Nonfunctional TGF-β/ALK1/ENG signaling pathway supports neutrophil proangiogenic activity in hereditary hemorrhagic telangiectasia

The transforming growth factor β (TGF-β)/ALK1/ENG signaling pathway maintains quiescent state of endothelial cells, but at the same time, it regulates neutrophil functions. Importantly, mutations of this pathway lead to a rare autosomal disorder called hereditary hemorrhagic telangiectasia (HHT), characterized with abnormal blood vessel formation (angiogenesis). As neutrophils are potent regulators of angiogenesis, we investigated how disturbed TGF-β/ALK1/ENG signaling influences angiogenic properties of these cells in HHT. We could show for the first time that not only endothelial cells, but also neutrophils isolated from such patients are ENG/ALK1 deficient. This deficiency obviously stimulates proangiogenic switch of such neutrophils. Elevated proangiogenic activity of HHT neutrophils is mediated by the increased spontaneous degranulation of gelatinase granules, resulting in high release of matrix-degrading matrix metalloproteinase 9 (MMP9). In agreement, therapeutic disturbance of this process using Src tyrosine kinase inhibitors impaired proangiogenic capacity of such neutrophils. Similarly, inhibition of MMP9 activity resulted in significant impairment of neutrophil-mediated angiogenesis. All in all, deficiency in TGF-β/ALK1/ENG signaling in HHT neutrophils results in their proangiogenic activation and disease progression. Therapeutic strategies targeting neutrophil degranulation and MMP9 release and activity may serve as a potential therapeutic option for HHT.

During early stages of cancer, neutrophils initiate anti-tumor immune responses in tumor-draining lymph nodes

Tumor-draining lymph nodes (LNs) play a crucial role during cancer spread and in initiation of anti-cancer adaptive immunity. Neutrophils form a substantial population of cells in LNs with poorly understood functions. Here, we demonstrate that, during head and neck cancer (HNC) progression, tumor-associated neutrophils transmigrate to LNs and shape anti-tumor responses in a stage-dependent manner. In metastasis-free stages (N0), neutrophils develop an antigen-presenting phenotype (HLA-DR⁺CD80⁺CD86⁺ICAM1⁺PD-L1^-) and stimulate T cells (CD27⁺Ki67^highPD-1^-). LN metastases release GM-CSF and via STAT3 trigger development of PD-L1⁺ immunosuppressive neutrophils, which repress T cell responses. The accumulation of neutrophils in T cell-rich zones of LNs in N0 constitutes a positive predictor for 5-year survival, while increased numbers of neutrophils in LNs of N1-3 stages predict poor prognosis in HNC. These results suggest a dual role of neutrophils as essential regulators of anti-cancer immunity in LNs and argue for approaches fostering immunostimulatory activity of these cells during cancer therapy.

IFNAR1 Deficiency Impairs Immunostimulatory Properties of Neutrophils in Tumor-Draining Lymph Nodes

Tumor-draining lymph nodes (TDLNs) are the first organs where the metastatic spread of different types of cancer, including head and neck cancer (HNC), occurs and have therefore high prognostic relevance. Moreover, first anti-cancer immune responses have been shown to be initiated in such LNs via tumor-educated myeloid cells. Among myeloid cells present in TDLNs, neutrophils represent a valuable population and considerably participate in the activation of effector lymphocytes there. Tumor-supportive or tumor-inhibiting activity of neutrophils strongly depends on the surrounding microenvironment. Thus, type I interferon (IFN) availability has been shown to prime anti-tumor activity of these cells. In accordance, mice deficient in type I IFNs show elevated tumor growth and metastatic spread, accompanied by the pro-tumoral neutrophil bias. To reveal the mechanism responsible for this phenomenon, we have studied here the influence of defective type I IFN signaling on the immunoregulatory activity of neutrophils in TDLNs. Live imaging of such LNs was performed using two-photon microscopy in a transplantable murine HNC model. Catchup^IVM-red and Ifnar1^-/- (type I IFN receptor- deficient) Catchup^IVM-red mice were used to visualize neutrophils and to assess their interaction with T-cells in vivo. We have evaluated spatiotemporal patterns of neutrophil/T-cell interactions in LNs in the context of type I interferon receptor (IFNAR1) availability in tumor-free and tumor-bearing animals. Moreover, phenotypic and functional analyses were performed to further characterize the mechanisms regulating neutrophil immunoregulatory capacity. We demonstrated that inactive IFNAR1 leads to elevated accumulation of neutrophils in TDLNs. However, these neutrophils show significantly impaired capacity to interact with and to stimulate T-cells. As a result, a significant reduction of contacts between neutrophils and T lymphocytes is observed, with further impairment of T-cell proliferation and activation. This possibly contributes to the enhanced tumor growth in Ifnar1^-/- mice. In agreement with this, IFNAR1-independent activation of downstream IFN signaling using IFN-λ improved the immunostimulatory capacity of neutrophils in TDLNs and contributed to the suppression of tumor growth. Our results suggest that functional type I IFN signaling is essential for neutrophil immunostimulatory capacity and that stimulation of this signaling may provide a therapeutic opportunity in head and neck cancer patients.

