Hyperferritinemic sepsis, macrophage activation syndrome, and mortality in a pediatric research network: a causal inference analysis

BACKGROUND

One of five global deaths are attributable to sepsis. Hyperferritinemic sepsis (> 500 ng/mL) is associated with increased mortality in single-center studies. Our pediatric research network's objective was to obtain rationale for designing anti-inflammatory clinical trials targeting hyperferritinemic sepsis.

METHODS

We assessed differences in 32 cytokines, immune depression (low whole blood ex vivo TNF response to endotoxin) and thrombotic microangiopathy (low ADAMTS13 activity) biomarkers, seven viral DNAemias, and macrophage activation syndrome (MAS) defined by combined hepatobiliary dysfunction and disseminated intravascular coagulation, and mortality in 117 children with hyperferritinemic sepsis (ferritin level > 500 ng/mL) compared to 280 children with sepsis without hyperferritinemia. Causal inference analysis of these 41 variables, MAS, and mortality was performed.

RESULTS

Mortality was increased in children with hyperferritinemic sepsis (27/117, 23% vs 16/280, 5.7%; Odds Ratio = 4.85, 95% CI [2.55-9.60]; z = 4.728; P-value < 0.0001). Hyperferritinemic sepsis had higher C-reactive protein, sCD163, IL-22, IL-18, IL-18 binding protein, MIG/CXCL9, IL-1β, IL-6, IL-8, IL-10, IL-17a, IFN-γ, IP10/CXCL10, MCP-1/CCL2, MIP-1α, MIP-1β, TNF, MCP-3, IL-2RA (sCD25), IL-16, M-CSF, and SCF levels; lower ADAMTS13 activity, sFasL, whole blood ex vivo TNF response to endotoxin, and TRAIL levels; more Adenovirus, BK virus, and multiple virus DNAemias; and more MAS (P-value < 0.05). Among these variables, only MCP-1/CCL2 (the monocyte chemoattractant protein), MAS, and ferritin levels were directly causally associated with mortality. MCP-1/CCL2 and hyperferritinemia showed direct causal association with depressed ex vivo whole blood TNF response to endotoxin. MCP-1/CCL2 was a mediator of MAS. MCP-1/CCL2 and MAS were mediators of hyperferritinemia.

CONCLUSIONS

These findings establish hyperferritinemic sepsis as a high-risk condition characterized by increased cytokinemia, viral DNAemia, thrombotic microangiopathy, immune depression, macrophage activation syndrome, and death. The causal analysis provides rationale for designing anti-inflammatory trials that reduce macrophage activation to improve survival and enhance infection clearance in pediatric hyperferritinemic sepsis.

Sepsis-induced changes in differentiation, maintenance, and function of memory CD8 T cell subsets

Formation of long-lasting memory lymphocytes is one of the foundational characteristics of adaptive immunity and the basis of many vaccination strategies. Following the rapid expansion and contraction of effector CD8 T cells, the surviving antigen (Ag)-specific cells give rise to the memory CD8 T cells that persist for a long time and are phenotypically and functionally distinct from their naïve counterparts. Significant heterogeneity exists within the memory CD8 T cell pool, as different subsets display distinct tissue localization preferences, cytotoxic ability, and proliferative capacity, but all memory CD8 T cells are equipped to mount an enhanced immune response upon Ag re-encounter. Memory CD8 T cells demonstrate numerical stability under homeostatic conditions, but sepsis causes a significant decline in the number of memory CD8 T cells and diminishes their Ag-dependent and -independent functions. Sepsis also rewires the transcriptional profile of memory CD8 T cells, which profoundly impacts memory CD8 T cell differentiation and, ultimately, the protective capacity of memory CD8 T cells upon subsequent stimulation. This review delves into different aspects of memory CD8 T cell subsets as well as the immediate and long-term impact of sepsis on memory CD8 T cell biology.

