Pneumonia in patients with systemic lupus erythematosus: Epidemiology, microbiology and outcomes

The role of innate lymphoid cells in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a connective tissue disorder that affects various body systems. Both the innate and adaptive immunity contribute to the onset and progression of SLE. The main mechanism of SLE is an excessive immune response of immune cells to autoantigens, which leads to systemic inflammation and inflammation-induced organ damage. Notably, a subset of innate immune cells known as innate lymphoid cells (ILCs) has recently emerged. ILCs are pivotal in the early stages of infection; participate in immune responses, inflammation, and tissue repair; and regulate the immune function of the body by resisting pathogens and regulating autoimmune inflammation and metabolic homeostasis. Thus, ILCs dysfunction can lead to autoimmune diseases. This review discusses the maturation of ILCs, the potential mechanisms by which ILCs exacerbate SLE pathogenesis, and their contributions to organ inflammatory deterioration in SLE.

An explainable machine learning-based model to predict intensive care unit admission among patients with community-acquired pneumonia and connective tissue disease

BACKGROUND

There is no individualized prediction model for intensive care unit (ICU) admission on patients with community-acquired pneumonia (CAP) and connective tissue disease (CTD) so far. In this study, we aimed to establish a machine learning-based model for predicting the need for ICU admission among those patients.

METHODS

This was a retrospective study on patients admitted into a University Hospital in China between November 2008 and November 2021. Patients were included if they were diagnosed with CAP and CTD during admission and hospitalization. Data related to demographics, CTD types, comorbidities, vital signs and laboratory results during the first 24 h of hospitalization were collected. The baseline variables were screened to identify potential predictors via three methods, including univariate analysis, least absolute shrinkage and selection operator (Lasso) regression and Boruta algorithm. Nine supervised machine learning algorithms were used to build prediction models. We evaluated the performances of differentiation, calibration, and clinical utility of all models to determine the optimal model. The Shapley Additive Explanations (SHAP) and Local Interpretable Model-Agnostic Explanations (LIME) techniques were performed to interpret the optimal model.

RESULTS

The included patients were randomly divided into the training set (1070 patients) and the testing set (459 patients) at a ratio of 70:30. The intersection results of three feature selection approaches yielded 16 predictors. The eXtreme gradient boosting (XGBoost) model achieved the highest area under the receiver operating characteristic curve (AUC) (0.941) and accuracy (0.913) among various models. The calibration curve and decision curve analysis (DCA) both suggested that the XGBoost model outperformed other models. The SHAP summary plots illustrated the top 6 features with the greatest importance, including higher N-terminal pro-B-type natriuretic peptide (NT-proBNP) and C-reactive protein (CRP), lower level of CD4 + T cell, lymphocyte and serum sodium, and positive serum (1,3)-β-D-glucan test (G test).

CONCLUSION

We successfully developed, evaluated and explained a machine learning-based model for predicting ICU admission in patients with CAP and CTD. The XGBoost model could be clinical referenced after external validation and improvement.

Severe pneumonia in patients with systemic lupus erythematosus admitted to the intensive care unit

BACKGROUND

The aim of this study was to investigate clinical characters and prognosis of patients with systemic lupus erythematosus (SLE) and severe pneumonia admitted to the intensive care unit (ICU).

MATERIALS AND METHODS

We conducted a retrospective study that reviewed all clinical records of patients with SLE and severe pneumonia admitted to the ICU between 2008 and 2020.

RESULTS

A total of 86 SLE patients with severe pneumonia during their first ICU admission were enrolled in this study. Most patients were female (n = 71, 82.5%), and the median age was 42.3 ± 14.7 years. The most common organisms were gram-positive bacteria (20.9%), followed by gram-negative bacteria (18.6%) and fungi (10.4%). A total of 31 patients died within 30 days of ICU admission, and the 30-day mortality was 36%. In binary logistic regression analysis, Acute Physiologic and Chronic Health Evaluation II (APACHE II) score, Sequential Organ Failure Assessment (SOFA) score and mechanical ventilation were dependently associated with 30-day mortality (odds ratio [OR] 2.97, P = 0.016; OR = 4.02, P = 0.023; OR = 1.52, P = 0.036; respectively). Among the other 55 patients, 5 patients died after discharge from the ICU during the long-term follow-up.

CONCLUSIONS

Mortality was high in SLE patients with severe pneumonia admitted to the ICU, and most of the patients died within 30 days of ICU admission.

