Is therapeutic hypothermia immunosuppressive?

Short-term effects of ambient temperature on acute exacerbation of inflammatory bowel disease: A nationwide case-crossover study with external validation

Inflammatory bowel disease (IBD) is an idiopathic inflammatory disorder characterized by chronic and relapsing manifestations. Several environmental factors are known as triggers for exacerbation of IBD. However, an association between exacerbation of IBD and ambient temperature is uncertain. This study aimed to estimate the risk of acute exacerbation of IBD due to ambient temperature. We performed a bidirectional case-crossover study using a nationwide claim data from South Korea. The external validation was conducted with a large prospective cohort in the United Kingdom. We confirmed significant associations between acute exacerbation of IBD and the short-term ambient temperature changes toward severe temperatures, in the cold weather (-19.4°C-4.3°C) (odd ratio [OR] = 1.13, 95% confidence interval [CI]: 1.13-1.14) and in the hot weather (21.3°C-33.5°C) (OR = 1.16, 95% CI: 1.15-1.17). However, the association was not significant in the moderate weather (4.3°C-21.3°C). The external validation suggested consistent results with additional elevation of acute exacerbation risk in the colder weather (-13.4°C to 2.6°C) (OR = 1.90, 95% CI: 1.62-2.22) and in the hotter weather (15.7°C-28.4°C) (OR = 1.41, 95% CI: 1.32-1.51). We observed and validated that the short-term ambient temperature changes were associated with acute exacerbation of IBD in the cold and hot weathers. Our findings provide evidence that temperature changes are associated with the acute exacerbation of IBD.

Systemic administration of clinical-grade multilineage-differentiating stress-enduring cells ameliorates hypoxic-ischemic brain injury in neonatal rats

Multilineage-differentiating stress-enduring (Muse) cells are endogenous reparative pluripotent stem cells present in the bone marrow, peripheral blood, and organ connective tissues. We assessed the homing and therapeutic effects of systemically administered nafimestrocel, a clinical-grade human Muse cell-based product, without immunosuppressants in a neonatal hypoxic-ischemic (HI) rat model. HI injury was induced on postnatal day 7 (P7) and was confirmed by T2-weighted magnetic resonance imaging on P10. HI rats received a single dose nafimestrocel (1 × 106 cells/body) or Hank's balanced salt solution (vehicle group) intravenously at either three days (on P10; M3 group) or seven days (on P14; M7 group) after HI insult. Radioisotope experiment demonstrated the homing of chromium-51-labeled nafimestrocel to the both cerebral hemispheres. The cylinder test (M3 and M7 groups) and open-field test (M7 group) showed significant amelioration of paralysis and hyperactivity at five weeks of age compared with those in the vehicle group. Nafimestrocel did not cause adverse events such as death or pathological changes in the lung at ten weeks in the both groups. Nafimestrocel attenuated the production of tumor necrosis factor-α and inducible nitric oxide synthase from activated cultured microglia in vitro. These results demonstrate the potential therapeutic benefits and safety of nafimestrocel.

Inhibiting nighttime melatonin and boosting cortisol increase patrolling monocytes, phagocytosis, and myelination in a murine model of multiple sclerosis

Conflicting results on melatonin synthesis in multiple sclerosis (MS) have been reported due to variabilities in patient lifestyles, which are not considered when supplementing melatonin. Since melatonin acts through its receptors, we identified melatonin receptors in oligodendrocytes (OLs) in the corpus callosum, where demyelination occurs; the subventricular zone, where neural stem/progenitor cells (NSPCs) are located; and the choroid plexus, which functions as a blood-cerebrospinal fluid barrier. Moreover, using chimeric mice, resident macrophages were found to express melatonin receptors, whereas bone marrow-derived macrophages lost this expression in the demyelinated brain. Next, we showed that cuprizone-fed mice, which is an MS model, tended to have increased melatonin levels. While we used different approaches to alter the circadian rhythm of melatonin and cortisol, only the constant light approach increased NSPC proliferation and differentiation to oligodendrocyte precursor cells (OPCs), OPCs maturation to OLs and recruitment to the site of demyelination, the number of patrolling monocytes, and phagocytosis. In contrast, constant darkness and exogenous melatonin exacerbated these events and amplified monocyte infiltration. Therefore, melatonin should not be considered a universal remedy, as is currently claimed. Our data emphasize the importance of monitoring melatonin/cortisol oscillations in each MS patient by considering diet and lifestyle to avoid melatonin overdose.

