Recipient donor sex combinations in solid organ transplantation and impact on clinical outcome: A scoping review

INTRODUCTION

Solid organ transplantation (SOT) is a lifesaving treatment for end-stage organ failure. Although many factors affect the success of organ transplantation, recipient and donor sex are important biological factors influencing transplant outcome. However, the impact of the four possible recipient and donor sex combinations (RDSC) on transplant outcome remains largely unclear.

METHODS

A scoping review was carried out focusing on studies examining the association between RDSC and outcomes (mortality, graft rejection, and infection) after heart, lung, liver, and kidney transplantation. All studies up to February 2023 were included.

RESULTS

Multiple studies published between 1998 and 2022 show that RDSC is an important factor affecting the outcome after organ transplantation. Male recipients of SOT have a higher risk of mortality and graft failure than female recipients. Differences regarding the causes of death are observed. Female recipients on the other hand are more susceptible to infections after SOT.

CONCLUSION

Differences in underlying illnesses as well as age, immunosuppressive therapy and underlying biological mechanisms among male and female SOT recipients affect the post-transplant outcome. However, the precise mechanisms influencing the interaction between RDSC and post-transplant outcome remain largely unclear. A better understanding of how to identify and modulate these factors may improve outcome, which is particularly important in light of the worldwide organ shortage. An analysis for differences of etiology and causes of graft loss or mortality, respectively, is warranted across the RDSC groups.

PRACTITIONER POINTS

Recipient and donor sex combinations affect outcome after solid organ transplantation. While female recipients are more susceptible to infections after solid organ transplantation, they have higher overall survival following SOT, with causes of death differing from male recipients. Sex-differences should be taken into account in the post-transplant management.

IgG in the control of FcεRI activation: a battle on multiple fronts

The rising global incidence of IgE-mediated allergic reactions poses a significant challenge to the quality of life of affected individuals and to healthcare systems, with current treatments being limited in effectiveness, safety, and disease-modifying capabilities. IgE acts by sensitizing the high-affinity IgE receptor FcεRI expressed by mast cells and basophils, tuning these cells for inflammatory degranulation in response to future allergen encounters. In recent years, IgG has emerged as an essential negative regulator of IgE-dependent allergic inflammation. Mechanistically, studies have proposed different pathways by which IgG can interfere with the activation of IgE-mediated inflammation. Here, we briefly summarize the major proposed mechanisms of action by which IgG controls the IgE-FcεRI inflammatory axis and how those mechanisms are currently applied as therapeutic interventions for IgE-mediated inflammation.

Müller matrix polarimetry for pancreatic tissue characterization

Polarimetry is an optical characterization technique capable of analyzing the polarization state of light reflected by materials and biological samples. In this study, we investigate the potential of Müller matrix polarimetry (MMP) to analyze fresh pancreatic tissue samples. Due to its highly heterogeneous appearance, pancreatic tissue type differentiation is a complex task. Furthermore, its challenging location in the body makes creating direct imaging difficult. However, accurate and reliable methods for diagnosing pancreatic diseases are critical for improving patient outcomes. To this end, we measured the Müller matrices of ex-vivo unfixed human pancreatic tissue and leverage the feature-learning capabilities of a machine-learning model to derive an optimized data representation that minimizes normal-abnormal classification error. We show experimentally that our approach accurately differentiates between normal and abnormal pancreatic tissue. This is, to our knowledge, the first study to use ex-vivo unfixed human pancreatic tissue combined with feature-learning from raw Müller matrix readings for this purpose.

The next generation virus-like particle platform for the treatment of peanut allergy

BACKGROUND

Allergy to peanut is one of the leading causes of anaphylactic reactions among food allergic patients. Immunization against peanut allergy with a safe and protective vaccine holds a promise to induce durable protection against anaphylaxis caused by exposure to peanut. A novel vaccine candidate (VLP Peanut), based on virus-like particles (VLPs), is described here for the treatment of peanut allergy.

