Cimetidine effects on the immunosuppression induced by burn injury

Association between histamine 2 receptor antagonists and sepsis outcomes in ICU patients: a retrospective analysis using the MIMI-IV database

Background

Sepsis is marked by elevated histamine, which is a vasodilator that increases vascular permeability. Although human studies are lacking, murine models of sepsis have indicated potential protective effects of histamine 2 receptor antagonist administration (H2RAs).

Objective

To assess any association between H2RA use in sepsis-3 patients admitted to the ICU and mortality, mechanical ventilation, length of stay, and markers of renal, liver, and lung dysfunction.

Design

Retrospective cohort study.

Setting

Intensive care units of the Beth Israel Deaconess Medical Center (BIDMC) accessed via the MIMIC-IV database spanning an 11-year period from 2008 to 2019.

Patients (or participants)

A total of 30,591 patients met the inclusion criteria for sepsis-3 on admission (mean age 66.49, standard deviation 15.92).

Main measures

We collected patient age, gender, ethnicity, comorbidities (contained within the Charlson comorbidity index), SOFA score, OASIS score, APS III score, SAPS II score, H2RA use, creatinine, BUN, ALT, AST, and P/F ratios. Primary outcomes were mortality, mechanical ventilation, and ICU length of stay.

Key results

A total of 30,591 patients met inclusion criteria over the 11-year sample period. The 28-day in hospital mortality rate was significantly lower among patients who received an H2RA (12.6% vs 15.1%, p < 0.001) as compared to those who did not receive an H2RA. Patients receiving an H2RA had significantly lower adjusted odds of mortality (0.802, 95% CI 0.741–0.869, p < 0.001), but significantly higher adjusted odds of invasive mechanical ventilation (4.426, 95% CI 4.132–4.741, p < 0.001) and significantly higher ICU LOS (3.2 days vs. 2.4 days, p < 0.001) as compared to the non-H2RA group. H2RA use was also associated with decreased severity of acute respiratory distress syndrome (ARDS) and lower serum creatinine.

Conclusion

Among patients hospitalized in the ICU for sepsis, the use of an H2RA was associated with significantly lower odds of mortality, decreased severity of ARDS, and a lower incidence of renal insufficiency.

Immunosuppression is Inappropriately Qualifying the Immune Status of Septic and SIRS Patients

Immunosuppression is the most commonly used concept to qualify the immune status of patients with either sterile systemic inflammatory response syndrome (SIRS) or sepsis. In this review we attempt to demonstrate that the concept of immunosuppression is an oversimplification of the complex anti-inflammatory response that occurs in patients dealing with a severe sterile or infectious insult. Particularly, the immune status of leukocytes varies greatly depending on the compartment from where they are derived from. Furthermore, although certain functions of immune cells present in the blood stream or in the hematopoietic organs can be significantly diminished, other functions are either unchanged or even enhanced. This juxtaposition illustrates that there is no global defect. The mechanisms called reprogramming or trained innate immunity are probably aimed at preventing a generalized deleterious inflammatory reaction, and work to maintain the defense mechanisms at their due levels.

Risk Factors for Multidrug-Resistant Acinetobacter baumannii Infections in a Mass Burn Casualty Incident

They investigated the risk factors of multidrug-resistant Acinetobacter baumannii infections in 33 burn patients in a mass burn casualty. The independent variables included sex, burn size, vancomycin, ampicillin/sulbactam, cefazolin, meropenem, third-/fourth-generation cephalosporin, the number of classes of antibiotic used, and the number of days of antibiotic use. Multidrug-resistant A. baumannii infection was the outcome variable. Logistic regressions and structural equation model were used for statistical analysis. The average age was 21.7 years (range, 17-32 years; M = 11 [33%], F = 22 [67%]; mean burn area, 42% of the total body surface area; study period, June 28, 2015 to July 31, 2015). The incidence of infection was 39% (n = 13/33). For every percent increase in burn size, the odds of developing A. baumannii infections increased by 1.1 (P < .05). Similarly, the odds increased by 2.5 in every number increase in the classes of antibiotic used, by 1.2 in everyday increase in the days of antibiotic used, and by 12 in patients treated with vancomycin (P < .05). The correlations of these risk factors were demonstrated in a hypothetical structural equation model (P-value of chi-squared test > .05 and root mean square error of approximation < 0.05) in which burn size was the fundamental risk factor of multidrug-resistant A. baumannii infections. The model did not predict the emergence of multidrug-resistant A. baumannii infections. Conclusively, the risks of multidrug-resistant A. baumannii infections in burns are correlated with burn size, the number of classes of antibiotic used, the number of days of antibiotic use, and the prior use of vancomycin.

