Egan, Ashley M.

Abstract IntroductionFungal infections, particularly in the Midwest, can often be asymptomatic and may mimic primary lung cancer. This case illustrates pulmonary histoplasmosis in an 80-year-old woman with a history of lung cancer highlighting the diagnostic challenges presented when both conditions coexist.Case SummaryAn 80-year-old woman (prior smoking history of 47-pack-years) with synchronous lung cancers (poorly differentiated non-small cell carcinoma with squamous differentiation in the left lower lobe and squamous cell carcinoma in the right lower lobe) previously underwent radiation therapy to both lesions. She was admitted for shortness of breath and cough and was initially diagnosed with pneumonia based on CT findings. Despite multiple courses of antibiotics, her symptoms persisted over 2 months, improving only temporarily with a short course of prednisone. A follow-up CT revealed increasing confluent thick-walled cavitation in the posterior right upper lobe and superior segment of the right lower lobe concerning for cavitating/necrotizing pneumonia versus possible cancer progression. A PET-CT scan (Fig.1A) showed significant FDG uptake in the right upper lobe lesion and mild uptake in mediastinal lymph nodes complicating the differentiation between cancer and infection. Bronchoscopy with biopsy of an endobronchial lesion in the posterior segment of right lower lobe revealed necrotizing granulomatous inflammation (Fig.1B) with GMS stain showing the presence of fungal organisms suggestive of histoplasmosis. Histoplasma PCR from bronchoalveolar lavage was also positive. She was subsequently started on antifungal therapy for a planned one-year treatment course. DiscussionHigh positron emission tomography (PET) avidity in chest imaging is often linked to aggressive tumors but can also indicate benign conditions such as fungal infections. A “flip-flop sign” on PET imaging, where nodal activity surpasses that of a lung nodule, is typically seen in benign lung lesions, particularly fungal infections. However, infections and inflammatory conditions may also show high PET avidity mimicking malignancy. Endobronchial lesions, common in lung cancer, are less frequently associated with infections. In patients with a history of cancer, active lung infection, and PET-avid lesions without the flip-flop sign, invasive testing is usually required to differentiate between infection and malignancy. In this case, our patient with a history of lung cancer and a PET-avid lung lesion was found to have pulmonary histoplasmosis after invasive testing highlighting the need for comprehensive evaluation.ConclusionThis case emphasizes the importance of considering fungal infections in the differential diagnosis of PET-avid pulmonary lesions, particularly in patients with a history of malignancy.

Abstract Background Acute respiratory exacerbations in idiopathic pulmonary fibrosis (IPF), often triggered by infection, are life threatening events characterized by rapid deterioration of lung function and associated with poor prognosis. Since microbial antigens modulate immunity by activating different pattern recognition receptors (PRR) expressed by innate immune cells (including B-cells), we sought to investigate how the activation of human B-cells through PRR stimulation by different microbial (CpG and β-glucan) and non-microbial (Mitochondrial DAMPs; MTDs) antigens resulted in the release of an inflammatory/fibrotic milieu that contributed to the pathogenesis of fibrosis in patients with IPF. Results Our results show that an inflammatory milieu is induced by stimulating circulating B-cells with both noninfectious (MTDs) and infectious antigens (CpG and β-glucan) commonly found in bacteria and fungi. Moreover, we show that the inflammatory milieu produced was specific to the inducing antigen, and that the microbial antigens (CpG and β-glucan) triggered distinct signaling pathways in B-cells. Specifically, CpG induced mTOR-activation while β-glucan was mTOR-independent and activated Src and p38. Furthermore, our results also show that B-cell aggregates are present within fibrotic areas of the lung in IPF patients and activated B-cells induce fibroblast migration, which was modified by antifibrotics (nintedanib and pirfenidone). Conclusion Our results highlight the potential contribution of activated B-cells through PRRs to the proinflammatory and profibrotic milieu seen in patients with idiopathic pulmonary fibrosis.

Abstract We hypothesize that B-lymphocytes are conducive to the pathogenesis of idiopathic pulmonary fibrosis (IPF), a progressive and fatal interstitial lung disease. B-lymphocytes aggregate in the lungs of IPF patients to form tertiary lymphoid follicles. How these follicles are formed and their role in the pathogenesis of IPF is not known. Hence, we sought to characterize how the activation of B-lymphocytes from IPF patients may contribute to the disease. Methods IPF patients defined by ATS guidelines were identified and recruited under local IRB #14-004714. B-lymphocytes were then isolated by negative selection. Cytokines and immunoglobulins from plasma or B-lymphocyte supernatants were measured by ELISA and signaling pathways were elucidated from whole-cell lysates by immunoblotting. Our results show that B-lymphocyte aggregates are present within fibrotic areas of the lung of IPF patients and that activated B-lymphocytes induce fibroblast migration. This effect was abrogated by nintedanib inhibition of B-lymphocyte activation. Furthermore, microbial antigen (β-glucan and CpG) activation of B-lymphocytes through pattern recognition receptors (PRRs; TLR9 and Dectin-1) contributed to the proinflammatory and profibrotic milieu seen in IPF patients. Stimulation of TLR9 and Dectin-1 resulted in activation of mTOR-dependent and -independent pathways, respectively. Rapamycin decreased TLR9 signaling, but not Dectin-1 mediated pathways. Nintedanib abrogated B-cell activation, IgM production, and the profibrotic milieu by interfering with both the mTOR-dependent and -independent pathways. In conclusion, our findings implicate activated B-lymphocytes in IPF pathogenesis highlighting the role of PRRs in this disease.

