The Contribution of Host Cells to Pneumocystis Immunity: An Update

Integrated analysis of microbiome and host transcriptome unveils correlations between lung microbiota and host immunity in bronchoalveolar lavage fluid of pneumocystis pneumonia patients

OBJECTIVE

The lung microbiota of patients with pulmonary diseases is disrupted and impacts the immunity. The microbiological and immune landscape of the lungs in patients with pneumocystis pneumonia (PCP) remains poorly understood.

METHODS

Multi-omics analysis and machine learning were performed on bronchoalveolar lavage fluid to explore interaction between the lung microbiota and host immunity in PCP. Then we constructed a diagnostic model using differential genes with LASSO regression and validated by qPCR. The immune infiltration analysis was performed to explore the landscape of lung immunity in patients with PCP.

RESULTS

Patients with PCP showed a low alpha diversity of lung microbiota, accompanied by the elevated abundance of Firmicutes, and the differential expressed genes (DEGs) analysis displayed a downregulation of MAPK signaling. The MAPK10, TGFB1, and EFNA3 indicated a potential to predict PCP (AUC = 0.86). The lung immune landscape in PCP showed the lower levels of naïve CD4+ T cells and activated dendritic cells. The correlation analysis of the MAPK signaling pathway-related DEGs and the differential microorganisms at the level of phylum showed that the Firmicutes was negatively correlated with these DEGs.

CONCLUSION

We profiled the characteristics of lung microbiota and immune landscape in PCP, which may contribute to elucidating the mechanism of PCP.

Pneumocystis murina lesions in lungs of experimentally infected Cd40l-/- mice

The Cd40l-/- mouse is a well-established model of X-linked hyper-immunoglobulin M (IgM) syndrome, an immunodeficiency disorder of human beings characterized by the lack of expression of the CD40 ligand (CD40L) on activated T-cells, predisposing to infections with opportunistic pathogens like Pneumocystis jirovecii. The aim of our study was to describe the pulmonary lesions in Cd40l-/- mice experimentally infected with Pneumocystis murina, in comparison with naturally infected severe combined immunodeficient (SCID) mice. Formalin-fixed paraffin-embedded lungs from 26 Cd40l-/-, 11 SCID, and 5 uninfected Cd40l-/- mice were examined by histology and immunohistochemistry for the presence of the pathogen and for leukocyte populations (CD3, CD4, CD45R/B220, CD8a, Iba-1, Ly-6G, CD206, MHC II, and NKp46/NCR1). Infection was confirmed by immunohistochemistry in 18/26 (69%) Cd40l-/- mice and in 11/11 (100%) SCID mice. Fourteen out of 26 (54%) Cd40l-/- mice had interstitial pneumonia. Twenty-three out of 26 (88%) Cd40l-/- mice had peribronchiolar/perivascular lymphoplasmacytic infiltrates, rich in B-cells and Mott cells. Acidophilic macrophage pneumonia was additionally found in 20/26 (77%) Cd40l-/- mice. Only 4/11 (36%) SCID mice had interstitial pneumonia, but no peribronchiolar/perivascular infiltrates or acidophilic macrophage pneumonia were observed in this strain. This study represents the first description of pulmonary histopathological lesions in Cd40l-/- mice infected with P. murina. We speculate that the singular characteristics of the inflammatory infiltrates observed in Cd40l-/- mice could be explained by the specific immune phenotype of the model.

