Older Patients Are Immunocompromised by Cytokine Depletion and Loss of Innate Immune Function After HIP Fracture Surgery

Decoding the immune landscape following hip fracture in elderly patients: unveiling temporal dynamics through single-cell RNA sequencing

BACKGROUND

Hip fractures in the elderly have significant consequences, stemming from the initial trauma and subsequent surgeries. Hidden blood loss and stress due to concealed injury sites could impact the whole osteoimmune microenvironment. This study employs scRNA-seq technique to map immune profiles in elderly hip fracture patients from post-trauma to the recovery period, investigating the dynamic changes of immune inflammation regulation subgroups.

METHODS

We collected peripheral blood samples from four elderly hip fracture patients (two males and two females, all > 75 years of age) at three different time points (24 h post-trauma, 24 h post-operation, and day 7 post-operation) and applied scRNA-seq technique to analyze the cellular heterogeneity and identify differentially expressed genes in peripheral blood individual immune cells from elderly hip fracture patients.

RESULTS

In this study, we analyzed the composition and gene expression profiles of peripheral blood mononuclear cells (PBMCs) from elderly hip fracture patients by scRNA-seq and further identified new CD14 monocyte subpopulations based on marker genes and transcriptional profiles. Distinct gene expression changes were observed in various cell subpopulations at different time points. C-Mono2 monocyte mitochondria-related genes were up-regulated and interferon-related and chemokine-related genes were down-regulated within 24 h post-operation. Further analysis of gene expression profiles at day 7 post-operation showed that C-Mono2 monocytes showed downregulation of inflammation-related genes and osteoblast differentiation-related genes. However, the expression of these genes in cytotoxic T cells, Treg cells, and B cell subsets exhibited a contrasting trend. GZMK+CD8+ cytotoxic T cells showed downregulation of chemokine-related genes, and Treg cells showed upregulation of genes related to the JAK/STAT signaling pathway. Furthermore, we examined interactions among diverse immune cell subsets, pinpointing specific ligand-receptor pairs. These findings imply cross-talk and communication between various cell types in the post-traumatic immune response.

CONCLUSIONS

Our study elucidates the notable alterations in immune cell subpopulations during different stages of hip fracture in elderly patients, both in terms of proportions and differential gene expressions. These changes provide significant clinical implications for tissue repair, infection prevention, and fracture healing in clinic.

Geriatric Surgery Produces a Hypoactive Molecular Phenotype in the Monocyte Immune Gene Transcriptome

Surgery is a major challenge for the immune system, but little is known about the immune response of geriatric patients to surgery. We therefore investigated the impact of surgery on the molecular signature of circulating CD14+ monocytes, cells implicated in clinical recovery from surgery, in older patients. We enrolled older patients having elective joint replacement (N = 19) or spine (N = 16) surgery and investigated pre- to postoperative expression changes in 784 immune-related genes in monocytes. Joint replacement altered the expression of 489 genes (adjusted p < 0.05), of which 38 had a |logFC| > 1. Spine surgery changed the expression of 209 genes (adjusted p < 0.05), of which 27 had a |logFC| > 1. In both, the majority of genes with a |logFC| > 1 change were downregulated. In the combined group (N = 35), 471 transcripts were differentially expressed (adjusted p < 0.05) after surgery; 29 had a |logFC| > 1 and 72% of these were downregulated. Notably, 21 transcripts were common across procedures. Thus, elective surgery in older patients produces myriad changes in the immune gene transcriptome of monocytes, with many suggesting development of an immunocompromised/hypoactive phenotype. Because monocytes are strongly implicated in the quality of surgical recovery, this signature provides insight into the cellular and molecular mechanisms of the immune response to surgery and warrants further study as a potential biomarker for predicting poor outcomes in older surgical patients.

The promising roles of macrophages in geriatric hip fracture

As aging becomes a global burden, the incidence of hip fracture (HF), which is the most common fracture in the elderly population and can be fatal, is rapidly increasing, and its extremely high fatality rate places significant medical and financial burdens on patients. Fractures trigger a complex set of immune responses, and recent studies have shown that with aging, the immune system shows decreased activity or malfunctions in a process known as immune senescence, leading to disease and death. These phenomena are the reasons why elderly individuals typically exhibit chronically low levels of inflammation and increased rates of infection and chronic disease. Macrophages, which are key players in the inflammatory response, are critical in initiating the inflammatory response, clearing pathogens, controlling the innate and adaptive immune responses and repairing damaged tissues. Tissue-resident macrophages (TRMs) are widely present in tissues and perform immune sentinel and homeostatic functions. TRMs are combinations of macrophages with different functions and phenotypes that can be directly influenced by neighboring cells and the microenvironment. They form a critical component of the first line of defense in all tissues of the body. Immune system disorders caused by aging could affect the biology of macrophages and thus the cascaded immune response after fracture in various ways. In this review, we outline recent studies and discuss the potential link between monocytes and macrophages and their potential roles in HF in elderly individuals.

