Rapid diagnosis of Mycoplasma pneumoniae in children with pneumonia by an immuno-chromatographic antigen assay

Mycoplasma pneumoniae is a particularly important pathogen that causes community acquired pneumonia in children. In this study, a rapid test was developed to diagnose M. pneumoniae by using a colloidal gold-based immuno-chromatographic assay which targets a region of the P1 gene. 302 specimens were analyzed by the colloidal gold assay in parallel with real-time PCR. Interestingly, the colloidal gold assay allowed M. pneumoniae identification, with a detection limit of 1 × 10(3) copies/ml. 76 samples were found to be positive in both real-time PCR and the colloidal gold assay; two specimens positive in real-time PCR were negative in the rapid colloidal gold assay. The specificity and sensitivity of the colloidal gold assay were 100% and 97.4%, respectively. These findings indicate that the newly developed immuno-chromatographic antigen assay is a rapid, sensitive and specific method for identifying M. pneumoniae, with potential clinical application in the early diagnosis of Mycoplasma pneumoniae infection.

The determinant of periodicity in Mycoplasma pneumoniae incidence: an insight from mathematical modelling

Until the early 1990 s, incidences of Mycoplasma pneumoniae (MP) infection showed three to five year epidemic cycles in multiple countries, however, the mechanism for the MP epidemic cycle has not been understood. Here, we investigate the determinant of periodicity in MP incidence by employing a mathematical model describing MP transmission dynamics. Three candidates for the determinant of periodicity were evaluated: school-term forcing, minor variance in the duration of immunity, and epidemiological interference between MP serotypes. We find that minor variation in the duration of immunity at the population level must be considered essential for the MP epidemic cycle because the MP cyclic incidence pattern did not replicate without it. Minor variation, in this case, is a less dispersed distribution for the duration of immunity than an exponential distribution. Various lengths of epidemic cycles, including cycles typically found in nature, e.g. three to five year cycles, were also observed when there was minor variance in the duration of immunity. The cyclic incidence pattern is robust even if there is epidemiological interference due to cross-immune protection, which is observed in the epidemiological data as negative correlation between epidemics per MP serotype.

Changes in levels of IL-9, IL-17, IFN-γ, dendritic cell numbers and TLR expression in peripheral blood in asthmatic children with Mycoplasma pneumoniae infection

Mycoplasma pneumoniae (MP) infection in children with asthma resulted in a more severe allergic state compared with a non-MP infected group. The infection rate of children with asthma was higher than that of the other groups, suggesting that being asthmatic may be a predisposing factor for MP infection and that the infection itself is an important co-factor in the disease progression of asthma. The number of dendritic cells (DCs) and the expression of TLR2 and TLR4 were compared in 22 asthmatic patients with MP infection, 22 asthmatic patients without MP infection, and 17 normal children as controls. The percentages of DCs in the peripheral blood of the three groups showed significant differences between asthmatic children with MP infection and controls, and asthmatic children without MP and controls (P<0.05), whereas no difference was found between asthmatic children with and without MP infection. The asthmatic children with MP infection group showed increased expression of TLR-2 and TLR-4 on DCs (P<0.01). Asthmatic patients infected with MP showed that DCs and TLRs (TLR-2, TLR-4) might play an important role in asthma pathogenesis with MP infection. The cytokines produced by the T-cell subsets in asthmatic children with MP infection showed a significant increase in IL-9 (P<0.01) and a decrease in IFN-γ (P<0.05) levels post-MP infection, while the IL-17 level remained stable (P>0.05), indicating a shift towards Th1/Th9 in the presence of MP infection.

[Determination of Th9 cells and IL-9 in children with Mycoplasma pneumoniae infection]

OBJECTIVE

To investigate the clinical significance of T helper type 9 (Th9) cells and interleukin-9 (IL-9) in children suffering from Mycoplasma pneumoniae (MP) infection.

METHODS

A total of 86 children who were diagnosed with MP infection between January 2013 and June 2014 were classified into upper respiratory infection (URI) group (n=29), mild MP pneumonia (MPP) group (n=32) and severe MPP group (n=25). Twenty-eight healthy children were used as the control group. Peripheral blood mononuclear cells were isolated by Ficoll density gradient centrifugation, and the percentage of Th9 cells in peripheral blood was measured by flow cytometry. Serum IL-9 level was determined using ELISA.