Endocytosis of peroxiredoxin 1 links sterile inflammation to immunoparalysis in pediatric patients following cardiopulmonary bypass

After cardiopulmonary bypass (CPB), the occurrence of systemic inflammatory response is often accompanied by a persistent compensatory anti-inflammatory response syndrome that can lead to a compromised immune competence termed immunoparalysis, rendering the patients susceptible to infections which is a leading complication following cardiac surgery. However, the underlying mechanisms of CPB-elicited immunoparalysis remain obscure. In this study we showed that peroxiredoxin 1 (Prdx1), a putative cytosolic antioxidant, was released immediately after CPB in a cohort of pediatric patients receiving congenital cardiac surgery. This increased Prdx1 was correlated to a reduced human leukocyte antigen-DR expression and an elevated interleukin-10 (IL-10) production, as well as a hypo-responsiveness of macrophages to endotoxin and a higher incidence of nosocomial infection. We demonstrated that substitution of Ser⁸³ for Cys⁸³ prevented Prdx1 from oligomerization and subsequent binding and internalization to macrophages. These effects mitigated Prdx1-induced IL-10 induction and endotoxin tolerance. Furthermore, after engagement with toll-like receptor (TLR) 4, clathrin-dependent endocytosis is crucial for Prdx1 to elicit IL-10 production in phagocytes. Congruently, inhibition of Prdx1/TLR4 endocytosis in phagocytes reversed the Prdx1/IL-10-mediated hypo-responsiveness to endotoxin. Our findings unveiled the possible mechanisms by which Prdx1 undertakes to cause immunoparalysis, and targeting endocytosis of Prdx1 could be a novel therapeutic approach for postoperative infections associated with CPB.

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Cardiopulmonary bypass-elicited ischemia/reperfusion injury causes release of Prdx1.

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High molecular weight forms of Prdx1 interact with TLR4 to initiate sterile inflammation.

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Endocytosis of Prdx1/TLR4 induces IL-10 production that leads to immunoparalysis and subsequent septic inflammation.

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Inhibition of Prdx1/TLR4 endocytosis reverses Prdx1/IL-10-mediated hypo-responsiveness to endotoxin in phagocytes.

Does Presence of Sepsis by Itself Predispose the Patients to HCAIs?

How to cite this article: Gaikwad S, Patil VP. Does Presence of Sepsis by Itself Predispose the Patients to HCAIs? Indian J Crit Care Med 2021;25(3):253-254.

Hydrocortisone treatment is associated with a longer duration of MODS in pediatric patients with severe sepsis and immunoparalysis

Background

Severe critical illness-induced immune suppression, termed immunoparalysis, is associated with longer duration of organ dysfunction in septic children. mRNA studies have suggested differential benefit of hydrocortisone in septic children based on their immune phenotype, but this has not been shown using a functional readout of the immune response. This study represents a secondary analysis of a prospectively conducted immunophenotyping study of pediatric severe sepsis to test the hypothesis that hydrocortisone will be differentially associated with clinical outcomes in children with or without immunoparalysis.

Methods

Children with severe sepsis/septic shock underwent blood sampling within 48 h of sepsis onset. Immune function was measured by quantifying whole blood ex vivo LPS-induced TNFα production capacity, with a TNFα response < 200 pg/ml being diagnostic of immunoparalysis. The primary outcome measure was number of days in 14 with MODS. Univariate and multivariable negative binomial regression models were used to examine associations between hydrocortisone use, immune function, and duration of MODS.

Results

One hundred two children were enrolled (age 75 [6–160] months, 60% male). Thirty-one subjects received hydrocortisone and were more likely to be older (106 [52–184] vs 38 [3–153] months, p = 0.04), to have baseline immunocompromise (32 vs 8%, p = 0.006), to have higher PRISM III (13 [8–18] vs 7 [5–13], p = 0.0003) and vasoactive inotrope scores (20 [10–35] vs 10 [3–15], p = 0.0002) scores, and to have more MODS days (3 [1–9] vs 1 [0–3], p = 0.002). Thirty-three subjects had immunoparalysis (TNFα response 78 [52–141] vs 641 [418–1047] pg/ml, p < 0.0001). Hydrocortisone use was associated with longer duration of MODS in children with immunoparalysis after adjusting for covariables (aRR 3.7 [1.8–7.9], p = 0.0006) whereas no association with MODS duration was seen in children without immunoparalysis (aRR 1.2 [0.6–2.3], p = 0.67).

