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Recruited neutrophils are among the first phagocytic cells to interact with the phagosomal pathogen Leishmania following inoculation into the mammalian dermis. Analysis of Leishmania-infected neutrophils has revealed alterations in neutrophil viability, suggesting that the parasite can both induce or inhibit apoptosis. In this study, we demonstrate that entry of Leishmania major into murine neutrophils is dependent on the neutrophil surface receptor CD11b (CR3/Mac-1) and is enhanced by parasite opsonization with C3. Infected neutrophils underwent robust NADPH oxidase isoform 2 (NOX2)-dependent respiratory burst based on detection of reactive oxygen species within the phagolysosome but largely failed to eliminate the metacyclic promastigote life cycle stage of the parasite. Infected neutrophils displayed an "apoptotic" phosphatidylserine (PS)-positive phenotype, which was induced by both live and fixed parasites but not latex beads, suggesting that PS expression was parasite specific but does not require active infection. In addition, neutrophils from parasite/neutrophil coculture had increased viability, decreased caspase 3, 8, and 9 gene expression, and reduced protein levels of both the pro and cleaved forms of the classical apoptosis-inducing executioner caspase, Caspase 3. Our data suggest that CD11b-mediated Leishmania internalization initiates respiratory burst and PS externalization, followed by a reduction in both the production and cleavage of caspase 3, resulting in a phenotypic state of "stalled apoptosis.", (Copyright © 2023 by The American Association of Immunologists, Inc.)

While the rapid advancement of immunotherapies has revolutionized cancer treatment, only a small fraction of patients derive clinical benefit. Eradication of large, established tumors appears to depend on engaging and activating both innate and adaptive immune system components to mount a rigorous and comprehensive immune response. Identifying such agents is a high unmet medical need, because they are sparse in the therapeutic landscape of cancer treatment. Here, we report that IL-36 cytokine can engage both innate and adaptive immunity to remodel an immune-suppressive tumor microenvironment (TME) and mediate potent antitumor immune responses via signaling in host hematopoietic cells. Mechanistically, IL-36 signaling modulates neutrophils in a cell-intrinsic manner to greatly enhance not only their ability to directly kill tumor cells but also promote T and NK cell responses. Thus, while poor prognostic outcomes are typically associated with neutrophil enrichment in the TME, our results highlight the pleiotropic effects of IL-36 and its therapeutic potential to modify tumor-infiltrating neutrophils into potent effector cells and engage both the innate and adaptive immune system to achieve durable antitumor responses in solid tumors.

Prevailing dogma holds that cell-cell communication through Notch ligands and receptors determines binary cell fate decisions during progenitor cell divisions, with differentiated lineages remaining fixed. Mucociliary clearance in mammalian respiratory airways depends on secretory cells (club and goblet) and ciliated cells to produce and transport mucus. During development or repair, the closely related Jagged ligands (JAG1 and JAG2) induce Notch signalling to determine the fate of these lineages as they descend from a common proliferating progenitor. In contrast to such situations in which cell fate decisions are made in rapidly dividing populations, cells of the homeostatic adult airway epithelium are long-lived, and little is known about the role of active Notch signalling under such conditions. To disrupt Jagged signalling acutely in adult mammals, here we generate antibody antagonists that selectively target each Jagged paralogue, and determine a crystal structure that explains selectivity. We show that acute Jagged blockade induces a rapid and near-complete loss of club cells, with a concomitant gain in ciliated cells, under homeostatic conditions without increased cell death or division. Fate analyses demonstrate a direct conversion of club cells to ciliated cells without proliferation, meeting a conservative definition of direct transdifferentiation. Jagged inhibition also reversed goblet cell metaplasia in a preclinical asthma model, providing a therapeutic foundation. Our discovery that Jagged antagonism relieves a blockade of cell-to-cell conversion unveils unexpected plasticity, and establishes a model for Notch regulation of transdifferentiation.

