Full-length IL-33 augments pulmonary fibrosis in an ST2- and Th2-independent, non-transcriptomic fashion

Mature IL-33 (MIL33) acting through its receptor, ST2, is known to regulate fibrosis. The precursor, full-length IL-33 (FLIL33), may function differently from MIL33 and independently of ST2. Here we report that genetic deletion of either IL-33 or ST2 attenuates pulmonary fibrosis in the bleomycin model, as does Cre-induced IL-33 deficiency in response to either acute or chronic bleomycin challenge. However, adenovirus-mediated gene delivery of FLIL33, but not MIL33, to the lungs of either wild-type or ST2-deficient mice potentiates the profibrotic effect of bleomycin without inducing a Th2 phenotype. In cultured mouse lung cells, FLIL33 overexpression induces moderate and distinct transcriptomic changes compared with a robust response induced by MIL33, whereas ST2 deletion abrogates the effects of both IL-33 forms. Thus, FLIL33 may contribute to fibrosis in an ST2-independent, Th2-independent, non-transcriptomic fashion, suggesting that pharmacological targeting of both FLIL33 and MIL33 may prove efficacious in patients with pulmonary fibrosis.

Aberrant integrin αv and α5 expression in prostate adenocarcinomas and bone-metastases is consistent with a bone-colonizing phenotype

Background

Collaborative signaling between fibronectin-binding αv and α5 integrins has been implicated in the lethal dissemination of prostate cancer in the bone-metastatic niche, the major source of morbidity and mortality in the disease.

Methods

We assessed the frequency and pattern of expression of these integrins in primary high-grade adenocarcinomas and bone metastases compared to the physiological gland. Formalin-fixed paraffin-embedded (FFPE) radical prostatectomy (RP) samples (n=25) containing ≥ Gleason grade 4 cancer and decalcified surgical or diagnostic bone metastatic samples from 10 patients were stained for integrin αv (ITGAV) and integrin α5 (ITGA5) expression. Antibody optimization and antigen-retrieval was performed beforehand.

Results

ITGAV was exclusively expressed in the basal layer of physiological prostate glands whereas αv expression was invariably recapitulated in the malignant gland and bone metastases (100%) in multiple distinct patterns: epithelial membranous, basilar/luminal membranous, punctate cytoplasmic, intense foci as single cells or clusters, and rim stromal layers. The luminal/basilar layer of ITGAV expression was striking in cribriform carcinomas, suggestive of a role in molecular pathogenesis. ITGA5 infrequently highlighted the basal layer of the physiological gland, was absent in primary adenocarcinoma, but was expressed with ITGAV exclusively in bone metastases (71%).

Conclusions

We conclude that ITGAV expression is aberrantly expressed in high frequency in high-grade prostatic adenocarcinomas in patterns suggestive of recapitulated basal cell functions, consistent with a stem-regulatory role that has been proposed. Co-expression and enrichment of αv and α5 in osseous metastases supports their proposed collaborative role in colonization of the bone microenvironment and as candidate targets for therapy.

Abstract 114: Aberrant integrin alpha v and alpha 5 expression patterns in prostate adenocarcinomas and bone-metastases from prostate cancer are consistent with a bone-colonizing phenotype

Background: Fibronectin-binding αv and α5 integrins mediate homing, adhesive and survival interactions of prostate cancer cells with bone-marrow mesenchymal stromal cells. Monospecific αv integrin antibody therapy slowed progression of bone metastases but failed to impact overall mortality in prostate cancer. Cross-regulation between αv and α5 integrin is a potential source of adaptive resistance to monospecific blockade of either integrin. We assessed the patterns of expression of these partner integrins in bone metastases and the transition from the physiological gland to the malignant phenotype.

Methods Formalin-fixed paraffin-embedded (FFPE) radical prostatectomy samples (n=25) from patients with a ≥ Gleason grade 4 component and decalcified FFPE samples of prostate cancer bone metastases (n=10) were obtained from institutional tissue biorepository. Optimized immunohistochemistry methods developed in prostate cancer cell suspensions were applied to assess expression patterns of αv and α5 integrins in benign and malignant glandular elements in primary tumors and bone specimens.

