Sylvia Knapp

Outcome and prognostic factors in critically ill cancer patients admitted to the intensive care unit

Objective: To assess survival in cancer patients admitted to an intensive care unit (ICU) with respect to the nature of malignancy, cause of ICU admittance, and course during ICU stay as well as to evaluate the prognostic value of the Acute Physiology and Chronic Health Evaluation (APACHE) III score. Design: Retrospective cohort study. Setting: ICU at a university cancer referral center. Patients: A total of 414 cancer patients admitted to the ICU during a period of 66 months. Interventions: None. Measurements: Charts of the patients were analyzed with respect to underlying disease, cause of admission, APACHE III score, need and duration of mechanical ventilation, neutropenia and development of septic shock, as well as ICU survival and survival after discharge. Mortality data were compared with two control groups: 1362 patients admitted to our ICU suffering from diseases other than cancer and 2,776 cancer patients not admitted to the ICU. Main Results: ICU survival was 53%, and 1‐yr survival was 23%. The 1‐yr mortality rate was significantly lower in both control groups. Patients admitted after bone marrow transplantation had the highest mortality. In a multivariate analysis, prognosis was negatively influenced by respiratory insufficiency, the need of mechanical ventilation, and development of septic shock during the ICU stay. Admission after cardiopulmonary resuscitation yielded high ICU mortality but a relatively good long‐term prognosis. Admission after surgery and as a result of acute hemorrhage was associated with a good prognosis. Age, neutropenia, and underlying disease did not influence outcome significantly. Admission APACHE III scores were significantly higher in nonsurvivors but failed to predict individual outcome satisfactorily. All patients with APACHE III scores of >80 died at the ICU. Conclusion: A combination of factors must be taken into account to estimate a critically ill cancer patients prognosis in the ICU. The APACHE III scoring system alone should not be used to make decisions about therapy prolongation. Admission to the ICU worsens the prognosis of a cancer patient substantially; however, as ICU mortality is 47%, comparable with severely ill noncancer patients, general reluctance to admit cancer patients to an ICU does not seem to be justified.

Toll-Like Receptor 2 Plays a Role in the Early Inflammatory Response to Murine Pneumococcal Pneumonia but Does Not Contribute to Antibacterial Defense

Toll-like receptors (TLR) are crucial pattern recognition receptors in innate immunity. The importance of TLR2 in host defense against Gram-positive bacteria has been suggested by the fact that this receptor recognizes major Gram-positive cell wall components, such as peptidoglycan and lipoteichoic acid. To determine the role of TLR2 in pulmonary Gram-positive infection, we first established that TLR2 is indispensable for alveolar macrophage responsiveness toward Streptococcus pneumoniae. Nonetheless, TLR2 gene-deficient mice intranasally inoculated with S. pneumoniae at doses varying from nonlethal (with complete clearance of the infection) to lethal displayed only a modestly reduced inflammatory response in their lungs and an unaltered antibacterial defense when compared with normal wild-type mice. These data suggest that TLR2 plays a limited role in the innate immune response to pneumococcal pneumonia, and that additional pattern recognition receptors likely are involved in host defense against this common respiratory pathogen.

Role of Toll-Like Receptor 4 in Gram-Positive and Gram-Negative Pneumonia in Mice

ABSTRACT To determine the role of Toll-like receptor 4 (TLR4) in the immune response to pneumonia, C3H/HeJ mice (which display a mutant nonfunctional TLR4) and C3H/HeN wild-type mice were intranasally infected with either Streptococcus pneumoniae (a common gram-positive respiratory pathogen) or Klebsiella pneumoniae (a common gram-negative respiratory pathogen). In cases of pneumococcal pneumonia, TLR4 mutant mice showed a reduced survival only after infection with low-level bacterial doses, which was associated with a higher bacterial burden in their lungs 48 h postinfection. In Klebsiella pneumonia, TLR4 mutant mice demonstrated a shortened survival after infection with either a low- or a high-level bacterial dose together with an enhanced bacterial outgrowth in their lungs. These data suggest that TLR4 contributes to a protective immune response in both pneumococcal and Klebsiella pneumonia and that its role is more important in respiratory tract infection caused by the latter (gram-negative) pathogen.

Cutting Edge: Expression Patterns of Surface and Soluble Triggering Receptor Expressed on Myeloid Cells-1 in Human Endotoxemia

Triggering receptor expressed on myeloid cells-1 (TREM-1) is a recently identified molecule involved in the amplification of inflammation. To determine the regulation of TREM-1, we studied TREM-1 expression and soluble TREM-1 plasma levels upon i.v. LPS challenge in healthy humans in vivo and in vitro. Granulocyte TREM-1 expression was high at baseline and immediately down-regulated upon LPS exposure along with an increase in soluble TREM-1. Monocytes displayed a gradual up-regulation of TREM-1 upon LPS in vivo and in vitro. In vitro studies extended these findings to highly purified lipoteichoic acid and Streptococcus pneumoniae. Nonbacterial TLR ligands such as polyinosine-polycytidylic acid and imidazoquinoline, as well as the TLR9 ligand CpG, did not impact TREM-1 expression. The LPS-induced alterations in TREM-1 surface expression were not a result of increased TNF-α or IL-10. Inhibitor studies disclosed a PI3K-dependent pathway in LPS-induced up-regulation of TREM-1 on monocytes, whereas MAPK played a limited role.

From expression to signaling: roles of TREM-1 and TREM-2 in innate immunity and bacterial infection.

