The effect of preoperative corticosteroids on peritoneal macrophage function after laparoscopic and open abdominal surgery in a rat model

A Review of the Effects of Pain and Analgesia on Immune System Function and Inflammation: Relevance for Preclinical Studies

One of the most significant challenges facing investigators, laboratory animal veterinarians, and IACUCs, is how to balance appropriate analgesic use, animal welfare, and analgesic impact on experimental results. This is particularly true for in vivo studies on immune system function and inflammatory disease. Often times the effects of analgesic drugs on a particular immune function or model are incomplete or don't exist. Further complicating the picture is evidence of the very tight integration and bidirectional functionality between the immune system and branches of the nervous system involved in nociception and pain. These relationships have advanced the concept of understanding pain as a protective neuroimmune function and recognizing pathologic pain as a neuroimmune disease. This review strives to summarize extant literature on the effects of pain and analgesia on immune system function and inflammation in the context of preclinical in vivo studies. The authors hope this work will help to guide selection of analgesics for preclinical studies of inflammatory disease and immune system function.

Post-operative complications in patients with a significant post-operative decrease in γδT cells

BACKGROUND

It has previously been shown that appropriate distribution of immune cells between different tissues and organs of the body is required for proper function of the immune system. Our previous work demonstrated that surgical trauma in mice induces γδT lymphocyte migration from peripheral blood to the peritoneal lymphoid organs. These described γδT cells have immunoregulatory activity as they suppress the cell-mediated immune response in vitro. We found a similar phenomenon in patients after different surgical operations. In the current study, we analyse post-operative complications in patients with a significant post-operative decrease in γδT cells.

METHODS

We investigated the percentage of γδT cells in peripheral blood of patients undergoing standard surgical procedures (gastric resection, colorectal resection, cholecystectomy and strumectomy) before and 3 days after the operation. The percentage of γδT cells was evaluated by the fluorescence-activated cell sorting cytofluorimeter. Patients were grouped based on the decrease of γδT cells. We compared the number of septic complications in patients with a large and small decrease in γδT cells.

RESULTS

After major surgery in the peritoneal cavity (gastric and colorectal surgery), in the group that had a large decrease in γδT cells we found significantly more septic complications than in the group of patients with small γδT decrease. That effect was not visible after less traumatic surgery.

CONCLUSION

Surgery results in a decreased percentage of γδT lymphocytes in the peripheral human blood which correlates with the number of septic complications. This observation may help to predict post-operative recovery after gastroabdominal surgery.

The Stress Hormone Cortisol Enhances Interferon-υ-Mediated Proinflammatory Responses of Human Immune Cells

BACKGROUND

Cortisol is a prototypical human stress hormone essential for life, yet the precise role of cortisol in the human stress response to injury or infection is still uncertain. Glucocorticoids (GCs) such as cortisol are widely understood to suppress inflammation and immunity. However, recent research shows that GCs also induce delayed immune effects manifesting as immune stimulation. In this study, we show that cortisol enhances the immune-stimulating effects of a prototypical proinflammatory cytokine, interferon-υ (IFN-υ). We tested the hypothesis that cortisol enhances IFN-υ-mediated proinflammatory responses of human mononuclear phagocytes (monocyte/macrophages [MOs]) stimulated by bacterial endotoxin (lipopolysaccharide [LPS]).

METHODS

Human MOs were cultured for 18 hours with or without IFN-υ and/or cortisol before LPS stimulation. MO differentiation factors granulocyte-macrophage colony stimulating factor (GM-CSF) or M-CSF were added to separate cultures. We also compared the inflammatory response with an acute, 4-hour MO incubation with IFN-υ plus cortisol and LPS to a delayed 18-hour incubation with cortisol before LPS exposure. MO activation was assessed by interleukin-6 (IL-6) release and by multiplex analysis of pro- and anti-inflammatory soluble mediators.

