SP-A preserves airway homeostasis during Mycoplasma pneumoniae infection in mice

The lung is constantly challenged during normal breathing by a myriad of environmental irritants and infectious insults. Pulmonary host defense mechanisms maintain homeostasis between inhibition/clearance of pathogens and regulation of inflammatory responses that could injure the airway epithelium. One component of this defense mechanism, surfactant protein-A (SP-A), exerts multifunctional roles in mediating host responses to inflammatory and infectious agents. SP-A has a bacteriostatic effect on Mycoplasma pneumoniae (Mp), which occurs by binding surface disaturated phosphatidylglycerols. SP-A can also bind the Mp membrane protein, MPN372. In this study, we investigated the role of SP-A during acute phase pulmonary infection with Mp using mice deficient in SP-A. Biologic responses, inflammation, and cellular infiltration, were much greater in Mp infected SP-A(-/-) mice than wild-type mice. Likewise, physiologic responses (airway hyperresponsiveness and lung compliance) to Mp infection were more severely affected in SP-A(-/-) mice. Both Mp-induced biologic and physiologic changes were attenuated by pharmacologic inhibition of TNF-alpha. Our findings demonstrate that SP-A is vital to preserving lung homeostasis and host defense to this clinically relevant strain of Mp by curtailing inflammatory cell recruitment and limiting an overzealous TNF-alpha response.

[Subclass distribution of human IgG antibodies to Mycoplasma pneumoniae in the course of mycoplasmosis]

The prevalence of human IgG1-IgG4 to sonicated antigen of M. pneumoniae in the 138 sera obtained from patients with mycoplasmosis was analysed. Antibodies of IgG1 were diagnosed in 47 (34.1%), IgG2 in 42 (30.4%) and IgG3 subclass in 58 (42.0%) serum samples. The concentration of IgG4 was below detection level. Generally, the frequency of occurrence of IgG2 antibodies increased with age reaching its peak among adults. On the other hand IgG1 and IgG3 for M. pneumoniae were diagnosed more often in serum samples obtained from children than from adults. We did not find any essential changes in the pattern of IgG subclass during the course of infection however it seems that the level of IgG3 antibodies decreased faster than IgG1 which may be caused by the fact that the IgG3 antibodies have a much shorter half-life in comparison to the IgG1.

Do serological tests provide adequate rapid diagnosis of Mycoplasma pneumoniae infection?

This study was designed to evaluate the serologic response to Mycoplasma pneumoniae infection. A total of 589 children < or =18 years (190 in the year 2004; 399 in 2005) and 2,073 adults > or = 18 years of age (980 in the year 2004; 1,093 in 2005) with respiratory symptoms underwent serological testing for M. pneumoniae infection. The tests included passive particle agglutination (PA) and enzyme-linked immunosorbent assay (ELISA). The seroprevalence rates of M. pneumoniae infection in the years 2004 and 2005 were 6.9 and 10.1%, respectively. The seropositivity rate was significantly higher in children (29.6% in 2005; 23.7% in 2004) than in adults (2.9% in 2005; 3.7% in 2004) (odds ratio, 8.138 in 2004; 13.923 in 2005; 95% confidence interval, 5.077-13.045 in 2004; 9.220-21.026 in 2005). Paired sera for the PA test were obtained from 32 of 399 children, and 22 of them demonstrated at least fourfold rises in antibody titer. ELISA had a sensitivity of 77.3% and a specificity of 40.0%; PA had a sensitivity of 9.5% and a specificity of 80%. The ELISA test was superior to the PA test in diagnosing acute M. pneumoniae infection in children. Both tests were significantly more sensitive when they were performed 1 week after the onset of infection.

