Effects of pentoxifylline on inflammation and lung dysfunction in ventilated septic animals

Therapeutic effects of pentoxifylline on invasive pulmonary aspergillosis in immunosuppressed mice

Background

The most common and severe infection of Aspergillus fumigatus is invasive pulmonary aspergillosis (IPA), which is usually seen in immunocompromised patients. Neutropenia is the primary risk factor implicated in IPA; however, IPA also occurs in patients without neutropenia, namely, those who are immunosuppressed owing to long-term corticosteroid use. With IPA-associated mortality as high as 51–79%, novel and effective treatment strategies are urgently needed. Pentoxifylline (PTX) has been shown to competitively inhibit the family 18 chitinases in fungi, which may be an new antifungal therapy. Hence, the aim of our study was to compare neutropenic and non-neutropenic IPA mouse models, and to evaluate the effect of PTX on IPA in immunosuppressed mice.

Methods

C57BL/6J mice were pre-treated with cyclophosphamide and hydrocortisone. Neutropenic model IPA mice (CTX-IPA) and non-neutropenic IPA mice (HC-IPA) were established by intranasal administration of Aspergillus fumigatus spore suspension. A subset of each group was injected with PTX post-infection. Among these groups, we compared overall survival, pulmonary fungal burden, lung hispathology, and myeloperoxidase (MPO), interleukin 8 (IL-8), and mammalian chitinase concentration in the bronchoalveolar lavage fluid (BALF).

Results

The survival rate of the HC-IPA group was higher than that of the CTX-IPA group, and pulmonary fungal burden was also lower (p < 0.05). The CTX-IPA group showed infiltration of alveolae and blood vessels by numerous hyphae of A. fumigatus. The HC-IPA group exhibited destruction of bronchi, expansion of alveolar septa, increased macrophages aggregation, significant neutrophil infiltration and a few hyphae in peribronchial areas. After PTX treatment, improvement was observed in survival duration and pulmonary fungal burden in HC-IPA mice. MPO and IL-8 levels were lower in the HC-IPA + PTX group compared to the corresponding levels in the HC-IP group. Chitotriosidase (CHIT1) and Chitinase 3-like 1 (CHI3L1) expression in the HC-IPA group was decreased after PTX treatment (p < 0.05).

Conclusion

PTX was found to exert a therapeutic effect in a non-neutropenic mouse model of IPA, which may lead to the development of novel strategies for IPA treatment.

Pentoxifylline Alleviates Early Brain Injury After Experimental Subarachnoid Hemorrhage in Rats: Possibly via Inhibiting TLR 4/NF-κB Signaling Pathway

Early brain injury (EBI) after subarachnoid hemorrhage (SAH) generally causes significant and lasting damage. Pentoxifylline (PTX), a nonselective phosphodiesterase inhibitor, has shown anti-inflammatory and neuroprotective properties in several brain injury models, but the role of PTX with respect to EBI following SAH remains uncertain. The purpose of this study was to investigate the effects of PTX on EBI after SAH in rats. Adult male Sprauge-Dawley rats were randomly assigned to the sham and SAH groups. PTX (30 or 60 mg/kg) or an equal volume of the administration vehicle (normal saline) was administrated at 30 min intervals following SAH. Neurological scores, brain edema, and neural cell apoptosis were evaluated. In order to explore other mechanisms, changes in the toll-like receptor 4 (TLR4) and the nuclear factor-κB (NF-κB) signaling pathway, in terms of the levels of apoptosis-associated proteins, were also investigated. We found that administration of PTX (60 mg/kg) notably improved neurological function and decreased brain edema at both 24 and 72 h following SAH. Treatment with PTX (60 mg/kg) significantly inhibited the protein expressions of TLR4, NF-κB, MyD88 and the downstream pro-inflammatory cytokines, such as the tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β). PTX also significantly reduced neural cell death and BBB permeability. Our observations may be the first time that PTX has been shown to play a neuroprotective role in EBI after SAH, potentially by suppressing the TLR4/NF-κB inflammation-related pathway in the rat brain.