METHODS AND RESULTS

VLP Peanut consist of two proteins: a capsid subunit derived from Cucumber mosaic virus engineered with a universal T cell epitope (CuMV_TT ) and a CuMV_TT subunit fused with peanut allergen Ara h 2 (CuMV_TT -Ara h 2), forming mosaic VLPs. Immunizations with VLP Peanut in both naïve and peanut-sensitised mice resulted in a significant anti-Ara h 2 IgG response. Local and systemic protection induced by VLP Peanut were established in mouse models for peanut allergy following prophylactic, therapeutic and passive immunizations. Inhibition of FcγRIIb function resulted in a loss of protection, confirming the crucial role of the receptor in conferring cross protection against peanut allergens other than Ara h 2.

CONCLUSION

VLP Peanut can be delivered to peanut-sensitized mice without triggering allergic reactions, whilst remaining highly immunogenic and offering protection against all peanut allergens. In addition, vaccination ablates allergic symptoms upon allergen challenge. Moreover, the prophylactic immunization setting conferred the protection against subsequent peanut-induced anaphylaxis, showing the potential for preventive vaccination. This highlights the effectiveness of VLP Peanut as a prospective break-through immunotherapy vaccine candidate towards peanut allergy. VLP Peanut has now entered clinical development with the study PROTECT.

AA-amyloidosis in cats (Felis catus) housed in shelters

Systemic AA-amyloidosis is a protein-misfolding disease characterized by fibril deposition of serum amyloid-A protein (SAA) in several organs in humans and many animal species. Fibril deposits originate from abnormally high serum levels of SAA during chronic inflammation. A high prevalence of AA-amyloidosis has been reported in captive cheetahs and a horizontal transmission has been proposed. In domestic cats, AA-amyloidosis has been mainly described in predisposed breeds but only rarely reported in domestic short-hair cats. Aims of the study were to determine AA-amyloidosis prevalence in dead shelter cats. Liver, kidney, spleen and bile were collected at death in cats from 3 shelters. AA-amyloidosis was scored. Shedding of amyloid fibrils was investigated with western blot in bile and scored. Descriptive statistics were calculated. In the three shelters investigated, prevalence of AA-amyloidosis was 57.1% (16/28 cats), 73.0% (19/26) and 52.0% (13/25), respectively. In 72.9% of cats (35 in total) three organs were affected concurrently. Histopathology and immunofluorescence of post-mortem extracted deposits identified SAA as the major protein source. The duration of stay in the shelters was positively associated with a histological score of AA-amyloidosis (B = 0.026, CI95% = 0.007-0.046; p = 0.010). AA-amyloidosis was very frequent in shelter cats. Presence of SAA fragments in bile secretions raises the possibility of fecal-oral transmission of the disease. In conclusion, AA-amyloidosis was very frequent in shelter cats and those staying longer had more deposits. The cat may represent a natural model of AA-amyloidosis.

Final safety and efficacy results from a 106 real-world patients registry with an ascites-mobilizing pump

BACKGROUND AND AIMS

Patients with cirrhotic refractory ascites ineligible for transjugular intrahepatic shunt (TIPSS) have limited treatment options apart from repeated large volume paracentesis. The alfapump® is an implantable device mobilizing ascites from the peritoneal cavity to the bladder, from where it can be excreted. The aim of this observational cohort study was to prospectively investigate safety and efficacy of the device in a real-world cohort with cirrhotic refractory ascites and contraindications for TIPSS.

METHODS

A total of 106 patients received an implant at 12 European centres and were followed up for up to 24 months. Complications, device deficiencies, frequency of paracentesis, clinical status and survival were recorded prospectively.

RESULTS

Approximately half of the patients died on-study, about a quarter was withdrawn because of serious adverse events leading to explant, a sixth were withdrawn because of liver transplant or recovery, and nine completed follow-up. The most frequent causes of on-study death and complication-related explant were progression of liver disease and infection. The device reduced the requirement for large-volume paracentesis significantly, with more than half of patients not having required any post-implant. Survival benefits were not observed. Device-related reinterventions were predominantly caused by device deficiencies. A post-hoc comparison of the first 50 versus the last 50 patients enrolled revealed a decreased reintervention rate in the latter, mainly related to peritoneal catheter modifications.