Transient acquired hemophilia associated with Mycoplasma pneumoniae pneumonia

Acquired hemophilia is a rare disorder caused by autoantibodies to factor VIII (FVIII) (also referred to as factor VIII inhibitors or anti-FVIII) and may be associated with pregnancy, underlying malignancy, or autoimmune disorders. A 33-month-old girl who presented with hematochezia and ecchymotic skin lesions was diagnosed with Mycoplasma pneumoniae pneumonia by serology and polymerase chain reaction. Hematologic studies showed a prolonged activated partial thromboplastin time (aPTT), partially corrected mixing test for aPTT, reduced levels of FVIII, and the presence of antibodies against FVIII. She was treated conservatively with prednisone and intravenous immunoglobulin (IVIG) without FVIII transfusion and recovered without sequelae. This report provides the first description of acquired hemophilia due to anti-FVIII in association with M. pneumoniae in Korea. We discuss this case in the context of the current literature on acquired hemophilia in children.

[Case of macrolide-ineffective Mycoplasma pneumoniae pneumonia successfully treated with intravenous ciprofloxacin]

A 18-year-old man complaining of remittent fever and nonproductive cough visited a nearby clinic. He did not recover despite treatment of oral azithromycin. We admitted him because his chest radiograph showed consolidation in the left upper lung field. We diagnosed his pneumonia as co-infection by non-bacterial and bacterial pathogens, and initiated treatment with intravenous ampicillin and oral clarithromycin. On the 3rd day after admission his symptom had not improved, so his treatment was changed to intravenous panipenem/betamipron and erythromycin. Ciprofloxacin was administered intravenously because consolidative shadows with atelectasis increased on the chest radiograph on the 6th day. Clinical symptoms such as fever, CRP and chest radiograph findings were rapidly improved after the start of ciprofloxacin treatment. He was discharged on the 22nd hospital day. Since serum antibody titer against Mycoplasma pneumoniae was elevated to x 20,480 on the 13th hospital day, it is confirmed that causative pathogen was macrolide-ineffective Mycoplasma Pneumoniae.

Function and regulation of SPLUNC1 protein in Mycoplasma infection and allergic inflammation

Respiratory infections, including Mycoplasma pneumoniae (Mp), contribute to asthma pathobiology. To date, the mechanisms underlying the increased susceptibility of asthmatics to airway Mp infection remain unclear. Short palate, lung, and nasal epithelium clone 1 (SPLUNC1) protein is a recently described large airway epithelial cell-derived molecule that was predicted to exert host defense activities. However, SPLUNC1 function and regulation in an infectious or allergic milieu are still unknown. We determined host defense and anti-inflammatory functions of SPLUNC1 protein in Mp infection and the regulation of SPLUNC1 by Mp and allergic inflammation (e.g., IL-13). SPLUNC1 function was examined in Mp or human airway epithelial cell cultures by using SPLUNC1 recombinant protein, overexpression and RNA interference. Human and mouse bronchial epithelial SPLUNC1 was examined using immunostaining, Western blotting, ELISA, laser capture microdissection, and real-time PCR. Mouse models of Mp infection and allergic inflammation and air-liquid interface cultures of normal human primary bronchial epithelial cells were used to study SPLUNC1 regulation by Mp and IL-13. We found that: 1) SPLUNC1 protein decreased Mp levels and inhibited epithelial IL-8 production induced by Mp-derived lipoproteins; 2) normal human and mouse large airway epithelial cells expressed high levels of SPLUNC1; and 3) although Mp infection increased SPLUNC1, IL-13 significantly decreased SPLUNC1 expression and Mp clearance. Our results suggest that SPLUNC1 serves as a novel host defense protein against Mp and that an allergic setting markedly reduces SPLUNC1 expression, which may in part contribute to the persistent nature of bacterial infections in allergic airways.

Is there any relationship between asthma and asthma attack in children and atypical bacterial infections; Chlamydia pneumoniae, Mycoplasma pneumoniae and Helicobacter pylori

Asthma is a chronic inflammatory airway disease characterized by variable airway obstruction and bronchial hyperresponsiveness. There are many factors affecting the development and severity of childhood asthma such as genetic predisposition, atopy, environmental factors, obesity, diet, socioeconomic status, and infectious triggers. In the present study we aimed to investigate the frequency of Mycdoplasma pneumoniae, Chlamydia pneumoniae, and Helicobacter pylori infections in asthmatic children. We investigated also whether there is a relationship between these agents and asthma attacks.

