Gail M. Kephart

Anti-interleukin-5 antibody treatment (mepolizumab) in active eosinophilic oesophagitis: a randomised, placebo-controlled, double-blind trial

Objective: Eosinophilic oesophagitis (EoO) is a clinicopathological condition defined by proton pump inhibitor-refractory oesophageal symptoms combined with oesophageal eosinophilia. The pharmacodynamic effect of mepolizumab (a humanised anti-interleukin-5 monoclonal antibody) in EoO was evaluated. Methods: Eleven adults with active EoO (>20 peak eosinophil number/high power field (hpf) and dysphagia) were randomised to 750 mg of mepolizumab (n = 5) or placebo (n = 6) and received two intravenous infusions, 1 week apart. Those not in complete remission (<5 peak eosinophil number/hpf) after 8 weeks received two further doses 4 weeks apart, 1500 mg of mepolizumab or placebo. The effect of mepolizumab was assessed clinically, endoscopically, histologically, and via blood and tissue biomarkers. Results: As assessed by immunofluorescence, a marked reduction of mean oesophageal eosinophilia (p = 0.03) was seen in the mepolizumab group (−54%) compared with the placebo group (−5%) 4 weeks after initiation of treatment. No further reduction of eosinophil numbers was observed in response to the two additional infusions in either group. Mepolizumab reduced tenascin C (p = 0.033) and transforming growth factor β1 (p = 0.05) expression in the oesophageal epithelial layer 13 weeks after initiation of treatment. Clinically, limited improvement of symptoms was seen, although a trend was seen between 4 and 13 weeks after initiation of mepolizumab treatment. Mepolizumab was well tolerated. Conclusions: Mepolizumab significantly reduced eosinophil numbers in oesophageal tissues in adult patients with active EoO, and changes in the expression of molecules associated with oesophageal remodelling were reversed. Minimal clinical improvement was achieved in a subgroup of patients with EoO. Mepolizumab had an acceptable safety profile, even at the high 1500 mg dose level. Trial registration number: NCT00274703

IL-33–Responsive Lineage−CD25+CD44hi Lymphoid Cells Mediate Innate Type 2 Immunity and Allergic Inflammation in the Lungs

Innate immunity provides the first line of response to invading pathogens and a variety of environmental insults. Recent studies identified novel subsets of innate lymphoid cells that are capable of mediating immune responses in mucosal organs. In this paper, we describe a subset of lymphoid cells that is involved in innate type 2 immunity in the lungs. Airway exposure of naive BALB/c or C57BL/6J mice to IL-33 results in a rapid (<12 h) production of IL-5 and IL-13 and marked airway eosinophilia independently of adaptive immunity. In the lungs of nonsensitized naive mice, IL-33–responsive cells were identified that have a lymphoid morphology, lack lineage markers, highly express CD25, CD44, Thy1.2, ICOS, Sca-1, and IL-7Rα (i.e., Lin−CD25+CD44hi lymphoid cells), and require IL-7Rα for their development. Airway exposure of naive mice to a clinically relevant ubiquitous fungal allergen, Alternaria alternata, increases bronchoalveolar lavage levels of IL-33, followed by IL-5 and IL-13 production and airway eosinophilia without T or B cells. This innate type 2 response to the allergen is nearly abolished in mice deficient in IL-33R (i.e., ST2), and the Lin−CD25+CD44hi lymphoid cells in the lungs are required and sufficient to mediate the response. Thus, a subset of innate immune cells that responds to IL-33 and vigorously produces Th2-type cytokines is present in mouse lungs. These cells may provide a novel mechanism for type 2 immunity in the airways and induction of allergic airway diseases such as asthma.

A clinical and pathologic study of chronic sinusitis: The role of the eosinophil

Evidence exists that the eosinophil plays an important role in mediating injury to bronchial epithelium in chronic asthma. Here, the role of the eosinophil in chronic inflammatory disease of the paranasal sinuses was studied with tissue from patients who underwent surgery for chronic sinusitis. Paranasal tissue from patients with chronic asthma and/or allergic rhinitis was extensively infiltrated with eosinophils. Immunofluorescent studies demonstrated a striking association between the presence of extracellular deposition of major basic protein and damage to sinus mucosa. The histopathology of paranasal respiratory epithelium appeared similar to that described in bronchial asthma. These findings suggest that the eosinophil acts as an effector cell in chronic inflammatory disease of paranasal respiratory epithelium. Thus, sinus disease in patients with asthma may be due to the same mechanisms that cause damage to bronchial epithelium.