Combination Therapy of Pulsed-Wave Ultrasound Hyperthermia and Immunostimulant OK-432 Enhances Systemic Antitumor Immunity for Cancer Treatment

PURPOSE

In this study, we hypothesized that systemic antitumor immunity might be enhanced by combining pulsed-wave ultrasound hyperthermia (pUSHT) with OK-432 and that the induced antitumor immunity could confer protection against tumorigenesis. These hypotheses were tested in bilateral and rechallenged tumor models.

METHODS AND MATERIALS

Bilateral and rechallenged tumor models were applied in the studies. In the bilateral tumor model, BALB/c mice were inoculated in both flanks with CT26-luc tumor cells. The tumors in the right flank were treated with 4 courses of pUSHT with or without OK-432. In the rechallenged tumor model, tumor cells were implanted into the right flank. Once formed, the tumors were treated with pUSHT with OK-432, followed by surgical resection. New tumor cells were then implanted into the contralateral flank. The antitumor response was evaluated via infiltrated immune cells and the severity of necrosis/apoptosis in tumors.

RESULTS

In the bilateral tumor model, the tumor growth rate and growth activity of both treated (100% reduction) and untreated tumors (90.5% reduction) were significantly inhibited with the combination treatment compared with the sham control group, and the systemic antitumor effect was prolonged. The survival rate was significantly enhanced (sham control, 8 days; OK plus pUSHT, >20 days). IFNγ⁺ CD4 (treated tumor, 8.6-fold; untreated tumor, 4-fold), IFNγ⁺ CD8 (treated tumor, 6.7-fold; untreated tumor, 2.6-fold), and T cell and NK cell (treated tumor, 4-fold; untreated tumor, 2.5-fold) infiltration was increased in the combination group compared with the control group. In the rechallenged tumor model, new tumors failed to form with the combination treatment.

CONCLUSION

This experimental study combining pUSHT and OK-432 explored a new therapeutic strategy for controlling colon cancer metastasis. The results show that the combination treatment may produce an effective antitumor immune response.

Hypothermia as an adjuvant treatment in paediatric refractory or super-refractory status epilepticus

Therapeutic hypothermia is among the adjuvant therapies suggested for refractory or super-refractory status epilepticus (R/SR-SE) in paediatric patients. Experimental evidence of neuroprotective and antiseizure effects provides a strong rationale for using therapeutic hypothermia in patients with status epilepticus. Thus, hypothermia between 20°C and 33°C in animals with status epilepticus is associated not only with significantly less neuronal damage, predominantly in the hippocampal CA1, CA2, and CA3 areas, but also with increased seizure latency and decreased seizure frequency and duration. Therapeutic hypothermia has rarely been used in paediatric R/SR-SE. In the few reported cases, seizure control was markedly improved but nearly half the patients experienced recurrences after rewarming. Studies are needed to clarify the modalities and indications of therapeutic hypothermia in paediatric patients with R/SR-SE. WHAT THIS PAPER ADDS: Hypothermia at 20°C to 33°C is neuroprotective and has antiseizure effects in experimental status epilepticus. In children, antiseizure effects are marked but recurrences after rewarming are common.

Association of triage hypothermia with in-hospital mortality among patients in the emergency department with suspected sepsis

PURPOSE

To identify if triage hypothermia (<36.0 °C) among emergency department (ED) encounters with sepsis are independently associated with mortality.

METHODS

We analyzed data from a multi-stage probability sample survey of visits to United States EDs between 2007 and 2015, using two inclusion approaches: an explicit definition based on diagnosis codes for sepsis and a severe sepsis definition, combining evidence of infection with organ dysfunction. We used multivariable regression to determine an association between hypothermia and in-hospital mortality.

RESULTS

Of 1.2 billion ED encounters (95% confidence interval [CI] 1.0-1.3 billion), 3.1 million (95% CI 2.7-3.5 million) met the explicit sepsis definition; 7.4% (95% CI 75.2-9.7%) had triage hypothermia. The adjusted odds ratio (aOR) for hypothermia for in-hospital mortality was 6.82 (95% CI 3.08-15.22). The severe sepsis definition identified 3.5 million (95% 3.1-4.0 million) encounters; 30.3% (95% CI 25.0-34.6%) had triage hypothermia. The aOR for hypothermia with mortality was 4.08 (95% CI 2.09-7.95). Depending on sepsis definition, 78.1-84.4% had other systemic inflammatory response syndrome vital sign abnormalities.