Conclusion

Hydrocortisone use was independently associated with longer duration of MODS in septic children with immunoparalysis but not in those with more robust immune function. Prospective clinical trials using a priori immunophenotyping are needed to understand optimal hydrocortisone strategies in this population.

The cellular basis of organ failure in sepsis-signaling during damage and repair processes

Sepsis is defined as life-threatening organ dysfunction caused by a dysregulated host response to infection. This definition, updated in 2016, shifted the conceptual focus from exclusive attention to the systemic inflammatory response toward the multifactorial tissue damage that occurs during the progression of infection to sepsis and shock. Whereas targeting the inflammatory host response to infection did not translate into improved clinical management of sepsis, recent findings might shed new light on the maladaptive host–pathogen interaction in sepsis and pave the way for “theranostic” interventions. In addition to the well-known resistance responses of the immune system that result in pathogen clearance, “disease tolerance” has recently been acknowledged as a coping mechanism of presumably equal importance. We propose that both defense mechanisms, “resistance” and “disease tolerance”, can get out of control in sepsis. Whereas excessive activation of resistance pathways propagates tissue damage via immunopathology, an inappropriate “tolerance” might entail immunoparalysis accompanied by fulminant, recurrent or persisting infection. The review introduces key signaling processes involved in infection-induced “resistance” and “tolerance”. We propose that elaboration of these signaling pathways allows novel insights into sepsis-associated tissue damage and repair processes. Moreover theranostic opportunities for the specific treatment of sepsis-related hyperinflammation or immunoparalysis will be introduced. Agents specifically affecting either hyperinflammation or immunoparalysis in the course of sepsis might add to the therapeutic toolbox of personalized care in the field of organ dysfunction caused by infection. (This article is freely available.)

Impact of bronchial colonization with Candida spp. on the risk of bacterial ventilator-associated pneumonia in the ICU: the FUNGIBACT prospective cohort study

INTRODUCTION

Respiratory tract Candida spp. colonization is associated with more frequent bacterial ventilator-associated pneumonia (VAP). However, this colonization could be causally related to VAP or simply reflect the immune paralysis associated with multiple organ failure.

OBJECTIVE

To prospectively evaluate the relationship between Candida spp. colonization and bacterial VAP in mechanically ventilated patients with multiple organ failure.

INCLUSION

Patients receiving mechanical ventilation for > 4 days and presenting multiple organ failure were included. Tracheal colonization with Candida spp. was evaluated at inclusion (day 0, D0) and every 4 days until extubation. Quantitative proximal and tracheal cultures were performed at each VAP episode. Monocyte human leukocyte antigen-DR isotype (mHLA-DR) expression and the ratio of polymononuclear leukocytes to lymphocytes were used to evaluate immunoparalysis at D0 and D7. The relationship between fungal colonization and VAP was modelled using cause-specific models for repeated events with adjustment for time-dependent confounders and immune factors.

RESULTS

A total of 213 patients, with a median age of 64, simplified acute physiology score II (SAPS II) score 55 and sequential organ failure assessment (SOFA) score 10, mainly admitted for medical reasons (n = 197, 92%), were enrolled in 2012-2015. The median ICU stay was 24 days and the mortality rate was 32% (69 cases). Median mHLA-DR was 5916 Ab-bound/cell [3863-8934]; median lymphocyte count, 0.9Giga/L [0.6-1.3]; neutrophil-to-lymphocyte ratio, 10.9 [6.5-19.7]. Overall, 146 cases (68.5%) had tracheal colonization with Candida spp. An episode of VAP occurred (either for the first or only time) in 62 (29.1%) cases 5.5 days (median) after D0; a second episode occurred in 12 (5.6%) cases, 15.5 days (median) after D0. After adjustment, bronchial colonization with Candida was not associated with VAP [adjusted cause-specific hazard ratio = 0.98 (0.59-1.65), p = 0.95].

CONCLUSION

In patients with mechanical ventilation for more than 4 days and multiple organ failure, bronchial colonization with Candida spp. was not associated with VAP, even after adjustment for immune function.