Enhanced innate type 2 immune response in peripheral blood from patients with asthma

BACKGROUND In mice, group 2 innate lymphoid cells (ILC2s) likely mediate helminth immunity, inflammation, and tissue repair and remodeling. However, the involvement of ILC2s in human diseases, such as asthma, is not well understood. OBJECTIVES The goals of this study were to investigate whether peripheral blood specimens can be used to monitor innate type 2 immunity in human subjects and to examine whether ILC2s are involved in human asthma. METHODS PBMCs from subjects with allergic asthma (AA), subjects with allergic rhinitis (AR), or healthy control (HC) subjects were cultured in vitro with IL-25 or IL-33. Flow cytometry and cell sorting were used to identify, isolate, and quantitate ILC2s in PBMCs. RESULTS Human PBMCs produced IL-5 and IL-13 when stimulated with IL-33 or IL-25 in the presence of IL-2 without antigens. In addition, IL-7 or thymic stromal lymphopoietin were able to replace IL-2. The cell population with phenotypic ILC2 characteristics, lineage(-)CD127(+)CRTH2(+) cells, responded to IL-33 and produced large quantities of IL-5 and IL-13 but undetectable levels of IL-4. PBMCs from subjects with AA produced significantly larger amounts of IL-5 and IL-13 in response to IL-25 or IL-33 than from subjects with AR or HC. The prevalence of ILC2s in blood was greater in the AA group than in the AR group or the HC group. CONCLUSIONS Innate type 2 immune responses are increased in asthma but not in AR, suggesting potential differences in the immunopathogenesis of these diseases. Peripheral blood is useful for evaluating innate type 2 immunity in humans.

Eosinophil infiltration and degranulation in normal human tissue

Localization of eosinophil granule major basic protein by immunofluorescence permits recognition of both eosinophil infiltration and degranulation. Over the past decade and a half, our laboratory has shown that eosinophil infiltration and degranulation occur in many diseased tissues in humans; among normal tissues studied as controls, only the gut showed striking eosinophil infiltration and degranulation. Using an indirect immunofluorescence procedure for the detection of major basic protein, we extended our analyses of normal human tissues to include tissues from essentially all body organs; a total of 117 biopsy/ autopsy specimens were analyzed. To determine whether the method of tissue procurement affected the level of eosinophil degranulation in the normal gastrointestinal tract, normal proximal jejunum from six patients was biopsied using either an endoscopic forceps or a scalpel at the time of elective surgery and examined by immunofluorescence. Spleen, lymph node, and thymus tissues showed eosinophil infiltration with scant evidence of degranulation, but the only organ showing both eosinophil infiltration and remarkable degranulation was the gastrointestinal tract. Eosinophil degranulation was significantly increased in specimens obtained by endoscopic forceps compared to those obtained by scalpel (P = 0.021). These results indicate that tissue procurement methods affect the degree of eosinophil degranulation in the gut. Thus, among normal human body organs, both eosinophil infiltration and appreciable degranulation consistently occur only in the gut. Anat. Rec. 252:418–425, 1998.

Conjunctival Deposition of Eosinophil Granule Major Basic Protein in Vernal Keratoconjunctivitis and Contact Lens-Associated Giant Papillary Conjunctivitis

To investigate the role of the eosinophil in vernal keratoconjunctivitis and contact lens-associated giant papillary conjunctivitis, we assessed the presence of eosinophil granule major basic protein in conjunctival tissues by immunofluorescence. Biopsy specimens of conjunctiva were taken from nine patients with vernal keratoconjunctivitis, seven patients with giant papillary conjunctivitis, and five control subjects. We performed a masked semiquantitative assessment of immunofluorescence on sections from each specimen. The vernal keratoconjunctivitis and giant papillary conjunctivitis groups had significantly (P less than .05) more major basic protein deposition than controls. No significant correlation between severity of disease and degree of major basic protein deposition was found. We found extracellular eosinophil granules in one of three vernal keratoconjunctivitis specimens examined by transmission electron microscopy. Thus, eosinophil degranulation commonly occurs in vernal keratoconjunctivitis and giant papillary conjunctivitis with release of eosinophil granule major basic protein and presumably other toxic granule proteins onto affected tissues. These cationic proteins are potent cytotoxins and are able to stimulate mast cell degranulation.

