Pulmonary Eosinophilic Infiltration Research Articles

ANCA-associated Vasculitis: The Focus is on Eosinophilic Granulomatosis With Polyangiitis (Eosinophilic Vasculitis of Charge-Strauss)

Eosinophilic granulomatosis with polyangiitis (Charge-Strauss syndrome) is an eosinophilic granulomatous disease characterized by small caliber vascular lesions and is autoimmune in nature. Patients with this syndrome experience weight loss, fever, arthralgias, and myalgias. The disease most often begins with respiratory tract involvement, including infectious allergic rhinitis, bronchial asthma, symmetric eosinophilic pulmonary infiltrates, and eosinophilic pneumonia. In older individuals, the syndrome manifests with multiple mononeuritis, asymmetric polyneuropathy, anemia, and muscle weakness. This scientific review presents the main aspects of the prevalence, mechanisms of development, spectrum of clinical manifestations, diagnosis and differential diagnosis of eosinophilic granulomatosis with polyangiitis.

CPC03 Triad of generalized rash, peripheral eosinophilia and coexisting obstructive airway disease

Abstract An 87-year-old woman was referred to the acute dermatology service with a 1-week history of a generalized painful rash. She was under the care of the medical team for treatment of pneumonia with symptoms of a cough, fevers and shortness of breath. Her past medical history included adult-onset asthma, hyponatraemia and hypertension. She had never smoked. On examination, she had erythematous smooth papules and plaques on her limbs and torso with palmoplantar involvement, alongside purple macules and patches where older lesions were present. There was no lymphadenopathy and no mucosal involvement. She had an oxygen requirement of 2 L per minute via nasal cannula. Initial blood tests showed eosinophils of 2.8 × 109 cells L−1 and a C-reactive protein (CRP) of 77 mg L−1. A chest radiograph showed bilateral ill-defined shadowing. Two skin punch biopsies were performed for histology and immunofluorescence. Vasculitis screen identified positive antinuclear antibodies (anti-Ro) and reduced complement C4 with negative antineutrophil cytoplasmic antibody (ANCA). The patient remained unwell with increasing CRP and peripheral eosinophilia (up to 9.2 × 109 cells L−1) with rash progressing to exhibit a reticular pattern. Alongside bilateral patchy ground glass opacification on chest computed tomography, a clinical diagnosis of eosinophilic granulomatosis with polyangiitis (EGPA) was made. Differential diagnoses included viral exanthem, erythema multiforme and urticarial vasculitis. Screening for cardiac, renal and sinus involvement was undertaken. The patient improved clinically following the initiation of systemic steroids and the peripheral eosinophilia returned to baseline. Skin histology reinforced the clinical diagnosis of EGPA, demonstrating a dermal and perivascular eosinophilic infiltrate with focal extension into vessel walls. EGPA is a rare small- to medium-sized vessel vasculitis with an annual incidence of 0.9–2.4 per million and a median age at diagnosis of 49–59 years. The clinicopathological hallmarks, as in this case, are asthma with peripheral eosinophilia and pulmonary eosinophilic infiltrates. Median time from onset of asthma to presentation with EGPA is 5–9 years. EGPA remains a clinical diagnosis, reinforced by serological and histological findings, although ANCA is reported to be negative in 60–70% of cases. Systemic steroids are the first-line therapy, with a role for second-line immunosuppressants such as methotrexate and rituximab. The key learning points from this case are to keep an open mind in considering a systemic cause for cutaneous manifestations, especially when the patient does not fulfil the usual demographic picture.

Gamma Irradiation-Inactivated Respiratory Syncytial Virus Vaccine Provides Protection but Exacerbates Pulmonary Inflammation by Switching from Prefusion to Postfusion F Protein.