MATERIAL AND METHODS

Seventy-nine asthmatic children (46 males, aged 5-15 years) were included in study. The study group was divided into two groups: group 1 consisted of 37 children with asthma attacks and group 2 consisted of 42 children with stable asthma. As a control group we studied 36 healthy children. Pulmonary function tests, skin prick tests for common allergens were performed; serum total IgE, phadiatop, specific IgM and IgG antibody levels (ELISA) for M. pneumoniae, C. pneumoniae and H. pylori were measured in all patients.

RESULTS

Mycoplasma IgM and Chlamidia IgM were positive in 8.1% (3 patients) and 18.9% (7 patients) of group 1 patients, respectively. There was a statistically significant difference for Mycoplasma IgM (p = 0.031) and Chlamidia IgM (p = 0.03) between group1 and other two groups. We have not found significant difference for M. pneumoniae IgG, C. pneumoniae IgG and H. pylori IgM and IgG among groups.

CONCLUSION

M. Pneumoniae and C. Pneumoniae may play a role in development of asthma exacerbations in childhood. We could not find a relationship between H. Pylori and asthma.

Evaluation of four commercial IgG- and IgM-specific enzyme immunoassays for detecting Mycoplasma pneumoniae antibody: comparison with particle agglutination assay

Diagnosis of Mycoplasma pneumoniae infection is important due to its variable clinical manifestations and absence of response to beta-lactams. Introduction of enzyme immunoassays (EIAs) for serologic diagnosis of M. pneumoniae has made it possible to separate the analyses of specific IgG and IgM antibodies. We compared four different commercial EIAs, ImmunoWELL IgG, IgM (GenBio), Medac IgG, IgA, IgM (Medac), Platelia IgG, IgM (Sanofi Pasteur), and Ridascreen IgG, IgA, IgM (r-Biopharm) with indirect particle agglutination assay (PA), Serodia-MycoII (Fujirebio). We tested 91 specimens from 73 pediatric patients (2-17 yr) hospitalized at a tertiary-care hospital between December 2005 and January 2006. The measurements of IgM EIAs were correlated with PA titers (Spearman's correlation coefficient, from 0.89 to 0.92) with high concordance rates, ranging from 82.4% to 92.3%. However, some negative IgM-EIA results in PA-positive specimens indicated that serial samplings with convalescent sera would be necessary to confirm M. pneumoniae infection.

Anti-galactocerebroside testing in Mycoplasma pneumoniae-associated encephalitis☆

Mycoplasma pneumoniae (Mp) is the most frequently identified pathogen in the California Encephalitis Project, but the role and mechanism of Mp is unclear. Since auto-antibodies to anti-galactocerebroside (anti-GalC) have been reported in patients with evidence of acute Mp infection of the central nervous system (CNS), serum and cerebrospinal fluid (CSF) samples from 26 patients with evidence of Mp were tested for anti-GalC antibodies. Anti-GalC antibody was found in the CSF of only eight (31%) of 21 Mp patients indicating that CSF anti-GalC antibody is not a specific marker for Mp CNS disease.

Isolation and immunological detection of Mycoplasma ovipneumoniae in sheep with atypical pneumonia, and lack of a role for Mycoplasma arginini

Mycoplasma ovipneumoniae NCTC 10151(T) and four new isolates from UK sheep flocks were compared. Only glucose and pyruvate were used as energy sources by the five strains: glucose was the best energy source for the type strain, pyruvate supported better growth of the new strains. Whole cell protein patterns and antigenic profiles showed high similarity between all five strains. The new isolates fell into two groups in ELISA tests. Serum samples from 30 pneumonic sheep were assessed for M. ovipneumoniae infection and Mycoplasma arginini co-infection. Fourteen (out of 30) serum samples were positive for M. ovipneumoniae both by ELISA and immunoblotting. Twelve antigenic proteins of M. ovipneumoniae were detected in infected serum samples: the antigen patterns were unique, with between one and at least seven occurring in any one sample. All serum samples were designated as negative for M. arginini antibodies by both ELISA and immunoblotting.

