IFN-γ Limits Immunopathogenesis but Delays Fungal Clearance during Pneumocystis Pneumonia

High levels of IFN-γ are produced in the lung during an adaptive immune response to Pneumocystis, but the effects of this prototypical Th1 cytokine on fungal clearance and immunopathogenesis have not been fully defined. Therefore, Pneumocystis-infected immunodeficient mice were immune reconstituted and administered control or anti-IFN-γ neutralizing Ab to determine how IFN-γ regulates the balance between host defense and immune-mediated lung injury. Mice treated with anti-IFN-γ demonstrated an initial worsening of Pneumocystis pneumonia-related immunopathogenesis, with greater weight loss, heightened lung inflammation, and more severe pulmonary function deficits than control mice. However, IFN-γ neutralization also enhanced macrophage phagocytosis of Pneumocystis and accelerated fungal clearance. When anti-IFN-γ-treated mice were also given IL-4 and IL-13 to promote a Th2-biased lung environment, the accelerated fungal clearance was preserved, but the severity of immunopathogenesis was reduced, and a more rapid recovery was observed. A direct suppressive effect of IFN-γ on macrophages was required but was not solely responsible for delayed fungal clearance, suggesting that IFN-γ acts through multiple mechanisms that likely include modulation of both macrophage and Th polarization. Enhanced Pneumocystis clearance in anti-IFN-γ-treated and IFN-γR-deficient mice was associated with significantly elevated IL-17+ CD4+ T cells and IL-17 protein in the lungs. Furthermore, neutralization of IL-17, but not IL-4, signaling blocked the accelerated fungal clearance observed in anti-IFN-γ-treated mice. Together, these data demonstrate that although IFN-γ delays fungal clearance by suppressing the lung Th17 response, it also serves an important regulatory role that limits immunopathogenesis and preserves pulmonary function.

Of "Cotton Balls" and "Owl's eyes"

Report of a 3-month old girl child who died due to multi-systemic infection of cytomegalovirus (CMV) involving the lungs, liver and kidneys along with pneumocystis jiroveci pneumonia (PJP). The mother of the child tested positive for CMV IgG and HIV with a very low CD4 count (160/ μl). Co-infection of cytomegalovirus and pneumocystis jiroveci always occurs in the setting of immunocompromise. Congenital CMV infection is transmitted through the placenta, especially during the first trimester and causes severe multi-systemic disease whereas perinatal infection is acquired during childbirth/ breastfeeding where the babies have maternal protective antibodies leading to much milder or asymptomatic infection. PJP is more common in infancy and presents as hypoxic pneumonia. CMV causes cyto-nucleomegaly and classic "owl's eye" inclusions on histology while PJP presents with characteristic fluffy "cotton ball" alveolar exudates.

Differences and similarities of high-resolution computed tomography features between pneumocystis pneumonia and cytomegalovirus pneumonia in AIDS patients

BACKGROUND

Accurately differentiating pneumocystis from cytomegalovirus pneumonia is crucial for correct therapy selection in AIDS patients. Hence, the goal of this study was to compare the computerized tomography (CT) features of pneumocystis pneumonia and cytomegalovirus pneumonia in AIDS patients and identify clinical hallmarks to accurately distinguish these two pathologies.

METHODS

A total of 112 AIDS patients (78 with pneumocystis pneumonia and 34 cytomegalovirus pneumonia) at Beijing Ditan Hospital from January 2017 to May 2019 were included in this study. Two experienced chest radiologists retrospectively reviewed CT images for 17 features including ground-glass opacity, consolidation, nodules, and halo sign. Binary logistic regression analyses were conducted to identify the significant parameters that distinguished pneumocystis pneumonia from cytomegalovirus pneumonia. Correlations were analyzed by Pearson or Spearman correlation analyses. Result were considered significant if P < 0.05.

RESULTS

The presence of consolidation, halo signs, and nodules (all P < 0.05) were significantly more frequent in patients with cytomegalovirus pneumonia than in those with pneumocystis pneumonia. Small nodules (32.5% in cytomegalovirus pneumonia, 6.41% in pneumocystis pneumonia, P < 0.001) without perilymphatic distribution were particularly common in patients with cytomegalovirus pneumonia. Large nodules were not found in any of patients with cytomegalovirus pneumonia. The presence of ground-glass opacity, reticulation, and bronchial wall thickening (all P > 0.05) were common in both groups.

CONCLUSIONS

Analysis of consolidation, nodules, and halo signs may contribute to the differential diagnosis of pneumocystis pneumonia or cytomegalovirus pneumonia. However, some CT features considered typical in one or other diseases appear with similar frequency in both cohorts of AIDS patients. CT features are potentially useful for the differential diagnosis of pneumocystis pneumonia and cytomegalovirus pneumonia in AIDS patients.

Ground Glass Opacity with Mixed Consolidation on Chest Computed Tomography Reflects the Severe Condition of Pneumocystis Pneumonia in Association with a Poor Prognosis in Patients with Connective Tissue Diseases

Objective Pneumocystis pneumonia (PCP) is a serious fungal infection that can be life threatening in immunocompromised hosts. We evaluated the association between the radiological patterns of PCP on high-resolution computed tomography (HRCT) and clinical characteristics and the prognosis of patients with connective tissue disease (CTD). Methods All CTD patients who developed PCP from January 1999 to April 2017 were retrospectively evaluated. Patients were divided into three groups based on their chest HRCT findings: Ground glass opacity (GGO) sharply demarcated from the adjacent normal lung by interlobular septa (demarcated GGO), diffuse GGO without obvious demarcation (diffuse GGO), and GGO with mixed consolidation (mixed GGO). We compared the clinical characteristics at the onset of PCP and the outcomes among the groups. Results A total of 35 cases were identified: demarcated GGO (n=8, 23%), diffuse GGO (n=19, 54%), and mixed GGO (n=8, 23%). The mixed GGO group showed a higher serum C-reactive protein level (p<0.0001), lower lymphocyte count (p=0.07), lower serum albumin (p<0.001), and lower partial pressure of arterial oxygen/fraction of inspiratory oxygen ratios (p<0.001) in comparison to the demarcated and diffuse GGO groups. The mixed GGO group showed significantly higher mortality in comparison to the demarcated and diffuse GGO groups (88% vs. 7%, p<0.0001). Conclusion GGO with mixed consolidation on chest HRCT was associated with a poor outcome of PCP in patients with CTD.

