Daily Sepsis Research Analysis

The organismal roles of the class II PI3K isoform PI3K-C2α remain poorly understood. Recent studies have found PI3K-C2α to promote arterial thrombosis and breast cancer metastasis, generating interest in this kinase as a drug target, with small molecule PI3K-C2α inhibitors now available. However, the consequences of systemic PI3K-C2α inactivation in the nondiseased, postnatal state are largely unknown. Here, we show that induction of genetic PI3K-C2α inactivation in adult mice is well tolerated, without adverse effects on normal physiology. Surprisingly, however, mice with inactive PI3K-C2α display strong sensitization to challenge with bacterial lipopolysaccharide (LPS), a model of endotoxic shock. This sensitization is recapitulated by vascular endothelial-specific deletion of PI3K-C2α. Furthermore, sensitization to LPS can be fully rescued by disabling extrinsic induction of cell death by combined caspase-8- and RIPK3 deficiency. These observations validate the tolerability of systemic PI3K-C2α inhibition in principle but reveal an unexpected role for PI3K-C2α in the regulation of extrinsic cell death pathways.

INTRODUCTION: Sepsis is a critical condition requiring timely and accurate pathogen identification. Traditional blood cultures are slow and often yield low sensitivity. Metagenomic next-generation sequencing (mNGS) offers broad and rapid pathogen detection but is hindered by excessive human DNA background in blood samples. This study evaluated a novel Zwitterionic Interface Ultra-Self-assemble Coating (ZISC)-based filtration device designed to deplete host cells and enhance microbial DNA recovery for improved mNGS diagnostics. METHODS: We assessed the novel filter's performance in depleting white blood cells (WBCs) while preserving microbial integrity using spiked blood samples. Comparisons were made with other host depletion techniques, including differential lysis and CpG-methylated DNA removal. Analytical sensitivity was tested using spiked microbial communities at varying genome equivalents (GEs). Clinical validation involved eight blood culture-positive sepsis patient samples, processed with and without filtration, for both genomic DNA (gDNA) and cell-free DNA (cfDNA)-based mNGS. All libraries were sequenced on a NovaSeq600 with at least 10 million reads per sample. RESULTS: The novel filter achieved > 99% WBC removal across various blood volumes and allowed unimpeded passage of bacteria and viruses. Compared to other depletion methods, the novel filtration was more efficient, less labor-intensive, and preserved microbial reads. mNGS with filtered gDNA detected all expected pathogens in 100% (8/8) of clinical samples, with an average microbial read count of 9351 reads per million (RPM), over tenfold higher than unfiltered samples (925 RPM). In contrast, cfDNA-based mNGS showed inconsistent sensitivity and was not significantly enhanced by filtration (1251-1488 RPM). Finally, the novel filtration did not alter the microbial composition, making it suitable for accurate pathogen profiling. CONCLUSION: The workflow with the novel host depletion method significantly enhanced the analytical sensitivity of gDNA-based mNGS by reducing the host DNA background and enriching microbial content. This approach improved diagnostic yield in sepsis and may be a valuable tool for further clinical infectious disease diagnostics.

BACKGROUND: Septic shock is a critical condition associated with high mortality and resource utilization. Although improvements in early recognition and management of sepsis have been reported globally, the trends in clinical outcomes among patients with septic shock in Japan remain unclear. METHODS: We conducted a retrospective cohort study using data from the Japanese Diagnosis Procedure Combination (DPC) nationwide medical claims database from 2010 to 2020. Adult inpatients (aged ≥ 18 years) with sepsis were identified based on the criteria for presumed serious infection (blood culture plus ≥ 4 days of intravenous antibiotics) and acute organ dysfunction, determined using the International Classification of Diseases, 10th Revision codes and treatment procedures. This approach is broadly consistent with the Sepsis-3 definition but adapted for administrative data. Septic shock was defined as the administration of at least one vasopressor, without requiring hypotension or lactate criteria, in line with previous administrative database studies. The primary outcome was in-hospital mortality rate. Secondary outcomes included deaths per 1,000 inpatients, hospital length of stay (LOS), intensive care unit (ICU) admission rates, and ICU LOS. Outcomes among patients with non-shock sepsis were also analyzed for comparison. Trends and subgroup analyses were performed according to age and sex and combinations of ICU admission and shock status. RESULTS: Among 4,426,342 patients with sepsis, 649,082 (14.7%) had septic shock. In-hospital mortality was significantly higher in the shock group than in the non-shock group (36.5% vs. 20.0%, P < 0.001), with a longer median LOS (38 vs. 25 days) and higher ICU admission (50.7% vs. 19.2%). From 2010 to 2020, in-hospital mortality decreased from 46.7 to 33.2% in the shock group and from 26.0 to 18.0% in the non-shock group. The number of deaths per 1,000 inpatients only slightly decreased in the shock group (2.8 to 2.4) but increased in the non-shock group (7.0 to 8.2). The proportion of patients with septic shock increased from 0.64 to 0.83%. Meanwhile, the mean LOS decreased from 61.0 to 53.6 days in the shock group and from 45.7 to 34.4 days in the non-shock group. Only about half of the patients with septic shock were admitted to ICUs, and mortality was higher in non-ICU patients throughout most of the study period, although the difference diminished in 2019. Subgroup analyses showed persistently high mortality rates among older patients (≥ 85 years) and males across the study period. CONCLUSIONS: Despite improvements in survival and LOS over the past decade, septic shock remains a highly lethal and resource-intensive condition in Japan, with in-hospital mortality rates exceeding 30%. Mortality was particularly high among older patients, with rates consistently exceeding 40% among those aged ≥ 85 years.