Impact of Advancing Age on the Status and Risk of Postoperative Infections After Liver Resection

BACKGROUND

Despite the recently increasing number of elderly patients undergoing liver resection, the impact of advancing age on postoperative infections (PIs) incidence and risk remains unclear. This study aimed to investigate the impact of advancing age on PIs incidence and status.

METHODS

This retrospective study included 744 patients undergoing liver resection without biliary reconstruction or combined resection of other organs. Multivariable analysis with a restricted cubic spline was used to evaluate the impact of advancing age on PIs and to determine its association with PIs risk in patients undergoing open and laparoscopic liver resection (OLR and LLR, respectively).

RESULTS

Multivariable analysis demonstrated that advancing age was significantly associated with increased PIs risk (P = 0.017). The spline curve showed that the odds ratio for PIs sharply increased starting approximately at 65 years of age. Unadjusted restricted cubic splines assessing the subcategories of PIs demonstrated that advancing age was associated with increased risks of organ/space surgical site infection and sepsis (P = 0,064 and 0.048, respectively). Multivariable analysis revealed that LLR was associated with the lower PIs risk compared with OLR (P = 0.025), whereas the lower PIs risk with LLR was not significantly obscured by advancing age (P = 0.29).

CONCLUSIONS

Advancing age was associated with increased risk of PIs, including organ/space surgical site infections and sepsis, after liver resection especially in patients aged ≥ 65 years.

Older patients with proximal femur fractures and SARS-CoV-2 infection - An observational study

Background: Older patients are at increased risk of severe COVID-19 infection and associated mortality. There are limited data evaluating the outcome of older patients with hip fractures treated during the COVID-19 pandemic, and it has been suggested that these patients should be treated non-operatively due to high mortality risk. The aim of this study was to report the outcomes of COVID-19 infected hip fracture patients treated at a single centre. Methods: This was a retrospective cohort study. Data were collected from February 2020 (after the first confirmed COVID-19 infected patient was reported in the Midlands region of the UK). All patients admitted to the hospital with femoral neck fractures were included. Patient demographics, comorbidity, COVID-19 status, and short-term clinical outcomes were obtained by review of electronic medical records. The outcomes of COVID-19 infected patients were compared with non-COVID-19 patients treated during the study period. Results: Twenty-nine patients were included (mean age of 80 years), of whom 14 (48%) were tested positive for COVID-19 infection in the postoperative period. Overall, 26 patients (90%) underwent surgical treatment. COVID-19 infected patients had significantly higher Charlson comorbidity scores compared to the control group (5 vs. 4; p = 0.047). Only 5 COVID-19 infected patients (36%) required supplemental oxygen therapy in the postoperative period, and no patients required respiratory or other organ support. The 30-day mortality rate in COVID-19 patients was 14% compared to 0% in the negative controls (p = 0.22). Interpretation: COVID-19 infection did not increase the mortality rate of older patients undergoing surgery for hip fractures during the pandemic. The authors recommend careful assessment of patient fitness and prompt surgical treatment. In addition, it was noted that nearly all admissions were either given large boluses of Vitamin D or were on maintenance supplementation, which may have affected the severity of the response to COVID-19 infections.

Factors Contributing to Extended Hospital Length of Stay in Emergency General Surgery†

BACKGROUND

Emergency general surgery (EGS) is a field characterized by disproportionately high costs, post-operative mortality, and complications. We attempted to identify independent factors predictive of an increased postoperative length of stay (LOS), a key contributor to economic burden and worse outcomes.

METHODS

The ACS-NSQIP database was queried for data from2005 to 2017. Current procedural terminology (CPT) codes were used to identify the most commonly performed EGS procedures: appendectomy, bowel resection, colectomy, and cholecystectomy. Cohorts above and below 75^th percentile LOS were determined, compared by preoperative variables, and evaluated with univariate and multivariate logistic regression to quantify risk.

RESULTS

Of 267,495 cases, 70,703 cases were above the 75^th percentile for LOS. A larger proportion of patients in the extended LOS group were 41 years or older (88.6% vs 45.7%). More Blacks (10.3% vs 6.7%) were observed in the extended LOS group. Age, race, cardiopulmonary, hepatic, and renal disease, diabetes, recent weight loss, steroid use, and sepsis history were significant factors on multivariate analysis but varied in terms of risk proportion by procedure. Age (61+), Black race, hypertension, sepsis, and cancer were significant for all 4 procedures.

CONCLUSIONS

Several factors are independently associated with extended LOS for those undergoing the most common EGS procedures. Five of these were associated with an increased LOS for all four procedures. These included, age (61+), hypertension, sepsis, cancer, and Black race.

Timing of hip hemiarthroplasty and the influence on prosthetic joint infection

Introduction

Previous research suggested that patients have increased risk of infection with increased time from presentation with a femoral neck fracture to treatment with a hip hemiarthroplasty (HHA). The purpose of this study was to determine if rates of prosthetic joint infections within 3 months of surgery was affected by the time from patient presentation with a femoral neck fracture to the time of treatment with HHA.