Results Integrin αv was universally expressed in the physiological basal layer of benign prostate glands (n=25;100%) but not in the luminal epithelium. With loss of the basal layer in malignant transition, αv expression was recapitulated in 100% of malignant glandular epithelium in distinct patterns including epithelial membranous (24/25;96%), luminal membranous (6/25; 24%), punctate cytoplasmic (14/25;56%), intense foci of membranous staining (single cells or clusters surrounded by αv-negative tumor) (10/25;40%), and rim stromal patterns (14/25;56%). Luminal membranous and rim stromal αv expression patterns were striking in tumors with cribriform morphology. Furthermore, integrin αv was identified in all evaluable bone metastatic samples (7/7:100%). By contrast, integrin α5 was identified infrequently in the physiological basal layer (1/10;10%), was not expressed in malignant glandular epithelium of primary tumors but was paradoxically expressed in malignant epithelium in bone metastases (5/7:71%).

Conclusion Integrin αv expression is universally and exclusively found in the physiological basal layer of the normal gland that harbors stem-functions and is recapitulated in high frequency in prostatic adenocarcinomas in diverse patterns suggestive of distinct biological functions that may contribute to disease progression. Co-expression and enrichment of integrins αv and α5 in osseous metastases is supportive of a proposed cooperative role of these fibronectin-binding integrins toward bone colonization. Given the adaptive cross-regulation we have observed with targeting of either integrin, combined αv and α5 integrin targeting in prostate cancer bone metastases may be required for effective therapy.

Citation Format: Brendan Connell, Pavel Kopach, Wenying Ren, Raghav Joshi, Steven Naber, Paul Mathew. Aberrant integrin alpha v and alpha 5 expression patterns in prostate adenocarcinomas and bone-metastases from prostate cancer are consistent with a bone-colonizing phenotype [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 114.

The significance of histologic examination of gastrectomy specimens: a clinicopathologic study of 511 cases

BACKGROUND

Sleeve gastrectomy (SG) is quickly becoming the preferred procedure for bariatric surgery. According to the American Society for Metabolic and Bariatric Surgery guidelines, routine preoperative upper gastrointestinal endoscopies are not recommended universally for bariatric surgery. Some studies have shown that the histologic examination of SG specimens is insignificant and not a cost-effective practice. However, some speculate SG examination may unveil pertinent findings and prevent further progression of precursor lesions.

OBJECTIVES

This study aims to explore the clinically significant or actionable lesions that can be revealed with SG examination.

SETTING

Tufts Medical Center, Boston, USA.

RESULTS

We analyzed 511 SG specimens obtained during bariatric surgery. Incidental findings were grouped in 2 categories: clinically significant/actionable and minor lesions. The clinically significant lesions accounted for 5.8%. This category included 5 cases of gastrointestinal stromal tumor; one case of MALT lymphoma; 4 cases of autoimmune gastritis with concomitant pancreatic metaplasia or neuroendocrine dysplasia. Intestinal metaplasia without dysplasia was identified in 3 cases; 14 cases of Helicobacter pylori associated active gastritis; 1 case of iron pill induced gastritis and 1 case of gastric glandular siderosis. The minor lesions accounted for 6.3%, showing findings other than chronic gastritis. This category included 19 cases of fundic polyps and 1 case of hyperplastic polyp; one case of leiomyoma; 11 cases of H pylori negative active gastritis.

CONCLUSIONS

The majority of histopathology results after SG showed no significant changes. However, a few cases had clinically significant lesions in seemingly healthy patients, altering patient's postoperative management.

Elevated expression of NEU1 sialidase in idiopathic pulmonary fibrosis provokes pulmonary collagen deposition, lymphocytosis, and fibrosis

Idiopathic pulmonary fibrosis (IPF) poses challenges to understanding its underlying cellular and molecular mechanisms and the development of better therapies. Previous studies suggest a pathophysiological role for neuraminidase 1 (NEU1), an enzyme that removes terminal sialic acid from glycoproteins. We observed increased NEU1 expression in epithelial and endothelial cells, as well as fibroblasts, in the lungs of patients with IPF compared with healthy control lungs. Recombinant adenovirus-mediated gene delivery of NEU1 to cultured primary human cells elicited profound changes in cellular phenotypes. Small airway epithelial cell migration was impaired in wounding assays, whereas, in pulmonary microvascular endothelial cells, NEU1 overexpression strongly impacted global gene expression, increased T cell adhesion to endothelial monolayers, and disrupted endothelial capillary-like tube formation. NEU1 overexpression in fibroblasts provoked increased levels of collagen types I and III, substantial changes in global gene expression, and accelerated degradation of matrix metalloproteinase-14. Intratracheal instillation of NEU1 encoding, but not control adenovirus, induced lymphocyte accumulation in bronchoalveolar lavage samples and lung tissues and elevations of pulmonary transforming growth factor-β and collagen. The lymphocytes were predominantly T cells, with CD8(+) cells exceeding CD4(+) cells by nearly twofold. These combined data indicate that elevated NEU1 expression alters functional activities of distinct lung cell types in vitro and recapitulates lymphocytic infiltration and collagen accumulation in vivo, consistent with mechanisms implicated in lung fibrosis.

