Infliximab for chronic obstructive pulmonary disease: towards a more specific inflammation targeting?

Monoclonal Antibodies and Airway Diseases

Monoclonal antibodies, biologics, are a relatively new treatment option for severe chronic airway diseases, asthma, allergic rhinitis, and chronic rhinosinusitis (CRS). In this review, we focus on the physiological and pathomechanisms of monoclonal antibodies, and we present recent study results regarding their use as a therapeutic option against severe airway diseases. Airway mucosa acts as a relative barrier, modulating antigenic stimulation and responding to environmental pathogen exposure with a specific, self-limited response. In severe asthma and/or CRS, genome-environmental interactions lead to dysbiosis, aggravated inflammation, and disease. In healthy conditions, single or combined type 1, 2, and 3 immunological response pathways are invoked, generating cytokine, chemokine, innate cellular and T helper (Th) responses to eliminate viruses, helminths, and extracellular bacteria/fungi, correspondingly. Although the pathomechanisms are not fully known, the majority of severe airway diseases are related to type 2 high inflammation. Type 2 cytokines interleukins (IL) 4, 5, and 13, are orchestrated by innate lymphoid cell (ILC) and Th subsets leading to eosinophilia, immunoglobulin E (IgE) responses, and permanently impaired airway damage. Monoclonal antibodies can bind or block key parts of these inflammatory pathways, resulting in less inflammation and improved disease control.

Pulmonary-intestinal cross-talk in mucosal inflammatory disease

Chronic obstructive pulmonary disease (COPD) and inflammatory bowel diseases (IBDs) are chronic inflammatory diseases of mucosal tissues that affect the respiratory and gastrointestinal tracts, respectively. They share many similarities in epidemiological and clinical characteristics, as well as in inflammatory pathologies. Importantly, both conditions are accompanied by systemic comorbidities that are largely overlooked in both basic and clinical research. Therefore, consideration of these complications may maximize the efficacy of prevention and treatment approaches. Here, we examine both the intestinal involvement in COPD and the pulmonary manifestations of IBD. We also review the evidence for inflammatory organ cross-talk that may drive these associations, and discuss the current frontiers of research into these issues.

The selective MMP-12 inhibitor, AS111793 reduces airway inflammation in mice exposed to cigarette smoke

BACKGROUND

Macrophage elastase (MMP-12) is involved in the inflammatory process of chronic obstructive pulmonary disease (COPD). The aim of this study was to investigate in mice the effect of MMP-12 inhibition on the inflammatory process induced by cigarette smoke (CS) or by lipopolysaccharide (LPS) exposure of the airways.

EXPERIMENTAL APPROACH

C57BL/6 mice were given, orally, either the selective MMP-12 inhibitor AS111793 (3, 10, 30 and 100 mg kg(-1)), the PDE-4 inhibitor roflumilast (3 mg kg(-1)) or vehicle, then exposed to CS (for 3 days) or to LPS (100 microg mL(-1), 30 min). Subsequent to the last smoke or LPS exposure, bronchoalveolar lavages (BAL) were performed and lungs were removed and homogenized to analyze various markers of inflammation at appropriate times.

KEY RESULTS

Inhibition of MMP-12 by AS111793 (10 and 30 mg kg(-1)) was associated with a reduction of the increase in neutrophil number in BAL fluids after 4 days and of macrophages after 11 days. On day 4, AS111793 also significantly reduced all the inflammation markers that had increased after CS exposure, including soluble TNF receptors I and II, MIP-1gamma, IL-6 and pro-MMP-9 activity in BAL fluids, and KC/CXCL1, fractalkine/CX3CL1, TIMP-1 and I-TAC/CXCL11 in lung parenchyma. In contrast, inhibition of MMP-12 did not reduce neutrophil influx, pro-MMP-9 activity or KC/CXCL1 release in BAL fluids of mice exposed to LPS.

CONCLUSION

Inhibition of MMP-12 with AS111793, reduced the inflammatory process associated with exposure of mice to CS, strongly suggesting a specific involvement of MMP-12 in lung inflammation following CS exposure.