Characterization of the Pneumocystis jirovecii and Pneumocystis murina phosphoglucomutases (Pgm2s): a potential target for Pneumocystis therapy

Pneumocystis cyst life forms contain abundant β-glucan carbohydrates, synthesized using β-1,3 and β-1,6 glucan synthase enzymes and the donor uridine diphosphate (UDP)-glucose. In yeast, phosphoglucomutase (PGM) plays a crucial role in carbohydrate metabolism by interconverting glucose 1-phosphate and glucose 6-phosphate, a vital step in UDP pools for β-glucan cell wall formation. This pathway has not yet been defined in Pneumocystis. Herein, we surveyed the Pneumocystis jirovecii and Pneumocystis murina genomes, which predicted a homolog of the Saccharomyces cerevisiae major PGM enzyme. Furthermore, we show that PjPgm2p and PmPgm2p function similarly to the yeast counterpart. When both Pneumocystis pgm2 homologs are heterologously expressed in S. cerevisiae pgm2Δ cells, both genes can restore growth and sedimentation rates to wild-type levels. Additionally, we demonstrate that yeast pgm2Δ cell lysates expressing the two Pneumocystis pgm2 transcripts individually can restore PGM activities significantly altered in the yeast pgm2Δ strain. The addition of lithium, a competitive inhibitor of yeast PGM activity, significantly reduces PGM activity. Next, we tested the effects of lithium on P. murina viability ex vivo and found the compound displays significant anti-Pneumocystis activity. Finally, we demonstrate that a para-aryl derivative (ISFP10) with known inhibitory activity against the Aspergillus fumigatus PGM protein and exhibiting 50-fold selectivity over the human PGM enzyme homolog can also significantly reduce Pmpgm2 activity in vitro. Collectively, our data genetically and functionally validate phosphoglucomutases in both P. jirovecii and P. murina and suggest the potential of this protein as a selective therapeutic target for individuals with Pneumocystis pneumonia.

Pneumocystis jirovecii pneumonia mortality risk associated with preceding long-term steroid use for the underlying disease: A multicenter, retrospective cohort study

OBJECTIVE

Long-term steroid use increases the risk of developing Pneumocystis pneumonia (PcP), but there are limited reports on the relation of long-term steroid and PcP mortality.

METHODS

Retrospective multicenter study to identify risk factors for PcP mortality, including average steroid dose before the first visit for PcP in non-human immunodeficiency virus (HIV)-PcP patients. We generated receiver operating characteristic (ROC) curves for 90-day all-cause mortality and the mean daily steroid dose per unit body weight in the preceding 10 to 90 days in 10-day increments. Patients were dichotomized by 90-day mortality and propensity score-based stabilized inverse probability of treatment weighting (IPTW) adjusted covariates of age, sex, and underlying disease. Multivariate analysis with logistic regression assessed whether long-term corticosteroid use affected outcome.

RESULTS

Of 133 patients with non-HIV-PcP, 37 died within 90 days of initial diagnosis. The area under the ROC curve for 1-40 days was highest, and the optimal cutoff point of median adjunctive corticosteroid dosage was 0.34 mg/kg/day. Past steroid dose, underlying interstitial lung disease and emphysema, lower serum albumin and lower lymphocyte count, higher lactate dehydrogenase, use of therapeutic pentamidine and therapeutic high-dose steroids were all significantly associated with mortality. Underlying autoimmune disease, past immunosuppressant use, and a longer time from onset to start of treatment, were associated lower mortality. Logistic regression analysis after adjusting for age, sex, and underlying disease with IPTW revealed that steroid dose 1-40 days before the first visit for PcP (per 0.1 mg/kg/day increment, odds ratio 1.36 [95% confidence interval = 1.16-1.66], P<0.001), low lymphocyte counts, and high lactate dehydrogenase revel were independent mortality risk factor, while respiratory failure, early steroid, and sulfamethoxazole/trimethoprim for PcP treatment did not.

CONCLUSION

A steroid dose before PcP onset was strongly associated with 90-day mortality in non-HIV-PcP patients, emphasizing the importance of appropriate prophylaxis especially in this population.