Characteristics of pulmonary complications in non-Hodgkin's lymphoma patients treated with rituximab-containing chemotherapy and impact on survival

Patients with non-Hodgkin’s lymphoma (NHL) receiving rituximab-containing chemotherapy are at risk of developing respiratory complications, but comprehensive information on these complications and their impact on survival is lacking. We performed a retrospective cohort analysis on 123 NHL patients who received rituximab-containing chemotherapy between 2009 and 2016 in order to describe the incidence, etiologies and effect on survival of respiratory complications defined by new or worsening respiratory symptoms requiring diagnostic work-up or hospitalization. Thirty patients (24%) developed respiratory complications during a follow-up time of 825 (555–1338) days after chemotherapy. They had a higher prevalence of congestive heart failure and lung or pleural involvement at diagnosis as compared to patients who did not develop complications. Overall, 58 episodes of pulmonary complications were observed after median (interquartile) times from the first and last rituximab doses of 205 (75–580) days and 27 (14–163) days respectively. Infectious etiologies accounted for 75% of the respiratory complications, followed by heart failure exacerbation, lymphomatous involvement, and ARDS. Two Pneumocystis jirovecii pneumonias were observed, and no complication was ascribed to rituximab toxicity. Respiratory complications required ICU admission in 19 cases (33%) and invasive mechanical ventilation in 14 cases (24%). Using a time-dependent Cox regression analysis, we observed that the occurrence of respiratory complications was associated with a 170% increase in death hazard (hazard ratio 2.65, 95% CI 1.60–4.40, p = 0.001). In conclusion, respiratory complications in NHL patients receiving chemotherapy are relatively frequent, severe, and mostly infectious and are associated with increased mortality.

β-Glucans Are Masked but Contribute to Pulmonary Inflammation During Pneumocystis Pneumonia

β-glucans, which can activate innate immune responses, are a major component in the cell wall of the cyst form of Pneumocystis In the current study, we examined whether β-1,3-glucans are masked by surface proteins in Pneumocystis and what role β-glucans play in Pneumocystis-associated inflammation. For 3 species, including Pneumocystis jirovecii, which causes Pneumocystis pneumonia in humans, Pneumocystis carinii, and Pneumocystis murina, β-1,3-glucans were masked in most organisms, as demonstrated by increased exposure following trypsin treatment. Using quantitative polymerase chain reaction and microarray techniques, we demonstrated in a mouse model of Pneumocystis pneumonia that treatment with caspofungin, an inhibitor of β-1,3-glucan synthesis, for 21 days decreased expression of a broad panel of inflammatory markers, including interferon γ, tumor necrosis factor α, interleukin 1β, interleukin 6, and multiple chemokines/chemokine ligands. Thus, β-glucans in Pneumocystis cysts are largely masked, which likely decreases innate immune activation; this mechanism presumably was developed for interactions with immunocompetent hosts, in whom organism loads are substantially lower. In immunosuppressed hosts with a high organism burden, organism death and release of glucans appears to be an important contributor to deleterious host inflammatory responses.

Role of APOBEC3F Gene Variation in HIV-1 Disease Progression and Pneumocystis Pneumonia

Human APOBEC3 cytidine deaminases are intrinsic resistance factors to HIV-1. However, HIV-1 encodes a viral infectivity factor (Vif) that degrades APOBEC3 proteins. In vitro APOBEC3F (A3F) anti-HIV-1 activity is weaker than A3G but is partially resistant to Vif degradation unlike A3G. It is unknown whether A3F protein affects HIV-1 disease in vivo. To assess the effect of A3F gene on host susceptibility to HIV- acquisition and disease progression, we performed a genetic association study in six well-characterized HIV-1 natural cohorts. A common six-Single Nucleotide Polymorphism (SNP) haplotype of A3F tagged by a codon-changing variant (p. I231V, with allele (V) frequency of 48% in European Americans) was associated with significantly lower set-point viral load and slower rate of progression to AIDS (Relative Hazards (RH) = 0.71, 95% CI: 0.56, 0.91) and delayed development of pneumocystis pneumonia (PCP) (RH = 0.53, 95% CI: 0.37-0.76). A validation study in the International Collaboration for the Genomics of HIV (ICGH) showed a consistent association with lower set-point viral load. An in vitro assay revealed that the A3F I231V variant may influence Vif mediated A3F degradation. Our results provide genetic epidemiological evidence that A3F modulates HIV-1/AIDS disease progression.

Neither classical nor alternative macrophage activation is required for Pneumocystis clearance during immune reconstitution inflammatory syndrome