Localization of eosinophil-derived neurotoxin and eosinophil cationic protein in neutrophilic leukocytes.

Eosinophil‐derived neurotoxin (EDN) and eosinophil cationic protein (ECP) are generally regarded as eosinophil‐specific proteins. We tested whether EDN and ECP are present in mature neutrophils. By indirect immunofluorescence, both eosinophils and neutrophils stained with antibodies to EDN and ECP. Lysates of purified (<0.1% eosinophil contamination) neutrophils contained EDN, 112 ± 4 ng/106 cells, and ECP, 163 ± 2 ng/106 cells, whereas eosinophil major basic protein (MBP) was not detectable. Electron microscopic examination of immunogold‐labeled buffy coat cells stained with EDN antibody showed that EDN is localized to neutrophil granules. Finally, EDN mRNA was detected in lysates of highly purified neutrophils (0.001% eosinophil contamination) by the reverse transcription‐polymerase chain reaction. We conclude that proteins that are either identical to or immunologically cross‐reactive with EDN and ECP are present in neutrophils and that EDN is synthesized and localized to neutrophil granules. Thus, caution must be exercised in interpreting the presence of EDN and ECP as specific markers of eosinophil‐associated inflammation in human disease. J. Leukoc. Biol. 63: 715–722; 1998.

Deposition of eosinophil granule major basic protein in eosinophilic gastroenteritis and celiac disease

Degrees of eosinophil infiltration and eosinophil degranulation, as evidenced by localization of the eosinophil granule major basic protein (MBP), were compared in patients with eosinophilic gastroenteritis, patients with celiac disease, and healthy controls using a specific indirect immunofluorescence technique for the localization of MBP. Formalin-fixed, paraffin-embedded biopsy specimens from the mucosa of the stomach and small intestine of 11 patients with eosinophilic gastroenteritis, from the small intestine of 4 patients with celiac disease, and from the stomach and/or upper small intestine of 18 healthy asymptomatic volunteers were tested. Degrees of eosinophil infiltration and extracellular deposition of MBP were graded by two blinded observers; each section was given a score from 0 (nil) to 4 (marked). In the small bowel biopsy specimens, both eosinophil infiltration and extracellular MBP deposition scores were significantly greater in patients with eosinophilic gastroenteritis and in patients with celiac disease than in controls. In the gastric biopsy specimens, extracellular MBP deposition scores were significantly increased in patients with eosinophilic gastroenteritis compared with controls even though eosinophil infiltration scores did not differ significantly at this site. The results support the hypothesis that the eosinophil, through toxic cationic proteins such as MBP, plays a role in the pathogenesis of these diseases.

Detection of fungal organisms in eosinophilic mucin using a fluorescein-labeled chitin-specific binding protein☆

BACKGROUND The ability to identify fungal hyphae in patients with chronic rhinosinusitis (CRS) has been inconsistent. A new fluorescein-labeled staining method targets chitin found in fungal cell walls. OBJECTIVE We hypothesize that this method would be able to more consistently detect fungi within the mucin of CRS patients. METHODS Fifty-four consecutive CRS surgical patients were evaluated. After ensuring sensitivity and specificity of this new method, all specimens were stained with either fluorescein-labeled chitinase or Grocott methanamine silver stain for comparison. RESULTS All 54 specimens contained eosinophilic mucin on hematoxylin and eosin staining. One or more fungal hyphae could be visualized within the mucin of 54 (100%) of 54 specimens stained using the fluorescein-labeled chitinase. Only 41 (76%) of 54 of the specimens stained with the Grocott methanamine silver stain technique demonstrated fungi. CONCLUSION The fluorescein-labeled chitinase-staining technique has greater sensitivity in detecting fungal organisms within eosinophilic mucin. Fungal organisms are present in the mucin of CRS patients.

Eosinophil granule major basic protein deposition in corneal ulcers associated with vernal keratoconjunctivitis

An indirect immunofluorescence assay detected eosinophil granule major basic protein in the inflammatory debris covering deepithelialized cornea in two patients with vernal keratoconjunctivitis. A slight degree of non-specific fluorescence was present in the control autopsy corneas. High concentrations of the eosinophil granule major basic protein inhibit epithelial migration and protein synthesis, whereas low concentrations affect epithelial migration. The results suggest participation of eosinophil granule major basic protein in the ulcerative process.