Trends in the Epidemiology of Pneumocystis Pneumonia in Immunocompromised Patients without HIV Infection

The increasing morbidity and mortality of life-threatening Pneumocystis pneumonia (PCP) in immunocompromised people poses a global concern, prompting the World Health Organization to list it as one of the 19 priority invasive fungal diseases, calling for increased research and public health action. In response to this initiative, we provide this review on the epidemiology of PCP in non-HIV patients with various immunodeficient conditions, including the use of immunosuppressive agents, cancer therapies, solid organ and stem cell transplantation, autoimmune and inflammatory diseases, inherited or primary immunodeficiencies, and COVID-19. Special attention is given to the molecular epidemiology of PCP outbreaks in solid organ transplant recipients; the risk of PCP associated with the increasing use of immunodepleting monoclonal antibodies and a wide range of genetic defects causing primary immunodeficiency; the trend of concurrent infection of PCP in COVID-19; the prevalence of colonization; and the rising evidence supporting de novo infection rather than reactivation of latent infection in the pathogenesis of PCP. Additionally, we provide a concise discussion of the varying effects of different immunodeficient conditions on distinct components of the immune system. The objective of this review is to increase awareness and knowledge of PCP in non-HIV patients, thereby improving the early identification and treatment of patients susceptible to PCP.

Ultrasmall Cortex Moutan Nanoclusters for the Therapy of Pneumonia and Colitis

Infectious pneumonia and colitis are hard to be treated due to tissue infection, mucosal immune disorders, and dysbacteriosis. Although conventional nanomaterials can eliminate infection, they also damage normal tissues and intestinal flora. Herein, this work reports bactericidal nanoclusters formed through self-assembly for efficient treatment of infectious pneumonia and enteritis. The ultrasmall (about 2.3 nm) cortex moutan nanoclusters (CMNCs) has excellent antibacterial, antiviral, and immune regulation activity. The formation of nanoclusters is analyzed from the molecular dynamics mainly through the binding between polyphenol structures through hydrogen bonding and ππ stacking interaction. CMNCs have enhanced tissue and mucus permeability ability compared with natural CM. CMNCs precisely targeted bacteria due to polyphenol-rich surface structure and inhibited broad spectrum of bacteria. Besides, they killed H1N1 virus mainly through the inhibition of the neuraminidase. These CMNCs are effective in treating infectious pneumonia and enteritis relative to natural CM. In addition, they can be used for adjuvant colitis treatment by protecting colonic epithelium and altering the composition of gut microbiota. Therefore, CMNCs showed excellent application and clinical translation prospects in the treatment of immune and infectious diseases.

Integrated multi-omics analyses reveal the altered transcriptomic characteristics of pulmonary macrophages in immunocompromised hosts with Pneumocystis pneumonia

Introduction

With the extensive use of immunosuppressants, immunosuppression-associated pneumonitis including Pneumocystis jirovecii pneumonia (PCP) has received increasing attention. Though aberrant adaptive immunity has been considered as a key reason for opportunistic infections, the characteristics of innate immunity in these immunocompromised hosts remain unclear.

Methods

In this study, wild type C57BL/6 mice or dexamethasone-treated mice were injected with or without Pneumocystis. Bronchoalveolar lavage fluids (BALFs) were harvested for the multiplex cytokine and metabolomics analysis. The single-cell RNA sequencing (scRNA-seq) of indicated lung tissues or BALFs was performed to decipher the macrophages heterogeneity. Mice lung tissues were further analyzed via quantitative polymerase chain reaction (qPCR) or immunohistochemical staining.