[Positive phase periods of ImmunoCard Mycoplasma tests]

We evaluated the positive phase period of ImmunoCard Mycoplasma tests. The subjects were 74 penumonia patients (male : 38, female : 36, 17-94 years old) with positive ImmunoCard Mycoplasma tests. ImmunoCard Mycoplasma tests were performed every week for 8 weeks later, then every 4 weeks until negative conversion. The positive phase period was within a week in 30 of 74 patients (40.5%) and within 4 weeks in 52 patients (70.3%). In each generation the positive phase period of the most patients was within a week. The positive phase period of the elderly had no tendency to be longer than that of the young patients. These results indicated that about half of the patients with positive ImmunoCard Mycoplasma tests showed Mycoplasma infection which occurred within the past 1 week.

A deficient TLR2 signaling promotes airway mucin production inMycoplasma pneumoniae-infected allergic mice

The original hygiene hypothesis suggests that early childhood respiratory infections preceding allergen exposure may decrease the prevalence of allergic diseases. We have recently demonstrated that Mycoplasma pneumoniae infection preceding allergen exposure reduced allergic responses in mice. However, the molecular mechanisms underlying the protective role of M. pneumoniae in allergic responses, particularly airway mucin production, remain unclear. Wild-type and Toll-like receptor 2 (TLR2)-deficient mice with a respiratory M. pneumoniae infection preceding allergen (ovalbumin) challenge were utilized to determine the regulatory role of TLR2-IFN-γ signaling pathway in airway mucin expression. Furthermore, air-liquid interface cultures of mouse primary tracheal epithelial cells were performed to examine the effects of IFN-γ on mucin expression. In wild-type mice, M. pneumoniae infection preceding allergen challenge significantly reduced airway mucins but increased IFN-γ. In sharp contrast, in TLR2-deficient mice, M. pneumoniae preceding allergen challenge resulted in increased mucin protein without a noticeable change of IFN-γ. In cultured mouse primary tracheal epithelial cells, IFN-γ was shown to directly inhibit mucin expression in a dose-dependent manner. Our study demonstrates for the first time that a respiratory M. pneumoniae infection preceding allergen challenge reduces airway epithelial mucin expression in part through TLR2-IFN-γ signaling pathway. A bacterial infection in asthmatic subjects with weakened TLR2-IFN-γ signaling may result in an exaggerated airway mucin production.

[Combined method of community-acquired pneumonia prevention in military staff]

Efficacy of pneumococcal polysaccharide vaccine "Pneumo 23" or its combination with food products prepared from vegetative material for prevention of community-acquired pneumonias has been compared. Advantages of combined method of prophylaxis in setting where pneumonia caused by different pathogens have been noted. Variability in etiology of community-acquired pneumonia was demonstrated by serological tests of patients' blood. During spring-summer season antibodies to Mycoplasma pneumoniae, Chlamydia pneumoniae, and Streptococcus pneumoniae were detected in 25.9, 2.5, and 7.0% of the patients respectively. During autumn-winter season antibodies to M. pneumoniae and S. pneumoniae were detected in 30.0 and 50.0% of the patients respectively.

Mycoplasma pneumoniae, splenic infarct, and transient antiphospholipid antibodies: a new association?

We report 2 children with Mycoplasma pneumoniae pulmonary infection with splenic infarcts and transient antiphospholipid antibodies. This association has not been reported previously.