Pneumocystis is a respiratory fungal pathogen that causes pneumonia (Pneumocystis pneumonia [PcP]) in immunocompromised patients. Alveolar macrophages are critical effectors for CD4(+) T cell-dependent clearance of Pneumocystis, and previous studies found that alternative macrophage activation accelerates fungal clearance during PcP-related immune reconstitution inflammatory syndrome (IRIS). However, the requirement for either classically or alternatively activated macrophages for Pneumocystis clearance has not been determined. Therefore, RAG2(-/-) mice lacking either the interferon gamma (IFN-γ) receptor (IFN-γR) or interleukin 4 receptor alpha (IL-4Rα) were infected with Pneumocystis. These mice were then immune reconstituted with wild-type lymphocytes to preserve the normal T helper response while preventing downstream effects of Th1 or Th2 effector cytokines on macrophage polarization. As expected, RAG2(-/-) mice developed severe disease but effectively cleared Pneumocystis and resolved IRIS. Neither RAG/IFN-γR(-/-) nor RAG/IL-4Rα(-/-) mice displayed impaired Pneumocystis clearance. However, RAG/IFN-γR(-/-) mice developed a dysregulated immune response, with exacerbated IRIS and greater pulmonary function deficits than those in RAG2 and RAG/IL-4Rα(-/-) mice. RAG/IFN-γR(-/-) mice had elevated numbers of lung CD4(+) T cells, neutrophils, eosinophils, and NK cells but severely depressed numbers of lung CD8(+) T suppressor cells. Impaired lung CD8(+) T cell responses in RAG/IFN-γR(-/-) mice were associated with elevated lung IFN-γ levels, and neutralization of IFN-γ restored the CD8 response. These data demonstrate that restricting the ability of macrophages to polarize in response to Th1 or Th2 cytokines does not impair Pneumocystis clearance. However, a cell type-specific IFN-γ/IFN-γR-dependent mechanism regulates CD8(+) T suppressor cell recruitment, limits immunopathogenesis, preserves lung function, and enhances the resolution of PcP-related IRIS.

Granulomatous Reaction to Pneumocystis jirovecii Diagnosed in a Bronchoalveolar Lavage: A Case Report

BACKGROUND

Granulomatous reaction to Pneumocystis jirovecii is a rare but well-known pathological finding encountered in the setting of immunosuppression, HIV infection being the most common cause. It can also potentially complicate the treatment of hematological malignancies, typically when drugs lowering the count and function of lymphocytes are used. Lung biopsy is considered the gold standard for the diagnosis of granulomatous P. jirovecii pneumonia, whereas the diffuse alveolar form is usually detected cytologically in bronchoalveolar lavage (BAL).

CASE

A female patient pursuing R-CHOP chemotherapy for the treatment of multiple hematological malignancies developed a rapidly progressing dyspnea. Chest CT scans revealed a worsening of a known infiltrative lung disease thought to be secondary to her chemotherapy. Alterations compatible with a drug-induced interstitial lung disease and well-formed focally necrotizing granulomas were observed on an open lung biopsy, but no microorganism was identified with special stains. Eventually, a granulomatous reaction to P. jirovecii was found in a BAL and allowed appropriate treatment with rapid improvement of the dyspnea.

CONCLUSION

Because granulomas are tissue-bound structures, they are rarely described in BAL. This article describes the first reported cytological diagnosis of a granulomatous reaction to P. jirovecii and the potential diagnostic interest of such a peculiar finding.

[Lung co-infection by Pneumocystis jirovecii and Pseudomonas aeruginosa in AIDS: report of two cases]

Rapporter deux cas cliniques de coinfections pulmonaires par Pneumocystis jirovecii et par Pseudomonas aeruginosa chez des patients vivant avec le VIH. Les deux patients étaient âgés respectivement de 32 ans et 46 ans. Un patient a été pris en charge à l'hôpital Yalgado Ouédraogo de Ouagadougou au Burkina Faso et l'autre a été pris en charge à l'hôpital Ténon de Paris, en France. Les deux souffraient de pneumopathie confirmée à la radiographie et à la tomodensitométrie. L'un des patients était sévèrement immuno déprimé, contrairement à l'autre. L'examen bactériologique dans les crachats avait permis d'isoler Pseudomonas aeruginosa et Pneumocystis jirovecii chez les deux patients. Sous traitement, l’évolution a été favorable. Les coinfections morbides sont relativement fréquentes chez les patients vivant avec le VIH. Devant une symptomatologie respiratoire du sujet vivant avec le VIH, il faut savoir rechercher en plus du Bacille de Koch, Pneumocystis jirovecii et Pseudomonas aeruginosa par un lavage broncho alvéolaire.

[Generalized pneumocystosis in HIV infection]

The paper describes a rare case of rapidly progressive generalized pneumocystosis in HIV infection in a 43-year-old patient who died 4.5-5 months after disease onset. The specific feature of the case is that in pneumocystosis there was multiple organ dysfunction, as well as infiltrate decay to form small and large lung cavities similar to tuberculosis ones. Autopsy disclosed Pneumocystis-induced changes in the liver, spleen, lymph nodes, and the wall of the ileum. Pneumocystosis and HIV infection were diagnosed only posthumously. The specificity of organ diseases was immunohistochemically verified.

[Cytomegalovirus infection and pneumocystis pneumonia after coronary stenting and cardiac transplantation for acute myocardial infarction]

The paper presents the clinical and anatomic data of combination treatment for acute myocardial infarction, by stenting the infarct-related artery, followed by cardiac transplantation, which have provided the optimal result of surgery and caused no severe rejection reaction. The immediate causes of death have been infectious complications (cytomegalovirus infection and pneumocystis pneumonia) developing in the presence of immunodeficiency state. The following diagnosis formulation is pathogenetically warranted: the underlying disease is "Secondary immunodeficiency due to immunosuppressive therapy" and infectious complications may be assigned to the individual rubric "Secondary disease" (i.e. occurring in immunodeficiency).

[Changes of superoxide dismutase and lipid peroxide in rats with Pneumocystis carinii pneumonia]

Sprague-Dawley (SD) rat model of Pneumocystis carinii pneumonia (PCP) was established by groin subcutaneous injection with dexamethasone sodium phosphate 35 mg each twice a week for eight weeks. There were two groups: infected group (eighteen rats) and normal control group (six rats) . Pathological changes in lung tissues were observed in the lung imprint after staining with Gomori methenamine silver (GMS) and in tissue sections after staining with hematoxylin-eosin (HE). The activity of superoxide dismutase (SOD) and the content of lipid peroxide (LPO) in lung tissue homogenate were detected by spectrophotometric method. Results showed that in infected group more PC cysts were found in the lung imprint and typical pathological change observed in the lung section. SOD activity in infected group [(31.49 +/- 7.18) U/mgprot] decreased significantly compared with the control [(54.41 +/- 8.97) U/mgprot] (P < 0.01), but LPO in infected group [(2.26 +/- 0.21) nmol/mgprot] was higher significantly than the control [(1.63 +/- 0.01) nmol/mgprot] (P < 0.01).