RESULTS

The URI, mild MPP, and severe MPP groups had significantly higher percentages of Th9 cells and IL-9 levels than the control group (P<0.05); the mild MPP and severe MPP groups had significantly higher percentages of Th9 cells and IL-9 levels than the URI group (P<0.05), and the two indices were significantly higher in the severe MPP group than in the mild MPP group (P<0.01).

CONCLUSIONS

Children with MP infection have an elevated percentage of Th9 cells and IL-9 expression, both of which are positively correlated with the severity of the disease. It can be predicted that Th9 cells and IL-9 can be used as evaluation indicators for the progression and outcome of children with MP infection.

Diagnostic sensitivity of a rapid antigen test for the detection of Mycoplasma pneumoniae: Comparison with real-time PCR

A rapid antigen kit for the detection of the Mycoplasma pneumoniae ribosomal protein L7/L12 using an immunochromatographic assay, Ribotest Mycoplasma, became available in Japan in 2013. To determine the sensitivity of Ribotest compared with real-time polymerase chain reaction (PCR), we prospectively performed these two tests simultaneously in adolescent and adult patients with community-acquired pneumonia (CAP). In addition, we retrospectively analyzed the theoretical sensitivity of Ribotest using M. pneumoniae PCR-positive specimens from previous studies. In prospective study, 118 CAP cases were enrolled, and 16 cases were diagnosed as M. pneumoniae pneumonia; eight cases were PCR-positive, one case was culture positive, and all cases demonstrated a four-fold increase in antibody titer. Ribotest was positive in 15 cases; five cases were PCR positive and 10 cases were PCR negative. For the PCR was control test, the sensitivity, specificity, and overall agreement with Ribotest were 62.5%, 90.9%, and 88.9%, respectively. In the retrospective study, we used 1110 M. pneumoniae PCR-positive specimens, which are collected from pediatric patients with respiratory tract infection who visited 65 institutions throughout Japan. Using a cut-off level for the Ribotest of 8.3 × 10(4) copy/mL in transport medium, 667 (60.0%) specimens were theoretically positive. In conclusion, our prospective and retrospective results demonstrated that the diagnostic sensitivity of Ribotest compared with PCR was not high, at approximately 60%. Thus, treatment decisions about M. pneumoniae pneumonia should be based on clinical findings such as Japanese Respiratory Society scoring system and not on Ribotest results alone.

[Etiologic deciphering of community-acquired pneumonia caused by mycoplasma pneumoniae]

AIM

Use of a complex of methods for etiologic deciphering of an acute respiratory infection.

MATERIALS AND METHODS

Clinical samples of blood sera, nasopharynx washes and sputum were obtained from 35 patients with acute respiratory disease (ARD). "Difco PPLO Broth" was used for M. pneumoniae cultivation. AHR, IFR, PCR, IFA were used in the study.

RESULTS

Results of the study have shown that M. pneumoniae antigens in blood, sera samples were detected in AHR in 32 patients, and specific G and M class antibodies--in 21 and 18 cases, respectively. Simultaneous detection of IgG and IgM was registered in 14 patients. M. pneumoniae cell DNA was detected in 10 of 20 blood sera samples. Circulating immune complexes were isolated from blood sera of 8 patients (4 with pneumonia, 4 with ARD) and M. pneumoniae antigens were detected in them by using direct-IFR. IFR study of sputum and nasopharynx smears has shown that M. pneumoniae antigens were detected in 29 of 35 samples. In 12 of 15 smear samples M. pneumoniae. DNA was detected by PCR. In 10 cases results of antigen detection by IFR as well as DNA in PCR coincided. Results of analysis of all the clinical material have shown that in 33 of 35 patients positive results coincided for 2 or 3 and in some cases 4 of the laboratory study methods used.

CONCLUSION

The use of diagnostic test complex significantly increases the accuracy of the study results, and detection of specific antibodies allows to determine disease period.

[Serum tumor necrosis factor-&alpha;, interleukin -6 and galctin-3 concentrations in children with Mycoplasma pneumoniae pneumonia]

OBJECTIVE

To study the changes in serum tumor necrosis factor-&alpha; (TNF- &alpha;), interleukin-6 (IL-6) and galctin-3 (Gal-3) concentrations in children with Mycoplasma pneumoniae pneumonia (MPP), and their roles in MPP.

METHODS

Serum TNF-&alpha;, IL-6 and Gal-3 concentrations were measured using double antibody sandwich ELISA in 48 children with acute MPP (severe: 21 cases; mild: 27 cases) and in 30 healthy children (control group).