CONCLUSIONS

The device reduced paracentesis frequency in a real-world setting. Technical complications were successfully decreased by optimization of management and device modification (NCT01532427).

[Neuroendocrine tumor of the pancreas: What is new?]

Neuroendocrine tumor of the pancreas: What is new? Abstract. Neuroendocrine neoplasms are a rare and heterogeneous group of tumors with very different clinical presentations. Accordingly, they are initially difficult to recognize in clinical practice and diagnosis is often delayed. The necessary diagnostic steps include radiological and functional / nuclear medicine examinations to determine the extent of the primary tumor on the one hand and the presence of metastases on the other. If indicated, tissue sampling / biopsy is indicated. The resulting treatments include surgical resection, treatment with somatostatin analogues or multimodal therapy concepts, depending on the type and spread of the tumor and the symptoms. The therapy of patients with NET must be discussed at an interdisciplinary tumor board at a specialized center.

Glycan-specific IgG anti-IgE autoantibodies are protective against allergic anaphylaxis in a murine model

BACKGROUND

IgE causes anaphylaxis in type I hypersensitivity diseases by activating degranulation of effector cells such as mast cells and basophils. The mechanisms that control IgE activity and prevent anaphylaxis under normal conditions are still enigmatic.

OBJECTIVE

We aimed to unravel how anti-IgE autoantibodies are induced and we aimed to understand their role in regulating serum IgE level and allergic anaphylaxis.

METHODS

We immunized mice with different forms of IgE and tested anti-IgE autoantibody responses and their specificities. We then analyzed the effect of those antibodies on serum kinetics and their in vitro and in vivo impact on anaphylaxis. Finally, we investigated anti-IgE autoantibodies in human sera.

RESULTS

Immunization of mice with IgE-immune complexes induced glycan-specific anti-IgE autoantibodies. The anti-IgE autoantibodies prevented effector cell sensitization, reduced total IgE serum levels, protected mice from passive and active IgE sensitization, and resulted in cross-protection against different allergens. Furthermore, glycan-specific anti-IgE autoantibodies were present in sera from subjects with allergy and subjects without allergy.

CONCLUSION

In conclusion, this study provided the first evidence that in the murine model, the serum level and anaphylactic activity of IgE may be downregulated by glycan-specific IgG anti-IgE autoantibodies.

Eosinophils regulate adipose tissue inflammation and sustain physical and immunological fitness in old age

Adipose tissue eosinophils (ATEs) are important in the control of obesity-associated inflammation and metabolic disease. However, the way in which ageing impacts the regulatory role of ATEs remains unknown. Here, we show that ATEs undergo major age-related changes in distribution and function associated with impaired adipose tissue homeostasis and systemic low-grade inflammation in both humans and mice. We find that exposure to a young systemic environment partially restores ATE distribution in aged parabionts and reduces adipose tissue inflammation. Approaches to restore ATE distribution using adoptive transfer of eosinophils from young mice into aged recipients proved sufficient to dampen age-related local and systemic low-grade inflammation. Importantly, restoration of a youthful systemic milieu by means of eosinophil transfers resulted in systemic rejuvenation of the aged host, manifesting in improved physical and immune fitness that was partially mediated by eosinophil-derived IL-4. Together, these findings support a critical function of adipose tissue as a source of pro-ageing factors and uncover a new role of eosinophils in promoting healthy ageing by sustaining adipose tissue homeostasis.

Vaccine against peanut allergy based on engineered virus-like particles displaying single major peanut allergens

BACKGROUND

Peanut allergy is a severe and increasingly frequent disease with high medical, psychosocial, and economic burden for affected patients and wider society. A causal, safe, and effective therapy is not yet available.

OBJECTIVE

We sought to develop an immunogenic, protective, and nonreactogenic vaccine candidate against peanut allergy based on virus-like particles (VLPs) coupled to single peanut allergens.

