Mineralocorticoid deficiency in hemorrhagic shock

Glucocorticoids with or without fludrocortisone in septic shock: a narrative review from a biochemical and molecular perspective

Two randomised controlled trials have reported a reduction in mortality when adjunctive hydrocortisone is administered in combination with fludrocortisone compared with placebo in septic shock. A third trial did not support this finding when hydrocortisone administered in combination with fludrocortisone was compared with hydrocortisone alone. The underlying mechanisms for this mortality benefit remain poorly understood. We review the clinical implications and potential mechanisms derived from laboratory and clinical data underlying the beneficial role of adjunctive fludrocortisone with hydrocortisone supplementation in septic shock. Factors including distinct biological effects of glucocorticoids and mineralocorticoids, tissue-specific and mineralocorticoid receptor-independent effects of mineralocorticoids, and differences in downstream signalling pathways between mineralocorticoid and glucocorticoid binding at the mineralocorticoid receptor could contribute to this interaction. Furthermore, pharmacokinetic and pharmacodynamic disparities exist between aldosterone and its synthetic counterpart fludrocortisone, potentially influencing their effects. Pending publication of well-designed, randomised controlled trials, a molecular perspective offers valuable insights and guidance to help inform clinical strategies.

The ultra-acute steroid response to traumatic injury: a cohort study

OBJECTIVE

Trauma-induced steroid changes have been studied post-hospital admission, resulting in a lack of understanding of the speed and extent of the immediate endocrine response to injury. The Golden Hour study was designed to capture the ultra-acute response to traumatic injury.

DESIGN

We conducted an observational cohort study including adult male trauma patients <60 years, with blood samples drawn ≤1 h of major trauma by pre-hospital emergency responders.

METHODS

We recruited 31 adult male trauma patients (mean age 28 [range 19-59] years) with a mean injury severity score (ISS) of 16 (IQR 10-21). The median time to first sample was 35 (range 14-56) min, with follow-up samples collected 4-12 and 48-72 h post-injury. Serum steroids in patients and age- and sex-matched healthy controls (HCs) (n = 34) were analysed by tandem mass spectrometry.

RESULTS

Within 1 h of injury, we observed an increase in glucocorticoid and adrenal androgen biosynthesis. Cortisol and 11-hydroxyandrostendione increased rapidly, whilst cortisone and 11-ketoandrostenedione decreased, reflective of increased cortisol and 11-oxygenated androgen precursor biosynthesis by 11β-hydroxylase and increased cortisol activation by 11β-hydroxysteroid dehydrogenase type 1. Active classic gonadal androgens testosterone and 5α-dihydrotestosterone decreased, whilst the active 11-oxygenated androgen 11-ketotestosterone maintained pre-injury levels.

CONCLUSIONS

Changes in steroid biosynthesis and metabolism occur within minutes of traumatic injury. Studies that address whether ultra-early changes in steroid metabolism are associated with patient outcomes are now required.

Mineralocorticoid Dysfunction during Critical Illness: A Review of the Evidence

The recent demonstration of the significant reduction in mortality in patients with septic shock treated with adjunctive glucocorticoids combined with fludrocortisone and the effectiveness of angiotensin II in treating vasodilatory shock have renewed interest in the role of the mineralocorticoid axis in critical illness. Glucocorticoids have variable interactions at the mineralocorticoid receptor. Similarly, mineralocorticoid receptor-aldosterone interactions differ from mineralocorticoid receptor-glucocorticoid interactions and predicate receptor-ligand interactions that differ with respect to cellular effects. Hyperreninemic hypoaldosteronism or selective hypoaldosteronism, an impaired adrenal response to increasing renin levels, occurs in a subgroup of hemodynamically unstable critically ill patients. The suggestion is that there is a defect at the level of the adrenal zona glomerulosa associated with a high mortality rate that may represent an adaptive response aimed at increasing cortisol levels. Furthermore, cross-talk exists between angiotensin II and aldosterone, which needs to be considered when employing therapeutic strategies.

Sugar or salt? The relative roles of the glucocorticoid and mineralocorticoid axes in traumatic shock

BACKGROUND

Glucocorticoid deficiency (GD) has been proposed as a key contributor to shock states, but the presence and role of acute mineralocorticoid deficiency may be of equal or greater significance. We sought to analyze the incidence and degree of acute mineralocorticoid deficiency and GD in an animal model of severe hemorrhage and shock.

METHODS

Fifty-seven swine underwent 35% volume-controlled hemorrhage followed by aortic cross-clamping for 50 minutes to induce truncal ischemia-reperfusion. Protocol-guided resuscitation was performed. Laboratory analysis included cortisol, aldosterone, and plasma renin activity. The aldosterone-to-renin ratio (ARR) was calculated at each time point, and changes were correlated to markers of perfusion.

