p.), 3 (i.p. and i.n) and 6 (i.p.) post RSV infection. Control groups were injected with rat IgG. (A) Illness was monitored daily by changes in weight for 8 days after RSV infection; the percentage of original weight is shown. (B) Viral titer was measured in the lung on day 4 post infection by quantifying RSV L gene copies by qPCR. (C) Total numbers of cells in the lung and BAL were enumerated on day 4 and 8 from naïve or RSV infected mice. (D) Total numbers of neutrophils in the BAL were quantified using differential cell counting of H&E stained cytospins slides on day 4 and 8 post infection. (E) Total numbers of NK cells (CD3⁻ NKp46⁺) and CD3-gated, CD4⁺Foxp3⁻ and CD8⁺ T cells in the lung were quantified using flow cytometry on day 4 and 8 post RSV infection. Error bars indicate the SEM. The data are representative of two independent experiments with n = 4–5 mice per group.</p