RESULTS

After the 18-hour incubation, we observed that cortisol significantly increased LPS-stimulated IL-6 release from IFN-υ-treated undifferentiated MOs. In GM-CSF-pretreated MOs, cortisol increased IFN-υ-mediated IL-6 release by >4-fold and release of the immune stimulant IFN-α2 (IFN-α2) by >3-fold, while suppressing release of the anti-inflammatory mediator, IL-1 receptor antagonist to 15% of control. These results were reversed by either the GC receptor antagonist RU486 or by an IFN-υ receptor type 1 antibody antagonist. Cortisol alone increased expression of the IFN-υ receptor type 1 on undifferentiated and GM-CSF-treated MOs. In contrast, an acute 4-hour incubation of MOs with IFN-υ and cortisol showed classic suppression of the IL-6 response to LPS.

CONCLUSIONS

These results reveal a surprisingly robust proinflammatory interaction between the human stress response hormone cortisol and the immune activating cytokine IFN-υ. The results support an emerging physiological model with an adaptive role for cortisol, wherein acute release of cortisol suppresses early proinflammatory responses but also primes immune cells for an augmented response to a subsequent immune challenge. These findings have broad clinical implications and provide an experimental framework to examine individual differences, mechanisms, and translational implications of cortisol-enhanced immune responses in humans.

Evaluation of Safe Systemic Immunosuppression Created with Dexamethasone in Prevention of Capsular Contracture: A Glance to Distinct Perspectives with Toll-Like Receptors

PURPOSE

The toll-like receptors (TLRs) stand at the interface of innate immune activation. We hypothesize to decrease the response of innate immunity activated by TLR4 by a safe, short-term, systemic immunosuppression.

METHODS

Two silicone block implants were placed into two dorsal subcutaneous pockets in 32 rats that were subdivided into four groups: The two study groups were the IV DEX group (single intravenous injection of dexamethasone 1 h before surgery) and the IV DEX + IP DEX group (in addition to a single intravenous injection of dexamethasone 1 h before surgery, intraperitoneal dexamethasone was administered for 10 days after surgery), and the two control groups were the untreated control group and the saline-treated control group. After 10 weeks, all animals were killed to determine capsular thickness, inflammatory cell density, presence of pseudoepitheliomatous hyperplasia, edema, necrosis, vascularization, TLR4 expression and myofibroblast proliferation.

RESULTS

No significant difference was observed in any parameter between the untreated and saline-treated control groups (p > 0.05). Capsular thickness, myofibroblast proliferation, TLR4 expression density were statistically different among study groups compared to control (p < 0.05).

CONCLUSIONS

This study demonstrates the relationship between toll-like receptors and fibrous capsule after implant surgery. Decreasing the innate immunity by a safe, short-term perioperative systemic immunosuppression resulted in decreased TLR4 expression and myofibroblast differentiation which could be a new research field in profibrotic pathophysiology underlying breast capsule formation.

NO LEVEL ASSIGNED

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Host responses to concurrent combined injuries in non-human primates

Background

Multi-organ failure (MOF) following trauma remains a significant cause of morbidity and mortality related to a poorly understood abnormal inflammatory response. We characterized the inflammatory response in a non-human primate soft tissue injury and closed abdomen hemorrhage and sepsis model developed to assess realistic injury patterns and induce MOF.

Methods

Adult male Mauritan Cynomolgus Macaques underwent laparoscopy to create a cecal perforation and non-anatomic liver resection along with a full-thickness flank soft tissue injury. Treatment consisted of a pre-hospital phase followed by a hospital phase after 120 minutes. Blood counts, chemistries, and cytokines/chemokines were measured throughout the study. Lung tissue inflammation/apoptosis was confirmed by mRNA quantitative real-time PCR (qPCR), H&E, myeloperoxidase (MPO) and TUNEL staining was performed comparing age-matched uninjured controls to experimental animals.

Results

Twenty-one animals underwent the protocol. Mean percent hepatectomy was 64.4 ± 5.6; percent blood loss was 69.0 ± 12.1. Clinical evidence of end-organ damage was reflected by a significant elevation in creatinine (1.1 ± 0.03 vs. 1.9 ± 0.4, p=0.026). Significant increases in systemic levels of IL-10, IL-1ra, IL-6, G-CSF, and MCP-1 occurred (11-2986-fold) by 240 minutes. Excessive pulmonary inflammation was evidenced by alveolar edema, congestion, and wall thickening (H&E staining). Concordantly, amplified accumulation of MPO leukocytes and significant pulmonary inflammation and pneumocyte apoptosis (TUNEL) was confirmed using qRT-PCR.