Respiratory syncytial virus (RSV) is a common respiratory pathogen that causes lower respiratory diseases among infants and elderly people. Moreover, formalin-inactivated RSV (FI-RSV) vaccine induces serious enhanced respiratory disease (ERD). Radiation has been investigated as an alternative approach for producing inactivated or live-attenuated vaccines, which enhance the antigenicity and heterogeneous protective effects of vaccines compared with conventional formalin inactivation. In this study, we developed an RSV vaccine using gamma irradiation and analyzed its efficacy against RSV vaccine-induced ERD in a mouse model. Although gamma irradiation-inactivated RSV (RI-RSV) carbonylation was lower than FI-RSV carbonylation and RI-RSV showed a significant antibody production and viral clearance, RI-RSV caused more obvious body weight loss, pulmonary eosinophil infiltration, and pulmonary mucus secretion. Further, the conversion of prefusion F (pre-F) to postfusion F (post-F) was significant for both RI-RSV and FI-RSV, while that of RI-RSV was significantly higher than that of FI-RSV. We found that the conversion from pre- to post-F during radiation was caused by radiation-induced reactive oxygen species. Although we could not propose an effective RSV vaccine manufacturing method, we found that ERD was induced by RSV vaccine by various biochemical effects that affect antigen modification during RSV vaccine manufacturing, rather than simply by the combination of formalin and alum. Therefore, these biochemical actions should be considered in future developments of RSV vaccine. IMPORTANCE Radiation inactivation for viral vaccine production has been known to elicit a better immune response than other inactivation methods due to less surface protein damage. However, we found in this study that radiation-inactivated RSV (RI-RSV) vaccine induced a level of immune response similar to that induced by formalin-inactivated RSV (FI-RSV). Although RI-RSV vaccine showed less carbonylation than FI-RSV, it induced more conformational changes from pre-F to post-F due to the gamma radiation-induced reactive oxygen species response, which may be a key factor in RI-RSV-induced ERD. Therefore, ERD induced by RSV vaccine may be due to pre-F to post-F denaturation by random protein modifications caused by external stress. Our findings provide new ideas for inactivated vaccines for RSV and other viruses and confirm the importance of pre-F in RSV vaccines.

Improvement of peripheral neuropathy in a patient with antineutrophil cytoplasmic antibody-negative eosinophilic granulomatosis with polyangiitis by additional mepolizumab

BackgroundEosinophilic granulomatosis with polyangiitis (EGPA) is a vasculitis characterized by abnormally high eosinophils and frequent peripheral neuropathy. Mepolizumab is an approved therapy for EGPA, but its efficacy against peripheral neuropathy remains unknown.Case presentationA 41-year-old woman was admitted in the hospital with dyspnea and neuropathy. Ground glass opacity and infiltrative shadow in the bilateral lungs were evident on chest computed tomography images. Eosinophils were increased in serum, in bronchoalveolar lavage fluid (BALF), and in transbronchial lung biopsy, and bacteria were not detected in BALF. EGPA resulting in severe eosinophilic asthma, sinusitis, pulmonary infiltrates, and peripheral neuropathy was diagnosed. Prednisolone (50 mg/day) caused remission of eosinophilic pneumonia and sinusitis, but not peripheral neuropathy. During prednisolone tapering (7 mg/day, 10 months after treatment), eosinophils were increased, and peripheral neuropathy relapsed. The humanized anti-IL-5 antibody mepolizumab (300 mg) was initially administered, followed by prednisolone. Mepolizumab caused sustained peripheral neuropathy remission and effective prednisolone tapering.ConclusionsIntroduction of mepolizumab combined with prednisolone may improve peripheral neuropathy.

Anaphylactic shock with pulmonary eosinophilic infiltration due to honeybee attack in a donkey: case report

ABSTRACT A case of a donkey attacked by Africanized honeybee is reported here with clinical signs of agitation, dehydration, congestion of the ocular mucous membranes, tongue edema, tachycardia and inspiratory dyspnea, and progression to death. At necropsy, diffuse, severe subcutaneous edema at face and cervical regions and severe diffuse pulmonary hyperemia with abundant edema without parenchymal collapse were observed. Microscopically, marked, diffuse deep dermis and panniculus carnosus edema and marked diffuse alveolar edema, with moderate population of eosinophils predominantly around larger caliber vessels were noted. The final diagnosis of anaphylactic shock was supported by history, clinical signs, and anatomic pathology findings. This is the first report of a honeybee attack with pulmonary eosinophilic infiltration in a mammal.