The Good, the Bad, and the Ugly: Neutrophils, Angiogenesis, and Cancer

Angiogenesis, the formation of new blood vessels from already existing vasculature, is tightly regulated by pro- and anti-angiogenic stimuli and occurs under both physiological and pathological conditions. Tumor angiogenesis is central for tumor development, and an “angiogenic switch” could be initiated by multiple immune cells, such as neutrophils. Tumor-associated neutrophils promote tumor angiogenesis by the release of both conventional and non-conventional pro-angiogenic factors. Therefore, neutrophil-mediated tumor angiogenesis should be taken into consideration in the design of novel anti-cancer therapy. This review recapitulates the complex role of neutrophils in tumor angiogenesis and summarizes neutrophil-derived pro-angiogenic factors and mechanisms regulating angiogenic activity of tumor-associated neutrophils. Moreover, it provides up-to-date information about neutrophil-targeting therapy, complementary to anti-angiogenic treatment.

NLRC4 Inflammasome-Mediated Regulation of Eosinophilic Functions

Eosinophils play critical roles in the maintenance of homeostasis in innate and adaptive immunity. Although primarily known for their roles in parasitic infections and the development of Th2 cell responses, eosinophils also play complex roles in other immune responses ranging from anti-inflammation to defense against viral and bacterial infections. However, the contributions of pattern recognition receptors in general, and NOD-like receptors (NLRs) in particular, to eosinophil involvement in these immune responses remain relatively underappreciated. Our in vivo studies demonstrated that NLRC4 deficient mice had a decreased number of eosinophils and impaired Th2 responses after induction of an allergic airway disease model. Our in vitro data, utilizing human eosinophilic EoL-1 cells, suggested that TLR2 induction markedly induced pro-inflammatory responses and inflammasome forming NLRC4 and NLRP3. Moreover, activation by their specific ligands resulted in caspase-1 cleavage and mature IL-1β secretion. Interestingly, Th2 responses such as secretion of IL-5 and IL-13 decreased after transfection of EoL-1 cells with short interfering RNAs targeting human NLRC4. Specific induction of NLRC4 with PAM3CSK4 and flagellin upregulated the expression of IL-5 receptor and expression of Fc epsilon receptors (FcεR1α, FcεR2). Strikingly, activation of the NLRC4 inflammasome also promoted expression of the costimulatory receptor CD80 as well as expression of immunoregulatory receptors PD-L1 and Siglec-8. Concomitant with NLRC4 upregulation, we found an increase in expression and activation of matrix metalloproteinase (MMP)-9, but not MMP-2. Collectively, our results present new potential roles of NLRC4 in mediating a variety of eosinopilic functions.