METHODS

To generate vaccine candidates, extracts of roasted peanut (Ara R) or the single allergens Ara h 1 or Ara h 2 were coupled to immunologically optimized Cucumber Mosaic Virus-derived VLPs (CuMVtt). BALB/c mice were sensitized intraperitoneally with peanut extract absorbed to alum. Immunotherapy consisted of a single subcutaneous injection of CuMVtt coupled to Ara R, Ara h 1, or Ara h 2.

RESULTS

The vaccines CuMVtt-Ara R, CuMVtt-Ara h 1, and CuMVtt-Ara h 2 protected peanut-sensitized mice against anaphylaxis after intravenous challenge with the whole peanut extract. Vaccines did not cause allergic reactions in sensitized mice. CuMVtt-Ara h 1 was able to induce specific IgG antibodies, diminished local reactions after skin prick tests, and reduced the infiltration of the gastrointestinal tract by eosinophils and mast cells after oral challenge with peanut. The ability of CuMVtt-Ara h 1 to protect against challenge with the whole extract was mediated by IgG, as shown via passive IgG transfer. FcγRIIb was required for protection, indicating that immune complexes with single allergens were able to block the allergic response against the whole extract, consisting of a complex allergen mixture.

CONCLUSIONS

Our data suggest that vaccination using single peanut allergens displayed on CuMVtt may represent a novel therapy against peanut allergy with a favorable safety profile.

A Single Monoclonal Antibody against the Peanut Allergen Ara h 2 Protects against Systemic and Local Peanut Allergy

BACKGROUND

Peanut allergy is the most prevalent and dangerous food allergy. Peanuts consist of a large number of different allergens and peanut-allergic patients are frequently sensitized to multiple allergens. Hence, conventional desensitization approaches aim at targeting as many allergens as possible.

METHODS

The monoclonal anti-Ara h 2 antibody (mAb) was produced by hybridoma cells derived from WT BALB/c mice after immunization with a vaccine based on virus-like particles coupled to Ara h 2. BALB/c mice were sensitized intraperitoneally with peanut extract absorbed to alum and mAbs were applied i.v. Challenge was performed the next day with the whole peanut extract intravenously and via skin prick test.

RESULTS

Here we show in peanut-allergic mice that a single high-affinity mAb specific for Ara h 2 is able to block systemic and local allergic reactions induced by the complex peanut extract. We confirm in vitro binding of the mAb to the inhibitory low-affinity FcγRIIb receptor using a sensitive biosensor and demonstrate in vivo that protection was dependent on FcγRIIb.

CONCLUSION

A single mAb specific for Ara h 2 is able to improve local and systemic allergic symptoms induced by the whole allergen mixture.

Ultrasound Based Planning and Navigation for Non-Anatomical Liver Resections – An Ex-Vivo Study

Goal: Non-anatomical resections of liver tumors can be very challenging as the surgeon cannot use anatomical landmarks on the liver surface or in the ultrasound image for guidance. This makes it difficult to achieve negative resection margins (R0) and still preserve as much healthy liver tissue as possible. Even though image-guided surgery systems have been introduced to overcome this challenge, they are still rarely used due to their inaccuracy, time-effort and complexity in usage and setup. Methods: We have developed a novel approach, which allows us to create an intra-operative resection plan using navigated ultrasound. First, the surface is scanned using a navigated ultrasound, followed by tumor segmentation on a midsection ultrasound image. Based on this information, the navigation system calculates an optimal resection strategy and displays it along with the tracked surgical instruments. In this study, this approach was evaluated by three experienced hepatobiliary surgeons on ex-vivo porcine models. Results: Using this technique, an R0 resection could be achieved in 22 out of 23 (95.7% R0 resection rate) cases with a median resection margin of 5.9 mm (IQR 3.5–7.7 mm). The resection margin between operators 1, 2 and 3 was 7.8 mm, 4.15 mm and 5.1 mm respectively (p = 0.054). Conclusions: This approach could represent a useful tool for intra-operative guidance in non-anatomical resection alongside conventional ultrasound guidance. However, instructions and training are essential especially if the operator has not used an image-guidance system before.