RESULTS

Serum concentrations of TNF-&alpha;, IL-6 and Gal-3 in both the severe and mild groups were significantly higher than in the control group before treatment. The concentrations of the three indexes in the severe group were significantly higher than in the mild group. Serum concentrations of the three indexes decreased significantly after treatment in both groups.

CONCLUSIONS

Serum TNF-&alpha;, IL-6 and Gal-3 play important roles in the occurrence and development of pediatric MPP and their levels are associated the severity of this disorder.

[Clinical efficacy of adjuvant therapy with glucocorticoids in children with lobar pneumonia caused by Mycoplasma pneumoniae]

OBJECTIVE

To study the clinical efficacy of adjuvant therapy with glucocorticoids in children with lobar pneumonia caused by Mycoplasma pneumoniae.

METHODS

One hundred and eight children with lobar pneumonia caused by Mycoplasma pneumoniae were randomly divided into routine treatment and hormone treatment groups. Both groups were treated with azithromycin and other symptomatic therapies. In addition to the basic treatment, the hormone treatment group was given dexamethasone 0.25-0.3 mg/(kg·d) by intravenous drip until the body temperature was normal. Then given oral prednisone tablets 0.5-1 mg/(kg·d) (gradually reduced) for a total treatment course of 7-10 days. Before and after treatment pulmonary functions were examined, and serum C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), interleukin-2 (IL-2) and interleukin-6 (IL-6) were measured.

RESULTS

The duration of fever, cough relief time and pulmonary shadow absorption time on chest X-ray were significantly shorter in the hormone treatment group than in the routine treatment group (P<0.05). After treatment, the two groups showed improvements in serum CRP, ESR, IL-2, and IL-6 (P<0.05), but the hormone treatment group showed significantly more improvement (P<0.05). Varying degrees of mixed ventilation dysfunction were seen in the two groups before treatment, and hormone therapy significantly improved pulmonary function, especially promoting the recovery of small airway function.

CONCLUSIONS

Adjuvant therapy with glucocorticoids can effectively alleviate clinical symptoms, promote the absorption of pulmonary inflammation, and improve pulmonary function in children with lobar pneumonia caused by Mycoplasma pneumoniae.

[Effect of Mycoplasma pneumoniae infection on function of T lymphocytes in bronchoalveolar lavage fluid of asthmatic children]

OBJECTIVE

To investigate the effect of Mycoplasma pneumoniae (MP) infection on the function of T lymphocytes in the bronchoalveolar lavage fluid (BALF) of asthmatic children in acute and stable periods and the relationship between MP infection and asthma.

METHODS

Seventy-one hospitalized children (with bronchitis, pneumonia, and asthma) were divided into non-MP infection control group (group A, pneumonia and bronchitis without MP infection), non-MP infection asthma group (group B), and MP infection asthma group (group C). Flow cytometry was used to determine CD3(+), CD4(+), and CD8(+) T cell counts and CD4(+)/CD8(+) ratio in BALF among all children in acute and stable periods.

RESULTS

Compared with group A, groups B and C showed significant differences in CD3(+), CD4(+), and CD8(+) T cell counts and CD4(+)/CD8(+) ratio (P<0.05) in acute and stable periods, had decreased CD3(+) and CD4(+) T cell counts, an increased CD8(+) T cell count, and a significantly decreased CD4(+)/CD8(+) ratio (P<0.05) in the acute period, and had decreased CD3(+) and CD4(+) T cell counts and CD4(+)/CD8(+) ratio and an increased CD8(+) T cell count (P<0.05) in the stable period. Compared with group B, group C had significantly decreased CD3(+) and CD4(+) T cell counts and CD4(+)/CD8(+) ratio (P<0.05) and a significantly increased CD8(+) T cell count (P<0.05) in the acute period and showed no significant differences in CD3(+), CD4(+), and CD8(+) T cell counts (P>0.05) and a significant decrease in CD4(+)/CD8(+) ratio (P<0.05) in the stable period.

CONCLUSIONS

The immunological function of T lymphocytes in the airway declines significantly among asthmatic children with MP infection in acute and stable periods, leading to immue system disorder. MP may be associated with the pathogenesis of asthma.

[Effect of low-dose methylprednisolone on serum TNF-α level in children with Mycoplasma pneumoniae pneumonia]

OBJECTIVE

To investigate the effect of low-dose methylprednisolone on serum tumor necrosis factor alpha (TNF-α) level in children with Mycoplasma pneumoniae pneumonia (MPP).