The effect of polymyxin B hemoperfusion on modulation of human leukocyte antigen DR in severe sepsis patients

BACKGROUND

Recent randomized trials have not found that polymyxin B hemoperfusion (PMX-HP) improves outcomes for patients with sepsis. However, it remains unclear whether the therapy could provide benefit for highly selected patients. Monocyte human leukocyte antigen (mHLA-DR) expression, a critical step in the immune response, is decreased during sepsis and leads to worsening sepsis outcomes. One recent study found that PMX-HP increased mHLA-DR expression while another found that the treatment removed HLA-DR-positive cells.

METHODS

We conducted a randomized controlled trial in patients with blood endotoxin activity assay (EAA) level ≥ 0.6. Patients in the PMX-HP group received a 2-h PMX-HP treatment plus standard treatment for 2 consecutive days. Patients in the non-PMX-HP group received only standard treatment. The primary outcome compared the groups on median change in mHLA-DR expression between day 3 and baseline. Secondary outcomes compared the groups on the mean or median change in CD11b expression, neutrophil chemotaxis, presepsin, cardiovascular Sequential Organ Failure Assessment (CVS SOFA) score, vasopressor dose, and EAA level between day 3 and baseline. We further compared the groups on mortality, ICU-free days, ventilator-free days, dialysis dependence status, renal recovery, serum creatinine, vasopressor-free days, and major adverse kidney events (MAKE 28), measured on day 28.

RESULTS

Fifty-nine patients were randomized to PMX-HP (n = 29) and non-PMX-HP (n = 30) groups. At baseline, mHLA-DR expression, CD11b, neutrophil chemotaxis, and clinical parameters were comparable between groups. The median change in mHLA-DR expression between day 3 and baseline was higher in PMX-HP patients than in patients receiving standard therapy alone (P = 0.027). The mean change in CD11b between day 3 and baseline was significantly lower in the PMX-HP group than in the non-PMX-HP group (P = 0.002). There were no significant changes from baseline in neutrophil chemotaxis, presepsin, CVS SOFA scores, vasopressor doses, or EAA level between groups. On day 28 after enrollment, mortality, ICU-free days, ventilator-free days, dialysis dependence status, renal recovery, serum creatinine, vasopressor-free days, and MAKE 28 were comparable between groups.

CONCLUSION

PMX-HP improved mHLA-DR expression in severe sepsis patients. Future studies should examine the potential benefit of PMX-HP in patients with low mHLA-DR expression.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT02413541 . Registered on 3 March 2015.

MicroRNAs 143 and 150 in whole blood enable detection of T-cell immunoparalysis in sepsis

Background

Currently, no suitable clinical marker for detection of septic immunosuppression is available. We aimed at identifying microRNAs that could serve as biomarkers of T-cell mediated immunoparalysis in sepsis.

Methods

RNA was isolated from purified T-cells or from whole blood cells obtained from septic patients and healthy volunteers. Differentially regulated miRNAs were identified by miRNA Microarray (n = 7). Validation was performed via qPCR (n = 31).

Results

T-cells of septic patients revealed characteristics of immunosuppression: Pro-inflammatory miR-150 and miR-342 were downregulated, whereas anti-inflammatory miR-15a, miR-16, miR-93, miR-143, miR-223 and miR-424 were upregulated. Assessment of T-cell effector status showed significantly reduced mRNA-levels of IL2, IL7R and ICOS, and increased levels of IL4, IL10 and TGF-β. The individual extent of immunosuppression differed markedly. MicroRNA-143, − 150 and − 223 independently indicated T-cell immunoparalysis and significantly correlated with patient’s IL7R-/ICOS-expression and SOFA-scores. In whole blood, composed of innate and adaptive immune cells, both traits of immunosuppression and hyperinflammation were detected. Importantly, miR-143 and miR-150 – both predominantly expressed in T-cells – retained strong power of discrimination also in whole blood samples.

Conclusions

These findings suggest miR-143 and miR-150 as promising markers for detection of T-cell immunosuppression in whole blood and may help to develop new approaches for miRNA-based diagnostic in sepsis.

Electronic supplementary material

The online version of this article (10.1186/s10020-018-0056-z) contains supplementary material, which is available to authorized users.