Results

We found that the secretion of both pro-inflammatory cytokines and metabolites in the Pneumocystis-infected mice are impaired by glucocorticoids. By scRNA-seq, we identified seven subpopulations of macrophages in mice lung tissues. Among them, a group of Mmp12⁺ macrophages is enriched in the immunocompetent mice with Pneumocystis infection. Pseudotime trajectory showed that these Mmp12⁺ macrophages are differentiated from Ly6c⁺ classical monocytes, and highly express pro-inflammatory cytokines elevated in BALFs of Pneumocystis-infected mice. In vitro, we confirmed that dexamethasone impairs the expression of Lif, Il1b, Il6 and Tnf, as well as the fungal killing capacity of alveolar macrophage (AM)-like cells. Moreover, in patients with PCP, we found a group of macrophages resembled the aforementioned Mmp12⁺ macrophages, and these macrophages are inhibited in the patient receiving glucocorticoid treatment. Additionally, dexamethasone simultaneously impaired the functional integrity of resident AMs and downregulated the level of lysophosphatidylcholine, leading to the suppressed antifungal capacities.

Conclusion

We reported a group of Mmp12⁺ macrophages conferring protection during Pneumocystis infection, which can be dampened by glucocorticoids. This study provides multiple resources for understanding the heterogeneity and metabolic changes of innate immunity in immunocompromised hosts, and also suggests that the loss of Mmp12⁺ macrophages population contributes to the pathogenesis of immunosuppression-associated pneumonitis.

Metabolomic Profiling of Lungs from Mice Reveals the Variability of Metabolites in Pneumocystis Infection and the Metabolic Abnormalities in BAFF-R-Deficient Mice

Purpose

The incidence of Pneumocystis pneumonia (PCP) in patients without human immunodeficiency virus (HIV) has been increasing. In this study, we aimed to investigate the metabolic changes in Pneumocystis infection and the metabolic abnormalities in B-cell-activating factor receptor (BAFF-R)-deficient mice with Pneumocystis infection.

Methods

The important function of B cells during Pneumocystis infection is increasingly recognized. In this study, a Pneumocystis-infected mouse model was constructed in BAFF-R^-/- mice and wild-type (WT) mice. Lungs of uninfected WT C57BL/6, WT Pneumocystis-infected, and BAFF-R^-/- Pneumocystis-infected mice were used for metabolomic analyses to compare the metabolomic profiles among the groups, with the aim of exploring the metabolic influence of Pneumocystis infection and the influence of mature B-cell deficiency during infection.

Results

The results indicated that many metabolites, mainly lipids and lipid-like molecules, were dysregulated in Pneumocystis-infected WT mice compared with uninfected WT C57BL/6 mice. The data also demonstrated significant changes in tryptophan metabolism, and the expression levels of key enzymes of tryptophan metabolism, such as indoleamine 2,3-dioxygenase 1 (IDO1), were significantly upregulated. In addition, B-cell development and function might be associated with lipid metabolism. We found a lower level of alitretinoin and the abnormalities of fatty acid metabolism in BAFF-R^-/- Pneumocystis-infected mice. The mRNA levels of enzymes associated with fatty acid metabolism in the lung were upregulated in BAFF-R^-/- Pneumocystis-infected mice and positively correlated with the level of IL17A, thus suggesting that the abnormalities of fatty acid metabolism may be associated with greater inflammatory cell infiltration in the lung tissue of BAFF-R^-/- Pneumocystis-infected mice compared with the WT Pneumocystis-infected mice.

Conclusion

Our data revealed the variability of metabolites in Pneumocystis-infected mice, suggesting that the metabolism plays a vital role in the immune response to Pneumocystis infection.

Neglected mycobiome in HIV infection: Alterations, common fungal diseases and antifungal immunity

Human immunodeficiency virus (HIV) infection might have effects on both the human bacteriome and mycobiome. Although many studies have focused on alteration of the bacteriome in HIV infection, only a handful of studies have also characterized the composition of the mycobiome in HIV-infected individuals. Studies have shown that compromised immunity in HIV infection might contribute to the development of opportunistic fungal infections. Despite effective antiretroviral therapy (ART), opportunistic fungal infections continue to be a major cause of HIV-related mortality. Human immune responses are known to play a critical role in controlling fungal infections. However, the effect of HIV infection on innate and adaptive antifungal immunity remains unclear. Here, we review recent advances in understanding of the fungal microbiota composition and common fungal diseases in the setting of HIV. Moreover, we discuss innate and adaptive antifungal immunity in HIV infection.