METHODS

A case-control study was conducted among 38 children with MPP who received treatment in the Affiliated Hospital of Yan'an University between January and December 2012, and who had not received glucocorticoids before hospitalization. They were randomly divided into methylprednisolone treatment (n=20) and conventional treatment groups (n=18). The methylprednisolone treatment group was administered with methylprednisolone (1 mg/kg·d) by intravenous drip for three days in addition to conventional treatment. Serum samples were collected from both groups before treatment and on days 4 and 7 of treatment. Twenty-five children who underwent physical examination in the healthcare clinic during the same period were randomly selected as a normal control group, and serum samples were collected on the same day that the physical examination was performed. Serum TNF-α levels in the three groups were measured using enzyme-linked immunosorbent assay.

RESULTS

On admission, the methylprednisolone treatment and conventional treatment groups had significantly higher serum TNF-α levels than the normal control group (P<0.01), but there was no significant difference between the methylprednisolone treatment and conventional treatment groups. On days 4 and 7 of treatment, the methylprednisolone treatment group had significantly lower serum TNF-α levels than the conventional treatment group (P<0.05; P<0.01). On day 7 of treatment, there was no significant difference in serum TNF-α level between the methylprednisolone treatment and normal control groups, but the conventional treatment group still had a significantly higher serum TNF-α level than the normal control group (P<0.01).

CONCLUSIONS

Low-dose methylprednisolone can significantly decrease serum TNF-α level and inhibit inflammatory response in children with MPP, and may reduce damage caused by inflammatory response.

Mycoplasma pneumoniae extract induces an IL-17-associated inflammatory reaction in murine lung: implication for mycoplasmal pneumonia

Mycoplasma pneumoniae (Mp) may cause immune cell reactions as pivotal aspects of this clinically common respiratory pathogen. Our aim is to determine if Mp extract induces a cellular immune response associated with interleukin (IL)-17, leading to lung inflammation and lung injury. BALB/c mice were immunized with Mp extract intraperitoneally followed by its intratracheal administration, to mimic repeated Mp infection found in humans (repeated inoculation, RI group). Those with a single inoculation were compared as single inoculation group (SI group). Analysis of bronchoalveolar lavage fluid (BALF) demonstrated that keratinocyte-derived cytokine, tumor necrosis factor-α, and IL-6 were produced and peaked on days 0.5 or 1, followed by IL-17 on day 2. Levels of these mediators in BALF were higher in RI group than SI group (P < 0.05). Further, significantly more neutrophils were recruited to the lungs of the RI group (P < 0.05). These observations suggest that IL-17 is involved in the prolonged induction of neutrophils in mice treated with Mp extract.

[Protective immune responses induced by intranasal immunization with Mycoplasma pneumoniae P1C-IL-2 fusion DNA vaccine in mice]

OBJECTIVE

To investigate the immune responses and immune protections of a DNA vaccine constructed by fusing Mycoplasma pneumoniae (M. pneumoniae) p1 gene car boxy terminal region (p1c gene) with interleukin-2 (IL-2) gene.

METHODS

BALB/c mice were immunized by intranasal inoculation of P1C-IL-2 fusion DNA vaccine. Levels of serum IgG, IgG isotypes, BAL fluids IgA, IFN-γ and IL-4 were detected by ELISA. We established the mouse models infected with M. pneumoniae, and then observed the histopathological changes in lungs and counted colonies in bronchoalveolar lavage fluid (BALF) after challenged intranasally with M. pneumoniae.

RESULTS

Serum total IgG, IgG1 and IgG2a isotypes, levels of IFN-γ and IL-4 in BALF increased significantly in the group inoculated with P1C-IL-2 fusion DNA vaccine as compared with the one with P1C DNA vaccine (P<0.05), while there was no significant difference in BALF IgA between the two groups (P>0.05). The lung tissue inflammation was aggravated and the histopathologic score (HPS) of P1C-IL-2 DNA vaccine immunized mice significantly increased as compared with those in P1C DNA vaccine immunized mice at 1, 3, 6 d after challenged intranasally with M. pneumoniae (P<0.05). The P1C-IL-2 fusion DNA vaccine did not show significant difference from P1C DNA vaccine in the detectable number of M. pneumoniae strain in BALF(P>0.05).

CONCLUSION

IL-2 can enhance the systemic immune responses of P1C DNA vaccine, but it also can develop a severe histopathological change in early days after infection of M. pneumoniae.

