C-Terminal Alpha-1 Antitrypsin Peptide: A New Sepsis Biomarker with Immunomodulatory Function.

Systemic inflammatory response syndrome (SIRS) is a life threatening condition and the leading cause of death in intensive care units. Although single aspects of pathophysiology have been described in detail, numerous unknown mediators contribute to the progression of this complex disease. The aim of this study was to elucidate the pathophysiological role of CAAP48, a C-terminal alpha-1 antitrypsin fragment, that we found to be elevated in septic patients and to apply this peptide as diagnostic marker for infectious and noninfectious etiologies of SIRS. Incubation of human polymorphonuclear neutrophils with synthetic CAAP48, the SNP-variant CAAP47, and several control peptides revealed intense neutrophil activation, induction of neutrophil chemotaxis, reduction of neutrophil viability, and release of cytokines. We determined the abundance of CAAP48 in patients with severe sepsis, severe SIRS of noninfectious origin, and viral infection. CAAP48 levels were 3-4-fold higher in patients with sepsis compared to SIRS of noninfectious origin and allowed discrimination of those patients with high sensitivity and specificity. Our results suggest that CAAP48 is a promising discriminatory sepsis biomarker with immunomodulatory functions, particularly on human neutrophils, supporting its important role in the host response and pathophysiology of sepsis.

Physical exercise induces specific adaptations resulting in reduced organ injury and mortality during severe polymicrobial sepsis.

OBJECTIVES: High physical activity levels are associated with wide-ranging health benefits, disease prevention, and longevity. In the present study, we examined the impact of regular physical exercise on the severity of organ injury and survival probability, as well as characteristics of the systemic immune and metabolic response during severe polymicrobial sepsis. DESIGN: Animal study. SETTING: University laboratory. SUBJECTS: Male C57BL/6N mice. INTERVENTIONS: Mice were trained for 6 weeks by treadmill and voluntary wheel running or housed normally. Polymicrobial sepsis in mice was induced by injection of fecal slurry. Subsequently, mice were randomized into the following groups: healthy controls, 6 hours postsepsis, and 24 hours postsepsis. MEASUREMENTS AND MAIN RESULTS: Blood and organ samples were collected and investigated by measuring clinical chemistry variables, cytokines, plasma metabolites, and bacterial clearance. Organ morphology and damage were characterized by histological staining. Physical exercise improved survival and the ability of bacterial clearance in blood and organs. The release of pro- and anti-inflammatory cytokines, including interleukin-6 and interleukin-10, was diminished in trained compared to untrained mice during sepsis. The sepsis-associated acute kidney tubular damage was less pronounced in pretrained animals. By metabolic profiling and regression analysis, we detected lysophosphatidylcholine 14:0, tryptophan, as well as pimelylcarnitine linked with levels of neutrophil gelatinase-associated lipocalin representing acute tubular injury (corrected R=0.910; p<0.001). We identified plasma lysophosphatidylcholine 16:0, lysophosphatidylcholine 17:0, and lysophosphatidylcholine 18:0 as significant metabolites discriminating between trained and untrained mice during sepsis. CONCLUSIONS: Regular physical exercise reduces sepsis-associated acute kidney injury and death. As a specific mechanism of exercise-induced adaptation, we identified various lysophosphatidylcholines that might function as surrogate for improved outcome in sepsis.

Immunoadsorption to treat patients with severe post-COVID syndrome.

INTRODUCTION: Following SARS-CoV-2-infection up to 21% of patients will develop post-COVID-syndrome. Autoantibodies (AAbs) targeting neuronal-ß-adrenergic and muscarinic receptors may provide crucial contributions to the pathophysiology of this condition. Immunoadsorption (IA) has been identified as an effective means of removing AAbs and has resulted in clinical improvements of other autoantibody-associated diseases. METHODS: We determined AAb-levels (anti-ß1/ß2 and anti-M3/M4 receptor) in 178 patients diagnosed with post-COVID-syndrome and described the clinical courses of two patients with elevated AAb-levels that underwent IA-treatment. RESULTS: AAbs were detected in 57% (101/178) of patients diagnosed with post-COVID-syndrome. Substantial reductions in AAb-levels and clinical remission were achieved in one of two patients who was treated with IA. However, this patient relapsed within 6 weeks with a concomitant increase in AAb-levels. CONCLUSION: Collectively, AAbs may play a pathophysiologic role in post-COVID and their removal provide transient benefits in some patients. However, these findings should be further investigated in randomized-controlled-trials.

Targeted metabolomics for discrimination of systemic inflammatory disorders in critically ill patients.

The occurrence of systemic inflammatory response syndrome (SIRS) remains a major problem in intensive care units with high morbidity and mortality. The differentiation between noninfectious and infectious etiologies of this disorder is challenging in routine clinical practice. Many biomarkers have been suggested for this purpose; however, sensitivity and specificity even of high-ranking biomarkers remain insufficient. Recently, metabolic profiling has attracted interest for biomarker discovery. The objective of this study was to identify metabolic biomarkers for differentiation of SIRS/sepsis. A total of 186 meta-bolites comprising six analyte classes were determined in 143 patients (74 SIRS, 69 sepsis) by LC-MS/MS. Two markers (C10:1 and PCaaC32:0) revealed significantly higher concentrations in sepsis. A classification model comprising these markers resulted in 80% and 70% correct classifications in a training set and a test set, respectively.This study demonstrates that acylcarnitines and glycerophosphatidylcholines may be helpful for differentiation of infectious from noninfectious systemic inflammation due to their significantly higher concentration in sepsis patients. Considering the well known pathophysiological relevance of lipid induction by bacterial components, metabolites as identified in this study are promising biomarker candidates in the differential diagnosis of SIRS and sepsis.