Pharmacological In Vivo Inhibition of S-Nitrosoglutathione Reductase Attenuates Bleomycin-Induced Inflammation and Fibrosis

Interstitial lung disease (ILD) characterized by pulmonary fibrosis and inflammation poses a substantial biomedical challenge due to often negative disease outcomes combined with the need to develop better, more effective therapies. We assessed the in vivo effect of administration of a pharmacological inhibitor of S-nitrosoglutathione reductase, SPL-334 (4-{[2-[(2-cyanobenzyl)thio]-4-oxothieno[3,2-d]pyrimidin-3(4H)-yl]methyl}benzoic acid), in a mouse model of ILD induced by intratracheal instillation of bleomycin (BLM). Daily i.p. administration of SPL-334 alone at 0.3, 1.0, or 3.0 mg/kg had no effect on animal body weight, appearance, behavior, total and differential bronchoalveolar lavage (BAL) cell counts, or collagen accumulation in the lungs, showing no toxicity of our investigational compound. Similar administration of SPL-334 for 7 days before and for an additional 14 days after BLM instillation resulted in a preventive protective effect on the BLM challenge-induced decline in total body weight and changes in total and differential BAL cellularity. In the therapeutic treatment regimen, SPL-334 was administered at days 7-21 after BLM challenge. Such treatment attenuated the BLM challenge-induced decline in total body weight, changes in total and differential BAL cellularity, and magnitudes of histologic changes and collagen accumulation in the lungs. These changes were accompanied by an attenuation of BLM-induced elevations in pulmonary levels of profibrotic cytokines interleukin-6, monocyte chemoattractant protein-1, and transforming growth factor-β (TGF-β). Experiments in cell cultures of primary normal human lung fibroblast have demonstrated attenuation of TGF-β-induced upregulation in collagen by SPL-334. It was concluded that SPL-334 is a potential therapeutic agent for ILD.

IFN-γ controls IL-33 protein level through a STAT1- and LMP2-dependent mechanism (CCR5P.268)

IL-33 levels and activity are differentially associated with Th1 and Th2 phenotypes. IL-33 mRNA is rapidly regulated but the fate of synthesized IL-33 protein is unknown. To assess the interplay between IL-33, IFN-γ, and IL-4 proteins, replication-deficient adenoviruses (AdV) were constructed for dual expression of IL-33 & IFN-γ or of IL-33 & IL-4. Combined IL-33 & IFN-γ or IL-33 & IL-4 effects were compared with similar AdV expression of each of these cytokines alone. Co-delivery of IL-33 & IFN-γ led to mutual suppression, and co-delivery of IL-33 & IL-4 led to mutual elevation of these proteins in cell culture and in vivo. Purified IFN-γ also attenuated IL-33 protein but not mRNA driven by the recombinant CMV promoter in AdV-IL-33-infected cells, suggesting that IFN-γ controls IL-33 protein degradation. Pharmacological inhibition, siRNA-mediated silencing, or gene deficiency of STAT1 potently upregulated IL-33 protein expression levels and attenuated the downregulating effect of IFN-γ on IL-33. Inhibition of caspase-1, -3, or -8 had minimal effect on IFN-γ-driven IL-33 protein downregulation. siRNA-mediated silencing of LMP2 proteasome subunit, which is known to be essential for IFN-γ-regulated antigen processing, also abrogated the effect of IFN-γ on IL-33. Thus, IL-33, IFN-γ, and IL-4 are engaged in a complex interplay, part of which involves IFN-γ-activated, caspase-independent, STAT1-mediated degradation of IL-33 protein through non-canonical use of LMP2 proteasome.

IFN-γ directly controls IL-33 protein level through a STAT1- and LMP2-dependent mechanism