An unexpected protective role of low-affinity allergen-specific IgG through the inhibitory receptor FcγRIIb

BACKGROUND

Induction of allergen-specific IgG antibodies is a critical parameter for successful allergen-specific immunotherapy. IgG antibodies can inhibit IgE-mediated mast cell activation through direct allergen neutralization or through the inhibitory receptor FcγRIIb. The affinity of IgE antibodies to the allergen has been shown to be critical for cellular activation.

OBJECTIVE

Here we addressed the question of affinity thresholds of allergen-specific IgG antibodies for inhibition of mast cell activation using 2 different mAbs against the major cat allergen Fel d 1 both in vitro and in vivo in mice.

METHODS

Sequences of the 2 high-affinity mAbs were back-mutated to germline, resulting in low-affinity (10-7 mol/L) antibodies of the exact same specificity.

RESULTS

Using these newly generated recombinant antibodies, we demonstrate that low-affinity antibodies are still able to inhibit mast cell activation through FcγRIIb but do not neutralize the allergen.

CONCLUSION

Antibody affinity dictates the mechanism of mast cell inhibition, and IgG antibodies triggering the inhibitory FcγRIIb pathway can show a broader cross-reactivity pattern than previously thought. This indicates that allergen-specific immunotherapy generates a larger protective umbrella of inhibitory IgG antibodies than previously appreciated.

Allergens displayed on virus-like particles are highly immunogenic but fail to activate human mast cells

BACKGROUND

The goal of allergen-specific immunotherapy is the induction of protective immune responses in the absence of anaphylactic reactions. We have previously shown that Fel d 1, the major cat allergen, displayed in a repetitive fashion on virus-like particles (VLPs) may fulfill these criteria. Specifically, Fel d 1 on VLPs induced strongly increased protective IgG responses compared to free allergen in mice while anaphylactic reactions were essentially abolished. Here we extend these findings to human mast cells and offer a mechanistic explanation for the reduced anaphylactic activity.

METHODS

We differentiated human mast cells in vitro from blood-derived stem cell progenitors and sensitized the cells with a monoclonal Fel d 1-specific IgE. We compared the capability of Fel d 1 to induce mast cell activation in its free form versus displayed on VLPs and we performed allergen binding studies by surface plasmon resonance as well as flow cytometry.

RESULTS

We show that free Fel d 1 induces degranulation of IgE-sensitized mast cells whereas Fel d 1 displayed on VLPs fails to induce mast cell activation. We demonstrate that this inability to activate mast cells is based on a biophysical as well as a biochemical mechanism. Firstly, Fel d 1 on VLPs showed a strongly impaired ability to bind to surface-bound IgE. Secondly, despite residual binding, repetitively displayed allergen on VLPs failed to cause mast cell activation.

CONCLUSION

These findings indicate that repetitively displaying allergens on VLPs increases their immunogenicity while reducing their potential to cause anaphylactic reactions by essentially eliminating IgE-mediated activation of mast cells.

Treatment of refractory ascites with an automated low-flow ascites pump in patients with cirrhosis

BACKGROUND

Refractory ascites (RA) is a frequent complication of cirrhosis, requiring large volume paracentesis or placement of a transjugular intrahepatic portosystemic shunt (TIPSS). The automated low-flow ascites pump (alfapump, Sequana Medical AG, Zurich, Switzerland) is an innovative treatment option for patients with RA.

AIM

To assess safety and efficacy of this treatment in patients with a contraindication to TIPSS.

METHODS

Fifty-six patients (43 males; mean age 62 years) from centres in Germany, Switzerland, UK and Spain were included and followed for up to 24 months. Complications, device deficiencies, paracentesis frequency and patient survival were recorded.