Steroids in severe pneumonia: a literature review

Despite more than sixty years of scientific medical research, severe pneumonia, either community-acquired or nosocomial, remains a leading cause of death regardless of the patients' immunity state. The clinical introduction of new and more potent antibiotic molecules and the continuous development of efficient respiratory assistance devices may not be able to radically improve the clinical outcome of pneumonia. Adjunctive therapies based on the physiopathological mechanisms of lung damage in severe pneumonia have been strongly advocated, and corticosteroids, which present many properties that theoretically interfere with these pathways, have been widely used, with conflicting results. The aim of this review is to examine existing literature data on steroid use in severe pneumonia. Molecular, endocrinological and clinical studies will be described to help physicians to clarify the reasons for the historical debate about steroid use as an adjunctive treatment in severe pneumonia. There is growing evidence that, during lung infection, an excessive inflammatory response can have deleterious effects and contribute to tissue damage mechanisms. Because of their immunomodulatory properties, glucocorticoids have been suggested as a useful tool for regulating the complex balance of cytokine networks, and they are commonly used as an adjunctive therapy during serious infections. In severe pneumonia, preclinical data, including cytokine level detection and animal studies, have shown encouraging results, although the clinical data is controversial. Moreover, large randomized controlled trials have not been conducted to determine steroid side effects and the risk of immunosuppression-induced superinfections. The benefits of steroid use in patients with severe pneumonia have not been proven by current literature, but ongoing investigations of anti-inflammatory molecules probably represent the key point of severe infection management in the near future.

Pneumocystis carinii infection causes lung lesions historically attributed to rat respiratory virus

Idiopathic lung lesions characterized by dense perivascular cuffs of lymphocytes and a lymphohistiocytic interstitial pneumonia have been noted in research rats since the 1990s. Although the etiology of this disease has remained elusive, a putative viral etiology was suspected and the term 'rat respiratory virus' (RRV) has been used in reference to this disease agent. The purpose of this study was to determine whether Pneumocystis carinii infection in immunocompetent rats can cause idiopathic lung lesions previously attributed to RRV. In archived paraffin-embedded lungs (n = 43), a significant association was seen between idiopathic lung lesions and Pneumocystis DNA detected by PCR. In experimental studies, lung lesions of RRV developed in 9 of 10 CD rats 5 wk after intratracheal inoculation with P. carinii. No lung lesions developed in CD rats (n = 10) dosed with a 0.22-μm filtrate of the P. carinii inoculum, thus ruling out viral etiologies, or in sham-inoculated rats (n = 6). Moreover, 13 of 16 CD rats cohoused with immunosuppressed rats inoculated with P. carinii developed characteristic lung lesions from 3 to 7 wk after cohousing, whereas no lesions developed in rats cohoused with immunosuppressed sham-inoculated rats (n = 7). Both experimental infection studies revealed a statistically significant association between lung lesion development and exposure to P. carinii. These data strongly support the conclusion that P. carinii infection in rats causes lung lesions that previously have been attributed to RRV.

[Pneumocystis jiroveci infection associated with organizing pneumonia in a kidney transplant patient]

The authors report the association of organizing pneumonia (OP) and a Pneumocystis jiroveci infection in a woman who benefited from a kidney transplant 13 years before and was under corticoids, cyclosporine and mycophenolate mofetil. The diagnosis was based on progressive dyspnoea with fever with an alteration in the general state associated with diffuse micronodular pneumopathy suggesting bronchiolitis. The conformation was obtained by the analysis of the alveolar bronchial washings and the histological examination of the distal biopsies revealing endo-alveolar vegetant fibromas. Transbronchial biopsies may be used for the diagnosis and thereby, avoid an invasive surgical pulmonary biopsy. The aetiology of OP may be related to the immunosuppressant treatment or infection by Pneumocystis jiroveci. The evolution in this case was favourable with trimethoprime and sulfamethoxazole associated with a transient increase in the corticoid treatment. This association is rarely described in patients undergoing solid organ transplants.

[Autopsy case of pulmonary zygomycosis and pneumocystis pneumonia in a patient with interstitial pneumonia treated by corticosteroid therapy]

We report a 75-year-old man with pneumoconiosis, interstitial pneumonia and diabetes mellitus, who had carcinoma of the buccal mucosa. After resection of the carcinoma, he was given corticosteroids for the deterioration of interstitial pneumonia, but 38 days after initiating steroid therapy, he was admitted to our hospital with severe hypoxemia and multiple cavitary lesions superimposed on ground-glass attenuation in both lung fields. The Aspergillus antigen was positive in his serum and examination of his bronchoalveolar lavage (BAL) fluid revealed mixed infections with filamentous fungus and Pneumocystis jirovecii. Pulmonary aspergillosis and pneumocystis pneumonia with an immunocompromised state was diagnosed, and voriconazole, sulfamethoxazole-trimethoprim and high-dose corticosteroids were given. At 20 days after these treatments he developed bloody sputum, and Cunninghamella bertholletiae was isolated from the BAL fluid obtained at admission. A diagnosis of pulmonary zygomycosis was finally established. Amphotericin B therapy was started, and the dose was increased thereafter. Despite intensive treatment he died 18 days later. Histological examination of lung tissue obtained at autopsy showed invasive growth of zygomycetes in the necrotic tissue and the cavity wall. To the best of our knowledge, this is the first report of concurrent Cunninghamella bertholletiae and Pneumocystis jirovecii infection during steroid therapy for interstitial pneumonia.

Relapsing infiltrates after pneumocystis pneumonia in stem cell transplant patients: think about BOOP!

Bronchiolitis Obliterans Organizing Pneumonia (BOOP) can complicate allogeneic haematopoietic stem cell transplantation. It is associated with prior graft-versus-host disease (GVHD) and the case fatality is 21%. In 22%, diagnosis is preceded by tapering the corticosteroids given as a treatment for GVHD. We report a fatal case of BOOP after tapering the corticosteroids that the patient received for a Pneumocystis jirovecii pneumonia after stem cell transplantation.