Hepatitis in Idiopathic Hypereosinophilic Syndrome: Report of an Unusual Case

World Health Organization defines a rare diagnosis Idiopathic hypereosinophilic syndrome (HES) as a persistent eosinophilia for 6 months and resulting in end-organ dysfunction. Most of the patients present with nonspecific symptoms, while others will present with symptoms of the affected organs, commonly those involving the heart, skin, or nervous system. Gastrointestinal or liver involvement is estimated to affect up to one-third of patients with HES, although patients with clinically significant disease are limited to case reports. This is the first report of a patient presenting with idiopathic HES related hepatitis and achalasia. Hypereosinophilic syndrome has been reported to be associated with hepatic dysfunction; liver histology is mainly characterized by a diffuse eosinophilic inflammatory infiltrate. A 49-yr-old woman, diagnosed as a case of idiopathic hypereosinophilic syndrome with bone marrow and pulmonary eosinophilic infiltrates associated with peripheral eosinophilia,high IgE level developed features of chronic gatrornteritis, hepatitis, with a significant eosinophil component. She responded well to systemic glucocorticoid and Imatinib therapy with normalization of liver function tests within a few weeks.

Macrophage-Derived Osteopontin Influences the Amplification of Cryptococcus neoformans-Promoting Type 2 Immune Response.

A multifunctional glycoprotein, osteopontin (OPN), can modulate the function of macrophages, resulting in either protective or deleterious effects in various inflammatory diseases and infection in the lungs. Although macrophages play the critical roles in mediating host defenses against cryptococcosis or cryptococcal pathogenesis, the involvement of macrophage-derived OPN in pulmonary infection caused by fungus Cryptococcus has not been elucidated. Thus, our current study aimed to investigate the contribution of OPN to the regulation of host immune response and macrophage function using a mouse model of pulmonary cryptococcosis. We found that OPN was predominantly expressed in alveolar macrophages during C. neoformans infection. Systemic treatment of OPN during C. neoformans infection resulted in an enhanced pulmonary fungal load and an early onset of type 2 inflammation within the lung, as indicated by the increase of pulmonary eosinophil infiltration, type 2 cytokine production, and M2-associated gene expression. Moreover, CRISPR/Cas9-mediated OPN knockout murine macrophages had enhanced ability to clear the intracellular fungus and altered macrophage phenotype from pathogenic M2 to protective M1. Altogether, our data suggested that macrophage-derived OPN contributes to the elaboration of C. neoformans-induced type 2 immune responses and polarization of M2s that promote fungal survival and proliferation within macrophages.

Fasting impairs type 2 helper T cell infiltration in the lung of an eosinophilic asthma mouse model.

Eosinophilic asthma is a form of bronchial asthma that is caused by the pulmonary infiltration of eosinophils and accounts for approximately half of the patients with severe asthma. Several cell types of the immune system in synergy with the epithelial cells of the lung provoke an inflammatory response in patients with asthma. Recently, the effect of fasting on immune cells and inflammation has attracted considerable attention. Therefore, we examined whether fasting may serve as novel preventive strategy in patients with asthma. In our study, we employed a previously established mouse model of eosinophilic asthma. C57BL/6 mice were inoculated intranasally with interleukin‐33 and ovalbumin (OVA) in order to induce eosinophil infiltration in the lung and subjected to a 48‐h long fasting period directly after or 7 days postinoculation. We used flow cytometry to characterise infiltrated immune cells in the lung and measured the quantity of inflammatory cytokines as well as antigen‐specific immunoglobins (Ig) by ELISA. Our results indicated that fasting lowered the number of eosinophilic pulmonary infiltrates in the eosinophilic asthma model mice. Furthermore, fasting suppressed anti‐OVA IgG1 production. Fasting suppressed Th2 cytokine production by impairing Th2 accumulation in the lung. The findings suggest that fasting may be a novel preventive strategy for eosinophilic asthma.

Eosinophilic pneumonia in allergological practice

In this article, current data on pulmonary eosinophilia are presented. Pulmonary eosinophilia is defined as the infiltration of eosinophils into the airways, interstitia, and alveoli. There are diverse processes in etiology, the common feature of which is the presence of pulmonary eosinophilic infiltrates, and as a rule, peripheral blood eosinophilia. Causes of pulmonary eosinophilia include various infections, medications, parasites, autoimmune processes, malignancies, and presence of obstructive pulmonary diseases. A unified classification of pulmonary eosinophilia is lacking, and instead, various versions of classifications have been presented. The most convenient classification option for use is also distinguished. This article discusses the historical transformation of the term eosinophilic pneumonia in the field of allergology, showing the lack of unambiguity in the concept of eosinophilic pneumonia, as well as the location of eosinophilic pneumonia in the pulmonary eosinophilia section. Eosinophilic pneumonia is defined as a disease characterized by an increase in the eosinophil content in the pulmonary tissue or bronchoalveolar lavage fluid. Most eosinophilic pneumonias are associated with peripheral blood eosinophilia. Two main variants of the disease are acute and chronic eosinophilic pneumonias. Thus, various ways to formulate diagnoses in various cases of eosinophilic pneumonia have been proposed.

