Bleier Lab group photo

Bleier Lab

In the Bleier Lab, we are focused on developing a wide array of novel sinonasal related diagnostic and therapeutic modalities. In addition to our work at Mass. Eye and Ear, the Bleier Lab maintains several active collaborations with Harvard Medical School, MIT, Boston University, Northeastern University, and Mass General. If you wish to contribute to Dr. Benjamin Bleier’s research, please contact Irene Hammer-Mclaughlin.

Our Current Projects 

Nasal Polyps
Chronic Sinusitis
Orbital Surgery
Trans-nasal Drug Delivery

Nasal Polyps


A significant component of our lab is devoted towards understanding the causes and developing new treatments for chronic rhinosinusitis with nasal polyps (CRSwNP). We have multiple ongoing projects in each of the areas listed below, where we have made several key advances:

What causes chronic rhinosinusitis with nasal polyps: The Role of P-glycoprotein

Permeability glycoprotein (P-gp) is an active efflux membrane transporter that has been researched extensively due to its ability to confer multidrug resistance in a wide range of cancers. The gene for P-gp, often referred to as ABCB1 or MDR1, is located on chromosome 7q21.12. P-gp has an impressively broad substrate specificity and is thought to be responsible for extruding xenobiotics and cellular metabolites, as well as maintaining tissue barriers at the blood-brain interface and gastrointestinal epithelium. P-gp is also thought be involved in regulating immune responses and is able to influence the secretion of cytokines and chemokines. 

In our lab, we first discovered the presence of localized P-gp overexpression within nasal polyps in 2012. Since then, we've shown that this overexpression leads directly to the hypersecretion of type 2 helper T-cell pro-inflammatory cytokines which, in turn, perpetuate the inflammatory cascade. Additionally, this overexpression leads to resistance to corticosteroid treatment in these patients. 

More recently, we have demonstrated that epithelial derived exosomes are capable of shuttling functional P-gp between cells, which may contribute to the field inflammatory effect characteristic of the disease.

Fluorescent immunohistochemical images of mucosaVertical columns depict findings from two distinct patients derived from the low (A, C, E) and high (B, D, F) P-gp expression groups. (A,B) Fluorescent immunohistochemical images of mucosa depicting representative low (A) and high (B) expression of epithelial P-gp (bar = 50 μM, lower right inset represents negative control in which the primary antibody was omit- ted). (C,D) Matched high-powered (400×) H&E stromal images depicting the absence (C) and presence (D) of mucosal eosinophilia (black arrows denote individual eosinophils). Note the thickened basement membrane in (C) consistent with CRSsNP. (E,F) Coronal CT scans demonstrating increased radiographic inflammation in the patient with high P-gp expression (F) relative to the patient with low P-gp expression (E). CRSsNP = chronic rhinosinusitis without nasal polyps; CT = computed tomography; H&E = hematoxylin and eosin; P-gp = P-glycoprotein.

Feldman RE, Lam AC, Sadow PM, Bleier BS. P-glycoprotein is a marker of tissue eosinophilia and radiographic inflammation in chronic rhinosinusitis without nasal polyps. Int Forum Allergy Rhinol. 2013 Aug;3(8):684–7.

How can we develop better therapies for nasal polyps: Therapeutic P-gp Inhibition

P-gp participates in the non-canonical regulation of cytokine secretion within nasal polyps and may represent a druggable target. Verapamil is a calcium channel blocker, which binds to the alpha subunit of L-type voltage dependent calcium (Cav1) channels and blocks the influx of calcium ions into the host cell. In addition to this function, Verapamil was also one of the first inhibitors of P-gp to be identified. Several studies, including studies by our group, have reported that Verapamil is capable of modulating inflammatory responses in human T cells, animal models of asthma, and nasal polyps. Using an organotypic explant model, we have shown that Verapamil has similar effects to dexamethasone in its ability abrogate both IL-5 and IL-6 secretion. While Verapamil is a cardioactive drug, it is considered the first-line prophylactic drug for cluster headache and is usually well tolerated by otherwise healthy patients.

Our lab recently completed a randomized, double-blind, placebo-controlled pilot study of Verapamil (80mg TID) in patients with CRSwNP (n=10 per group) following a four week washout of local and systemic corticosteroids. The primary endpoint was SNOT-22 confirmed with 10cm Visual Analog Score(VAS) score reduction at eight weeks. Secondary endpoints included difference in Lund-Mackay computed tomography and change in Lund-Kennedy endoscopy scores (LMS and LKS). This was the first study to explore P-gp modulation as a treatment for CRSwNP. The effect size of Verapamil with respect to improvement in SNOT-22 was comparable to previously reported values using both biologic agents and corticosteroids. While the small population size was not adequately powered to confirm efficacy, the significant improvement evident across multiple outcome measures opens the door to further exploration of the P-gp inhibitory strategy. Our data also demonstrated that low dose Verapamil monotherapy is well tolerated by patients with less side effects and lower costs than those reported in previous studies using biologic agents.

SNOT-22 scores

Primary and Secondary end points for all patients. SNOT-22 (Sinonasal Outcome Test-22), MCID (Minimal Clinically Important Difference), LKS(Lund-Kennedy Score); Error Bars indicate Standard Error of the Mean (SEM). LMS(Lund-Mackay Score), Boxes are mean and 95% Confidence Interval, bars are maximum and minimum.