Pneumocystis jirovecii Pneumonia

Pneumocystis jirovecii has gained attention during the last decade in the context of the AIDS epidemic and the increasing use of cytotoxic and immunosuppressive therapies. This article summarizes current knowledge on biology, pathophysiology, epidemiology, diagnosis, prevention, and treatment of pulmonary P jirovecii infection, with a particular focus on the evolving pathophysiology and epidemiology. Pneumocystis pneumonia still remains a severe opportunistic infection, associated with a high mortality rate.

Chest radiographic features of lymphocytic interstitial pneumonitis in HIV-infected children

AIM

To review the radiological features of biopsy-proven lymphocytic interstitial pneumonitis (LIP) in human immunodeficiency virus (HIV)-infected children and establish whether these are based on systematic radiological analysis, and to investigate whether more specific radiological diagnostic criteria can be developed.

MATERIALS AND METHODS

A Medline search of English-language articles on the radiological features of biopsy-proven LIP in HIV-infected children was conducted for the period 1982 to 2007 inclusive. Radiological findings were compared with the Centers for Disease Control and Prevention (CDC) criteria for a presumptive diagnosis of LIP.

RESULTS

Pulmonary pathology was recorded as "diffuse" and "bilateral" in 125 (97.6%) of 128 reported cases of LIP. Twenty-five different terms were used to describe the pulmonary parenchyma. In 96 (75%), the terminology was consistent with CDC diagnostic criteria. Radiological evolution was documented in 43 (33.5%). Persistent focal opacification superimposed on diffuse pulmonary nodularity was demonstrated in 10 (7.8%). The method of radiological evaluation was described in six (4.6%). In no instance was the terminology defined.

CONCLUSION

The radiological features of LIP have not been systematically analysed. However, CDC criteria remain reliable, allowing diagnosis of at least 75% of cases. The sensitivity of these criteria may be increased by including cases with persistent focal pulmonary opacification superimposed on diffuse nodularity. Longitudinal studies utilizing standardized radiographic analysis are needed to elucidate the natural history of LIP.

[Influence of baicalin on TNF-alpha and soluble intercellular adhesion molecule-1 in rats infected with Pneumocystis carinii]

OBJECTIVE

To explore the effect of baicalin on tumour necrosis factor-alpha (TNF-alpha) and soluble intercellular adhesion molecule-1 (sICAM-1) of immunosuppressed rats infected with Pneumocystis carinii.

METHODS

Forty-nine SD rats were randomly divided into 7 groups: normal control (A), immunosuppressed control (B), SMZ/TMP control (C), baicalin prevention (D), low dose (E), moderate dose (F) and high dose (G). Rats of group D received six injections at three-day intervals with 3.5 mg dexamethasone sodium phosphate for 3 weeks, while groups B, C, E, F and G received same immunosuppressor but for 6 weeks. Rats in group D were given 100 mg/kg baicalin daily for 5 weeks, and groups C, E, F and G were given 250 mg/kg SMZ+50 mg/kg TMP, low dose [100mg/(kg x d)], moderate dose [200 mg/(kg x d)], and high dose [400 mg/(kg x d)] baicalin daily for 2 weeks, respectively. At the end of 8th week after immunosuppression, the contents of TNF-alpha and sICAM-1 in peripheral blood were detected by radioimmunoassay (RIA) and ELISA, respectively. The pathological change of lung was observed by lung imprint smear with gomori methenamine silver (GMS) staining and lung section with hematoxylin-eosin (HE) staining.

RESULTS

The content of TNF-alpha in group D [(2.14 +/- 0.14) ng/ml], group E [(2.57 +/- 0.15) ng/ml], group F [(1.46 +/- 0.14) ng/ml], group G [(1.12 +/- 0.13) ng/ml] and group C [(1.59 +/- 0.14) ng/ml] were higher than that of group A [(0.70 +/- 0.21) ng/ml] (P < 0.05, P < 0.01), and lower than group B [(3.65 +/- 0.73) ng/ml] (P < 0.01). The content of sICAM-1 in group D [(618.68 +/- 52.42) pg/ml], group E [(814.29 +/- 61.11) pg/ml], group F [(498.08 +/- 32.56) pg/ml], group G [(377.06 +/- 56.56) pg/ml] and group C [(386.95 +/- 44.98) pg/ml] were lower than group B [(1 247.39 +/- 288.57) pg/ml] (P < 0.05). Compared with immunosuppressed control group, there were less alveolar interstitial lymphocytes, foamy intra-alveolar exudate and inflammation of lung tissue in rats of drug treatment groups.

CONCLUSION

Baicalin can decrease the contents of TNF-alpha and sICAM-1, and alleviate inflammation in lung tissues of rats infected with Pneumocystis carinii.

[Lung pathology in HIV-associated infections]

The lung and intrathoracic lymph nodes taken from 153 persons who had taken from HIV infection at the age of 20 to 32 years, with the development of various infectious diseases were examined. Secondary diseases were of generalized progressive pattern. Among these diseases accompanied by pulmonary lesions tuberculosis, as well as bacterial pneumonias, cytomegalovirus infection, pneumocystic pneumonia, cryptococcosis, and non-tuberculous mycobacterial diseases were most common. Lung tissue reactions at terminal stages of HIV infection were polymorphic, which had been caused by severe immunodeficiency, a change in the course of diseases, obliteration of typical morphological signs, and a mixed lung lesion. This makes the differential diagnosis of diseases difficult and requires a comprehensive study of specimens in each specific case, by widely employing additional methods and stains to detect different pathogens.

CT findings in immunocompromised patients with pulmonary infections

PURPOSE

To evaluate computed tomography (CT) findings of pulmonary infections in immunocompromised patients with hematologic malignancies, and to detect the accuracy of first-choice diagnoses.