IL-33 contributes to disease processes in association with Th1 and Th2 phenotypes. IL-33 mRNA is rapidly regulated, but the fate of synthesized IL-33 protein is unknown. To understand the interplay among IL-33, IFN-γ, and IL-4 proteins, recombinant replication-deficient adenoviruses were produced and used for dual expression of IL-33 and IFN-γ or IL-33 and IL-4. The effects of such dual gene delivery were compared with the effects of similar expression of each of these cytokines alone. In lung fibroblast culture, co-expression of IL-33 and IFN-γ resulted in suppression of the levels of both proteins, whereas co-expression of IL-33 and IL-4 led to mutual elevation. In vivo, co-expression of IL-33 and IFN-γ in the lungs led to attenuation of IL-33 protein levels. Purified IFN-γ also attenuated IL-33 protein in fibroblast culture, suggesting that IFN-γ controls IL-33 protein degradation. Specific inhibition of caspase-1, -3, and -8 had minimal effect on IFN-γ-driven IL-33 protein down-regulation. Pharmacological inhibition, siRNA-mediated silencing, or gene deficiency of STAT1 potently up-regulated IL-33 protein expression levels and attenuated the down-regulating effect of IFN-γ on IL-33. Stimulation with IFN-γ strongly elevated the levels of the LMP2 proteasome subunit, known for its role in IFN-γ-regulated antigen processing. siRNA-mediated silencing of LMP2 expression abrogated the effect of IFN-γ on IL-33. Thus, IFN-γ, IL-4, and IL-33 are engaged in a complex interplay. The down-regulation of IL-33 protein levels by IFN-γ in pulmonary fibroblasts and in the lungs in vivo occurs through STAT1 and non-canonical use of the LMP2 proteasome subunit in a caspase-independent fashion.

Interleukin-33 potentiates bleomycin-induced lung injury

The mechanisms of interstitial lung disease (ILD) remain incompletely understood, although recent observations have suggested an important contribution by IL-33. Substantial elevations in IL-33 expression were found in the lungs of patients with idiopathic pulmonary fibrosis and scleroderma lung disease, as well as in the bleomycin injury mouse model. Most of the observed IL-33 expression was intracellular and intranuclear, suggesting involvement of the full-length (fl) protein, but not of the proteolytically processed mature IL-33 cytokine. The effects of flIL-33 on mouse lungs were assessed independently and in combination with bleomycin injury, using recombinant adenovirus-mediated gene delivery. Bleomycin-induced changes were not affected by gene deficiency of the IL-33 receptor T1/ST2. Combined flIL-33 expression and bleomycin injury exerted a synergistic effect on pulmonary lymphocyte and collagen accumulation, which could be explained by synergistic regulation of the cytokines transforming growth factor-β, IL-6, monocyte chemotactic protein-1, macrophage inflammatory protein\x{2013}1α, and tumor necrosis factor-α. By contrast, no increase in the levels of the Th2 cytokines IL-4, IL-5, or IL-13 was evident. Moreover, flIL-33 was found to increase the expression of several heat shock proteins (HSPs) significantly, and in particular HSP70, which is known to be associated with ILD. Thus, flIL-33 is a synergistic proinflammatory and profibrotic regulator that acts by stimulating the expression of several non-Th2 cytokines, and activates the expression of HSP70.

IL-33 precursor regulates inflammation in vivo in a T1/ST2-independent, Th2-independent fashion (P6270)

IL-33 precursor (IL33PR) released from damaged cells is known to bind to the receptor T1/ST2 and activate cells in culture. However, we found that in patients with interstitial lung diseases (ILD) and in the bleomycin mouse model of lung injury, pulmonary expression of IL33PR is elevated intracellularly and intranuclearly. Recombinant adenoviral gene delivery of IL33PR to mouse lungs in vivo did not lead to IL-33 maturation and produced a phenotype that was strikingly different from that induced by mature IL33 (MIL33). IL33PR induced pulmonary lymphocytosis and neutrophilia, whereas MIL33 induced eosinophilia, goblet cell hyperplasia, and increases in Th2 cytokines. The effects of MIL33 were, but the effects of IL33PR were not, abrogated by gene deficiency of T1/ST2. When combined with bleomycin injury, IL33PR potentiated lymphocytosis, collagen accumulation, and the expression of proinflammatory and profibrotic cytokines TGF-β, IL-6, MCP-1, and MIP-1α in the lungs. Gene expression profiling in cultured fibroblasts and epithelial cells overexpressing IL33PR revealed 10 - 100 fold increases in HSP70 mRNA, further confirmed by RT-Q-PCR. Previous reports have associated HSP70 with ILD. Immunohistochemical analyses showed strong HSP70 protein increases in mice challenged with bleomycin, IL33PR gene delivery, and particularly in mice challenged with these factors combined. Thus, IL33PR promotes ILD by inducing proinflammatory and profibrotic cytokines and HSP70.