Triggering receptor expressed on myeloid cells (TREM) proteins play important roles in innate and adaptive immunity. Since the discovery of TREM-1 and TREM-2 in 2000, the field has exploded over the past 8 years and currently TREM-1 is thought of as an amplifier of the immune response, while TREM-2 is believed to be a negative regulator. Here, we discuss the current state of the literature on TREMs, with a focus on TREM-1 and TREM-2 and their expression, signaling in mononuclear phagocytes and roles in innate immunity and bacterial infection.

CD14 is a coreceptor of Toll-like receptors 7 and 9

CD14 interacts with and is essential for the functions of endosomal TLR7 and TLR9 in mice.

Successful treatment of familial Mediterranean fever with Anakinra and outcome after renal transplantation

Familial Mediterranean fever (FMF) is an autosomal recessive disease characterized by recurrent episodes of fever and inflammation. The most severe complication of FMF is the development of AA amyloidosis, which can be life threatening. The only current effective treatment for FMF is colchicine. Regular prophylactic treatment with colchicine at a dose of 1-2 mg daily prevents or substantially reduces the clinical manifestations of FMF in at least 90% of cases. However, approximately 10% of patients are reported to be resistant or non-responsive to colchicine and in these cases there is no consensus as to which second line agents should be used. We describe the first case, to our knowledge, of a patient with FMF and end-stage renal failure due to AA amyloidosis, successfully treated with IL-1 receptor blockade. Our data suggest that the IL-1 receptor antagonist Anakinra (Kineret; r-metHuIL-1 ra) may represent a safe and effective therapy for the treatment of colchicine-resistant FMF, in patients requiring renal replacement therapy, with dialysis or transplantation.

Type I interferon production induced by Streptococcus pyogenes-derived nucleic acids is required for host protection.

Streptococcus pyogenes is a Gram-positive human pathogen that is recognized by yet unknown pattern recognition receptors (PRRs). Engagement of these receptor molecules during infection with S. pyogenes, a largely extracellular bacterium with limited capacity for intracellular survival, causes innate immune cells to produce inflammatory mediators such as TNF, but also type I interferon (IFN). Here we show that signaling elicited by type I IFNs is required for successful defense of mice against lethal subcutaneous cellulitis caused by S. pyogenes. Type I IFN signaling was accompanied with reduced neutrophil recruitment to the site of infection. Mechanistic analysis revealed that macrophages and conventional dendritic cells (cDCs) employ different signaling pathways leading to IFN-beta production. Macrophages required IRF3, STING, TBK1 and partially MyD88, whereas in cDCs the IFN-beta production was fully dependent on IRF5 and MyD88. Furthermore, IFN-beta production by macrophages was dependent on the endosomal delivery of streptococcal DNA, while in cDCs streptococcal RNA was identified as the IFN-beta inducer. Despite a role of MyD88 in both cell types, the known IFN-inducing TLRs were individually not required for generation of the IFN-beta response. These results demonstrate that the innate immune system employs several strategies to efficiently recognize S. pyogenes, a pathogenic bacterium that succeeded in avoiding recognition by the standard arsenal of TLRs.

Lipocalin 2 deactivates macrophages and worsens pneumococcal pneumonia outcomes

Macrophages play a key role in responding to pathogens and initiate an inflammatory response to combat microbe multiplication. Deactivation of macrophages facilitates resolution of the inflammatory response. Deactivated macrophages are characterized by an immunosuppressive phenotype, but the lack of unique markers that can reliably identify these cells explains the poorly defined biological role of this macrophage subset. We identified lipocalin 2 (LCN2) as both a marker of deactivated macrophages and a macrophage deactivator. We show that LCN2 attenuated the early inflammatory response and impaired bacterial clearance, leading to impaired survival of mice suffering from pneumococcal pneumonia. LCN2 induced IL-10 formation by macrophages, skewing macrophage polarization in a STAT3-dependent manner. Pulmonary LCN2 levels were tremendously elevated during bacterial pneumonia in humans, and high LCN2 levels were indicative of a detrimental outcome from pneumonia with Gram-positive bacteria. Our data emphasize the importance of macrophage deactivation for the outcome of pneumococcal infections and highlight the role of LCN2 and IL-10 as determinants of macrophage performance in the respiratory tract.

TREM-1 Activation Alters the Dynamics of Pulmonary IRAK-M Expression In Vivo and Improves Host Defense during Pneumococcal Pneumonia

Triggering receptor expressed on myeloid cells-1 (TREM-1) is an amplifier of TLR-mediated inflammation during bacterial infections. Thus far, TREM-1 is primarily associated with unwanted signs of overwhelming inflammation, rendering it an attractive target for conditions such as sepsis. Respiratory tract infections are the leading cause of sepsis, but the biological role of TREM-1 therein is poorly understood. To determine the function of TREM-1 in pneumococcal pneumonia, we first established TREM-1 up-regulation in infected lungs and human plasma together with augmented alveolar macrophage responsiveness toward Streptococcus pneumoniae. Mice treated with an agonistic TREM-1 Ab and infected with S. pneumoniae exhibited an enhanced early induction of the inflammatory response that was indirectly associated with lower levels of negative regulators of TLR signaling in lung tissue in vivo. Later in infection, TREM-1 engagement altered S. pneumoniae-induced IRAK-M (IL-1R-associated kinase-M) kinetics so as to promote the resolution of pneumonia and remarkably led to an accelerated elimination of bacteria and consequently improved survival. These data show that TREM-1 exerts a protective role in the innate immune response to a common bacterial infection and suggest that caution should be exerted in modulating TREM-1 activity during certain clinically relevant bacterial infections.