Pentoxifylline attenuates nitrogen mustard-induced acute lung injury, oxidative stress and inflammation

Nitrogen mustard (NM) is a toxic alkylating agent that causes damage to the respiratory tract. Evidence suggests that macrophages and inflammatory mediators including tumor necrosis factor (TNF)α contribute to pulmonary injury. Pentoxifylline is a TNFα inhibitor known to suppress inflammation. In these studies, we analyzed the ability of pentoxifylline to mitigate NM-induced lung injury and inflammation. Exposure of male Wistar rats (150-174 g; 8-10 weeks) to NM (0.125 mg/kg, i.t.) resulted in severe histopathological changes in the lung within 3d of exposure, along with increases in bronchoalveolar lavage (BAL) cell number and protein, indicating inflammation and alveolar-epithelial barrier dysfunction. This was associated with increases in oxidative stress proteins including lipocalin (Lcn)2 and heme oxygenase (HO)-1 in the lung, along with pro-inflammatory/cytotoxic (COX-2(+) and MMP-9(+)), and anti-inflammatory/wound repair (CD163+ and Gal-3(+)) macrophages. Treatment of rats with pentoxifylline (46.7 mg/kg, i.p.) daily for 3d beginning 15 min after NM significantly reduced NM-induced lung injury, inflammation, and oxidative stress, as measured histologically and by decreases in BAL cell and protein content, and levels of HO-1 and Lcn2. Macrophages expressing COX-2 and MMP-9 also decreased after pentoxifylline, while CD163+ and Gal-3(+) macrophages increased. This was correlated with persistent upregulation of markers of wound repair including pro-surfactant protein-C and proliferating nuclear cell antigen by Type II cells. NM-induced lung injury and inflammation were associated with alterations in the elastic properties of the lung, however these were largely unaltered by pentoxifylline. These data suggest that pentoxifylline may be useful in treating acute lung injury, inflammation and oxidative stress induced by vesicants.

A comparative study of pentoxifylline effects in adult and aged rats submitted to lung dysfunction by thermal injury

PURPOSE

To investigate the protective effects of pentoxifylline against lung injury observed after dorsal scald in aged animals.

METHODS

Adult (eight months old) and aged (20 months old) rats were subjected to thermal injury or sham procedure. The six hours post-trauma animals received pentoxifylline and after 24 hours were euthanatized and lung tissue samples collected. The bronchoalveolar lavage fluid was evaluated for total protein content and tumor necrosis factor-alpha cytokine. Malondialdehyde and myeloperoxidase activity in the lung homogenate were measured and a histological lung examination was undertaken.

RESULTS

Burn injury induced oxidative stress in lung homogenate was higher in elderly-burned rats compared to adult-burned rats (p<0.001). Total protein and cytokine in bronchoalveolar lavage increased in the elderly-burned group when compared to the adult-burned group (p<0.001). All parameters decreased in both groups treated with pentoxifylline (p<0.05).

CONCLUSIONS

The injury was augmented in elderly rats when compared to adult rats. Damage was reduced with the use of pentoxifylline, however further studies are needed to evaluate the dose-response of the drug.

Biomarkers in acute lung injury: insights into the pathogenesis of acute lung injury

Studies of potential biomarkers of acute lung injury (ALI) have provided information relating to the pathophysiology of the mechanisms of lung injury and repair. The utility of biomarkers remains solely among research tools to investigate lung injury and repair mechanisms. Because of lack of sensitivity and specificity, they cannot be used in decision making in patients with ALI or acute respiratory distress syndrome. The authors reviewed known biomarkers in context of their major biologic activity. The continued interest in identifying and studying biomarkers is relevant, as it provides information regarding the mechanisms involved in lung injury and repair and how this may be helpful in identifying and designing future therapeutic targets and strategies and possibly identifying a sensitive and specific biomarker.