Causal relationship between humidifier disinfectant exposure and Th17-mediated airway inflammation and hyperresponsiveness

In this study, we investigated whether humidifier disinfectants (HDs) induce asthmatic airway inflammation in an animal model and compared the features of HD-induced inflammatory symptoms with ovalbumin (OVA)-induced allergic asthma. Mice were intratracheally instilled three times with either the control or 0.1, 0.3, or 0.5 mg/kg of polyhexamethylene guanidine phosphate (PHMG-P). To characterize asthmatic features, the following parameters were analyzed: (i) differential cell counts and cytokine expression in the bronchoalveolar lavage fluid (BALF); (ii) presence of mucus-producing goblet cells and pulmonary eosinophilic infiltration in the lungs; (iii) serum immunoglobulin levels; and (iv) airway hyperresponsiveness (AHR). RNA-Seq and bioinformatics tools were used to investigate whether PHMG-P altered asthma-related gene expression in lung tissues. The PHMG-P exposure groups showed higher peribronchial/perivascular inflammation, elevated goblet cell hyperplasia, and inhaled methacholine-induced airway resistance. Additionally, IL-13 and IL-17 in BALF were significantly increased in the PHMG-P exposure groups. However, there were no significant differences in total serum IgE and BALF IL-4 and IL-5 levels in the PHMG-P exposure groups compared to the control group. PHMG-P exposure modulated the expression of genes related to Th17 signaling pathways including the IL-17A, IL-23, and STAT3 signaling pathways, but not the Th2 signaling pathway. Altogether, our results suggest that repeated exposure to low does PHMG-P induces asthma-like symptoms and is thus a possible risk factor for developing asthma. The PHMG-P-induced asthmatic airway inflammation showed a different pattern from that found in typical allergic asthma and may be related to irritant-induced airway inflammation and hyperresponsiveness characterized by Th2-low, Th17-related, IgE-independent, and mixed granulocytic features.

Yeast-expressed SARS-CoV recombinant receptor-binding domain (RBD219-N1) formulated with aluminum hydroxide induces protective immunity and reduces immune enhancement

We developed a severe acute respiratory syndrome (SARS) subunit recombinant protein vaccine candidate based on a high-yielding, yeast-engineered, receptor-binding domain (RBD219-N1) of the SARS beta-coronavirus (SARS-CoV) spike (S) protein. When formulated with Alhydrogel®, RBD219-N1 induced high levels of neutralizing antibodies against both pseudotyped virus and a clinical (mouse-adapted) isolate of SARS-CoV. Here, we report that mice immunized with RBD219-N1/Alhydrogel® were fully protected from lethal SARS-CoV challenge (0% mortality), compared to ~30% mortality in mice immunized with the SARS S protein formulated with Alhydrogel®, and 100% mortality in negative controls. An RBD219-N1 formulation with Alhydrogel® was also superior to the S protein, unadjuvanted RBD, and AddaVax (MF59-like adjuvant)-formulated RBD in inducing specific antibodies and preventing cellular infiltrates in the lungs upon SARS-CoV challenge. Specifically, a formulation with a 1:25 ratio of RBD219-N1 to Alhydrogel® provided high neutralizing antibody titers, 100% protection with non-detectable viral loads with minimal or no eosinophilic pulmonary infiltrates. As a result, this vaccine formulation is under consideration for further development against SARS-CoV and potentially other emerging and re-emerging beta-CoVs such as SARS-CoV-2.

Bacillus clausii, a Foreshore-Derived Probiotic, Attenuates Allergic Airway Inflammation Through Downregulation of Hypoxia Signaling