Ultrasound for diagnosis of interstitial lung disease in diffuse connective tissue diseases

Patients with diffuse connective tissue diseases frequently develop interstitial lung disease, which carries a worse prognosis and shortens survival. High-resolution computed tomography is the first-choice test, and is competitive with histopathology, however, the cost and radiation may limit its use, particularly for screening. Lung ultrasound is a rapid, accessible, reproducible, and inexpensive study that is useful for diagnosis of interstitial lung disease. Furthermore, extensive training is not required to identify the alterations associated with these lung diseases. B lines and pleural irregularities compose the ultrasonographic interstitial syndrome, although, it must be kept in mind that it is not specific, and it is necessary to rule out haemodynamic, cardiovascular, and infectious abnormalities. This review highlights the elevated prevalence of this lung condition in the main rheumatological diseases, with emphasis on the usefulness of pulmonary ultrasound.

Pneumonia in myasthenia gravis: Microbial etiology and clinical management

Introduction

Patients with myasthenia gravis (MG) are prone to the development of pneumonia due to the long-term immunotherapies they receive and a tendency for aspiration. Pneumonia remains a risk factor for MG worsening and is the most prevalent cause of mortality in MG patients. Classification of the pathogens involved and exploration of the risk factors for mechanical ventilation (MV) could aid in improving clinical outcomes.

Methods

Between January 2013 and October 2022, we performed an inpatient database review for MG patients with pneumonia concurrence in a tertiary research center specializing in neuromuscular disorders. The clinical and microbiological characteristics of 116 MG patients with pneumonia were retrospectively analyzed.

Results

In our cohort, 90.32% (112/124) of organisms were bacteria and 42.86% (48/112) of pathogenic bacteria were carbapenem-resistant. A high abundance of Epstein-Barr virus (EBV) was detected using next-generation sequencing (NGS) in 12 patients, while cytomegalovirus (CMV) was detected in 8 patients. Non-fermentative Gram-negative bacilli were the most prevalent microorganisms, in which ampicillin, sulfamethoxazole-trimethoprim (SMZ-TMP), piperacillin, cefoperazone, ceftazidime, and cefepime may have an anti-infectious effect. Moreover, peripheral lymphocyte percentage [odds ratio (OR) 0.88, 95% CI 0.75-0.96, p = 0.02] and serum globulin (OR 1.16, 95% CI 1.02-1.35, p = 0.03) were significantly associated with the risk of MV demand.

Discussion

Our identification of the microbial etiology of pneumonia in MG patients may provide future perspectives on accurate antibiotic options and enable early interventions when risk factors are present.

Systemic lupus erythematosus presenting as non-resolving pneumonia: a case report

BackgroundSystemic lupus erythematosus (SLE) is a rheumatological disorder with a heterogeneous clinical presentation and disease course. Case presentationWe report a case concerning a young woman with pleuropneumonia, non-responsive to conventional antibiotic therapy, who was, upon further inquiry and passage of time, diagnosed with SLE. Key pointsBy means of this case, we would like to emphasize the clinical implications and prognostic significance of lymphopenia in patients with SLE. Moreover, we attempt to make the reader aware of some of the protean manifestations of SLE and we would like to raise suspicion of acute lupus pneumonitis by demonstrating a case of a young female with non-resolving pneumonia.

Bacterial infections in lupus: Roles in promoting immune activation and in pathogenesis of the disease

BACKGROUND

Bacterial infections of the lung, skin, bloodstream and other tissues are common in patients with systemic lupus erythematosus (lupus) and are often more severe and invasive than similar infections in control populations. A variety of studies have explored the changes in bacterial abundance in lupus patients, the rates of infection and the influence of particular bacterial species on disease progression, using both human patient samples and mouse models of lupus.

OBJECTIVE

The aim of this review is to summarize human and mouse studies that describe changes in the bacterial microbiome in lupus, the role of a leaky gut in stimulating inflammation, identification of specific bacterial species associated with lupus, and the potential roles of certain common bacterial infections in promoting lupus progression.

METHODS

Information was collected using searches of the Pubmed database for articles relevant to bacterial infections in lupus and to microbiome changes associated with lupus.

RESULTS

The reviewed studies demonstrate significant changes in the bacterial microbiome of lupus patients as compared to control subjects and in lupus-prone mice compared to control mice. Furthermore, there is evidence supporting the existence of a leaky gut in lupus patients and in lupus-prone mice. This leaky gut may allow live bacteria or bacterial components to enter the circulation and cause inflammation. Invasive bacterial infections are more common and often more severe in lupus patients. These include infections caused by Staphylococcus aureus, Salmonella enterica, Escherichia coli, Streptococcus pneumoniae and mycobacteria. These bacterial infections can trigger increased immune activation and inflammation, potentially stimulating activation of autoreactive lymphocytes and leading to worsening of lupus symptoms.

CONCLUSIONS

Together, the evidence suggests that lupus predisposes to infection, while infection may trigger worsening lupus, leading to a feedback loop that may reinforce autoimmune symptoms.