Analysis of lncRNA and mRNA Repertoires in Lung From BAFF-R-Deficient Pneumocystis-Infected Mice

Background

Pneumocystis pneumonia (PCP) is a common medical issue in immunosuppressive patients. Increasing evidence supports that B cells may play an essential role in PCP individuals. The present study aims to integrate lncRNA and mRNA expression profiles and further investigate the molecular function of mature B cells in PCP.

Methods

The lung tissue of wild-type (WT) mice and B-cell-activating factor receptor–deficient (mature B-cell deficiency, BAFF-R–/–) mice were harvested at 3 weeks after being infected with pneumocystis. After total RNAs were extracted, transcriptome profiling was performed following the Illumina HiSeq 3000 protocol. lncRNA-targeted miRNA pairs were predicted using the online databases. The Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) enrichment pathways were analyzed to functionally annotate these differentially expressed genes. Additionally, the immune-related lncRNA–miRNA–mRNA–ceRNA network was subsequently performed. The quantitative real-time PCR (RT-PCR) analysis was conducted to evaluate the lncRNA and mRNA expression profiles in WT-PCP mice and BAFF-R–/– PCP mice.

Results

Compared with the control group, 166 mRNAs were observed to be aberrantly expressed (fold change value ≥2; P &lt;0.05) in the BAFF-R–/– PCP group, including 39 upregulated and 127 downregulated genes, while there were 69 lncRNAs differently expressed in the BAFF-R–/– PCP group, including 15 upregulated and 54 downregulated genes. In addition, GO and KEGG pathway analyses showed that BAFF-R deficiency played an important role in the primary and adaptive immune responses in PCP. Furthermore, the lncRNA and mRNA co-expression network was established. We noted that the core network of lncRNA-TF (transcription factor) pairs could be classified into the categories including infection and immunity pathways.

Conclusion

In summary, in this study, we further explored the role of mature B cells in the pathogenesis and progression of PCP and the data demonstrated that BAFF-R deficiency could play a significant role in immune regulation in the PCP population.

Comparison of the oxidative respiratory burst and mitogen-induced leukocyte responses of camels, goats, sheep, and cows

Background and Aim:

The reports from the Ministry of Agriculture and Fisheries suggest that camels suffer less compared to goats, sheep, and cows from a number of common infectious diseases in Oman. However, there is no immunological evidence to substantiate this claim. This present study is, therefore, an attempt to study the immunological responses of camels, goats, sheep, and cows by comparing their oxidative respiratory burst of peripheral blood leukocytes (PBLs) as a marker of innate immunity occurring during phagocytosis and the mitogenic responses of their peripheral blood mononuclear leukocytes (PBMLs) as a marker of their adaptive immune response.

Materials and Methods:

Ten female adult animals (n = 10) were selected from each species (goats, sheep, and cows). The goats, sheep, and cows were maintained at the Agricultural Experiment Station, while camels were kept at the Royal Camel Corps (RCC). Blood samples were collected from the jugular vein in 7 mL of heparin and ethylenediaminetetraacetic acid vacutainer tubes. The oxidative respiratory burst of PBLs was measured using a chemiluminescence (CL) assay. Reactants consisted of 75 mL of whole blood diluted (1:50), 75 mL of luminol/isoluminol, and 75 mL of zymosan opsonized with non-heat inactivated serum/heat-inactivated serum or non-opsonized zymosan. CL responses were measured as relative light units and expressed as the mean count per minute and peak CL values. The mitogenic response of PBMLs to concanavalin A (Con-A), phytohemagglutinin (PHA), and pokeweed mitogen (PWM) was tested using a WST-8 assay and read spectrophotometrically at 450 nm.

