Advanced Asthma Clinic · Plantation, FL · Dr. Frank Hull, Pulmonologist
When standard asthma treatment — inhaled corticosteroids, long-acting bronchodilators, even biologic injections — fails to control your symptoms, there is a reason that is often overlooked: not all asthma is driven by the same type of airway inflammation. Neutrophilic asthma is a distinct phenotype affecting an estimated 20–40% of patients with severe asthma, yet it is routinely under-identified because it requires specific airway testing to diagnose and does not respond to the same treatments used for the more common eosinophilic form.
This guide from Dr. Frank Hull's team at the Advanced Asthma Clinic in Plantation, FL explains what neutrophilic asthma is, how it is identified, and what evidence-based and emerging treatment options exist.
Asthma is not a single disease. It is a clinical syndrome with multiple inflammatory endotypes (underlying biological mechanisms). Current guidelines recognize four main inflammatory phenotypes based on airway cell differentials:
| Phenotype | Dominant Cell | Key Cytokines | ICS Response | Prevalence |
|---|---|---|---|---|
| Eosinophilic | Eosinophils | IL-4, IL-5, IL-13 | Good–excellent | ~50% severe asthma |
| Neutrophilic | Neutrophils | IL-8, IL-17, TNF-alpha | Poor (resistant) | ~25–40% severe asthma |
| Mixed granulocytic | Both eosinophils + neutrophils | Mixed T2 + innate | Variable | ~10–15% |
| Paucigranulocytic | Neither elevated | Structural/neural | Variable | ~20–30% |
Patients with neutrophilic asthma are frequently misclassified as "refractory" or "difficult-to-treat" when in fact the problem is receiving the wrong category of treatment.
In eosinophilic asthma, the culprit is type-2 (Th2) adaptive immune activation triggered by allergens. Neutrophilic asthma involves a fundamentally different pathway:
These mechanisms explain why high-dose ICS therapy not only fails but can worsen the picture: corticosteroids prolong neutrophil survival by inhibiting neutrophil apoptosis.
Neutrophilic asthma has a distinct clinical profile. Risk factors include:
| Risk Factor | Mechanism |
|---|---|
| Current or former smoking | Cigarette smoke is the most potent CXCL8/IL-8 inducer; oxidative stress compounds steroid resistance |
| Obesity (BMI >30) | Adipokines (leptin, adiponectin) promote neutrophilic airway inflammation; mechanical restriction compounds breathlessness |
| Adult-onset asthma (>40 years) | Late-onset asthma has lower T2 immune activity; innate immune pathways predominate |
| Occupational exposures | Endotoxin (agriculture, grain handling), industrial particulates, chlorine, ozone |
| Recurrent bacterial infections | Airway colonization with Haemophilus influenzae activates IL-8 pathway persistently |
| High-dose OCS use | Chronic systemic corticosteroids select for neutrophilic phenotype by suppressing eosinophil-mediated inflammation |
Standard asthma workup — spirometry, bronchodilator reversibility, FeNO, blood eosinophils — does not identify neutrophilic asthma on its own. Specific testing is required:
No FDA-approved biologic specifically targets neutrophilic asthma as of mid-2026. Treatment rests on modifying the neutrophilic inflammatory environment and optimizing background bronchodilator therapy.
Azithromycin has emerged as the most evidence-supported intervention for neutrophilic and non-eosinophilic asthma. The AMAZES trial (2017, NEJM) demonstrated that azithromycin 500 mg three times per week for 48 weeks reduced asthma exacerbations by 41% compared to placebo in adults with uncontrolled asthma, with the greatest benefit in the non-eosinophilic subgroup. Macrolides act through multiple mechanisms independent of antibiotic effect: suppression of IL-8 and TNF-alpha production, inhibition of neutrophil migration, impairment of biofilm formation by airway bacteria, and anti-inflammatory effects on airway epithelium.
Important: Long-term macrolide use carries risk of hearing loss and QT prolongation; audiometry and baseline ECG are recommended before initiating. Macrolide resistance emergence is a known concern with prolonged use. Use requires specialist supervision.
Tiotropium (Spiriva Respimat) is FDA-approved as add-on therapy in asthma Step 4–5 and has demonstrated particular benefit in patients with low eosinophil counts (T2-low phenotype). The mechanism includes bronchodilation independent of eosinophilic inflammation and possible anti-inflammatory effects via cholinergic signaling in airway neutrophils.
If smoking is contributing to the neutrophilic phenotype, cessation is mandatory and must precede any other intervention. No pharmacological approach to neutrophilic asthma will be effective in an actively smoking patient. Smoking cessation counseling and varenicline or bupropion therapy should be initiated simultaneously with asthma management.