Background and Objectives: The immunomodulatory effects and mechanism of probiotics in allergic airway disease are largely unknown. We studied whether <i>Bacillus clausii</i> (BC), a probiotic derived from mudflats, had anti-allergic effects and compared the results with those of <i>Lactobacillus paracasei</i> (LP). We also examined whether the anti-allergic mechanisms of probiotics are associated with hypoxia signaling.Materials and Method: Forty-two BALB/c mice were randomly assigned to six experimental groups: controls, ovalbumin (OVA)-induced mice for inducing asthma, and OVA-induced mice that were orally administered LP or BC, at 1×10<sup>9</sup> or 5×10<sup>9</sup> CFU/mL each. We performed differential cell count testing on bronchoalveolar lavage fluid (BALF), lung histopathology, serum totals and OVA-specific IgE and IgG1 assessments, Th2 cytokine titers (IL-4, IL-5) in BALF and pulmonary parenchyma, quantitative PCR for <i>heme oxygenase (HO)-1</i> and <i>Hif-1α</i>, and immunohistochemistry.Results: Compared to the OVA group mice, OVA-sensitized mice treated with LP or BC showed significantly reduced numbers of eosinophils and neutrophils in the BALF (p<0.05). Both probiotics also significantly reduced pulmonary inflammation and eosinophil infiltration. Mice in the LP or BC group had a substantially lower titer of IL-4 and IL-5 in BALF, and decreased IL-4 and IL-5 expression in the lung parenchyma. Real-time PCR and immunohistochemistry showed that both LP and BC could significantly suppress <i>HO-1</i> and <i>Hif-1α</i> expression in asthmatic mice (p<0.05).Conclusion: BC can attenuate murine allergic asthma by regulating HIF-1α signaling, and its anti-allergic effect is comparable to that of LP.

A surprising discovery - idiopathic hypereosinophilic syndrome

Allergy/Immunology The role of investigating and initiating therapy for hypereosinophilia when end organ involvement is present. A 51-year-old man with past medical history of allergic rhinitis was admitted to the hospital and treated for a right sided multi-lobar pneumonia. He presented with progressively worsening dry cough, malaise and diffuse (hip, knee, elbow, hands) joint pain. He had a history of multiple episodes of sinusitis and upper respiratory tract infections in the preceding six months requiring steroids and antibiotics with varying responses. He had no history of childhood asthma or recurrent ear/nose/throat infections. He was a previous tobacco smoker with ∼ 13-pack year history, and quit smoking in 1996. His most recent travel was to Las Vegas, Colorado, and Seattle. He had also been on a cruise to Mexico 3 years prior to presentation. On admission, he had a fever of 102*F, tachycardic, normotensive, with normal oxygen saturation. Physical exam findings were relevant for decreased breath sounds on lower and middle lung fields. Complete blood count revealed eosinophil count of > 9 eosinophils x 109/L. A bronchoalveolar lavage was performed and revealed over 90% eosinophils on analysis. He had a bone marrow biopsy showing moderate hypercellularity with marked eosinophilic hyperplasia and moderate megakaryocytic hyperplasia. FISH results were negative for PDGFRA, PDGFRB and FGFR1 rearrangements and presented normal cytogenetics. JAK2 and BCR-ABL were both negative. His clinical presentation along with the above findings was consistent with a diagnosis of idiopathic hypereosinophilic syndrome. He was started on prednisone in combination with hydroxyurea. He responded well to his current regimen. However, when his treatment was tapered he had a flare with now left sided pulmonary infiltrates and respiratory symptoms. With increase of treatment, this again resolved. Idiopathic hypereosinopillic syndrome is a diagnosis of exclusion, once reactive and neoplastic causes have been excluded and it comprises the largest category. This case report highlights the importance of investigating and initiating therapy for hypereosinophilia especially when end organ involvement is present. The goal of HES treatment is to mitigate eosinophil-mediated organ damage. Furthermore, the case shows eosinophilic pulmonary infiltrates can be unilateral despite this being a systemic process. It details the work-up that precludes diagnosis of this condition, and exclusion of multiple causes. Our case further highlights the need for steroid sparing agents in long-term management of idiopathic hypereosinophilic syndrome. With increased use of next-generation sequencing, somatic mutations are being detected in an increasing number of IHES cases. Anti–IL-5 antibodies (mepolizumab and reslizumab), and anti-CD52 antibodies (alemtuzumab) have been successful in treating HES. Additional eosinophil-targeted therapies currently in preclinical trials include those targeting Siglec-8, an eosinophil-selective receptor, and CCR3, an eosinophil-specific chemokine receptor.

Progress and Concept for COVID-19 Vaccine Development.