RESULTS

At the time of this analysis, 3 patients completed the 24-month observation period, monitoring of 3 was ongoing, 9 underwent liver transplantation, 17 patients were withdrawn due to serious adverse events and 23 patients died. Most frequently observed technical complication was blocking of the peritoneal catheter. Twenty-three pump-related reinterventions (17 patients) and 12 pump exchanges (11 patients) were required during follow-up. The pump system was explanted in 48% of patients (in 17 patients due to serious adverse events, in 9 at the time of liver transplantation and in 1 due to recovery from RA). Median frequency of paracentesis dropped from 2.17 to 0.17 per month.

CONCLUSIONS

The alfapump can expand therapeutic options for cirrhotic patients with RA. Continuous drainage of ascites in a closed loop automated system led to significant reduction in paracentesis frequency. Technical and procedural improvements are required to reduce the rate of adverse events and reinterventions. https://clinicaltrials.gov/ct2/show/NCT01532427.

Automated low-flow ascites pump for the treatment of cirrhotic patients with refractory ascites

Cirrhotic patients with refractory ascites (RA) can be treated with repeated large volume paracentesis (LVP), with the insertion of a transjugular intrahepatic portosystemic shunt (TIPS) or with liver transplantation. However, side effects and complications of these therapeutic options, as well as organ shortage, warrant the development of novel treatments. The automated low-flow ascites pump (alfapump^®) is a subcutaneously-implanted novel battery-driven device that pumps ascitic fluid from the peritoneal cavity into the urinary bladder. Ascites can therefore be aspirated in a time- and volume-controlled mode and evacuated by urination. Here we review the currently available data about patient selection, efficacy and safety of the alfapump and provide recommendations for the management of patients treated with this new method.

Efficient and safe small-bowel adhesiolysis

Small-intestine adhesiolysis can be very time consuming and may be associated with bowel wall damage. The risk for injuries to the small or large bowel resulting in increased morbidity and costs is considerable. Both efficient and gentle dissection of adhesions is important in order to avoid intraoperative perforation or, worse, postoperative intestinal leaks. We present a technique using drops of body-warm isotonic saline solution to create an edematous swelling of the adhesions. This procedure not only protects the bowel from cooling and drying, but also simplifies the dissection and, thus, lowers the risk of intestinal lesions.

A selective COX-2 inhibitor suppresses chronic pancreatitis in an animal model (WBN/Kob rats): significant reduction of macrophage infiltration and fibrosis

INTRODUCTION

Therapeutic strategies to treat chronic pancreatitis (CP) are very limited. Other chronic inflammatory diseases can be successfully suppressed by selective cyclooxygenase 2 (COX-2) inhibitors. As COX-2 is elevated in CP, we attempted to inhibit COX-2 activity in an animal model of CP (WBN/Kob rat). We then analysed the effect of COX-2 inhibition on macrophages, important mediators of chronic inflammation.

METHODS

Male WBN/Kob rats were continuously fed the COX-2 inhibitor rofecoxib, starting at the age of seven weeks. Animals were sacrificed 2, 5, 9, 17, 29, 41, and 47 weeks later. In some animals, treatment was discontinued after 17 weeks, and animals were observed for another 24 weeks.

RESULTS

Compared with the spontaneous development of inflammatory injury and fibrosis in WBN/Kob control rats, animals treated with rofecoxib exhibited a significant reduction and delay (p<0.0001) in inflammation. Collagen and transforming growth factor beta synthesis were significantly reduced. Similarly, prostaglandin E(2) levels were markedly lower, indicating strong inhibition of COX-2 activity (p<0.003). If treatment was discontinued at 24 weeks of age, all parameters of inflammation strongly increased comparable with that in untreated rats. The correlation of initial infiltration with subsequent fibrosis led us to determine the effect of rofecoxib on macrophage migration. In chemotaxis experiments, macrophages became insensitive to the chemoattractant fMLP in the presence of rofecoxib.

CONCLUSION

In the WBN/Kob rat, chronic inflammatory changes and subsequent fibrosis can be inhibited by rofecoxib. Initial events include infiltration of macrophages. Cell culture experiments indicate that migration of macrophages is COX-2 dependent.