Conclusion

We created a clinically relevant large animal multi-trauma model using laparoscopy that resulted in a significant systemic inflammatory response and MOF. With this model, we anticipate studying systemic inflammation and testing innovative therapeutic options.

Glucocorticoids enhance the in vivo migratory response of human monocytes

Glucocorticoids (GCs) are best known for their potent anti-inflammatory effects. However, an emerging model for glucocorticoid (GC) regulation of in vivo inflammation also includes a delayed, preparatory effect that manifests as enhanced inflammation following exposure to an inflammatory stimulus. When GCs are transiently elevated in vivo following exposure to a stressful event, this model proposes that a subsequent period of increased inflammatory responsiveness is adaptive because it enhances resistance to a subsequent stressor. In the present study, we examined the migratory response of human monocytes/macrophages following transient in vivo exposure to stress-associated concentrations of cortisol. Participants were administered cortisol for 6h to elevate in vivo cortisol levels to approximate those observed during major systemic stress. Monocytes in peripheral blood and macrophages in sterile inflammatory tissue (skin blisters) were studied before and after exposure to cortisol or placebo. We found that exposure to cortisol induced transient upregulation of monocyte mRNA for CCR2, the receptor for monocyte chemotactic protein-1 (MCP-1/CCL2) as well as for the chemokine receptor CX3CR1. At the same time, mRNA for the transcription factor IκBα was decreased. Monocyte surface expression of CCR2 but not CX3CR1 increased in the first 24h after cortisol exposure. Transient exposure to cortisol also led to an increased number of macrophages and neutrophils in fluid derived from a sterile inflammatory site in vivo. These findings suggest that the delayed, pro-inflammatory effects of cortisol on the human inflammatory responses may include enhanced localization of effector cells at sites of in vivo inflammation.

Development of a standardized laparoscopic caecum resection model to simulate laparoscopic appendectomy in rats

Background

Laparoscopic appendectomy (LA) has become one of the most common surgical procedures to date. To improve and standardize this technique further, cost-effective and reliable animal models are needed.

Methods

In a pilot study, 30 Wistar rats underwent laparoscopic caecum resection (as rats do not have an appendix vermiformis), to optimize the instrumental and surgical parameters. A subsequent test study was performed in another 30 rats to compare three different techniques for caecum resection and bowel closure.

Results

Bipolar coagulation led to an insufficiency of caecal stump closure in all operated rats (Group 1, n = 10). Endoloop ligation followed by bipolar coagulation and resection (Group 2, n = 10) or resection with a LigaSure™ device (Group 3, n = 10) resulted in sufficient caecal stump closure.

Conclusions

We developed a LA model enabling us to compare three different caecum resection techniques in rats. In conclusion, only endoloop closure followed by bipolar coagulation proved to be a secure and cost-effective surgical approach.

Variant alveolar lipoproteinosis: a syndrome with distinct clinical and pathological features

Pulmonary alveolar proteinosis (PAP) is a rare condition in which pulmonary macrophages fail to clear surfactant, resulting in the alveolar accumulation of lipoproteinaceous debris. The histopathology of PAP is typified by diffuse filling of terminal airways with eosinophilic, PAS/diastase (PAS/D)-positive acellular material. We present five patients who showed histopathological changes in the lungs consistent with mild PAP. However, these cases were notable for the abundance of degenerating alveolar macrophages, weak PAS staining of lipoproteinaceous material and paucity of lamellated bodies on ultrastructural examination. Only one patient showed the CT finding of mosaiform 'crazy-paving' and the opalescent bronchoalveolar lavage fluid characteristic of PAP. In one case, therapeutic lung lavage based on a presumptive diagnosis of PAP exacerbated respiratory distress. Three patients showed partial or near-complete resolution of disease in response to high-dose corticosteroid therapy, a treatment approach that is generally ineffective in PAP. We conclude that distinguishing 'variant alveolar lipoproteinosis' from classical PAP is clinically important. Despite the otherwise typical appearance of lipoproteinaceous alveolar material in lung biopsies, the presence of degenerating foamy macrophages and atypical histochemical, ultrastructural and radiographic features suggest a steroid-responsive form of proteinosis that is likely pathogenetically distinct and may not be amenable to whole-lung lavage.