Results:

The present findings showed that camel PBLs generate significantly higher CL responses, both intracellularly as well as extracellularly, with zymosan opsonized with autologous serum. Camel PBLs demonstrated a significantly higher (p = 0.001) response when stimulated with zymosan opsonized with heat-inactivated serum compared to those of goat, sheep, and cow lymphocytes from camels exhibited significantly higher (p = 0.001) stimulation indices (SI) with Con-A, PHA, and PWM.

Conclusion:

The present study suggests that camels are capable of mounting both superior innate as well as adaptive immune responses and provide immunological evidence supporting the belief of some authors, who have proposed that camels are less susceptible to a number of common infectious diseases than other domesticated ruminants.

Proteomic Profiling and Functional Analysis of B Cell-Derived Exosomes upon Pneumocystis Infection

Pneumocystis is a life-threatening fungal pathogen that frequently causes fatal pneumonia (PCP) in immunocompromised individuals. Recently, B cells have been reported to play a crucial role in the pathogenesis of PCP through producing antibodies and activating CD4+ T cell response. Exosomes are nanoscale small extracellular vesicles abundant with protein cargo and can mediate immune response during infectious disease. In this study, using tandem mass tag-based quantitative proteomics coupled with bioinformatic analysis, we attempted to characterize exosomes derived from B lymphocytes in response to PCP. Several proteins were verified by parallel reaction monitoring (PRM) analysis. Also, the effects of B cell exosomes on CD4+ T cell response and phagocytic function of macrophages were clarified. Briefly, 1701 proteins were identified from B cell exosomes, and the majority of them were reported in Vesiclepedia. A total of 51 differentially expressed proteins of B cell exosomes were found in response to PCP. They were mainly associated with immune response and transcription regulation. PRM analysis confirmed the significantly changed levels of histone H1.3, vimentin, and tyrosine-protein phosphatase nonreceptor type 6 (PTPN6). Moreover, a functional study revealed the proinflammatory profile of B cell exosomes on CD4+ T cell response in PCP. Taken together, our results suggest the involvement of exosomes derived from B cells in cell-to-cell communication, providing new information on the function of B cells in response to PCP.

Immune Response in Pneumocystis Infections According to the Host Immune System Status

The host immune response is critical in Pneumocystis pneumonia (PCP). Immunocompetent hosts can eliminate the fungus without symptoms, while immunodeficient hosts develop PCP with an unsuitable excessive inflammatory response leading to lung damage. From studies based on rodent models or clinical studies, this review aimed to better understand the pathophysiology of Pneumocystis infection by analysing the role of immune cells, mostly lymphocytes, according to the immune status of the infected host. Hence, this review first describes the immune physiological response in infected immunocompetent hosts that are able to eliminate the fungus. The objective of the second part is to identify the immune elements required for the control of the fungus, focusing on specific immune deficiencies. Finally, the third part concentrates on the effect of the different immune elements in immunocompromised subjects during PCP, to better understand which cells are detrimental, and which, on the contrary, are beneficial once the disease has started. This work highlights that the immune response associated with a favourable outcome of the infection may differ according to the immune status of the host. In the case of immunocompetency, a close communication between B cells and TCD4 within tertiary lymphocyte structures appears critical to activate M2 macrophages without much inflammation. Conversely, in the case of immunodeficiency, a pro-inflammatory response including Th1 CD4, cytotoxic CD8, NK cells, and IFNγ release seems beneficial for M1 macrophage activation, despite the impact of inflammation on lung tissue.