IL-23-dependent IL-17 production is essential in neutrophil recruitment and activity in mouse lung defense against respiratory Mycoplasma pneumoniae infection

IL-23 induces IL-17 production in activated CD4+ T cells and participates in host defense against many encapsulated bacteria. However, whether the IL-23/IL-17 axis contributes to a Mycoplasma pneumoniae (Mp)-induced lung inflammation (e.g., neutrophils) has not been addressed. Using an acute respiratory Mp infection murine model, we found significantly up-regulated lung IL-23p19 mRNA in the early phase of infection (4h), and alveolar macrophages were an important cell source of Mp-induced IL-23. We further showed that Mp significantly increased IL-17 protein levels in bronchoalveolar lavage (BAL). Lung gene expression of IL-17, IL-17C and IL-17F was also markedly up-regulated by Mp in vivo. IL-17 and IL-17F were found to be derived mainly from lung CD4+ T cells, and were increased upon IL-23 stimulation in vitro. In vivo blocking of IL-23p19 alone or in combination with IL-23/IL-12p40 resulted in a significant reduction of Mp-induced IL-17 protein and IL-17/IL-17F mRNA expression, which was accompanied by a trend toward reduced lung neutrophil recruitment, BAL neutrophil activity, and Mp clearance. However, IL-23 neutralization had no effect on Mp-induced lung IL-17C mRNA expression. These results demonstrate that IL-17/IL-17F production is IL-23-dependent in an acute Mp infection, and contributes to neutrophil recruitment and activity in the lung defense against the infection.

Respiratory tract infection with Mycoplasma pneumoniae in interleukin-12 knockout mice results in improved bacterial clearance and reduced pulmonary inflammation

Mycoplasma pneumoniae is a leading cause of pneumonia and is associated with asthma. Evidence links M. pneumoniae respiratory disease severity with interleukin-12 (IL-12) concentration in respiratory secretions. We evaluated the microbiologic, inflammatory, and pulmonary function indices of M. pneumoniae pneumonia in IL-12 (p35) knockout (KO) mice and wild-type (WT) mice to determine the role of IL-12 in M. pneumoniae respiratory disease. Eight-week-old wild-type BALB/c mice and 8-week-old IL-12 (p35) KO BALB/c mice were inoculated once intranasally with 10(7) CFU of M. pneumoniae. Mice were evaluated at days 2, 4, and 7 after inoculation. Outcome variables included quantitative bronchoalveolar lavage (BAL) M. pneumoniae culture, lung histopathologic scores (HPS), BAL cytokine concentrations determined by enzyme-linked immunosorbent assay (tumor necrosis factor alpha [TNF-alpha], gamma interferon [IFN-gamma], IL-1beta, IL-2, IL-4, IL-5, IL-6, IL-10, and granulocyte-macrophage colony-stimulating factor) and plethysmography, before and after methacholine, to assess airway obstruction (AO) and airway hyperreactivity (AHR). IL-12 (p35) KO mice infected with M. pneumoniae were found to have significantly lower BAL M. pneumoniae concentrations compared with M. pneumoniae-infected WT mice. Lung HPS and the parenchymal pneumonia subscores (neutrophilic alveolar infiltrate), as well as AO, were significantly lower in infected KO mice. No difference was found for AHR. Infected KO mice had significantly lower BAL concentrations of IFN-gamma than WT mice; a trend toward lower BAL concentrations was observed for IL-10 (P = 0.065) and TNF-alpha (P = 0.078). No differences were found for IL-1beta, IL-2, IL-4, IL-5, or IL-6. The lack of IL-12 in experimental M. pneumoniae pneumonia was associated with less severe pulmonary disease and more rapid microbiologic and histologic resolution.

[Serum levels of IFN-gamma and IL-4 in children with Mycoplasmal pneumonia at the acute phase]

OBJECTIVE

Interferon-gamma (IFN-gamma) and interleukin-4 (IL-4) are typical cytokines produced by CD4(+) T cells under antigenic stimulations, and the changes of serum levels of the two cytokines can indirectly reflect the immune state and the progress of inflammation. The aim of this study was to investigate the changes of IFN-gamma and IL-4 in peripheral blood of children with Mycoplasmal pneumonia.