CONCLUSION

Up to one in three patients with sepsis have triage hypothermia, which is independently associated with mortality. 10-20% of patients with hypothermic sepsis do not have other vital sign abnormalities.

Infection in critically ill pediatric patients on continuous renal replacement therapy

INTRODUCTION

Continuous renal replacement therapies (CRRT) are frequently used in critically ill children and may increase the risk of infection. However, the incidence, characteristics and prognosis of infection in critically ill children on CRRT have not been studied.

METHODS

Data from a prospective, single-center register of critically ill children treated with CRRT was analyzed.

RESULTS

55 children (40% under 1 year of age) were treated with CRRT between June 2008 and January 2012; 43 patients (78.2%) presented 1 or more infections. The most common condition of patients requiring CRRT was heart disease (69%). Infection occurred a median of 11 days after the initiation of CRRT (IQ range: 4 to 21 days). A total of 21 patients (48.8 %) developed 1 infection, 7 (16.2%) developed 2 infections and 15 (34.9%) developed 3 or more infections. The most frequent infection was catheter-related bacteremia, with no differences in catheter location. CRRT duration longer than 4.5 days was the only risk factor for infection. Patients with infection had a longer length of stay (LOS) in the Pediatric Intensive Care Unit (PICU) than patients without it (37.8 vs. 17.6, p = 0.019), but there were no differences in mortality (30.2% vs. 33.3%; p = 0.84).

CONCLUSIONS

Infection rate is high in critically ill children treated with CRRT. More than 4 days of CRRT increases the risk of infection. Infection in these patients entails a longer stay in the PICU but did not increase mortality.

Impact of Hypothermia Initiation and Duration on Perihemorrhagic Edema Evolution After Intracerebral Hemorrhage

BACKGROUND AND PURPOSE

Intracerebral hemorrhage (ICH) causes high morbidity and mortality. Recently, perihemorrhagic edema (PHE) has been suggested as an important prognostic factor. Therapeutic hypothermia may be a promising therapeutic option to treat PHE. However, no data exist about the optimal timing and duration of therapeutic hypothermia in ICH. We examined the impact of therapeutic hypothermia timing and duration on PHE evolution.

METHODS

In this retrospective, single-center, case-control study, we identified patients with ICH treated with mild endovascular hypothermia (target temperature 35°C) from our institutional database. Patients were grouped according to hypothermia initiation (early: days 1-2 and late: days 4-5 after admission) and hypothermia duration (short: 4-8 days and long: 9-15 days). Patients with ICH matched for ICH volume, age, ICH localization, and intraventricular hemorrhage were identified as controls. Relative PHE, temperature, and intracranial pressure course were analyzed. Clinical outcome on day 90 was assessed using the modified Rankin scale (0-3=favorable and 4-6=poor).

RESULTS

Thirty-three patients with ICH treated with hypothermia and 37 control patients were included. Early hypothermia initiation led to relative PHE decrease between admission and day 3, whereas median relative PHE increased in control patients (-0.05 [interquartile range, -0.4 to 0.07] and 0.07 [interquartile range, -0.07 to 0.26], respectively; P=0.007) and patients with late hypothermia initiation (0.22 [interquartile range 0.12-0.27]; P=0.037). After day 3, relative PHE increased in all groups without difference. Outcome was not different between patients treated with hypothermia and controls.

CONCLUSIONS

Early hypothermia initiation after ICH onset seems to have an important impact on PHE evolution, whereas our data suggest only limited impact later than day 3 after onset.

Targeted temperature management in brain protection: An evidence-based review

Targeted temperature management (TTM) for neuroprotection involves maintaining the temperature of the brain at predetermined levels by various techniques. It is aimed at avoiding the harmful effects of hyperthermia on the brain and at exploiting the protective effects of lower tissue temperature. There has been an explosion in the use of TTM for neuroprotection in a variety of clinical scenarios apart from the commonly accepted fields of resuscitation and ischaemic, hypoxic encephalopathy. This review briefly discusses the evidence base for TTM. The focus is on various areas of application for neuroprotection, the practical issues pertaining to TTM implementation, the recent data that support it and the present areas of controversy.