Signatures of B Cell Receptor Repertoire Following Pneumocystis Infection

B cells play vital roles in host defense against Pneumocystis infection. However, the features of the B cell receptor (BCR) repertoire in disease progression remain unclear. Here, we integrated single-cell RNA sequencing and single-cell BCR sequencing of immune cells from mouse lungs in an uninfected state and 1–4 weeks post-infection in order to illustrate the dynamic nature of B cell responses during Pneumocystis infection. We identified continuously increased plasma cells and an elevated ratio of (IgA + IgG) to (IgD + IgM) after infection. Moreover, Pneumocystis infection was associated with an increasing naïve B subset characterized by elevated expression of the transcription factor ATF3. The proportion of clonal expanded cells progressively increased, while BCR diversity decreased. Plasma cells exhibited higher levels of somatic hypermutation than naïve B cells. Biased usage of V(D)J genes was observed, and the usage frequency of IGHV9-3 rose. Overall, these results present a detailed atlas of B cell transcriptional changes and BCR repertoire features in the context of Pneumocystis infection, which provides valuable information for finding diagnostic biomarkers and developing potential immunotherapeutic targets.

Single-Cell TCR Sequencing Reveals the Dynamics of T Cell Repertoire Profiling During Pneumocystis Infection

T cell responses play critical roles in host adaptive immunity against Pneumocystis. However, the dynamics and diversity of the T cell immune repertoire in human immunodeficiency virus (HIV)-negative Pneumocystis pneumonia (PCP) remains unclear. In this study, single-cell RNA and single-cell T cell receptor (TCR) sequencing were applied to cells sorted from lung tissues of mice infected with Pneumocystis. Our findings demonstrated the clonal cells were mainly composed of CD4⁺ T cells in response to Pneumocystis, which were marked by highly expressed genes associated with T cell activation. Mice infected with Pneumocystis showed reduced TCR diversity in CD4⁺ T cells and increased diversity in CD8⁺ T cells compared with uninfected controls. Furthermore, Th17 cells were mostly clonal CD4⁺ T cells, which exhibited the phenotype of tissue-resident memory-like Th17 cells. In addition, Pneumocystis-infected mice showed biased usage of TCRβ VDJ genes. Taken together, we characterized the transcriptome and TCR immune repertoires profiles of expanded T cell clones, which demonstrate a skewed TCR repertoire after Pneumocystis infection.

COVID-19 and Pneumocystis jirovecii Pulmonary Coinfection-The First Case Confirmed through Autopsy

Background: Establishing the diagnosis of COVID-19 and Pneumocystisjirovecii pulmonary coinfection is difficult due to clinical and radiological similarities that exist between the two disorders. For the moment, fungal coinfections are underestimated in COVID-19 patients. Case presentation: We report the case of a 52-year-old male patient, who presented to the emergency department for severe dyspnea and died 17 h later. The RT-PCR test performed at his admission was negative for SARS-CoV-2. Retesting of lung fragments collected during autopsy revealed a positive result for SARS-CoV-2. Histopathological examination showed preexisting lesions, due to comorbidities, as well as recent lesions: massive lung thromboses, alveolar exudate rich in foam cells, suprapleural and intra-alveolar Pneumocystisjirovecii cystic forms, and bilateral adrenal hemorrhage. Conclusion: COVID-19 and P.jirovecii coinfection should be considered, particularly in critically ill patients, and we recommend the systematic search for P. jirovecii in respiratory samples.

Modeling, optimization, and comparable efficacy of T cell and hematopoietic stem cell gene editing for treating hyper-IgM syndrome

Precise correction of the CD40LG gene in T cells and hematopoietic stem/progenitor cells (HSPC) holds promise for treating X‐linked hyper‐IgM Syndrome (HIGM1), but its actual therapeutic potential remains elusive. Here, we developed a one‐size‐fits‐all editing strategy for effective T‐cell correction, selection, and depletion and investigated the therapeutic potential of T‐cell and HSPC therapies in the HIGM1 mouse model. Edited patients’ derived CD4 T cells restored physiologically regulated CD40L expression and contact‐dependent B‐cell helper function. Adoptive transfer of wild‐type T cells into conditioned HIGM1 mice rescued antigen‐specific IgG responses and protected mice from a disease‐relevant pathogen. We then obtained ~ 25% CD40LG editing in long‐term repopulating human HSPC. Transplanting such proportion of wild‐type HSPC in HIGM1 mice rescued immune functions similarly to T‐cell therapy. Overall, our findings suggest that autologous edited T cells can provide immediate and substantial benefits to HIGM1 patients and position T‐cell ahead of HSPC gene therapy because of easier translation, lower safety concerns and potentially comparable clinical benefits.