MATERIALS AND METHODS

CT chest scans of 57 immunocompromised patients who had pulmonary infections were evaluated retrospectively, and a first and second interpretation of etiology (first- and second-choice diagnosis) was proposed. The etiology of pulmonary infection was verified by microbiological tests such as blood, sputum, bronchoalveolar lavage (BAL) cultures, sputum, and BAL smears, or diagnosed on the basis of response to treatment and clinical follow-up.

RESULTS

Nineteen patients had a bacterial infection, 20 patients had a fungal infection, 8 patients had a cytomegalovirus (CMV) infection, 8 patients had Pneumocystis jiroveci pneumonia (PCP) and 2 patients had a Mycobacterium tuberculosis infection. There were consolidations in 13 patients (68.4%) and areas of ground-glass attenuation and ground-glass nodules in 6 patients (31.6%) with bacterial infection. Six of 8 eight patients (75%) with CMV infection had centrilobular nodules associated with bronchial wall thickening and ground-glass areas and nodules. There were parenchymal nodules in 18 of 20 patients (90%) who had a fungal infection. All 8 patients who had PCP had bilateral areas of ground-glass densities on CT scans. The first-choice diagnosis was accurate in most of the fungal infections (95.0%) and PCP (87.5%), but was less accurate for bacterial and viral infections (73.7% and 75.0%, respectively). Neither of the 2 tuberculous infections was identified on the basis of CT findings.

CONCLUSION

In the evaluation of febrile immunocompromised patients, pulmonary fungal infection and PCP may be identified with high accuracy on the basis of CT findings.

[A case of Pneumocystis jiroveci pneumonia that presented with cavity and cystic changes in a malignant thymoma patient]

A 53-year-old man had received various chemotherapy and steroid treatments for malignant thymoma. He had demonstrated persistent fever since the beginning of January 2006, and chest radiograph showed consolidation in the left middle lung fields. Bacterial pneumonia was suspected, but antibiotics were not effective. He was referred and admitted to our hospital on January 16. Chest radiograph and CT scan on admission showed diffuse ground-glass opacities, consolidation with cavity, and cystic changes. Pneumocystis jiroveci Pneumonia was diagnosed by examination of alveolar lavage. This patient was regarded as immunodeficient because of steroid treatment, low counts of CD4-positive lymphocytes, and the complication of hypogammagloblinemia. We reported this case of a non-HIV patient with atypical images demonstrating Pneumocystis jiroveci pneumonia.

Decreased inflammatory response in Toll-like receptor 2 knockout mice is associated with exacerbated Pneumocystis pneumonia

Pneumocystis pneumonia (PcP) is marked by substantial inflammatory damage to the lung. We have found that Toll-like receptor 2 (TLR2) mediates macrophage inflammatory responses to Pneumocystis and hypothesized that TLR2 deficiency would lead to less severe inflammation and milder lung injury during PcP. Histopathology examination showed that TLR2-/- mice with PcP indeed exhibited milder pulmonary inflammation. TLR2-/- mouse lungs contained less TNF-alpha and displayed lower levels of NF-kappaB activation during PcP. However, TLR2-/- mice with PcP displayed increased severity in symptoms and organism burden. The increased organism burden is likely due to defects in protective mechanisms in TLR2-/- mice. mRNA levels of the inducible nitric oxide synthase and NADPH oxidase p47phox, as well as nitric oxide levels in the lungs, were decreased in TLR2-/- PcP mice. Taken together, this study shows that TLR2-mediated inflammatory responses contribute to a certain degree to the clearance of Pneumocystis organism in mice.

Genotyping of Pneumocystis jiroveci pneumonia in Italian AIDS patients. Clinical outcome is influenced by dihydropteroate synthase and not by internal transcribed spacer genotype

BACKGROUND

Two Pneumocystis jiroveci independent genomic regions, internal transcribed spacer (ITS) 1 and ITS2, and dihydropteroate synthase (DHPS) gene have been used for typing a cohort of HIV-infected Italian patients with P jiroveci pneumonia (PcP).

METHODS

Bronchoalveolar lavage samples isolated from 207 HIV-infected adults were ITS and DHPS genotyped by DNA sequencing and by restriction fragment length polymorphism analysis, respectively. Mutant DHPS samples were cloned and ITS typed. Data on severity, treatment, and outcome of PcP were obtained by chart review.

RESULTS

High diversity with 46 different ITS genotypes was observed. At the DHPS locus, 9.1% of samples analyzed were found to be mutated. A correlation was observed between DHPS mutants and greater severity of PcP, as defined by higher lactate dehydrogenase (P = 0.015) and need for intubation (P = 0.002), and worse outcomes, as defined by failure of sulfa treatment (P = 0.04), death, and/or relapse of PcP (P = 0.008). There was a significant difference in ITS genotype patterns between DHPS wild-type and mutants (P = 0.028).

CONCLUSIONS

The present data suggest the absence of a correlation between P jiroveci ITS types and specific clinical characteristics. DHPS mutations correlate with possible failure of anti-P jiroveci sulfa therapy, and a trend of association is shown between DHPS mutations and some clinical PcP features.

Pneumocystis carinii pneumonia in a patient on etanercept for psoriatic arthritis

BACKGROUND

Pneumocystis carinii pneumonia (PCP) is a rare form of pneumonia associated with immune-suppression. It is common in patients with AIDS and with a CD4 count of less than 200 cells/mm(3). We report a case of PCP secondary to immune-suppression in a 41-year-old man with psoriatic arthritis being treated with the immune-modulatory agent etanercept.

METHODS

Diagnosis of PCP was made histologically using tissue obtained via transbronchial biopsy.

RESULTS

There was a good response to standard treatment with high-dose co-trimoxazole.

CONCLUSION

This report highlights a recognised but previously unreported complication of etanercept.