Impact of supplemental parenteral nutrition early during critical illness on invasive fungal infections: a secondary analysis of the EPaNIC randomized controlled trial

OBJECTIVE

In the EPaNIC RCT (N=4640), postponing the administration of parenteral nutrition (PN) to beyond 1 week in the intensive care unit (ICU) (late-PN) reduced the number of ICU-acquired infections and the costs for antimicrobial drugs compared with initiation of PN within 24-48 hours of admission (early-PN). In a secondary analysis, we hypothesize that late-PN reduces the odds to acquire an invasive fungal infection (IFI) in the ICU.

METHODS

The impact of late-PN (N=2328) versus early-PN (N=2312) on acquired IFI and on the likelihood to acquire an IFI over time was assessed in univariable and multivariable analyses. Subsequently, we performed multivariable analyses to assess the effect of the mean total daily administered calories from admission until day 3, day 5, and day 7 on the likelihood over time of acquiring an IFI.

RESULTS

Fewer late-PN patients acquired an IFI compared with early-PN patients (77/2328 versus 112/2312) (p 0.008). After adjusting for risk factors, the odds to acquire an IFI and the likelihood of acquiring an IFI at any time were lower in late-PN (adjusted odds ratio 0.66, 95% CI 0.48-0.90, p 0.009; adjusted hazard ratio (HRadj) 0.70, 95% CI 0.52-0.93, p 0.02). Larger caloric amounts from admission until day 7 were associated with a higher likelihood to acquire an IFI over time (HRadj 1.09, 95% CI 1.02-1.16, p 0.009).

CONCLUSION

Postponing PN to beyond 1 week and smaller caloric amounts until day 7 in the ICU reduced ICU-acquired IFIs and the likelihood to develop an IFI over time.

Immunoparalysis in Pediatric Critical Care

Although many forms of critical illness are initiated by a proinflammatory stimulus, a compensatory anti-inflammatory response can occur with systemic inflammation. Immunoparalysis, an important form of acquired immunodeficiency, affects the innate and adaptive arms of the immune system. Immunoparalysis has been associated with increased risks for nosocomial infection and death in a variety of pediatric critical illnesses. Evidence suggests that immunoparalysis is reversible with immunostimulants. Highly standardized, prospective immune monitoring regimens are needed to better understand the immunologic effects of critical care treatment regimens and to enrich clinical trials with subjects most likely to benefit from immunostimulatory therapies.

Release of Danger-Associated Molecular Patterns following Chemotherapy Does Not Induce Immunoparalysis in Leukemia Patients

Chemotherapy may result in the release of danger-associated molecular patterns (DAMPs), which can cause immunoparalysis (deactivation of the immune system). We investigated DAMPs following chemotherapy and their relationship with markers of immunoparalysis in leukemia patients. In 6 patients with acute myeloid leukemia or myelodysplastic syndrome and 12 healthy subjects, DAMPs, cytokines, and markers of immunoparalysis were determined before and during the first week after chemotherapy initiation. In the patients, plasma levels of nuclear DNA (a marker of general DAMP release) were profoundly increased before chemotherapy and further increased 4-6 h afterwards, while the specific DAMP mitochondrial DNA showed only a trend towards increase. Circulating cytokine levels did not change following chemotherapy. Leukocyte cytokine production capacity and HLA-DR expression were similar in patients and healthy controls until day 4 when leukocytes were found to be virtually absent. In conclusion, in the early phase following chemotherapy in leukemia patients, increased DAMP release does not induce immunoparalysis.

Immunoparalysis: Clinical and immunological associations in SIRS and severe sepsis patients

INTRODUCTION

This study was designed to identify changes in the monocytic membrane marker HLA-DR and heat shock proteins (HSPs) in relation to T-regulatory cells (T-regs) and other immunological marker changes in patients with systemic inflammatory response syndrome (SIRS) or sepsis/septic shock.

METHODS

Healthy volunteers, intensive care unit (ICU) patients with SIRS due to head injury and ICU patients with severe sepsis/septic shock were enrolled in the current study. Determination of CD14+/HLA-DR+ cells, intracellular heat-shock proteins and other immunological parameters were performed by flow cytometry and RT-PCR techniques as appropriate. Univariate and multivariate analysis examined associations of CD14/HLA-DR, HSPs, T-regs and suppressor of cytokine signalling (SOCS) proteins with SIRS, sepsis and outcome.