Systemic lupus erythematosus in the intensive care unit: a systematic review

Systemic lupus erythematosus (SLE) is an autoimmune disease with heterogeneous pathophysiologic mechanisms and diverse clinical manifestations. SLE is a frequent cause of intensive care unit (ICU) admissions. Multiple studies with controversial findings on the causes, evolution and outcomes of ICU-admitted patients with SLE have been published. The aim of this paper is to review the literature reporting the clinical characteristics and outcomes, such as mortality and associated factors, in such patients. Among the main causes of ICU admissions are SLE disease activity, respiratory failure, multi-organ failure and infections. The main factors associated with mortality are a high Acute Physiology and Chronic Health Evaluation (APACHE) score, the need for mechanical ventilation, and vasoactive and inotropic agent use. Reported mortality rates are 18.4%-78.5%. Therefore, it is important to evaluate SLE disease severity for optimizing clinical management and patient outcomes.

Bronchoalveolar lavage fluid analysis and mortality risk in systemic lupus erythematosus patients with pneumonia and respiratory failure

BACKGROUND

Our aim was to characterize etiologic diagnoses obtained from bronchoalveolar lavage fluid (BALF) and blood specimens, and to identify risk factors for mortality in systemic lupus erythematosus (SLE) patients with pneumonia and respiratory failure.

METHODS

We conducted a retrospective analysis of SLE patients with pneumonia and respiratory failure. Clinical characteristics, laboratory profiles, and microbiology in BALF and blood samples were evaluated. We performed univariable analyses to identify mortality risk factors.

RESULTS

All 24 patients (F:M = 21:3, median age 46.5 years; disease duration 11 years) received mechanical ventilation (median duration: 11 days). Pathogens identified in BALF included Pneumocystis jiroveci (12 patients [50%]), cytomegalovirus (CMV, 7 patients [29.2%]), and bacteria (11 patients [45.8%]). Thirteen patients (54.2%) yielded pathogens in blood (CMV in 8 patients [33.3%] and Escherichia coli in 5 patients [20.8%]). Eight developed septic shock, and 9 died within 30 days. Univariable analysis identified thrombocytopenia (odds ratio [OR]: 8.0, 95% confidence interval [CI]: 1.23-52.25), bacteremia within 30 days before or after endotracheal intubation (OR: 8.0, 95% CI: 1.23-52.5), and P. jiroveci pneumonia (PJP, OR: 7.0, 95% CI: 1.04-46.95) as risk factors for 30-day mortality. Kaplan-Meier analysis confirmed an increased risk of 30-day mortality with thrombocytopenia and bacteremia.

CONCLUSION

There are high prevalence rates of PJP and CMV infections as evidenced by BALF analyses in SLE patients with pneumonia and respiratory failure. BALF analysis can facilitate rescue therapy per pathogen. Thrombocytopenia, bacteremia, and PJP in SLE patients can increase their 30-day mortality, so warrant early and aggressive treatments.

Clinical characterization, outcomes, and prognosis in patients with systemic lupus erythematosus admitted to the intensive care unit

OBJECTIVE

Systemic lupus erythematosus (SLE) is a clinically heterogeneous autoimmune disease, and in some conditions, admission to the intensive care unit (ICUs) is required. This study describes the clinical and prognostic factors in SLE patients admitted to the ICU.

METHODS

We conducted a retrospective study that reviewed all clinical records of patients with SLE admitted to the ICU between 2011 and 2018.

RESULTS

We evaluated 188 patients, with 279 ICU admissions. Most patients were female (n = 159; 84.57%) with a median age of 35 years (interquartile range (IQR) = 25-48 years). Infection was the leading cause of admission in 77 (27.60%) cases, followed by lupus flare. The average length of hospitalization was 5 days (IQR 3-11 days), and the SLE Disease Activity Index 2000, Acute Physiology, Age and Chronic Health Evaluation (APACHE II), and Sequential Organ Failure Assessment (SOFA) scores were 9 (IQR 2-17), 14 (IQR 10-17), and 3 (IQR 2-5), respectively. Non-survivors presented with higher APACHE II and SOFA scores. Infection was the leading cause of mortality (n = 38; 20.21%), and predictors of mortality included invasive mechanical ventilation, vasoactive medication requirement, higher SOFA scores, and antiphospholipid syndrome comorbidity.

CONCLUSIONS

We found that infection was the leading cause of ICU admissions and mortality in patients with SLE. Factors identified here as predictors of mortality should be accurately identified at admission for the prompt treatment of SLE patients.