OBJECTIVES: To summarize the most impactful articles relevant to the pharmacotherapy of critically ill adult patients published in 2021. DATA SOURCE: PubMed/MEDLINE. STUDY SELECTION: Randomized controlled trials, prospective studies, or systematic review/meta-analyses of adult critical care patients assessing a pharmacotherapeutic intervention and reporting clinical endpoints published between January 1, 2021, and December 31, 2021. DATA EXTRACTION: Candidate articles were organized by clinical domain based on the emerging themes from all studies. A modified Delphi process was applied to obtain consensus on the most impactful publication within each clinical domain based on overall contribution to scientific knowledge and novelty to the literature. DATA SYNTHESIS: The search revealed 830 articles, of which 766 were excluded leaving 64 candidate articles for the Delphi process. These 64 articles were organized by clinical domain including: emergency/neurology, cardiopulmonary, nephrology/fluids, infectious diseases, metabolic, immunomodulation, and nutrition/gastroenterology. Each domain required the a priori defined three Delphi rounds. The resultant most impactful articles from each domain included five randomized controlled trials and two systematic review/meta-analyses. Topics studied included sedation during mechanical ventilation, anticoagulation in COVID-19, extended infusion beta-lactams, interleukin-6 antagonists in COVID-19, balanced crystalloid resuscitation, vitamin C/thiamine/hydrocortisone in sepsis, and promotility agents during enteral feeding. CONCLUSIONS: This synoptic review provides a summary and perspective of the most impactful articles relevant to the pharmacotherapy of critically ill adults published in 2021.

Abstract BackgroundIdiopathic pulmonary fibrosis (IPF) is a chronic, progressive pulmonary disease characterized by aberrant tissue remodeling, formation of scar tissue within the lungs and continuous loss of lung function. The areas of fibrosis seen in lungs of IPF patients share many features with normal aging lung with cellular senescence being one. The contribution of the immune system to the etiology of IPF remains poorly understood. Evidence obtained from animal models and human studies suggests that innate and adaptive immune processes can orchestrate existing fibrotic responses. Currently, there is only modestly effective pharmacotherapy for IPF. Mesenchymal stem cells (MSCs)-based therapies have emerged as a potential option treatment of IPF. This study explores the possibility of using autologous MSCs as an IPF therapy and present an attempt to determine if the disease occurring in the lungs can be reflected on peripheral blood immune status. MethodsComprehensive characterization of autologous adipose derived MSCs (aMSCs) from five IPF patients and five age and gender matched Healthy Controls (HC) was done using flow cytometry, Droplet Digital PCR (ddPCR), Multiplex Luminex xMAP technology and confocal microscopy. For assessing the self renewal capacity and osteogenic differentiation IncuCyte Live Cell Imaging technology was used. Multi-parameter quantitative flow cytometry of un-manipulated whole blood of another group of 15 IPF patients and 87 (30 age and gender matched) HC was used to analyze 110 peripheral phenotypes.ResultsThere are no differences between autologous aMSCs from IPF patients and HC in their stem cell properties, self renewal capacity, plasticity for osteogenic differentiation, secretome content, cell cycle inhibitor marker levels and mitochondrial health. IPF patients had altered peripheral blood immunophenotype including reduced B cells subsets, increased T cell subsets, and increased granulocytes among others demonstrating clear and significant differences.ConclusionsOur results indicate that there is no difference in aMSCs properties from IPF patients and HC, suggesting that autologous aMSCs may be an acceptable option for IPF therapy.Characterization of peripheral immune phenotype may be a valuable indicator for successful therapy, and for potentially staging the disease.

Abstract B-cell activation is increasingly linked to numerous fibrotic lung diseases, and it is well known that aggregates of lymphocytes form in the lung of many of these patients. Activation of B-cells by pattern recognition receptors (PRRs) drives the release of inflammatory cytokines, chemokines, and metalloproteases important in the pathophysiology of pulmonary fibrosis. However, the specific mechanisms of B-cell activation in patients with idiopathic pulmonary fibrosis (IPF) are poorly understood. Herein, we have demonstrated that B-cell activation by microbial antigens contributes to the inflammatory and profibrotic milieu seen in patients with IPF. B-cell stimulation by CpG and β-glucan via PRRs resulted in activation of mTOR-dependent and independent pathways. Moreover, we showed that the B-cell–secreted inflammatory milieu is specific to the inducing antigen and causes differential fibroblast migration and activation. B-cell responses to infectious agents and subsequent B-cell–mediated fibroblast activation are modifiable by antifibrotics, but each seems to exert a specific and different effect. These results suggest that, upon PRR activation by microbial antigens, B-cells can contribute to the inflammatory and fibrotic changes seen in patients with IPF, and antifibrotics are able to at least partially reverse these responses.