The recent outbreak of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), previously known by the provisional name 2019 novel coronavirus (2019-nCoV), in the city of Wuhan in China's Hubei province in 2019–2020 has been causing significant numbers of mortality and morbility in humans with the coronavirus infection diseases (COVID-19) with fever, severe respiratory illness, and pneumonia.[1-3] Till April 8, 2020, there have been over 1 431 973 confirmed cases globally, leading to at least 82 085 deaths. These SARS-CoV-2 isolates belong to the Betacoronavirus genus of the Coronaviradae family which is an enveloped single-stranded RNA virus containing a 30 kb genome with 14 open reading frames including four major viral structure proteins: spike (S), membrane (M), envelope (E), and nucleocapsid (N) proteins.[4-7] The S gene sequences of SARS-CoV-2 isolates have a 93.1% nucleotide sequence identity to the Rhinolophus affinis bat coronavirus RaTG13, but only less than 75% nucleotide sequence identity to the severe acute respiratory syndrome coronavirus (SARS-CoV). The viral S sequences of SARS-CoV-2 compared to SARS-CoV have three additional short insertions in the N-terminal domain, and four out of five key residues changes in the receptor-binding motif of S protein receptor binding domain (RBD).[6, 7] Although both SARS-CoV-2 and SARS-CoV share the same human cellular receptor-angiotensin converting enzyme II, SARS-CoV-2 appears to be more readily transmitted from human to human.[1, 8, 9] The S protein is the major target for COVID-19 vaccine development, mainly based on the elicitation of virus neutralizing antibodies as the immune correlates to vaccine protection. The current status of COVID-19 vaccine development includes, i) three phase I vaccine candidates, ii) 11 preclinical vaccine candidates, and iii) 26 research-stage vaccine candidates (Table 1; [https://www.raps.org/news-and-articles/news-articles/2020/3/covid-19-vaccine-tracker?feed=Regulatory-Focus?utm_source=Facebook&utm_medium=social&utm_campaign=Regulatory-Focus]). Most of these vaccine candidates are based on the S antigen either as inactivated vaccines, subunit vaccines, viral vectored vaccines, and nucleic acid-based DNA or mRNA vaccines. Among these vaccine candidates, the Coalition for Epidemic Preparedness Innovations (CEPI) has provided funding to develop COVID-19 vaccines using the following platform technology: a) Curevac Inc. (mRNA), b) Inovio Pharmaceuticals Inc. (DNA), c) Moderna, Inc. (mRNA), d) University of Queensland (molecular clam), e) Novavax (nanoparticles), f) University of Oxford (adenovirus vector), g) University of Hong Kong (live-attenuated influenza virus), and h) Institute of Pasteur (measles vector) to accelerate the development of vaccines and enable equitable access to these vaccines for people during outbreaks [https://cepi.net/covid-19/]. Phase I NCT04283461 Phase I ChiCTR2000030906 Phase I NCT04336410 Re-purposed SARS vaccine; S1 or RBD protein vaccine To date, many previous studies of SARS-CoV, Middle East respiratory syndrome-related coronavirus (MERS-CoV), and other coronavirus vaccines revealed several safety concerns associated with the use of coronavirus S-based vaccines, including inflammatory and immunopathological effects such as pulmonary eosinophilic infiltration and antibody-dependent disease enhancement (ADE) following subsequent viral challenge of vaccinated animals.[10-21] The anti-S antibodies for ADE may facilitate uptake by macrophage expressing FcR, leading to macrophage stimulation and the production of proinflammatory cytokines (IL-6, IL-8, and MCP1) and loss of tissue-repaired cytokine (TGFβ).[22] Moreover, the Th2-associated immunopathology has been documented for the inactivated vaccines of respiratory syncytial virus after viral challenge[23-25] and the inactivated vaccines of MERS-CoV after virus challenge.[20] Thus, the safety and the potentially harmful responses in vaccines to develop ADE antibodies against any coronaviruses should be carefully assessed in human trials.[26] It has been proposed that the neutralizing epitope-rich S1 region, or the RBD region, instead of the entire full-length S protein as an alternative target for MERS-CoV vaccine development.[27] Whether the use of S1 or RBD antigen of SARS-CoV-2, or the selection of Th1-skewed adjuvants rather than alum adjuvant, can avoid the inflammatory, immunopathological, and ADE effects, requires further studies from animal models and human trials. These findings are particularly important for developing a safe and effective COVID-19 vaccine. Suh-Chin Wu This work was supported by the Ministry of Science and Technology, Taiwan (MOST108-2321-B-007-001, MOST108-2321-B-002-006), and National Tsing Hua University (109R2807E1). The author declares no conflict of interest.

Possible Mechanisms of Eosinophil Accumulation in Eosinophilic Pneumonia.