METHODS

The peripheral blood concentrations of IFN-gamma and IL-4 were measured using ELISA in 40 children with Mycoplasmal pneumonia at the acute stage. The samples from 40 healthy children were used as the Control group.

RESULTS

The serum concentrations of IFN-gamma and IL-4 in the Mycoplasmal pneumonia group were 99.43 +/- 13.18 and 44.61 +/- 17.46 pg/mL, respectively, which were higher than those in the Control group (86.23 +/- 6.31 and 25.97 +/- 9.40 pg/mL respectively; P < 0.05).

CONCLUSIONS

There was an imbalance in cytokine secretion in children with Mycoplasmal pneumonia at the acute phase, suggesting that adjuvant immunological therapy is needed for Mycoplasmal pneumonia.

[Serologic diagnosis of chlamydial and Mycoplasma pneumoniae infections]

The diagnosis of Chlamydia trachomatis infection can be based either on direct detection of the organism or its components or indirectly by measuring antibodies as markers of the individual's response to the infection. The latter is currently of limited value. Neither IgG or IgA antibodies can be used to diagnose current genital infection by Chlamydia trachomatis or to exclude such an infection. There is no solid ground as yet for the use of IgA antibodies as a marker of persistant or unresolved infection. Commercial tests in the Elisa format based on peptides from the MOMP of Chlamydia trachomatis are available and show good specificities and sensitivities. Hsp60 seems to have a unique role in the development of tubal scarring and antibodies to chsp60 could predict tubal factor infertility. Serology is the main diagnostic tool for the diagnosis of Mycoplasma pneumoniae infection. The serologic assays are the complement fixation test (CF), immunofluorescence, the microparticle agglutination and recently EIAs. The CF test is still used for serodiagnosis of Mycoplasma pneumoniae infection because of the sensitivity of 90%. Single titer of >or= 64 are considered to be indicative of recent infection. A number of commercial EIAs have been developped. The difficulty for IgG interpretation is a definition of a cutoff value for discriminating infected and healthy subjects. Most of the IgM assays show good diagnostic sensitivities and are valuable tools for the early diagnosis of Mycoplasma pneumoniae infection in children. There are no wholly satisfactory serological methods for diagnosis of Chlamydia pneumoniae infection. Problems arise from the high background of IgG antibody prevalence, the lack of standardized testing methods.

Seroprevalence of Mycoplasma pneumoniae in HIV-infected patients using a microparticle agglutination test

Mycoplasma pneumoniae is increasingly recognized as a common and important pathogen in community settings, and is responsible for various pulmonary and extrapulmonary conditions in the normal population. However, the seroepidemiology of acute M. pneumoniae infection in HIV-infected individuals is still unclear worldwide. This study examined the seroprevalence of antibodies to M. pneumoniae in HIV-infected patients admitted with respiratory complaints at a tertiary AIDS care centre in Chennai, India. A commercial gelatin microparticle agglutination test (Serodia-Myco II, Fujirebio) was used for the determination of antibodies against M. pneumoniae in acute serum specimens. Of the 200 HIV-infected patients with underlying pulmonary conditions tested, 34 (17 % positivity; 95 % CI 12-23 %) had antibodies specific to M. pneumoniae, while among the 40 patients with no underlying pulmonary symptoms, five (12.5 % positivity; 95 % CI 4-27 %) had evidence of anti-M. pneumoniae antibody. This shows that the incidence of M. pneumoniae seropositivity is greater in patients with underlying pulmonary complaints. Most positive titres were found in the age group 28-37 years in the symptomatic and symptom-free groups (64.7 and 60 %, respectively). The positive titres ranged from 40 to >20 480. High titres (> or =320) were found in 10 out of the 39 patients (25.6 %). This seroprevalence study reports a 16.2 % prevalence of M. pneumoniae infections in HIV-infected patients by a particle agglutination test.