Dendritic cells are the major antigen presenting cells in inflammatory lesions of murine Mycoplasma respiratory disease

Mycoplasmas cause chronic respiratory diseases in animals and humans, and to date, development of vaccines have been problematic. Using a murine model of mycoplasma pneumonia, lymphocyte responses, specifically T cells, were shown to confer protection as well as promote immunopathology in mycoplasma disease. Because T cells play such a critical role, it is important to define the role of antigen presenting cells (APC) as these cells may influence either exacerbation of mycoplasma disease pathogenesis or enhancement of protective immunity. The roles of APC, such as dendritic cells and/or macrophages, and their ability to modulate adaptive immunity in mycoplasma disease are currently unknown. Therefore, the purpose of this study was to identify individual pulmonary APC populations that may contribute to the activation of T cell responses during mycoplasma disease pathogenesis. The present study indeed demonstrates increasing numbers of CD11c⁻ F4/80⁺ cells, which contain macrophages, and more mature/activated CD11c⁺ F4/80⁻ cells, containing DC, in the lungs after infection. CD11c⁻ F4/80⁺ macrophage-enriched cells and CD11c⁺ F4/80⁻ dendritic cell-enriched populations showed different patterns of cytokine mRNA expression, supporting the idea that these cells have different impacts on immunity in response to infection. In fact, DC containing CD11c⁺ F4/80⁻ cell populations from the lungs of infected mice were most capable of stimulating mycoplasma-specific CD4⁺ Th cell responses in vitro. In vivo, these CD11c⁺F4/80⁻ cells were co-localized with CD4⁺ Th cells in inflammatory infiltrates in the lungs of mycoplasma-infected mice. Thus, CD11c⁺F4/80⁻ dendritic cells appear to be the major APC population responsible for pulmonary T cell stimulation in mycoplasma-infected mice, and these dendritic cells likely contribute to responses impacting disease pathogenesis.

[Mycoplasma pneumoniae capsular polysaccharides bind to DC-SIGN and promote the secretion of IL-10]

OBJECTIVE

To explore the interaction of Mycoplasma pneumoniae (M. pneumoniae) capsular polysaccharide (CPS) with dendritic cell-specific intercellular adhesion molecule-3-grabbing nonintegrin (DC-SIGN) and its influence on the secretions of IL-10 and IL-12.

METHODS

M. pneumoniae CPS and lipid-associated membrane proteins (LAMPs) were extracted and purified, and the specific binding of CPS and DC-SIGN was detected using indirect immunofluorescence staining. The expressions of IL-10 and IL-12 was tested by ELISA in immature DC after treated by CPS or/and LAMPs.

RESULTS

Indirect immunofluorescence staining showed CPS could recognized and bind specifically to the DC, which could be blocked by the DC-SIGN-specific blocking antibody. ELISA revealed that the production of immunosuppressive cytokine IL-10 increased when immature DC were stimulated by CPS, and the effect was more obvious with the presence of LAMPs(P<0.05). But the production of IL-12 did not change significantly after stimulation of CPS or/and LAMPs.

CONCLUSION

The CPS of M.pneumoniae can recognize and bind to the DC-SIGN specifically and promote the immature DC to secret IL-10.

Syndrome de Miller Fisher avec anticorps anti GQ1b négatif au cours d’une pneumonie à Mycoplasma pneumoniae

Le Syndrome de Miller Fisher est caractérisé par l'association d'une ophtalmoplégie, d'une ataxie et d'une aréflexie ostéo-tendineuse. Une infection virale est le plus souvent retrouvée dans les jours ou semaines qui précèdent la symptomatologie. Nous rapportons un cas de syndrome de Miller Fisher survenu chez une femme de 75 ans, et ce au décours d'une infection pulmonaire à Mycoplasma pneumoniae. Les sérologies virales habituelles étaient négatives. Les anticorps anti GQ1b étaient absents. Il n'y avait pas de lésion du tronc cérébral à l'imagerie par résonnance magnétique. L’évolution clinique était favorable après perfusion d'immunoglobulines humaines polyvalentes et des macrolides en comprimés. La sérologie Mycoplasma pneumoniae doit être systématiquement recherchée dans le bilan du syndrome de Miller Fisher.