Materials and methods

Acute hip fractures treated with HHA between 2005 and 2017 at three centres in Norway were enrolled in the study. Multi-trauma patients were excluded. Univariable analysis was performed to determine any significant effect of pre-operative waiting time on infection rate. Two pre-planned analyses dichotomizing pre-operative waiting time cut-offs were performed.

Results

There were 2300 patients with an average age of 82 (range, 48–100) years included of which 3.4% experienced a prosthetic joint infection within 3 months. The primary analysis found no significant difference in infection rate depending on time to surgery (OR = 1.06 (95% CI 0.94–1.20, p = 0.33)). The secondary analyses showed no significant differences in infection rates when comparing pre-operative waiting time of <24 hours vs ≥24 hours (OR = 0.92 (95% CI 0.58–1.46, p = 0.73)) and <48 hours vs ≥48 hours (OR = 1.39 (95% CI 0.81–2.38, p = 0.23)).

Conclusion

Based off of a large retrospective Norwegian database of hip fractures there did not appear to be a significant difference in infection rate based on pre-operative wait time to surgery.

Humoral Factors From Musculoskeletal Polytrauma Patients Impair Antibacterial Responses Of Neutrophils In vitro

Polytrauma is associated with increased risk of sepsis, but the risk for implant infection is less clear. Neutrophil antibacterial responses are significantly reduced in polytrauma patients (n= 9, ISS≥15) for at least 5 days compared to healthy controls. Reduced neutrophil activity could influence implant infection in addition to sepsis.

Increasing Risk of Hospital-Treated Infections and Community-Based Antibiotic Use After Hip Fracture Surgery: A Nationwide Study 2005-2016

We aimed to examine trends in the incidence of treated infections following hip fracture surgery in Denmark from 2005 to 2016. We conducted a nationwide cohort study using individual-level linked data from Danish population-based registries. We calculated cumulative incidence considering death as competing risk and, based on the pseudo-observation method, risk ratios (RRs) with 95% confidence interval (CI) using the period 2005-2006 as a reference. RRs were adjusted for age, sex, and comorbidity. A total of 74,771 patients aged 65 years or older with first-time hip fracture surgery were included. The risk of postoperative (at 15, 30, 90, and 365 days) infections increased during 2005-2016. The 30-day cumulative incidence of all hospital-treated infections increased from 10.8% (95% CI, 10.2% to 11.3%) in 2005-2006 to 14.3% (95% CI, 13.7% to 15.0%) in 2015-2016 (adjusted RR 1.32; 95% CI, 1.23 to 1.42). Adjusted RR for 30-day hospital-treated pneumonia was 1.70 (95% CI, 1.49 to 1.92). The 30-day cumulative incidence of redeeming community-based antibiotic prescriptions increased from 17.5% (95% CI, 16.8% to 18.2%) in 2005-2006 to 27.1% (95% CI, 26.3% to 27.9%) in 2015-2016 (adjusted RR 1.54; 95% CI, 1.47 to 1.62). The largest increase was observed for broad-spectrum antibiotic use (adjusted RR 1.79; 95% CI, 1.68 to 1.90). During 2005-2016, risk of infections was substantially higher in hip fracture patients than in the general population. The risk of hospital-treated pneumonia and antibiotic prescriptions increased more over time among hip fracture patients. We found increased risks of postoperative treated infections following hip fracture surgery during the 12-year study period, which could not entirely be explained by similar infection trends in the general population. Given the high mortality following infections in the elderly, further research is needed to identify patients at increased risk to target preventive treatment and potentially reduce complications and mortality in hip fracture patients. © 2018 American Society for Bone and Mineral Research.

Smoking, Gender, and Overweight Are Important Influencing Factors on Monocytic HLA-DR before and after Major Cancer Surgery

Background

Monocytic human leukocyte antigen D related (mHLA-DR) is essential for antigen-presentation. Downregulation of mHLA-DR emerged as a general biomarker of impaired immunity seen in patients with sepsis and pneumonia and after major surgery. Influencing factors of mHLA-DR such as age, overweight, diabetes, smoking, and gender remain unclear.

Methods

We analyzed 20 patients after esophageal or pancreatic resection of a prospective, randomized, placebo-controlled, double-blind trial (placebo group). mHLA-DR was determined from day of surgery (od) until postoperative day (pod) 5. Statistical analyses were performed using multivariate generalized estimating equation analyses (GEE), nonparametric multivariate analysis of longitudinal data, and univariate post hoc nonparametric Mann–Whitney tests.

Results

In GEE, smoking and gender were confirmed as significant influencing factors over time. Univariate analyses of mHLA-DR between smokers and nonsmokers showed lower preoperative levels (p = 0.010) and a trend towards lower levels on pod5 (p = 0.056) in smokers. Lower mHLA-DR was seen in men on pod3 (p = 0.038) and on pod5 (p = 0.026). Overweight patients (BMI > 25 kg/m²) had lower levels of mHLA-DR on pod3 (p = 0.039) and pod4 (p = 0.047).

Conclusion

Smoking is an important influencing factor on pre- and postoperative immune function while postoperative immune function was influenced by gender and overweight. Clinical trial registered with ISRCTN27114642.