B-Helper Neutrophils in Regional Lymph Nodes Correlate with Improved Prognosis in Patients with Head and Neck Cancer

Simple Summary

Neutrophils exhibit multiple functions during cancer progression and are believed to regulate adaptive immune responses to cancer. In addition to their interactions with T cells in this context, these cells are also believed to interact with B cells. Neutrophils have been found in the marginal zone of the spleen, where they exhibit helper cell characteristics, supporting B cell proliferation and activation. Here, we investigate the effect of neutrophils on B cells in the regional lymph nodes (RLN) of head-and-neck cancer (HNC) patients. We have identified that, in RLNs, neutrophils express a helper cell phenotype that was associated with the increased activation and proliferation of B cells. Importantly, the high abundance of neutrophils in the B cell follicles of regional lymph nodes is associated with significantly improved HNC patient survival.

Abstract

The role of neutrophils during cancer formation and elimination is diverse. Here, for the first time, we investigate neutrophil helper cells (N_BH), their influence on B cell activity in the regional lymph nodes (RLN) of head-and-neck cancer patients and the effect of this neutrophil/B cell interaction on patient prognosis. Circulating and RLN neutrophils of patients with stage I–IV head-and-neck squamous cell carcinoma were investigated with flow cytometry and qPCR. In addition, neutrophil/B cell co-localization in RLNs was evaluated using immunohistochemistry. B cell proliferation was assessed and correlated with the distance to neutrophils. Patient survival was evaluated. Neutrophils with the helper cell phenotype were identified in the RLN of HNC patients. B cells in close proximity to such N_BH showed significantly higher proliferation rates, together with elevated activation-induced cytidine deaminase (AID) expression. Notably, patient survival was significantly higher in individuals with high N_BH frequencies in the B follicles of RLNs. Neutrophils in RLN can support T cell-independent activation of the adaptive immune system through B cell stimulation, capturing helper cell phenotype character. The presence of such helper neutrophils in the RLNs of HNC patients positively correlates with patient prognosis.

Quantitation of defecation function using radionuclide artificial stool in children with chronic constipation

We aimed to investigate the value of scintigraphically determined evacuation fraction (EVF) as an objective follow-up criterion in medically treated children with chronic constipation, and to evaluate the relation between patients' symptoms and rectal emptying rate. Thirty children (m: 22, f: 8, mean age: 8.9 +/- 0.9 year) suffering from chronic constipation were assessed by scintigraphic evacuation study. All patients underwent anal manometric and scintigraphic examinations before their therapy was started. During 3 months, they received conventional laxative treatment for constipation, and scintigraphic studies were repeated in 20 of 30 patients. Scintigraphic examinations consisted of instillation of artificial stool into the rectum up to the volume impending rectal evacuation, and acquisition of pre- and post-evacuation images. EVF values were then calculated from the images using a fixed region of interest. All of the patients had high resting anal canal pressure (75 +/- 12 mmHg) and had positive rectoanal inhibitory reflex. In 14/20 patients (70%) who benefited from therapy, mean EVF changed from 43.6% to 62.2% (p < 0.001), while decreasing in 6120 who did not benefit. The volume arousing rectal evacuation was significantly lower at the second scintigraphic study (261 +/- 98 ml) than the first study (354 +/- 138 ml) (p < 0.05). As a conclusion: 1) EVF was low in chronically constipated children, 2) it was improved after conventional laxative treatment and, 3) radionuclide EVF determination may be a useful method for follow-up.

Sigmoidoscopy in minor lower gastrointestinal bleeding

The role of sigmoidoscopic examination in the diagnosis, evaluation, and treatment of minor lower gastrointestinal bleeding was investigated. A hundred patients with minor rectal bleeding were examined by rigid sigmoidoscopy under general anaesthesia between January 1989 and July 1996. Patients who had bleeding secondary to infections, anal fissure, or haemorrhoids were excluded from study. Patients were reviewed retrospectively according to their diagnosis and endoscopic and histopathological findings. Twenty nine of these patients were girls and 71 boys; their ages ranged between 8 month and 14 years (mean 7.2 years). Endoscopic pathological findings were established in 60 patients; 32 had rectal polyps, 16 non-specific proctitis, four solitary rectal ulcers, three internal haemorrhoids, two ulcerative colitis, two Hirschsprung's enterocolitis, and one haemangioma. It is concluded that sigmoidoscopic examination should be performed for the diagnosis, prognosis, and choice of treatment in patients with minor rectal bleeding and the diagnosis should be confirmed histopathologically.