Eosinophilic pneumonia (EP), including acute EP and chronic EP, is characterized by the massive pulmonary infiltration of eosinophils into the lung. However, the mechanisms underlying the selective accumulation of eosinophils in EP have not yet been fully elucidated. We reported that bronchoalveolar lavage fluid (BALF) from EP patients induced the transmigration of eosinophils across endothelial cells in vitro. The concentrations of eotaxin-2 (CCL24) and monocyte chemotactic protein (MCP)-4 (CCL13), which are CC chemokine receptor (CCR) 3 ligands, were elevated in the BALF of EP patients, and anti-CCR3 monoclonal antibody inhibited the eosinophil transmigration induced by the BALF of EP patients. The concentration of macrophage inflammatory protein 1β (CCL4), a CCR5 ligand that induces eosinophil migration, was increased in the BALF of EP patients. Furthermore, the concentration of interleukin (IL) 5 was increased in the BALF of EP patients, and it has been reported that anti-IL-5 antibody treatment resulted in remission and the reduction of glucocorticoid use in some cases of chronic EP. The concentrations of lipid mediators, such as leukotriene (LT) B4, damage-associated molecular pattern molecules (DAMPs), such as uric acid, or extracellular matrix proteins, such as periostin, were also increased in the BALF of EP patients. These findings suggest that chemokines, such as CCR3/CCR5 ligands, cytokines, such as IL-5, lipid mediators, such as LTB4, DAMPs, and extracellular matrix proteins may play roles in the accumulation or activation of eosinophils in EP.

A SURPRISING DISCOVERY - IDIOPATHIC HYPEREOSINOPHILIC SYNDROME

Introduction A 51-year old man with past medical history of allergic rhinitis was admitted to the hospital and treated for a right sided multi-lobar pneumonia. He presented with progressively worsening dry cough, malaise and diffuse (hip, knee, elbow, hands) joint pain. He had a history of multiple episodes of sinusitis and upper respiratory tract infections in the preceding six months requiring steroids and antibiotics with varying responses. A CBC revealed eosinophil count of > 9 eosinophils x 109/L. A BAL revealed over 90% eosinophils. He had a bone marrow biopsy showing moderate hypercellularity with marked eosinophilic hyperplasia and moderate megakaryocytic hyperplasia, though negative FISH results for PDGFRA, PDGFRB and FGFR1 rearrangements and normal cytogenetics. JAK2 and BCR-ABL were both negative. His clinical presentation along with the above findings was consistent with a diagnoses of idiopathic hypereosinophilic syndrome. He was started on prednisone in combination with hydroxyurea. He responded well to his current regimen. However, when his treatment was tapered he had a flare with now left sided pulmonary infiltrates and respiratory symptoms. With increase of treatment this again resolved. This case highlights the importance of investigating and initiating therapy for hypereosinophilia especially when end organ involvement is present. Furthermore, it shows eosinophilic pulmonary infiltrates can be unilateral despite this being a systemic process. It details the work-up that precludes diagnosis of this condition. Our case highlights the need for steroid sparing agents in long term management of idiopathic hypereosinophilic syndrome.

Protostemonine attenuates alternatively activated macrophage and DRA-induced asthmatic inflammation

Asthma is one of the most common pulmonary diseases that threatens human life because of lack of effective medicines. Protostemonine (PSN), an active alkaloid extracted from the roots of Stemona sesslifolia, has anti-inflammatory effects on acute lung injury and acute liver failure. However, it has not been defined whether PSN alleviates asthmatic inflammation. Here, we reported that PSN inhibits pulmonary eosinophil infiltration, goblet cell hyperplasia, mucus secretion, IgE and Th2 cytokine (IL-4, IL-5, IL-13 and IL-33) production by using DRA (dust mites, ragweed and aspergillus)-induced murine asthma model. Moreover, PSN also attenuated the expression of Arginase-1 (Arg-1), Ym-1 and Fizz-1, markers of AAM (alternatively activated macrophage) polarization, in lung tissues. In addition, PSN attenuated IL-4-induced expression of Arg-1, Ym-1 and Fizz-1 in bone marrow derived macrophages (BMDMs). Treatment with PSN decreased IL-4-induced STAT6 phosphorylation, KLF4 and IRF4 expression in BMDMs. Collectively, our results indicated that PSN ameliorates AAM polarization and asthmatic inflammation and might be a potential agent for treating asthma.