Airway epithelial NF-κB activation promotes Mycoplasma pneumoniae clearance in mice

BACKGROUND/OBJECTIVE

Respiratory infections including atypical bacteria Mycoplasma pneumoniae (Mp) contribute to the pathobiology of asthma and chronic obstructive pulmonary disease (COPD). Mp infection mainly targets airway epithelium and activates various signaling pathways such as nuclear factor κB (NF-κB). We have shown that short palate, lung, and nasal epithelium clone 1 (SPLUNC1) serves as a novel host defense protein and is up-regulated upon Mp infection through NF-κB activation in cultured human and mouse primary airway epithelial cells. However, the in vivo role of airway epithelial NF-κB activation in host defense against Mp infection has not been investigated. In the current study, we investigated the effects of in vivo airway epithelial NF-κB activation on lung Mp clearance and its association with airway epithelial SPLUNC1 expression.

METHODOLOGY/MAIN RESULTS

Non-antimicrobial tetracycline analog 9-t-butyl doxycycline (9-TB) was initially optimized in mouse primary tracheal epithelial cell culture, and then utilized to induce in vivo airway epithelial specific NF-κB activation in conditional NF-κB transgenic mice (CC10-(CA)IKKβ) with or without Mp infection. Lung Mp load and inflammation were evaluated, and airway epithelial SPLUNC1 protein was examined by immunohistochemistry. We found that 9-TB treatment in NF-κB transgene positive (Tg+), but not transgene negative (Tg-) mice significantly reduced lung Mp load. Moreover, 9-TB increased airway epithelial SPLUNC1 protein expression in NF-κB Tg+ mice.

CONCLUSION

By using the non-antimicrobial 9-TB, our study demonstrates that in vivo airway epithelial NF-κB activation promotes lung bacterial clearance, which is accompanied by increased epithelial SPLUNC1 expression.

[Levels of interleukin-4 and interferon-gamma in the bronchoalveolar lavage fluid of children with refractory Mycoplasma pneumoniae pneumonia]

OBJECTIVE

To measure levels of interleukin-4 (IL-4) and interferon-gamma (INF-γ) in the bronchoalveolar lavage fluid (BALF) of children with refractory Mycoplasma pneumoniae pneumonia (RMPP), and to investigate changes in local Th1-Th2-type cytokine levels in children with RMPP and their significance.

METHODS

A total of 42 children with RMPP were divided into atopic (n=11) and non-atopic groups (n=31) according to whether they had eczema, allergic rhinitis, urticaria, and family history of allergic disease. The study also included a control group of 12 children with bronchial foreign bodies who underwent foreign body removal and were re-examined by fiberoptic bronchoscopy four weeks later. The different cells in BALF from all children were analyzed, and the levels of IL-4 and INF-γ in BALF were measured using enzyme-linked immunosorbent assay.

RESULTS

Compared with the control group, the total number of cells in BALF from children with RMPP increased significantly (P<0.05), the increase mainly accounted for by neutrophils (P<0.01), and levels of IL-4 and INF-γ in BALF from children with RMPP increased significantly (P<0.05). Compared with the control group, levels of IL-4 and INF-γ in BALF in the atopic group increased significantly (P<0.05). The level of INF-γ in BALF in the non-atopic group also increased significantly (P<0.05). There were no significant differences in INF-γ/IL-4 ratio among all groups (P>0.05).

CONCLUSIONS

Significant increase in cell numbers, especially neutrophils, as well as IL-4 and INF-γ levels, can be seen in BALF from children with RMPP, but there is no change to the INF-γ/IL-4 ratio. This indicates a significant local inflammatory response in children with RMPP, but there is no evidence of Th2-dominated inflammatory response.

Optimized serodiagnosis of Mycoplasma pneumoniae infections

Serologic methods are well established for the diagnosis of Mycoplasma pneumoniae infections in humans, but they are less sensitive than polymerase chain reaction (PCR). To improve their sensitivity, a new panel of antigens was tested. Compared with PCR results, up to 92% of PCR-positive patients were confirmed by our immunoblotting approach having a specificity between 92.6% and 100%.

Mast cell TNF receptors regulate responses to Mycoplasma pneumoniae in surfactant protein A (SP-A)-/- mice

BACKGROUND

Mycoplasma pneumoniae (Mp) frequently colonizes the airways of patients with chronic asthma and likely contributes to asthma exacerbations. We previously reported that mice lacking surfactant protein A (SP-A) have increased airway hyperresponsiveness (AHR) during M pneumoniae infection versus wild-type mice mediated by TNF-α. Mast cells (MCs) have been implicated in AHR in asthma models and produce and respond to TNF-α.

OBJECTIVE

Determine the contribution of MC/TNF interactions to AHR in airways lacking functional SP-A during Mp infection.