Cancer patients, particularly during chemotherapy, often encounter functional status limitations. This study examines fear of falling, balance, gait and lower limb strength in cancer patients during ongoing or recently completed (≤12 months) chemotherapeutic treatment in comparison to age-matched and senior controls (≥65 years). Data were obtained from 69 subjects; 21 cancer patients (51±7 years) with histological confirmed diagnosis and two control groups (2×n=24): one age-matched (53±7 years) and one senior group (70±3 years). Fear of falling (FoF) was evaluated using the Falls Efficacy Scale-International Version. Motor function measurement included postural sway (centre of pressure) in upright stance with eyes covered, gait speed (comfortable fluid walking) and maximum voluntary isometric quadriceps strength (MIVF). One-way ANOVA followed by corrected post hoc paired-sample t-test revealed inferior values in cancer patients than in age-matched healthy regarding all parameters. Gait speed and MIVF of cancer patients were higher than in the senior control group (p<.05), whereas their FoF and postural sway were comparable (p>.05). Physical performance parameters of cancer patients were found to be lower in comparison to healthy age-matched subjects. Cancer patients show physical impairments which may limit independence and may increase fall risk. The present findings call for routine screening of physical function in cancer patients, and further stress the relevance of exercise interventions during and after chemotherapy., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Objective: Etrolizumab (rhuMAb β7, anti-β7, PRO145223) is a humanised monoclonal antibody targeting the β7 subunit of the heterodimeric integrins α4β7 and αEβ7, which are implicated in leucocyte migration and retention in ulcerative colitis (UC). This randomised phase I study evaluated the safety and pharmacology of etrolizumab in patients with moderate to severe UC., Design: In the single ascending dose (SAD) stage, etrolizumab (0.3, 1.0, 3.0, 10 mg/kg intravenous, 3.0 mg/kg subcutaneous (SC) or placebo) was administered 4:1 (n=25) in each cohort. In the multiple dose (MD) stage, new patients received monthly etrolizumab (0.5 mg/kg SC (n=4), 1.5 mg/kg SC (n=5), 3.0 mg/kg SC (n=4), 4.0 mg/kg intravenous (n=5)) or placebo (n=5). The pharmacokinetics was studied and Mayo Clinic Score evaluated at baseline, day 29 (SAD), and days 43 and 71 (MD)., Results: In the SAD stage, there were no dose limiting toxicities, infusion or injection site reactions. Two impaired wound healing serious adverse events occurred in two patients receiving etrolizumab. In the MD stage, there were no dose limiting toxicities, and no infusion or injection site reactions. Headache was the most common adverse event, occurring more often in etrolizumab patients. Antietrolizumab antibodies were detected in two subjects. The duration of β7 receptor full occupancy was dose related. A clinical response was observed in 12/18 patients, and clinical remission in 3/18 patients treated with etrolizumab in the MD stage, compared with 4/5 and 1/5 placebo patients, respectively., Conclusion: Etrolizumab is well tolerated in moderate to severe UC. Further investigation is warranted.

Objective: To better define the nature of the transient neutropenia shortly following granulocyte-colony stimulating factor (G-CSF) administration., Materials and Methods: To evaluate the disappearance of neutrophils, we investigated neutrophil trafficking. Ratios of neutrophil number to background cellularity for C57BL/6 LysM-EGFP knock-in mice and rhesus macaques were determined in the lung, liver, spleen, and kidney after G-CSF administration., Results: For the C57BL/6 LysM-EGFP knock-in mice, the enhanced green fluorescent protein expression (EGFP(+)) cells increased in the lung and spleen within 15 minutes of administering 50 μg/kg G-CSF subcutaneously, and continued to increase in the lung and spleen from 15 minutes to 30 minutes. At 240 minutes, the pulmonary infiltrate declined to a level comparable to the level at 15 minutes, while in the spleen EGFP(+) cells continued to increase. For rhesus macaques, CD18(+) cells also significantly increased in the lung 30 minutes after administration of 10 μg/kg G-CSF subcutaneously compared to the control level., Conclusions: These results suggest that the transient neutropenia following G-CSF administration in the mouse and nonhuman primate is associated with an accumulation of neutrophils within pulmonary and splenic vasculature., (Published by Elsevier Inc.)

Leishmaniasis is transmitted between mammalian hosts by the bites of bloodsucking vector sand flies. The dose of parasites transmitted to the mammalian host has never been directly determined. We developed a real-time PCR-based method to determine the number of Leishmania major parasites inoculated into the ears of living mice during feeding by individual infected flies (Phlebotomus duboscqi). The number of parasites transmitted varied over a wide range in the 58 ears in which Leishmania were detected and demonstrated a clear bimodal distribution. Most of the infected mice were inoculated with a low dose of <600 parasites. One in four received a higher dose of >1,000 and up to 100,000 cells. High-dose transmission was associated with a heavy midgut infection of >30,000 parasites, incomplete blood feeding, and transmission of a high percentage of the parasite load in the fly. To test the impact of inoculum size on infection outcome, we compared representative high- (5,000) and low- (100) dose intradermal needle infections in the ears of C57BL/6 mice. To mimic natural transmission, we used sand fly-derived metacyclic forms of L. major and preexposed the injection site to the bites of uninfected flies. Large lesions developed rapidly in the ears of mice receiving the high-dose inoculum. The low dose resulted in only minor pathology but a higher parasite titer in the chronic phase, and it established the host as an efficient long-term reservoir of infection back to vector sand flies.

The T cell compartment of adaptive immunity provides vertebrates with the potential to survey for and respond specifically to an incredible diversity of antigens. The T cell repertoire must be carefully regulated to prevent unwanted responses to self. In the periphery, one important level of regulation is the action of costimulatory signals in concert with T cell antigen-receptor (TCR) signals to promote full T cell activation. The past few years have revealed that costimulation is quite complex, involving an integration of activating signals and inhibitory signals from CD28 and CTLA-4 molecules, respectively, with TCR signals to determine the outcome of a T cell's encounter with antigen. Newly emerging data suggest that inhibitory signals mediated by CTLA-4 not only can determine whether T cells become activated, but also can play a role in regulating the clonal representation in a polyclonal response. This review primarily focuses on the cellular and molecular mechanisms of regulation by CTLA-4 and its manipulation as a strategy for tumor immunotherapy.