Increased mRNA expression of key cytokines among suspected cases of Pneumocystis jirovecii infection

Background

Pneumocystis pneumonia (PCP) is a fatal infectious disease caused by Pneumocystis jirovecii (PJP). The major factor relevant to morbidity and mortality seems to be the host inflammatory reaction. The objective of this study was to evaluate the role of IL-2, IL-4, IL-10, and IL-13 cytokine mRNA expression among suspected P. jirovecii infection.

Methods

This was a cross-sectional analytical study undertaken in Aseer region, Saudi Arabia. One hundred suspected PCP cases and 100 healthy controls were included in the study. Basic clinical manifestations, radiological findings, microbiological and immunological findings were extracted from the hospital records from January 2019 to August 2019, Pneumocystis detection was done by immune-fluorescent staining (IFAT, Gomorimethanamine silver staining (GMSS), Giemsa staining, Toluidine blue O (TBO), and Pneumocystis RT-PCR.

Results

Increased more than 5 fold, 3 fold, 4 fold, and 7 fold of IL-2, IL-4, IL-10, and IL-13 mRNA expression were observed in PCP cases compared to controls. Higher expression of IL-2 mRNA was connected with crept, wheezing and chest X-ray findings like central perihilar infiltrate, patchy infiltrate, consolidation, hilar lymphadenopathy, pneumothorax, pleural effusion which showed higher expression compared to counterpart (p< 0.0001). Higher expression of IL-4 mRNA was found to be significantly associated with weight loss (p=0.002), dyspnea (p=0.003), crept (p=0.01), and chest X-ray findings (p< 0.0001). Significantly increased expression of IL-10 mRNA was observed to be associated with weight loss, dyspnea, night sweats, wheezing, and different findings of chest X-ray compared to their counterparts, whereas, IL-13 mRNA was observed in cases with fever. Suspected cases of PCP confirmed positive by IFTA with higher IL-2, IL-4, and IL-10 mRNA expression compared to negative cases. RT-PCR confirmed PCP cases had significantly higher expression of IL-2, IL-4, and IL-10 as well as IL-13 mRNA compared to negative cases. Positive detected cases by GMSS showed higher IL-2, IL-10 mRNA expression, while Giemsa showed only higher IL-4 mRNA expression compared to negative cases.

Conclusion

Confirmed cases of P. jirovecii showed higher IL-2, IL-4, IL-10, and IL-13 mRNA expression comparatively to negative cases. Increased expression of cytokines may be indicative of infection severity and could help in patients’ management.

Anti-fungal T cell responses in the lung and modulation by the gut-lung axis

The lung is a central organ for immune-environmental interactions ranging from tolerance against harmless substances to protection against pathogens, which are particularly sensitive to regulation by the intestinal microbiota. Airborne fungi, can cause variety of diseases, including allergies and inflammatory disorders, as well as life-threatening invasive infections. Remarkable differences exist between ubiquitous fungal species with regard to protective immune mechanisms. Recent data have surprisingly identified Aspergillus-specific regulatory T cells as an essential tolerance checkpoint and provided mechanistic insight for the loss of tolerance in the course of immune pathologies. Furthermore, pathogenic Th17 cells in Aspergillus-associated inflammatory disease seem to be induced by cross-reactivity to the intestinal commensal Candida albicans. Here we review and discuss what is known about fungus-specific T cell responses in the lung how they are modulated by the gut-lung axis and in particular discussing the modulation of adaptive immune responses by cross-reactivity to the microbiota.