Miyake MM, Nocera A, Levesque P, Guo R, Finn CA, Goldfarb J, Gray S, Holbrook E, Busaba N, Dolci JE, Bleier BS.

Double-blind placebo-controlled randomized clinical trial of verapamil for chronic rhinosinusitis with nasal polyps. J Allergy Clin Immunol. 2017 Jan 11.



Chronic Sinusitis


How can we more accurately diagnose chronic sinusitis: The Exosomal Proteomic Biosignature

Our work has shown that mucus derived exosomes contain an array of proteins, in addition to P-gp, which reflect the inflammatory and metabolic state of their parent cell. The development of a reproducible, non-invasive, serial, and quantitative test for chronic sinusitis, which can predict endotype, prognosis, and therapeutic response, represents a holy grail in rhinology. A major project currently underway is to identify the exosomal proteomic biosignature in a variety of sinonasal disease states to determine how this signature can be used to provide a point-of-care diagnostic test.

Proteomic analysis in human plasma and nasal mucus

Proteomic analysis in human plasma and nasal mucus derived exosomes. A. Transmission electron microscopy images demonstrating. a. Whole mounted exosomes purified from nasal mucus (bar 500nm). b. Negative control (bar 100nm for b-d) confirming the typical exosome size and morphology. c-d. Immunogold labeling of exosome marker CD63 and the transmembrane protein P-gp localizing to the exosome membrane. B. SOMAscan analysis of 16 signature proteins associated with the presence of exosomes in two independent human nasal mucus exosome samples. While both samples demonstrate significant protein detection above background buffer controls (p<0.001), there is no difference between patient samples demonstrating the excellent reproducibility of both exosome recovery and analysis using our proposed methods.



Orbital Surgery


Endoscopic orbital surgery is one of the most rapidly advancing areas in modern day rhinology and ophthalmic plastic surgery. While endoscopic techniques have been adapted for lacrimal and orbital decompression surgery for more than two decades, advanced endoscopic endonasal and periocular approaches to the orbital apex and skull base have only recently been developed. Dr. Bleier and his collaborators at the Center for Thyroid Eye Disease and Orbital Surgery are global leaders in pioneering multiple new minimally invasive approaches to remove orbital tumors entirely through the nose as well as novel techniques in orbital decompression and dacryocystorhinostomy.

3-dimensionally rendered orbital tumors3-dimensionally rendered orbital tumors of two different patients (a-c and d-f). Line 1 represents the long axis of the Optic Nerve (N) while Line 2 represents the plane of resectability which dictates which tumors are amenable to endoscopic resection. Note how these lines divide the tumor into 3 zones (T1) easily resectable, (T2) resectable, and (T3) unresectable.




Illustration of bimanual technique Illustration of bimanual technique, which allows multiple instruments to be introduced into both nostrils. For a tumor of the left orbital apex (white arrow), the endoscope (1) and retractor (2) are placed in the right nostril and access the lesion through a posterior septectomy. The assistant controls the endoscope and may introduce a fourth instrument if necessary. The primary dissecting instrument (3) is introduced through the left nostril and controlled with the primary surgeon’s dominant hand.
Healy DY, Jr, Lee NG, Freitag SK, Bleier BS. Endoscopic bimanual approach to an intraconal cavernous hemangioma of the orbital apex with vascularized flap reconstruction. Ophthal Plast Reconstr Surg. 2014 Jul–Aug;30(4):e104–6. PMID: 2483343.





ndoscopic view of the left medial intraconal space in the cadaveric dissectionA. Endoscopic view of the left medial intraconal space in the cadaveric dissection. The medial rectus muscle (MRM) is retracted medially to reveal the oculomotor nerve trunk (black arrow) emanating from the orbital apex at the level of the sphenoid sinus (SS) face. Two discreet branches of the inferomedial muscular trunk of the ophthalmic artery (white arrows) are clearly seen crossing the intraconal space dividing it into three conceptual anatomic zones (A, B, and C). B. Illustration of the lateral surface of the MRM demonstrating the general pattern of innervation with a large proximal oculomotor trunk which divides into a variety of smaller distal branches. The red circles represent the approximate location and caliber of all vascular branches identified in the ten cadaveric orbits. Note the clustering of vessels along the midportion and inferior border of the MRM. C and D. Matched endoscopic surgical view of the left orbit demonstrating the appearance of the arterial branches (white arrows) and oculomotor trunk (black arrow) during endoscopic resection of a cavernous hemangioma (CH).
Bleier BS, Healy DY, Jr, Chhabra N, Freitag S. Compartmental endoscopic surgical anatomy of the medial intraconal orbital space. Int Forum Allergy Rhinol. 2014 Jul;4(7):587–91. PMID: 24687956.



Trans-nasal Drug Delivery


Harvard Otolaryngology magazine coverWe have developed the first and only method to permanently bypass the blood-brain barrier using nasal mucosal grafts. We used this method to deliver high molecular weight proteins and nucleic acids to the brain, which would otherwise be restricted by the blood-brain barrier. This approach has been recognized by the Michael J. Fox Foundation, Boston Magazine, Harvard Medicine Magazine, and the Scientist Magazine. Current projects are directed at using this delivery pathway to develop new treatments for neurodegenerative disorders including Alzheimer’s and Parkinson’s disease.