METHODS

Bronchoalveolar lavage fluid was collected from healthy and asthmatic subjects to examine TNF-α levels and M pneumoniae positivity. To determine how SP-A interactions with MCs regulate airway homeostasis, we generated mice lacking both SP-A and MCs (SP-A(-/-)Kit(W-sh/W-sh)) and infected them with M pneumoniae.

RESULTS

Our findings indicate that high TNF-α levels correlate with M pneumoniae positivity in human asthmatic patients and that human SP-A inhibits M pneumoniae-stimulated transcription and release of TNF-α by MCs, implicating a protective role for SP-A. MC numbers increase in M pneumoniae-infected lungs, and airway reactivity is dramatically attenuated when MCs are absent. Using SP-A(-/-)Kit(W-sh/W-sh) mice engrafted with TNF-α(-/-) or TNF receptor (TNF-R)(-/-) MCs, we found that TNF-α activation of MCs through the TNF-R, but not MC-derived TNF-α, leads to augmented AHR during M pneumoniae infection when SP-A is absent. Additionally, M pneumoniae-infected SP-A(-/-)Kit(W-sh/W-sh) mice engrafted with TNF-α(-/-) or TNF-R(-/-) MCs have decreased mucus production compared with that seen in mice engrafted with wild-type MCs, whereas burden was unaffected.

CONCLUSION

Our data highlight a previously unappreciated but vital role for MCs as secondary responders to TNF-α during the host response to pathogen infection.

[A family associated outbreak of Mycoplasma pneumoniae infection in a hospital ward]

OBJECTIVE

To describe the epidemiological and serological features on a family associated outbreak caused by Mycoplasma pneumoniae (MP) infection occurred in Beijing in August 2007.

METHODS

Mutual exposure of the family members was investigated and retrospective medical record was reviewed for the hospitalized patients. Serum antibodies to MP were measured and chest X-rays were taken for all the family members.

RESULTS

This family consisted of 5 members, with fixed members as the boy (13 years old), his father (43 years old) and mother (44 years old), grandmother (64 years old) and uncle (32 years old) who was involved in taking care of the sick boy and his father. During 23 days of the event, four of all the five family members were ill. Three (boy, father and uncle) had radiographic pneumonia, whose paired sera all showed a ≥ fourfold increase in antibody titer, and two of them were confirmed by chest X-ray on day 2 after onset of fever. The grandmother suffered from bronchitis, with positive (PA) serum antibody to MP. Serum MP-IgG from the father and uncle was positive, 3 days and 2 days after the onset of fever. The chances of contact between grandmother with the boy and uncle with the father were both only in the hospital wards. Only the mother remained asymptomatic, with her serum MP-IgM(-) and MP-IgG(+) for which the blood sample was collected 37 days after close contact with the boy. The longest time of exposure to the patients was between mother and the boy but only the mother did not increase her total workload or feeling for fatigue.

RESULTS

of MP-IgG from post-infection did not completely defend against the repeated MP infection. Combined risk factors as index patients with severe cough, prolonged close contact, poorly ventilation of the environment, and family members with excessive fatigue might work as the causes of this family MP outbreak.

[Levels of TNF-α, IL-6 and IL-10 in bronchoalveolar lavage fluid in children with Mycoplasma pneumoniae pneumonia]

OBJECTIVE

To study the levels and roles of cytokines TNF-α, IL-6 and IL-10 in bronchoalveolar lavage fluid (BALF) in children with Mycoplasma pneumoniae pneumonia (MPP).

METHODS

The levels of TNF-α, IL-6 and IL-10 in BALF were measured using ELISA in children with MPP at acute stage (n=45) and at remission stage (n=30). Twenty children without lung lesions severed as the control group.

RESULTS

The TNF-α, IL-6 and IL-10 levels in BALF were higher in children with MPP at acute stage than those in the control group (P<0.05). The levels of TNF-α and IL-6 in BALF at remission stage were reduced to the levels similar to the control group and were significantly lower than those at the acute stage in children with MPP. However, the levels of IL-10 in BALF remained at higher levels at remission stage in children with MPP.

CONCLUSIONS

The levels of TNF-α, IL-6 and IL-10 in BALF increase in children with MPP at acute stage, suggesting that the cytokines may be involved in the pathogenesis of MPP.

