Cathelicidin (LL-37) and human β2-defensin levels of children with post-infectious bronchiolitis obliterans

Serum concentrations of antimicrobial peptide cathelicidin LL-37 in patients with bacterial lung infections

Nowadays, data indicate that antimicrobial peptides play an important role in immunological defense. Human cathelicidin LL-37 possesses a broad spectrum of antimicrobial properties against Gram-positive and Gram-negative bacteria, and is thereby an important component of defense mechanisms within the respiratory tract. In this study, we determined the LL-37 serum level in patients with pneumonia caused by different bacteria species in comparison with healthy subjects. Twenty-two patients with pneumonia caused by coccal Gram-positive bacteria (I), 16 patients with pneumonia caused by Haemophilus influenzae (II), 29 patients with pneumonia caused by members of the Enterobacteriaceae (III), 13 patients caused by non-fermenting Gram-negative bacteria (IV), and 30 healthy controls were enrolled in the study. Serum LL-37 concentration was measured using an enzyme-linked immunosorbent assay (ELISA). The mean LL-37 concentration in pneumonia patients was significantly higher in group I (p = 0.0032), group II (p = 0.0022), and group III (p = 0.019), and significantly lower in group IV (p = 0.000004) as compared with healthy volunteers. Our data suggest that LL-37 plays an important role in defense mechanisms during pneumonia. The reduced level of this peptide in subjects with pneumonia caused by opportunistic bacteria may reflect weakened immune system reactivity in these patients.

Circulating cathelicidin LL-37 level is increased in euthymic patients with bipolar disorder

More and more data seems to imply that immune mechanisms are involved in the pathomechanism of bipolar disorder (BD). However, the primary role of cathelicidin LL-37 is defense against pathogens, more and more data indicated that this peptide strongly modulates immune system functioning and contributes to immune pathology of chronic and inflammatory diseases. No data is available on the level of LL-37 in bipolar patients. The aim of the study was to examine the circulating levels of cathelicidin LL-37 in euthymic patients with BD. Forty patients with BD and fifty-nine healthy volunteers were enrolled into the study. Concentration of LL-37 in serum was assessed using immunoenzymatic test ELISA. The mean LL-37 concentration in bipolar patients and in healthy subjects were 4.60 ± 7.65 ng/mL and 1.92 ± 2.89 ng/mL, respectively, and the difference was statistically significant (p = 0.035). Within the BD group LL-37 level was significantly higher in women than in men (p = 0.045). The evaluation of serum LL-37 concentration during stable 8 week treatment indicated that at baseline (T1) mean level of LL-37 was 5.82 ± 10.59 ng/mL; and after treatment (T2) was 4.33 ± 5.87 ng/mL; the difference between T1 and T2 was not significant. Elevated serum levels of LL-37 in bipolar patients may suggest the role of this peptide in the pathomechanism of BD.

Endogenous antimicrobial factors in the treatment of infectious diseases

Nowadays, a number of antibiotic-resistant bacteria strains is increasing. It is a serious clinical problem and poses a threat to the effectiveness of conventional antibiotic therapy. Thus, scientists are constantly seeking new alternatives for treatment of infectious diseases. There are some natural endogenous factors, which possess antimicrobial activities against a large number of microorganisms, including both Gram-positive and Gram-negative bacteria, viruses and fungi. These factors are present in all eukaryotic organisms and constitute an essential element of their immune system. A large number of in vitro and in vivo models have been used to show the activity of antimicrobial factors, and only few studies have been conducted on people. Results indicate that administration of these molecules is therapeutically beneficial. This review summarizes knowledge of selected endogenous antimicrobial agents, such as cathelicidins, defensins, histatins, lysozyme and lactoferrin. We also discuss potential uses of these factors in the treatment of infectious diseases.

Hypoxemia is an independent predictor of bronchiolitis obliterans following respiratory adenoviral infection in children

Bronchiolitis obliterans (BO) is an uncommon and severe sequela of chronic obstructive lung disease in children that results from an insult to the lower respiratory tract. Few prognostic factors achieved worldwide acknowledgment. In the present study, we retrospectively collected the children with respiratory adenoviral infection and identified the predictive factors of BO. In the period between Jan 2011 and December 2014, the consecutive in-hospital acute respiratory infection children with positive result for adenovirus were enrolled into the present study. High resolution computerized tomography and clinical symptoms were utilized as the diagnostic technique for BO. Multivariate analysis using a Logistic proportional hazards model was used to test for independent predictors of BO. A total of 544 children were included with 14 (2.57 %) patients developed BO. Compared with children without BO, BO children presented higher LDH (523.5 vs. 348 IU/ml, p = 0.033), lower blood lymphocyte count (2.23 × 10⁹/L vs. 3.24 × 10⁹/L, p = 0.025) and higher incidence of hypoxemia (78.6 vs. 20.8 %, p = 0.000). They presented relatively persistent fever (15.5 vs. 7 days, p = 0.000) and needed longer treatment in hospital (19.5 vs. 7 days, p = 0.000). Concerning treatment, they were given more intravenous γ-globulin (85.7 vs. 36.8 %, p = 0.000), glucocorticoids (78.6 vs. 24.3 %, p = 0.000) and mechanical ventilation (35.7 vs. 5.5 %, p = 0.001). Multiple analyses determined that hypoxemia was the only independent predictor for BO. The present study identified hypoxemia as the independent predictive factor of BO in adenoviral infected children, which was a novel and sensitive predictor for BO.

Proteomic Changes in Chicken Plasma Induced by Salmonella typhimurium Lipopolysaccharides

Lipopolysaccharides (LPS) are cell wall components of Gram-negative bacteria that produce inflammation and sickness in higher animals. The objective was to identify plasma proteomic changes in an avian model of inflammation. Chickens were treated with either saline or LPS, and blood was collected at 24 hours postinjection. The pooled plasma samples were depleted of high-abundant proteins and analyzed by matrix-assisted laser desorption ionization (MALDI)-time-of-flight mass spectrometry and liquid chromatography–tandem mass spectrometry (LC–MS/MS). MALDI analyses showed an increase in fibrinogen beta-derived peptide and a decrease in apolipoprotein-AII-derived peptide in LPS samples. Label-free quantitation of LC–MS/MS spectra revealed an increase in the levels of α1-acid glycoprotein, a chemokine CCLI10, and cathelicidin-2, but a decrease in an interferon-stimulated gene-12-2 protein in the LPS group. These differentially expressed proteins are associated with immunomodulation, cytokine changes, and defense mechanisms, which may be useful as candidate biomarkers of infection and inflammation.

Role of intestinal flora and defensins in colorectal carcinogenesis

Colorectal cancer is a common malignant tumor of the digestive system. In recent years, the morbidity and mortality of colorectal cancer in China have been rising continuously, causing heavy medical burden; however, the exact etiology is still unknown. Therefore, there is an urgent need to elucidate the etiology and pathogenesis of colorectal cancer to promote early prevention, effective screening and targeted therapy. At present, the research on the correlation between intestinal flora and colorectal cancer is being deepened constantly. Defensins, mediating interaction between intestinal flora and the intestinal mucosa, have attracted more and more attention because of their potential role in the development of colorectal cancer. Here we briefly introduce human intestinal flora and defensins, review new advances in our understanding of their role in colorectal carcinogenesis and the possible mechanism, and preliminarily explore their mutual interaction.