Full-length IL-33 promotes inflammation but not Th2 response in vivo in an ST2-independent fashion

Expression of IL-33 is elevated in patients with pulmonary diseases, and full-length (not proteolytically processed) IL-33 is the predominant form in the lungs in health and disease. To determine whether activation of IL-33 is needed for functional effects, activities of full-length mouse and mature mouse (mm) forms of IL-33 were compared in vivo. Replication-deficient adenoviral constructs were used for gene delivery. Both isoforms caused pulmonary infiltration of lymphocytes and neutrophils, whereas mm IL-33 also caused pulmonary eosinophilia and goblet cell hyperplasia and increased expression of IL-4, IL-5, IL-13, IL-17, MCP-1, and KC. The different effects were not associated with differential release from IL-33-producing cells or by differences in subcellular distributions of IL-33 isoforms. Germline deficiency of the cell surface receptor chain ST2 abrogated the mm IL-33-induced Th2-associated effects (pulmonary eosinophilia, goblet cell hyperplasia, and increased IL-4 and IL-5), yet the lymphocytic infiltration induced by full-length mouse IL-33 or mm IL-33 was not fully abrogated by the absence of ST2. The similar effects of IL-33 isoforms were associated with comparable regulation of gene expression, notably matrix metalloproteinases 3, 10, and 13. Thus, full-length IL-33 is functionally active in vivo in an ST2-independent fashion, and its effects are partially different from those of mature IL-33. The different effects of these isoforms, particularly the pro-Th2 effects of mature IL-33, are due to differential utilization of the IL-33R chain ST2, whereas their similar effects result from regulation of gene expression.

Full-length Interleukin-33 modulates the effects of Interleukin-4 in the lungs in vivo (120.8)

Previous reports have been inconsistent on whether Interleukin (IL)-33 necessarily promotes Th2 effects in vivo. This diversity of findings may be due to post-synthetic processing of IL-33. We compared the in vivo effects of full-length mouse (flm) and mature mouse (mm) IL-33 utilizing replication-deficient adenovirus (AdV)-mediated gene delivery. mmIL-33 promoted pulmonary eosinophilia, neutrophilia, and significant elevations in IL-4, IL-5, and IL-13 compared to AdV-NULL-infected controls (p < 0.05 in all cases), whereas flmIL-33 had no such effects. A possibility was considered that flmIL-33 may modulate the effects of a prototypic Th2 cytokine, IL-4. The effects of AdV-mediated gene delivery of IL-4 were compared with the effects of combined flmIL-33 and mIL-4. In the latter case, a bicistronic AdV construct encoding flmIL-33 and mIL-4 was used to ensure co-localization of expression of both cytokines. On day 7 after instillation of the viral particles, IL-4-expressing mice had elevated eosinophils and neutrophils in their BAL, and animals expressing both flmIL-33 and IL-4 had yet significantly more BAL eosinophils and neutrophils compared with IL-4-expressing mice (p < 0.05). Similar potentiating effects of flmIL-33 were observed on IL-4-driven increases in pulmonary cytokines TNF-α, IL-5, IL-13, MCP-1, and in goblet cell hyperplasia. These results suggest that although full-length IL-33 has no independent pro-Th2 effect on the lung, it potentiates such effects of IL-4.

Full-length IL-33 acts differently from mature IL-33 in vivo partially in an ST2-independent fashion (120.30)

IL-33 is a key regulator of inflammation and immunity. It remains controversial whether protease-mediated activation of IL-33 is needed for functional effects. We constructed and validated recombinant adenoviruses for gene delivery of full-length mouse (flm) and mature mouse (mm) (aa 109-266) IL-33 to mouse lungs in vivo. Gene expression was confirmed by RT-Q-PCR and ELISA. Analyses of BAL samples and lung tissues revealed substantial differences between flmIL-33 and mmIL-33. Both isoforms caused pulmonary infiltration and BAL influx of T and B lymphocytes and neutrophils, whereas mmIL-33 also caused significant pulmonary eosinophilia (~47-55% of BAL cell count) and hyperplasia of mucus-producing goblet cells. Multiplex analyses showed that mmIL-33 caused significant increases in IL-4, IL-5, IL-13, IL-17, and KC; flmIL-33 tended to stimulate IFN-γ; and both isoforms induced MCP-1 with a greater increase induced by mmIL-33. Subsequent analyses were performed in mice deficient of ST2 (IL-33 receptor). ST2 deficiency completely abrogated mmIL-33-induced pulmonary eosinophilia, goblet cell hyperplasia, and elevations in IL-4 and IL-5. However, lymphocytic infiltration induced by flmIL-33 or mmIL-33 was attenuated but persistent in the absence of ST2. These data suggest that full-length IL-33 is independently functionally active in vivo, in part in an ST2-independent fashion, and that Th2 effects but not lymphocytosis induced by mature IL-33 are ST2-dependent.