Pulmonary hypertension can be a sequela of prior Pneumocystis pneumonia

Improved treatment regimens have reduced fatalities from opportunistic diseases, such as Pneumocystis pneumonia, in AIDS patients. However, serious chronic conditions, including pulmonary hypertension (PH), are increasing in this group. We report here that when CD4 T cells in Pneumocystis-infected mice are temporally depleted and then allowed to return, the extended inflammation results in PH that persists after Pneumocystis is eliminated. Using this model of PH, we have found that i) the onset of PH is correlated with the return of CD4 T cells, but PH persists after CD4 levels diminish; ii) vascular remodeling accompanies PH, but whereas temporary medial hypertrophy is evident with transient PH in immunocompetent mice, persistent PH is associated with perivascular fibrosis; iii) elevated levels of the fibrotic mediator FIZZ1 are found in bronchoalveolar lavage fluid of mice with persistent PH; and iv) although Th2-related mechanisms may be involved in PH etiology, PH still occurs in interleukin-4 receptor-deficient mice under these conditions. Overall, the data presented here demonstrate that the immune response to an infectious disease pathogen, such as Pneumocystis, can, when perturbed and prolonged, lead to later development of a serious chronic condition such as PH.

Development and evaluation of a real-time PCR assay for detection of Pneumocystis jiroveci

Pneumocystis jiroveci is an important agent of pneumonia in immunocompromised hosts. Usually, this pathogen is detected by Giemsa or direct fluorescence stains of bronchoalveolar lavage (BAL) fluids. Microscopic methods, however, have 2 disadvantages. P. jiroveci is not stable outside the human body, which means that slow sample transport might result in false-negative results. Additionally, exact quantification, which is needed for therapy monitoring, is not possible. In this study, we developed a real-time polymerase chain reaction assay for the LightCycler. Two Pneumocystis-specific TaqMan systems, one based on the sequence of the 5.8S ribosomal gene and another one targeting the dihydrofolate reductase gene were evaluated. Additionally, the amount of human DNA in the sample was measured by a TaqMan assay based on the human albumin gene, allowing assessment of sample quality and quantification normalized on sample concentration. For clinical evaluation, 69 BAL specimens from 26 positive patients as well as 60 negative controls were tested. Both systems were able to detect all proven cases of Pneumocystis pneumonia. Differentiation of carriage, asymptomatic reactivation, and clinical infection as well as normalized quantification by calculating the ratio of Pneumocystis DNA to human DNA are discussed.

Type I Interferon Signaling and B Cells Maintain Hemopoiesis duringPneumocystisInfection of the Lung

Loss of CD4 T cells is the hallmark of HIV infection. However, type I IFN-producing plasmacytoid dendritic cells may also be lost. This results in susceptibility to an opportunistic infection such as Pneumocystis pneumonia. In addition, regenerative bone marrow failure resulting in pancytopenia is another common problem in advanced stage AIDS. This may be linked to both the failing immune system and recurrent opportunistic infections. We generated lymphocyte-deficient type I IFN receptor-deficient mice (IFrag-/-) to study the effects on Pneumocystis infection of the lung. When IFrag-/- animals were infected with Pneumocystis they died between days 16 and 21 postinfection with minimal pneumonia but severe anemia due to complete bone marrow failure. This included the loss of uncommitted hemopoietic precursor cells. Bone marrow failure was prevented by the reconstitution of IFrag-/- mice with wild-type lymphocytes, especially B cells. T and B cells lacking type I IFN receptor signaling could only partially prevent bone marrow failure in response to Pneumocystis infection. However, the presence of T and B cells lacking type I IFN signaling resulted in compensatory extramedullary hemopoiesis in the liver and spleen. Lymphocyte support of the regenerative capacity of the bone marrow was provided by both type I IFN-dependent and -independent mechanisms that acted synergistically. Our findings point to the requirement of both type I IFNs and lymphocytes in the regenerative capabilities of the hemopoietic system under the pressure of Pneumocystis infection, but not during steady-state hemopoiesis. This may have implications in the management of pancytopenia in AIDS.

Current insights into the biology and pathogenesis of Pneumocystis pneumonia

The fungal infection Pneumocystis pneumonia is the most prevalent opportunistic infection in patients with AIDS. Although the analysis of this opportunistic fungal pathogen has been hindered by the inability to isolate it in pure culture, the use of molecular techniques and genomic analysis have brought insights into its complex cell biology. Analysis of the intricate relationship between Pneumocystis and the host lung during infection has revealed that the attachment of Pneumocystis to the alveolar epithelium promotes the transition of the organism from the trophic to the cyst form. It also revealed that Pneumocystis infection elicits the production of inflammatory mediators, culminating in lung injury and impaired gas exchange. Here we discuss these and other recent findings relating to the biology and pathogenesis of this intractable fungus.

Fiberoptic bronchoscopy and bronchoalveolar lavage for the evaluation of pulmonary disease in children with primary immunodeficiency and cancer

BACKGROUND

Patients with childhood cancer or primary immunodeficiencies (PID) are at high risk for developing pulmonary infections and non-infectious complications. The broad differential diagnoses and the critical condition of these patients often drive physicians to start broad-spectrum antibiotic therapy before a definite diagnostic procedure is performed. A definite diagnosis may be achieved in these situations by fiberoptic bronchoscopy (FOB) and bronchoalveolar lavage (BAL).

PATIENTS AND METHODS

The records of 58 PIDs and cancer (immunocompromised group) pediatric patients who underwent 62 fiberoptic bronchoscopies between 2000 and 2004 were retrospectively reviewed and compared to 158 non-cancer patients who underwent 182 fiberoptic bronchoscopies during the same period.

RESULTS

The overall diagnostic rate achieved by macroscopic inspection of purulent secretions or hemorrhage, abnormal cell count, and infectious agent isolation in the immunocompromised patients was 84%. A definite organism was recovered in 53.2% of the patients. Probable infection defined as purulent secretions or abnormal cell count without infectious agent isolation was diagnosed in another 21% of the patients. The rate of complications was 30.6%. In the control group, the overall diagnostic rate was 76.9% (n.s) and an infectious agent was demonstrated in 12.1% (P < 0.001). Probable infection was diagnosed in 24.2% (n.s) while the rate of complications was lower (15%) (P < 0.01).