Evaluation of the anti-inflammatory effect of infliximab in a mouse model of acute asthma

BACKGROUND AND OBJECTIVE

To evaluate the potential role of anti-tumour necrosis factor (TNF)-alpha mAb (infliximab) on the inflammatory response in a mouse model of acute asthma.

METHODS

BALB/c mice received intraperitoneal (i.p.) ovalbumin (OVA) on days 0 and 14, 100 microg of OVA intranasally on day 14 and 50 microg of OVA intranasally on days 25, 26 and 27. The low-dose (2.5 mg/kg) and high-dose (6.25 mg/kg) infliximab groups received i.p. infliximab before each i.p. sensitization and on challenge days 1, 6, 13, 20 and 27. The control group received i.p. injections of normal saline with alum on days 0 and 14 and normal saline without alum on days 14, 25, 26 and 27.

RESULTS

There were statistically significant decreases in the numbers of BAL fluid (BALF) neutrophils, eosinophils, as well as lung eosinophils in both the low- and high-dose infliximab groups when compared with the control OVA sensitized/challenged group. The lower dose of infliximab did not alter lung neutrophil counts, but a marked decrease was seen with the high dose of infliximab. After treatment with low and high doses of infliximab, BALF levels of regulated on activation normal T cell expressed and secreted (RANTES), granulocyte macrophage-colony stimulating factor (GM-CSF), TNF-alpha, IL-6, macrophage inflammatory protein (MIP)-2, and levels of RANTES, IL-4, GM-CSF, TNF-alpha, IL-6 and MIP-2 in lung tissue were significantly decreased when compared with the control OVA sensitized/challenged group. There was a significant decrease in BALF IL-4 only in the high-dose infliximab group.

CONCLUSIONS

These results show that an anti-TNF-alpha mAb has a considerable anti-inflammatory effect on allergen-induced lung inflammation in an animal model of acute asthma.

Targeting lung inflammation: novel therapies for the treatment of COPD

Chronic obstructive pulmonary disease (COPD) is a global health problem. As understanding of pathology of COPD has increased it has been established that COPD is associated with the progressive pulmonary inflammation and destruction of lung parenchyma (emphysema) that relate to disease severity. Therefore, it is anticipated that drugs that reduce pulmonary inflammation will provide effective, disease modifying therapy for COPD. Several specific therapies are directed against the influx of inflammatory cells into the airways and lung parenchyma that occurs in COPD; these include agents directed against cytokines and chemokines. Broad-range anti-inflammatory drugs are now in phase III development for COPD; they include inhibitors of phosphodiesterase 4 (PDE4). Other drugs that inhibit cell signaling include inhibitors of p38 mitogen-activated protein kinase (MAPK), nuclear factor-κB (NF-κB), and phosphoinositide-3-kinase (PI3K). There is also a search for inhibitors of proteinases and matrix metalloproteinases (MMPs) to prevent lung destruction and the development of emphysema. This review highlights studies on novel or potential anti-inflammatory agents that might be considered in the development of new future therapies for COPD.

Role of TNFalpha in pulmonary pathophysiology

Tumor necrosis factor alpha (TNFα) is the most widely studied pleiotropic cytokine of the TNF superfamily. In pathophysiological conditions, generation of TNFα at high levels leads to the development of inflammatory responses that are hallmarks of many diseases. Of the various pulmonary diseases, TNFα is implicated in asthma, chronic bronchitis (CB), chronic obstructive pulmonary disease (COPD), acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). In addition to its underlying role in the inflammatory events, there is increasing evidence for involvement of TNFα in the cytotoxicity. Thus, pharmacological agents that can either suppress the production of TNFα or block its biological actions may have potential therapeutic value against a wide variety of diseases. Despite some immunological side effects, anti-TNFα therapeutic strategies represent an important breakthrough in the treatment of inflammatory diseases and may have a role in pulmonary diseases characterized by inflammation and cell death.