RESULTS

Mean baseline cortisol levels were 5.8 μg/dL. Following hemorrhage, there was a significant increase in mean cortisol to 9.2 μg/dL (p < 0.001). After 1 hour of reperfusion, there was no change in mean cortisol levels (9.8 μg/dL, p = 0.12). Mean baseline aldosterone was 13.3 pg/mL. Aldosterone levels before cross-clamp removal increased significantly to 115.1 pg/mL (p < 0.001) and then rapidly declined to 49.2 pg/mL (p < 0.001) after 1 hour of reperfusion. Conversely, baseline plasma renin activity was 0.75 ng/mL per hour and increased significantly before cross-clamp removal (1.8) and at 1 hour (8.9, both p < 0.001). The ARR at baseline was 96.1 and increased to 113.5 (p = 0.68) before cross-clamp removal but significantly declined following 1 hour of reperfusion to 7.6 (p < 0.001). Overall, this represented a 93% reduction in mean ARR following reperfusion. The degree of aldosterone deficiency correlated with degree of systemic shock as measured by arterial base deficit (r = 0.47, p = 0.04), while cortisol showed no correlation.

CONCLUSION

Hemorrhagic shock with ischemia-reperfusion injury resulted in only modest impact on the glucocorticoid axis, but major dysfunction of the mineralocorticoid axis and severe hyperreninemic hypoaldosteronism. The degree of aldosterone deficiency may provide prognostic information or offer potential targets for pharmacologic intervention.

LEVEL OF EVIDENCE

Diagnostic study, level III.

Biliary tract external drainage alleviates kidney injury in shock

BACKGROUND

Kidney injury is common in hemorrhagic shock (HS). Kidney injury leads to a systemic increase in serum chemokines and cytokines and causes injuries to other vital organs. Our previous studies showed that vitamin C led to organ protection and inflammation inhibitory effects in rat models of HS via induction heme oxygenase-1 (HO-1). We also found that biliary tract external drainage (BTED) increased the expression levels of HO-1 in rat livers. We investigated roles of BTED in kidney injury and its relationship with the HO-1 pathway in HS in this research.

METHODS

Rat models of HS were induced by drawing blood from the femoral artery. BTED was performed by inserting a catheter into the bile duct. Thirty-six Sprague-Dawley rats were randomized to sham group; HS group; zinc protoporphyrin IX (Znpp) group; BTED group; BTED + Znpp group, and BTED + bile infusion group. The expression levels of HO-1 in the kidney were analyzed by Western blotting. The expression levels of occludin messenger RNA in the kidney were analyzed by real-time reverse transcription-polymerase chain reaction. The expression levels of occludin in the kidney were analyzed by immunohistochemistry. Histology of renal was performed by hematoxylin and eosin staining.

RESULTS

Occludin messenger RNA and protein levels in the kidney increased markedly after BTED under HS conditions. Renal histopathologic scores decreased significantly after BTED under HS conditions. Znpp significantly inhibited all mentioned effects.

CONCLUSIONS

BTED alleviates kidney injury in rats of HS via the HO-1 pathway.

Changes in renal tissue proteome induced by mesenteric lymph drainage in rats after hemorrhagic shock with resuscitation

Kidney injury commonly occurs after hemorrhagic shock. Previous studies have shown that post-hemorrhagic shock mesenteric lymph (PHSML) return negatively affects the kidneys and may induce injury. This study investigates the effect of PHSML drainage on the proteome in renal tissue. A controlled hemorrhagic shock model was established in the shock and shock+drainage groups. After 1 h of hypotension, fluid resuscitation was implemented within 30 min. Meanwhile, PHSML was drained in the shock+drainage group. After 3 h of resuscitation, renal tissue was extracted for proteome analysis using two-dimensional fluorescence difference gel electrophoresis. Differential proteins with intensities that either increased or decreased by 1.5-fold or greater were selected for trypsin digestion and analyzed by matrix-assisted laser desorption/ionization time-of-flight (TOF) mass spectrometry and tandem TOF/TOF mass spectrometry. Enzyme-linked immunosorbent assay was used to validate the identified partial proteins. Compared with the sham group, hnRNPC and Starp decreased in the shock group, whereas Hadha, Slc25a13, Atp5b, hnRNPC, Starp, Rps3, and actin were downregulated in the shock+drainage group. Meanwhile, Atp5b and actin decreased in the shock+drainage group relative to the shock group. The identified proteins can be classified into different categories, such as cell proliferation (hnRNPC, Strap, and Rps3), energy metabolism (Hadha, Atp5b, and Slc25a13), cell motility, and cytoskeleton (actin). Moreover, enzyme-linked immunosorbent assay measurement validated the changed levels of Atp5b and Actg2. Our findings provide a starting point for investigating the functions of differentially expressed proteins in acute kidney injury induced by hemorrhagic shock. These findings hold great potential for the development of therapeutic interventions.