Prominent release of lipoxygenase generated mediators in a murine house dust mite-induced asthma model

The profile of activation of lipid mediator (LM) pathways in asthmatic airway inflammation remains unclear. This experimental study quantified metabolite levels of ω3-, ω6- and ω9-derived polyunsaturated fatty acids in bronchoalveolar lavage fluid (BALF) after 4-weeks of repeated house dust mite (HDM) exposure in a murine (C57BL/6) asthma model. The challenge induced airway hyperresponsiveness, pulmonary eosinophil infiltration, but with low and unchanged mast cell numbers. Of the 112 screened LMs, 26 were increased between 2 to >25-fold in BALF with HDM treatment (p < 0.05, false discovery rate = 5%). While cysteinyl-leukotrienes were the most abundant metabolites at baseline, their levels did not increase after HDM treatment, whereas elevation of PGD2, LTB4 and multiple 12/15-lipoxygenase products, such as 5,15-DiHETE, 15-HEDE and 15-HEPE were observed. We conclude that this model has identified a global lipoxygenase activation signature, not linked to mast cells, but with aspects that mimic chronic allergic airway inflammation in asthma.

Emodin alleviates alternatively activated macrophage and asthmatic airway inflammation in a murine asthma model.

Alternatively activated macrophages (AAMs) are not only associated with asthma but also lead to asthmatic airway inflammation and remodeling. Inhibition of AAMs is an alternative therapeutic strategy for treating asthma. In this study we investigated whether emodin (1,3,8-trihydroxy-6-methylanthraquinone), isolated from the rhizome of Rheum palmatum, alleviated asthmatic airway inflammation and reduced AAM polarization in a murine asthma model. Mice were sensitized with a triple allergen mix containing dust mite, ragweed and aspergillus (DRA). In mice with DRA-induced asthma, asthmatic inflammation was significantly enhanced. Intraperitoneal injection of emodin (20 mg·kg-1·d-1, ip) 1 h prior to DRA challenge on days 12-14 significantly decreased pulmonary eosinophil and lymphocyte infiltration, mucus secretion and serum IgE production, as well as IL-4 and IL-5 production in bronchoalveolar lavage fluid. In response to emodin treatment, activated markers of AAM Ym-1, Fizz-1 and arginase-1 in the lung tissues were remarkably decreased. In mouse bone marrow-derived macrophages (BMDMs) in vitro, emodin (2-50 μmol/L) dose-dependently inhibited IL-4-induced AAM polarization and STAT6 phosphorylation. Collectively, our results suggest that emodin effectively ameliorates asthmatic airway inflammation and AAM polarization, and it may therefore become a potential agent for the treatment of asthma.

Eosinophil transendothelial migration induced by the bronchoalveolar lavage fluid of acute eosinophilic pneumonia.

Acute eosinophilic pneumonia (AEP) is characterized by a massive pulmonary infiltration of eosinophils. Mechanisms regulating the selective accumulation of eosinophils in AEP have not been fully established. The objective of this study was to evaluate the mechanisms of eosinophil accumulation in alveolar spaces through examination of bronchoalveolar lavage fluid (BALF) from AEP patients (AEP-BALF). Eosinophils were isolated from the blood of healthy subjects and were placed on a human pulmonary microvascular endothelial cell monolayer cultured on Transwell filters (Coster, Cambridge, MA, USA). A saline control solution or BALF from patients with AEP, sarcoidosis or hypersensitivity pneumonitis was applied to the lower compartment, and the transendothelial migration of the eosinophils was evaluated. The concentrations of cytokines and chemokines in BALF were also measured. Transmigration of eosinophils across endothelial cells was only induced by the AEP-BALF. This transmigration was blocked by anti-β2 integrin mAb. The concentrations of eotaxin-2 and monocyte chemotactic protein (MCP)-4, which are CC chemokine receptor (CCR) 3 ligands, were elevated in the AEP-BALF, and anti-CCR3 mAb or anti-MCP-4 mAb inhibited the AEP-BALF-induced transmigration of eosinophils. Furthermore, the concentration of leukotriene (LT) B4 was increased in the AEP-BALF, and an LTB4 receptor antagonist partially suppressed the AEP-BALF-induced transmigration of eosinophils. These findings suggest that CCR3 ligands including eotaxin-2 and MCP-4, and LTB4 play a role in the accumulation of eosinophils in AEP.