RESULTS

Fifty patients (37 with severe sepsis and 13 with SIRS) were enrolled, together with 20 healthy volunteers used as a control group. Compared to healthy individuals, patients with SIRS and severe sepsis showed progressive decline of their CD14/HLA-DR expression (0% to 7.7% to 50% within each study subpopulation, p<0.001). Mean fluorescent intensity (MFI) levels of HSP70 and HSP90 on monocytes and polymorphonuclear cells were significantly higher in SIRS patients compared to controls and fell significantly in severe sepsis/septic shock patients (p<0.05 for all comparisons). There was no statistically significant difference between subgroups for levels of T-regulatory cells or relative copies of Suppressor of Cytokine Signalling 3 (SOCS3) proteins. In univariate models percent of CD14/HLA-DR was associated with mortality (OR: 1.8 95%CI 1.02-3.2, p=0.05), while in multivariate models after adjusting for CD14/HLA-DR only younger age and lower Acute Physiology and Chronic Health Evaluation II (APACHE II) scores were associated with increased chances of survival (beta -0.05, OR 0.9, 95% CI 0.9-0.99, p=0.038 for age and beta -0.11, OR 0.89, 95% CI 0.8-0.99, p=0.037 for APACHE II score).

CONCLUSIONS

Significant associations with SIRS and sepsis were found for CD14/HLA-DR expression and monocyte and polymorphonuclear cell levels of HSP70 and 90. The role of these biomarkers in assessing the prognosis of sepsis needs to be further explored and validated in prospective studies.

Sepsis in cirrhosis: emerging concepts in pathogenesis, diagnosis and management. Hepatol Int. 2016;10:871-882. [PMID: 27422251 DOI: 10.1007/s12072-016-9753-2]

Infections and sepsis are more common in cirrhotic than in the general population and constitute the commonest cause of sudden worsening and death. The diagnosis of systemic inflammatory syndrome and sepsis are challenging in cirrhotics due to an underlying a state of hyperdynamic circulation. Further, poor nutritional and bone marrow reserves lead to modest host immune response, the so called immunoparalysis state and the outcome of antibiotic therapy is suboptimal. In this review, a comprehensive description of current and emerging concepts in the pathogenesis and diagnosis of sepsis with importance to current and novel biomarkers for diagnosis of sepsis in cirrhosis is presented. Furthermore, novel treatment options and preventive strategies are discussed to improve the overall survival.

The immune response after stimulation with wall components of gram-positive bacteria and fungi

Although several components of the microbial wall of gram-positive bacteria and fungi possess immunostimulatory properties, their pathogenetic role remains incompletely evaluated. The purpose of this study was to assess the basic immune status of patients susceptible to infections and their capability for cytokine production after stimulation with wall components of gram-positive bacteria and fungi. We measured serum cytokine levels as well as cytokine production after ex vivo lipoteichoic acid (LTA) and mannan stimulation of whole blood. The blood was taken from 10 healthy volunteers, 10 patients with end-stage renal disease (ESRD), 10 patients with diabetes mellitus (DM), and 10 patients on their 2nd day of stay in the Intensive Care Unit (ICU), who suffered from non septic systemic inflammatory response syndrome (SIRS) and had an APACHE II score ≥25. We used 1 μg/ml LTA and 100 μg/ml mannan for an incubation period of 8 h to stimulate 100 μl aliquots of whole blood. All patient groups had higher baseline values of TNF-α, IL-6, IL-1β, and IL-10 compared to the control group, but only for ICU patients the difference was statistically significant. The ratio IL-10/IL-6 was found 0.33, 0.22, and 0.96 in healthy persons, ESRD, and DM patients respectively, and 1.32 in ICU patients. In all examined groups, the levels of cytokines significantly increased after stimulation by LTA and mannan, although in severely ill patients this change was considerably smaller, possibly reflecting a state of monocytes' depression and relative hyporesponsiveness. No significant differences between the LTA and the mannan stimulation were observed.