Successful use of plasma exchange in fulminant lupus myocarditis coexisting with pneumonia: A case report

BACKGROUND

Fulminant lupus myocarditis is a rare but fatal manifestation of systemic lupus erythematosus. Aggressive immunosuppressive treatments are important in its successful management. However, they can significantly damage the immunity and are associated with a considerable risk of infection development and spread. We present a rare and complicated case of a 20-year-old female diagnosed with fulminant lupus myocarditis accompanied by pneumonia. The patient was successfully treated with plasma exchange (PE) for fulminant lupus myocarditis.

CASE SUMMARY

A 20-year-old Chinese woman presented to the Hematology Department complaining of fatigue and knee pain. Blood test showed anemia and thrombocytopenia. On the second day of hospitalization, she was transferred to the ICU due to dyspnea and hypotension. Autoimmune profiles showed hypocomplementemia and positive antinuclear antibodies. Computer tomography showed an enlarged heart and pneumonia. Ultrasound revealed an enlarged heart with a low left ventricular ejection fraction. Fulminant lupus myocarditis with cardiogenic shock was initially considered. Due to the accompanying pneumonia, aggressive immunosuppression was contraindicated. Her cardiac function remained critical after the initial therapy of intravenous immunoglobulin and corticosteroids at a conventional dose, but she responded well to later PE therapy plus corticosteroids administration. The patient fully recovered with normal cardiac function.

CONCLUSION

This case indicates that PE is a valuable treatment choice without adverse effects of immunosuppression in patients with fulminant lupus myocarditis and coexisting infection.

Severe pneumonia in Chinese patients with systemic lupus erythematosus

Objective

This study aimed to investigate the clinical characteristics and risk factors associated with severe pneumonia in systemic lupus erythematosus (SLE) patients from China.

Method

We performed a retrospective study in 112 hospitalized SLE patients who had had pneumonia for 8 years. The primary outcome was severe pneumonia, followed by descriptive analysis, group comparison and bivariate analysis.

Results

A total of 28 SLE patients were diagnosed with severe pneumonia, with a ratio of 5:23 between men and women. The mean age at diagnosis was 44.36 ± 12.389 years. The median disease duration was 72 months, and the median SLE Disease Activity Index 2000 (SLEDAI 2K) score was 8. The haematological system was the most affected, with an incidence of anaemia in 85.7% of cases and thrombocytopenia in 75% of cases, followed by lupus nephritis in 50% of cases and central nervous system involvement in 10.71% of cases. Cultured sputum specimens were positive in 17 (68%) SLE patients with severe pneumonia, of whom nine (36%) were cases of fungal infection, five (20%) were cases of bacterial infection and three (12%) were cases of mixed infection. Using multivariate logistic regression analysis, we concluded that a daily dosage of prednisone (>10 mg; odds ratio (OR) = 3.193, p = 0.005), a low percentage of CD4+ T lymphocytes (OR = 0.909, p = 0.000), a high SLEDAI 2K score (OR = 1.182, p = 0.001) and anaemia (OR = 1.182, p = 0.001) were all independent risk factors for pneumonia in SLE patients, while a low percentage of CD4+ T lymphocytes (OR = 0.908, p = 0.033), a daily dose of prednisone of >10 mg (OR = 35.67, p = 0.001) were independent risk factors for severe pneumonia in SLE patients.

Conclusion

Severe pneumonia is not rare in lupus, and is associated with high mortality and poor prognosis. Monitoring CD4+ T-cell counts and giving a small dose of glucocorticoids can reduce the occurrence of severe pneumonia and improve the prognosis of patients with lupus.

Infection with Opportunistic Bacteria Triggers Severe Pulmonary Inflammation in Lupus-Prone Mice

Infection is a common cause of hospitalization and mortality in patients with systemic lupus erythematosus (SLE). How the underlying immune dysfunctions affect the antimicrobial immunity remains largely unknown. In the present study, employing the pulmonary infection model, we determined the antimicrobial defence of lupus-prone mice. After infecting with opportunistic bacterium Haemophilus influenzae (Hi), lupus-prone mice (B6/lpr) exhibited inefficient bacterial elimination and recovered slowly. They generated severer inflammation at the early stage of infection, as excessive accumulation of neutrophils and enhanced production of proinflammatory cytokines were observed in the lung. In addition, a large number of apoptotic cells were detected in the lungs of B6/lpr mice. For adaptive immune responses, B6/lpr mice were capable to generate enough protective Hi-specific Th17 cells. They evoked stronger Hi-specific γδ T17 response in both lungs and spleens. Unexpectedly, both CD4 and γδ T cells from lupus-prone mice showed deficiency in IFN-γ production. For humoral immune responses, compared with those of WT mice, the concentrations of Hi-specific IgA, IgM, and IgG, especially IgG, were significantly higher in the B6/lpr mice. Our findings suggest that lupus mice are capable to generate antibacterial immune responses; however, the overwhelming inflammation and overactivated immune responses increase the severity of infection.