Candida sepsis from local infection in a patient with a urostomy on SGLT2 inhibitor therapy.

Sodium-glucose co-transporter 2 (SGLT2) inhibitors exhibit impressive cardio-renal benefits in patients with a high cardiovascular risk. Genital yeast infections are important side effects of this class of drugs. We report a case of Candida glabrata sepsis secondary to a Candida infection of the urostomy of a patient on SGLT2 inhibitor therapy. In urostomy patients, one should critically evaluate the risk of mycotic infections against the cardiovascular and glycaemic benefits of SGLT2 inhibition. Urostomy patients without a high cardiovascular risk should not be treated with SGLT2 inhibitors.

CAAP48, a New Sepsis Biomarker, Induces Hepatic Dysfunction in an in vitro Liver-on-Chip Model.

Sepsis is a leading cause of mortality in the critically ill, characterized by life-threatening organ dysfunctions due to dysregulation of the host response to infection. Using mass spectrometry, we identified a C-terminal fragment of alpha-1-antitrypsin, designated CAAP48, as a new sepsis biomarker that actively participates in the pathophysiology of sepsis. It is well-known that liver dysfunction is an early event in sepsis-associated multi-organ failure, thus we analyzed the pathophysiological function of CAAP48 in a microfluidic-supported in vitro liver-on-chip model. Hepatocytes were stimulated with synthetic CAAP48 and several control peptides. CAAP48-treatment resulted in an accumulation of the hepatocyte-specific intracellular enzymes aspartate- and alanine-transaminase and impaired the activity of the hepatic multidrug resistant-associated protein 2 and cytochrome P450 3A4. Moreover, CAAP48 reduced hepatic expression of the multidrug resistant-associated protein 2 and disrupted the endothelial structural integrity as demonstrated by reduced expression of VE-cadherin, F-actin and alteration of the tight junction protein zonula occludens-1, which resulted in a loss of the endothelial barrier function. Furthermore, CAAP48 induced the release of adhesion molecules and pro- and anti-inflammatory cytokines. Our results show that CAAP48 triggers inflammation-related endothelial barrier disruption as well as hepatocellular dysfunction in a liver-on-chip model emulating the pathophysiological conditions of inflammation. Besides its function as new sepsis biomarker, CAAP48 thus might play an important role in the development of liver dysfunction as a consequence of the dysregulated host immune-inflammatory response in sepsis.

Fast differentiation of SIRS and sepsis from blood plasma of ICU patients using Raman spectroscopy.

Currently, there is no biomarker that can reliable distinguish between infectious and non-infectious systemic inflammatory response syndrome (SIRS). However, such a biomarker would be of utmost importance for early identification and stratification of patients at risk to initiate timely and appropriate antibiotic treatment. Within this proof of principle study, the high potential of Raman spectroscopy for the fast differentiation of non-infectious SIRS and sepsis is demonstrated. Blood plasma collected from 70 patients from the intensive care unit (31 patients with sepsis and 39 patients classified with SIRS without infection) was analyzed by means of Raman spectroscopy. A PCA-LDA based classification model was trained with Raman spectra from test samples and yielded for sepsis a sensitivity of 1.0 and specificity of 0.82. These results have been confirmed with an independent dataset (prediction accuracy 80%).

Mass spectometry-based protein patterns in the diagnosis of sepsis/systemic inflammatory response syndrome.

Early differential diagnosis of systemic inflammatory reactions in critically ill patients is essential for timely implementation of lifesaving therapies. Despite many efforts made, reliable biomarkers to discriminate between infectious and noninfectious causes of systemic inflammatory response syndrome (SIRS) are currently not available. Recent advances in mass spectrometry-based methods have raised hopes that identification of spectral patterns from serum/plasma samples can be instrumental in this context. We compared protein expression patterns from patients with SIRS of infectious and noninfectious origin. Plasma samples from 166 patients obtained under rigorously standardized preanalytical conditions were applied to Q10 and CM10 ProteinChips. Protein profiles were used to train and develop decision tree classification algorithms. Discriminatory peaks were isolated and identified. Classification trees distinguished patients with noninfectious SIRS with organ dysfunction following open heart surgery using cardiopulmonary bypass from those with severe sepsis or septic shock with distinct sensitivities and specificities. Results were validated in a blinded test set in two independent experiments and in a second independently collected test set. Discriminatory peaks at 13.8 and 55.7 kd were identified as transthyretin and α1-antitrypsin; the third protein at m/z 4,798 was assigned to a proteolytic fragment of α1-antitrypsin. Taken together, our data demonstrate that plasma protein profiling allows reproducible discrimination between patients with infectious and noninfectious SIRS with high sensitivity and specificity. However, rigorous standardization as well as considering drug-related interferences is essential when interpreting protein profiling studies. Identification of discriminatory proteins suggests a direct link between infectious-related protease activity and a sepsis-specific diagnostic pattern for discrimination of patients with SIRS.