In obese patients (BMI >30) with neutrophilic or paucigranulocytic asthma, a 10% reduction in body weight produces clinically meaningful improvement in asthma control scores, spirometry, and exacerbation frequency. Adipose-derived IL-6 and leptin directly amplify neutrophilic airway inflammation; this effect reverses with weight loss.
Low-dose theophylline (serum level 5–10 mg/L, below the bronchodilator threshold) has anti-inflammatory and immunomodulatory properties including enhancement of corticosteroid sensitivity. It partially reverses glucocorticoid resistance by activating histone deacetylase (HDAC2) activity. Evidence base is smaller than macrolides; reserved for patients who cannot tolerate or fail azithromycin.
| Agent | Target | Mechanism | Development Stage |
|---|---|---|---|
| Danirixin (GSK1325756) | CXCR2 | Blocks IL-8-driven neutrophil recruitment to airways | Phase II (COPD/asthma) |
| AZD5069 | CXCR2 | Same class as danirixin; oral once-daily | Phase II completed |
| Secukinumab | IL-17A | Neutralizes Th17-driven neutrophilic inflammation | Phase II (severe asthma) |
| Itepekimab (REGN3500) | IL-33 | Blocks upstream innate cytokine driving neutrophilic + eosinophilic inflammation | Phase III (ex-smoker asthma) |
| Roflumilast | PDE4 | Reduces neutrophilic inflammation; approved COPD, studied in asthma | Off-label use |
Clinical trial eligibility for these agents and others may be available through research programs in South Florida. Contact Lung Research Florida (954-520-7296) to inquire about current studies in severe non-eosinophilic and neutrophilic asthma.
Neutrophilic airway inflammation is also the hallmark of COPD, which creates diagnostic overlap — especially in older adults, former smokers, and patients with fixed airflow obstruction. Key distinctions:
Accurate diagnosis guides treatment: LAMA therapy benefits both conditions, but macrolide therapy is primarily supported in asthma; inhaled corticosteroids have a clear role in asthma and limited/selected role in COPD.
If your asthma has not responded to standard therapy, phenotyping may reveal the reason. Dr. Frank Hull's team offers comprehensive asthma evaluation including FeNO testing and phenotype-directed treatment planning at our Plantation, FL clinic.
Call 954-522-7226Eosinophilic asthma is a T2-high inflammatory phenotype driven by eosinophils and cytokines IL-4, IL-5, and IL-13. It typically responds well to ICS and eosinophil-targeting biologics. Neutrophilic asthma is T2-low, driven by IL-8, IL-17, and neutrophil-dominant inflammation. It is generally steroid-resistant, does not respond to eosinophil-targeting biologics, and requires macrolide therapy, LAMA add-on, and addressing modifiable drivers like smoking and obesity.
The gold standard is induced sputum differential cell count with greater than 61–76% neutrophils (cutoff varies by lab). FeNO is typically low (below 25 ppb). Blood eosinophils are usually below 150–300 cells/uL. Bronchoalveolar lavage can confirm diagnosis. Combination of clinical profile (smoking history, obesity, adult onset, poor ICS response) plus sputum/BAL findings establishes the diagnosis.
Corticosteroids extend neutrophil survival by suppressing apoptosis, potentially worsening neutrophilic inflammation at high doses. Oxidative stress from neutrophil activity also reduces glucocorticoid receptor sensitivity (glucocorticoid resistance). This is why patients exacerbate despite high-dose ICS, and why adding more corticosteroid is not the solution.
No FDA-approved biologic specifically targets neutrophilic asthma as of 2026. Evidence-based options include azithromycin (macrolide) 500 mg three times per week (strongest evidence), LAMA add-on (tiotropium), smoking cessation, weight loss in obese patients, and low-dose theophylline. All require specialist supervision and individualized treatment planning. Consult your pulmonologist.
Several pipeline agents are in clinical trials: CXCR2 antagonists (danirixin, AZD5069) block neutrophil recruitment via the IL-8 receptor; anti-IL-17A agents (secukinumab) target Th17-driven neutrophilic inflammation; anti-IL-33 (itepekimab) is in Phase III for ex-smoker asthma. None are FDA-approved for asthma as of 2026. Clinical trial participation may be an option — contact Lung Research Florida at 954-520-7296.
Highest-risk groups include current and former smokers, obese individuals (BMI above 30), patients with adult-onset asthma diagnosed after age 40, those with occupational exposures to endotoxin or industrial particulates, patients with recurrent airway infections, and those on chronic high-dose oral corticosteroids. If you have severe asthma unresponsive to standard treatment, phenotype evaluation is warranted.
This article is for educational purposes only and does not constitute medical advice. Asthma phenotyping and treatment decisions require evaluation by a qualified physician. Always consult your physician — including Dr. Frank Hull's team at Advanced Asthma Clinic (954-522-7226) — before making any changes to your treatment regimen. Information reflects published clinical evidence and guidelines current as of June 2026.