Immunomodulatory properties of cimetidine: Its therapeutic potentials for treatment of immune-related diseases

Histamine exerts potent modulatory impacts on the cells of innate- [including neutrophils, monocytes, macrophages, dendritic cells (DCs), natural killer (NK) cells and NKT cells] and adaptive immunity (such as Th1-, Th2-, Th17-, regulatory T-, CD8⁺ cytotoxic T cells, and B cells) through binding to histamine receptor 2 (H2R). Cimetidine, as an H2R antagonist, reverses the histamine-mediated immunosuppression, as it has powerful stimulatory effects on the effector functions of neutrophils, monocytes, macrophages, DCs, NK cells, NKT cells, Th1-, Th2-, Th17-, and CD8⁺ cytotoxic T cells. However, cimetidine reduces the regulatory/suppressor T cell-mediated immunosuppression. Experimentally, cimetidine potentiate some immunologic activities in vitro and in vivo. The therapeutic potentials of cimetidine as an immunomodulatory agent were also investigated in a number of human diseases (such as cancers, viral warts, allergic disorders, burn, and bone resorption) and vaccination. This review aimed to provide a concise summary regarding the impacts of cimetidine on the immune system and highlight the cellular mechanisms of action and the immunomodulatory effects of this drug in various diseases to give novel insights regarding the therapeutic potentials of this drug for treatment of immune-related disorders. The review encourages more investigations to consider the immunomodulatory characteristic of cimetidine for managing of immune-related disorders.

LED phototherapy in full-thickness burns induced by CO2 laser in rats skin

Many studies have been conducted on the treatment of burns because they are important in morbidity and mortality. These studies are mainly focused on improving care and quality of life of patients. The aim of this study was evaluate the LED phototherapy effects in rats skin full-thickness burns induced by CO₂ laser. The animals were divided in NT group that did not received any treatment and LED group that received LED irradiation at 685 nm, 220 mW, and 4.5 J/cm² during 40 s by burned area. Biopsies were obtained after 7, 14, and 21 days of treatment and submitted to histological and immunohistochemical analysis. The LED phototherapy shows anti-inflammatory effects, improves angiogenesis, and stimulates the migration and proliferation of fibroblasts. The T CD8+ lymphocytes were more common in burned areas compared to T CD4+ lymphocytes since statistically significant differences were observed in the LED group compared to the NT group after 7 days of treatment. These results showed that LED phototherapy performs positive influence in full-thickness burns repair from the healing process modulated by cellular immune response. The obtained results allowed inferring that burns exhibit a characteristic cell immune response and this cannot be extrapolated to other wounds such as incision and wounds induced by punch, among others.

Effects of oral cimetidine on the reproductive system of male rats

Cimetidine is widely used for the treatment of digestive tract ulcers, but it induces testis injury. To explore the mechanisms underlying cimetidine-induced toxicity towards the testis, the effects of oral cimetidine on the reproductive system of male rats were assessed. Cimetidine was orally administered to male rats at 20, 40 or 120 mg/kg/day for 9 weeks. The rats were then euthanized, and serum, testis, epididymis, prostate gland, seminal vesicle, preputial gland, levator ani muscle and sphincter ani samples were collected. Sperm parameters were obtained by computer-assisted sperm analysis. Serum hormone levels were measured by ELISA. Protein expression levels were detected by immunohistochemistry. Apoptosis was assessed with the DeadEnd™ Colorimetric Apoptosis Detection System. The results indicated that the sperm average path velocity, straight line velocity and curvilinear velocity were significantly decreased in the 120 mg/kg cimetidine group compared with the control group, while luteinizing hormone and testosterone levels were significantly higher compared with the control group. Testicular lesions were observed by histopathology in the 120 mg/kg cimetidine group. The amounts of cells positive for cyclooxygenase-2 (COX-2) and nuclear factor κB (NF-κB) were increased in the 120 mg/kg cimetidine group compared with the control group. The amounts of cells positive for iNOS were increased in all cimetidine treatment groups. In addition, apoptotic cells were significantly more abundant in the 120 mg/kg cimetidine group compared with the control group, as indicated by terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick end labeling. Overall, 9 weeks of oral cimetidine induced pathological changes in the testicles and hormone secretion disorder in rats. COX-2, iNOS and NF-κB upregulation and induction of apoptosis may be associated with the reproductive toxicity caused by cimetidine.