SPLUNC1 promotes lung innate defense against Mycoplasma pneumoniae infection in mice

Short palate, lung, and nasal epithelium clone 1 (SPLUNC1) protein is highly expressed in normal airways, but is dramatically decreased in allergic and cigarette smoke exposure settings. We have previously demonstrated SPLUNC1 in vitro antibacterial property against Mycoplasma pneumoniae (Mp). However, its in vivo biological functions remain unclear. The objectives of this study were to determine the in vivo functions of SPLUNC1 following bacterial (eg, Mp) infection, and to examine the underlying mechanisms. We generated SPLUNC1-deficient mice and utilized transgenic mice overexpressing human SPLUNC1 exclusively within the airway epithelium. These mice were infected with Mp and, twenty-four hours post infection, their host defense responses were compared to littermate controls. Mp levels and inflammatory cells increased in the lungs of SPLUNC1(-/-) mice as compared to wild type controls. SPLUNC1 deficiency was shown to contribute to impaired neutrophil activation. In contrast, mice overexpressing hSPLUNC1 exclusively in airway epithelial cells demonstrated lower Mp levels. Furthermore, neutrophil elastase activity was significantly increased in mice overexpressing hSPLUNC1. Lastly, we demonstrated that SPLUNC1 enhanced Mp-induced human neutrophil elastase (HNE) activity, and HNE directly inhibited the growth of Mp. Our findings demonstrate a critical in vivo role of SPLUNC1 in host defense against bacterial infection, and likely provide a novel therapeutic approach to restore impaired lung innate immune responses to bacteria in patients with chronic lung diseases.

PAComplex: a web server to infer peptide antigen families and binding models from TCR-pMHC complexes

One of the most adaptive immune responses is triggered by specific T-cell receptors (TCR) binding to peptide-major histocompatibility complexes (pMHC). Despite the availability of many prediction servers to identify peptides binding to MHC, these servers are often lacking in peptide-TCR interactions and detailed atomic interacting models. PAComplex is the first web server investigating both pMHC and peptide-TCR interfaces to infer peptide antigens and homologous peptide antigens of a query. This server first identifies significantly similar TCR-pMHC templates (joint Z-value ≥ 4.0) of the query by using antibody-antigen and protein-protein interacting scoring matrices for peptide-TCR and pMHC interfaces, respectively. PAComplex then identifies the homologous peptide antigens of these hit templates from complete pathogen genome databases (≥10(8) peptide candidates from 864,628 protein sequences of 389 pathogens) and experimental peptide databases (80,057 peptides in 2287 species). Finally, the server outputs peptide antigens and homologous peptide antigens of the query and displays detailed interacting models (e.g. hydrogen bonds and steric interactions in two interfaces) of hitTCR-pMHC templates. Experimental results demonstrate that the proposed server can achieve high prediction accuracy and offer potential peptide antigens across pathogens. We believe that the server is able to provide valuable insights for the peptide vaccine and MHC restriction. The PAComplex sever is available at http://PAcomplex.life.nctu.edu.tw.

Preceding infections and anti-ganglioside antibody profiles assessed by a dot immunoassay in 306 French Guillain-Barré syndrome patients

We describe by an in-house dot immunoassay, specific anti-ganglioside and sulfatide antibodies, by comparing the results from a large group of 134 infected French GBS patients and those from 172 noninfected French GBS and 142 control groups. A recent infection was identified in 134/306 (43.8%) GBS patients: Campylobacter jejuni (24.6%) was the most common agent, followed by cytomegalovirus (12.4%), Mycoplasma pneumoniae (3.2%) and Epstein-Barr virus (1.3%). Anti-ganglioside antibodies were detected in 97/306 (31.7%) of total GBS patients, 82/134 (61.2%) of GBS patients with a recent identified infection and 15/172 (8.7%) of the patients without identified infection. According to the specificities and antibody classes, four specific IgG antibody profiles were individualised against the two major GM1 and GD1a gangliosides in motor axonal C. jejuni-associated GBS variants, against GQ1b and disialylated gangliosides in Miller Fisher syndrome and its variants. One specific IgM profile against GM2 was found in 16/38 (42%) of severe sensory demyelinating CMV-associated GBS and in 8/17 (47%) of subjects with recent CMV infection with no neurological disease. IgG or IgM antibodies to GM1 were found in 5/10 M. pneumoniae-infected patients. IgM antibodies to GM1 were observed in the control groups, 15% of the 74 patients with amyotrophic lateral sclerosis, 19% of the 51 patients with chronic inflammatory demyelinating polyneuropathy, and 9% of the 21 healthy control subjects. The fine specificity of the four IgG antibody profiles and the IgM anti-GM2 profile is closely related to the nature of the preceding infections and the pattern of clinical features.