CONCLUSIONS

Rapid and accurate diagnoses were achieved in most procedures performed on immunocompromised patients. Although the rate of complications was higher in the immunocompromised group, they were usually very mild with no mortality. Based on these results, broncoalveolar lavage should be considered as an initial diagnostic tool in pediatric immunocompromised patients with pulmonary complications.

Pneumocystis pneumonia in patients with HIV infection: clinical manifestations, laboratory findings, and radiological features

Pneumocystis pneumonia (PCP) remains the most common opportunistic infection in patients with acquired immunodeficiency syndrome (AIDS). Familiarity with the clinical features of PCP is crucial for prompt diagnosis, even if the patient is unaware of their HIV serostatus. We describe herein the clinical features of 34 episodes in 32 patients with AIDS-associated PCP and review the existing literature. As for symptoms, the frequency of fever, cough, and dyspnea was 74%, 74%, and 65%, respectively, and the complete triad was present in only 14 of the 34 episodes on first examination. Median duration from onset of symptoms until diagnosis was 3 weeks, and AIDS-associated PCP tended to take an insidious clinical course. Although laboratory findings were generally nonspecific, measurement of beta-D-glucan levels in the serum or plasma was highly useful in the diagnosis of PCP. All but 1 of the patients showed beta-D-glucan levels higher than the cutoff value (median, 147 pg/ml; range, 5-6920 pg/ml). Typical radiographic features of PCP are bilateral, symmetrical ground-glass opacities, but a wide variety of radiographic findings were observed. In our patients, high-resolution computed tomography (HRCT) of the lung showed ground-glass opacities sparing the lung periphery (41% of episodes) or displaying a mosaic pattern (29%), or being nearly homogeneous (24%), ground-glass opacities associated with air-space consolidation (21%), associated with cystic formation (21%), associated with linear-reticular opacities (18%), patchily and irregularly distributed (15%), associated with solitary or multiple nodules (9%), and associated with parenchymal cavity lesions (6%).

Polyamine-mediated apoptosis of alveolar macrophages during Pneumocystis pneumonia

The number of alveolar macrophages is decreased during Pneumocystis pneumonia (Pcp), partly because of activation of apoptosis in these cells. This apoptosis occurs in both rat and mouse models of Pcp. Bronchoalveolar lavage (BAL) fluids from Pneumocystis-infected animals were found to contain high levels of polyamines, including spermidine, N1-acetylspermine, and N1-acetylspermidine. These BAL fluids and exogenous polyamines were able to induce apoptosis in alveolar macrophages. Apoptosis of alveolar macrophages during infection, after incubation with BAL fluids from Pneumocystis-infected animals, or after incubation with polyamines was marked by an increase in intracellular reactive oxygen species, activation of caspases-3 and -9, DNA fragmentation, and leakage of mitochondrial cytochrome c into the cytoplasm. When polyamines were depleted from the BAL fluids of infected animals, the ability of these BAL fluids to induce apoptosis was lost. Interestingly, the apoptosis inducing activity of the polyamine-depleted BAL fluids was restored when polyamines were added back. The results of this study suggested that Pneumocystis infection results in accumulation of high levels of polyamines in the lung. These polyamines activate apoptosis of alveolar macrophages, perhaps because of the ROS that are produced during polyamine metabolism.

Effects of Protostrongylus sp. and Pneumocystis sp. on the pulmonary tissue and the condition of mountain and brown hares from Finland

Mountain hares (Lepus timidus) and brown hares (Lepus europaeus) shot by hunters in several game management districts in southern and central Finland during the hunting season from September to the end of February 1998-2001 were examined for Protostrongylus sp. and Pneumocystis sp. Of the mountain hares, 96.5% (194/201) were infected with the lungworm Protostrongylus sp. and 16.9% (32/189) had cyst forms of the fungus Pneumocystis sp. in the lungs. The prevalence of the lungworm and fungus in brown hares was 60% (18/30) and 20.0% (6/30), respectively. The tissue changes associated with the lungworms were macroscopically and microscopically well demarcated. The majority and most severe histopathologic changes were seen at the distal part of the caudal lobes. Inflammatory cells, mainly eosinophils and macrophages, and in lesser degree neutrophils, lymphocytes, and plasma cells were typical findings in the worm-infected tissue. The condition and weight of the hare did not show any significant association with the intensity of the lungworm infection. All Pneumocystis-infected mountain hares were young, and their condition and weight correlated negatively with the intensity of the infection. The intensity of the Pneumocystis infection did not correlate with that of the lungworm infection. Within a tissue section, a slight but significant positive correlation was observed between presence of cysts and inflammatory cells.

Regulatory T cells dampen pulmonary inflammation and lung injury in an animal model of pneumocystis pneumonia

CD4+CD25+FoxP3+ regulatory T cells are decreased in patients infected with HIV and have been shown to be critical in mediating Ag tolerance in the lung. Because a subset of Pneumocystis-infected individuals develop substantial lung injury, which can be modeled in immune reconstituted scid mice, we used mouse models of Pneumocystis carinii to investigate the role of regulatory T cells in opportunistic infection and immune reconstitution. In this study, we show that CD4+CD25+FoxP3+ cells are part of the host response to Pneumocystis in CD4+ T cell-intact mice. Moreover, lung injury and proinflammatory Th1 and Th2 cytokine levels in the bronchoalveolar lavage fluid and lung homogenate were increased following CD4+CD25- immune reconstitution in Pneumocystis-infected SCID mice but not in CD4+CD25+ T cell-reconstituted animals. The ability of CD4+CD25+ T cells to control inflammation and injury during the course of Pneumocystis was confirmed by treatment of wild-type C57BL/6 mice with anti-CD25 mAb. These data show that CD4+CD25+ T cells control pulmonary inflammation and lung injury associated with Pneumocystis infection both in the setting of immune reconstitution as well as new acquisition of infection.