Autoantibodies production and immunological abnormalities after bariatric surgery

Immunometabolic Changes Following Gastric Bypass and Sleeve Gastrectomy: A Comparative Study

BACKGROUND

Immunometabolism is the interaction between immune system and nutrient metabolism. Severe obesity is considered a state of meta-inflammation associated with obesity that influences the development of chronic-degenerative diseases.

OBJECTIVE

We aimed to establish the immunometabolic differences in bariatric patients and to determine whether cellular immunity is associated with metabolic changes.

METHODOLOGY

We conducted an observational study in patients who underwent laparoscopic sleeve gastrectomy (LSG) or laparoscopic Roux-en-Y gastric bypass (LRYGB). We explored the differences in the immunometabolic profile before and after surgery in the study group, by surgical technique, and we evaluated the changes in immunological variables as a function of metabolic variables with correlation analysis.

RESULTS

The follow-up rate was 88.7%. After the intervention, there were changes in cellular immunity, with a decrease in effector T lymphocytes (CD8+CD28-) and an increase in B lymphocytes, memory helper T cells, and cytotoxic T lymphocytes. LSG resulted in a greater decrease in (CD4+CD62-) T lymphocytes compared with LRYGB. Patients who underwent surgery with LRYGB presented greater clinical and metabolic improvements, as well as improvement of obesity-associated medical problems. Women who underwent LRYGB showed a greater reduction in fat-free mass compared with women who underwent LSG.

CONCLUSION

Bariatric surgery, mainly LRYGB, leads to immunometabolic changes and improves associated medical problems.

Impact of RYGB surgery on plasma immunoglobulins: association between blood pressure and glucose levels six months after surgery

We aimed to study levels of natural antibodies in plasma, and their associations to clinical and fecal biomarkers, before and 6 months after Roux-en-Y gastric bypass (RYGB) surgery. Thirty individuals with obesity [16 type 2 diabetic, 14 non-diabetic (ND)] had RYGB surgery. Total plasma IgA, IgG and IgM antibody levels and specific antibodies to oxidized low-density lipoprotein (oxLDL), malondialdehyde-acetaldehyde adducts, Porphyromonas gingivalis gingipain A hemagglutinin domain (Rgp44), and phosphocholine were measured using chemiluminescence immunoassay. Associations between plasma and fecal antibodies as well as clinical markers were analyzed. RYGB surgery reduced blood pressure, and the glycemic state was improved. A higher level of diastolic blood pressure was associated with lower plasma antibodies to oxLDL after surgery. Also, lower level of glucose markers associated with lower level of plasma antibodies to bacterial virulence factors. Antibodies to oxLDL decreased after surgery, and positive association between active serum lipopolysaccharide and specific oxLDL antibodies was detected. Total IgG levels decreased after surgery, but only in ND individuals. Reduced level of total plasma IgG, improved state of hypertension and hyperglycemia and their associations with decreased levels of specific antibodies in plasma, suggest an improved state of systemic inflammation after RYGB surgery.

Distinct B cell profiles characterise healthy weight and obesity pre- and post-bariatric surgery

BACKGROUND/OBJECTIVES

Obesity-associated metabolic dysfunction and inflammation can be ameliorated by bariatric surgery. While obesity is also linked to impaired B cell activation, differentiation, and persistence in response to infection and vaccination little is known about post-operative immune B cell compartment and to what extent dysregulation in B cell pathways can be reversed. To bridge this gap in knowledge, we carried out in-depth evaluation of B cell composition in individuals with obesity prior to and following bariatric surgery compared to lean controls.

SUBJECTS/METHODS

We recruited individuals with obesity (BMI at least 35 kg/m2) before bariatric surgery (n = 21) and followed them up 6 months post-operatively (n = 17). As controls we recruited age- and sex-matched lean (BMI < 25) individuals (n = 18). We carried out comprehensive immunophenotyping of peripheral blood B cells as well as interrogated their association with inflammatory and metabolic parameters.

RESULTS

In obesity the balance of antigen-inexperienced and memory B cells in the peripheral blood is altered, with an expansion of naïve and a reduction in total memory B cells. 6 months following bariatric surgery this balance is restored. However, post-operative patients are uniquely characterised by an increase in B cell subsets associated with chronic inflammation - CD11c+CXCR5-IgD-CD27- double negative 2 (DN2) B cells and CD27+CD38++ plasmablasts. Correlations between B cells subsets, inflammatory and metabolic parameters were distinct in lean people and individuals with obesity pre- and post-bariatric surgery.

CONCLUSIONS

Bariatric surgery patients display a unique B cell profile 6 months post-operatively; this bears minimal resemblance to that of pre-operative patients and only partially overlaps with that of lean controls. Post-operative differences in the B cell compartment compared to lean controls are detected despite global amelioration of inflammation and restoration of metabolic health. Collectively, this indicates that bariatric surgery creates a specific immunometabolic state with potential implications for health outcomes.

Can Bariatric Surgery Help to Prevent Autoimmunity?

BACKGROUND

Obesity has been linked to the development and progression of autoimmune diseases.

AIM

To investigate the presence of autoantibodies in the sera of bariatric-surgery patients.

METHODS

During the pre- and postoperative period, sera from 79 patients undergoing bariatric surgery were tested for the presence of antinuclear antibodies (ANA), Rheumatoid Factor (RF), IgG and IgM anticardiolipin antibodies, and anti-endomysial antibodies. Anti-dsDNA and ENA profiles were also determined in positive ANA sera. A chart review was used to obtain clinical, epidemiological, and anthropometric data.

RESULTS

Preoperatively, 23/79 (29.1%) of the sera tested positive for ANA; postoperatively, this frequency decreased to 8/79 (10.1%) with p = 0.002 (OR = 3.6; 95%; CI = 1.4-8.3). The fine-speckled ANA pattern was the most common (73.9% preoperative and 87.3% postoperative). Preoperative ANA-positive and negative patients did not differ in epidemiological or anthropometric measurements (all p >0.05), but ANA-positive patients had lower serum vitamin D levels than the negatives (p = 0.002). RF positivity was found in 5/76 (6.5%) of preoperative sera and 3/76 (3.9%) of postoperative sera, with p = 0.71. Anti-ds-DNA, ENA profile, and anti-endomysial antibodies were all negative in all patients, both before and after surgery; anticardiolipin IgM was weakly positive in one postoperative sample.

CONCLUSION

Positive ANA is common in obese patients undergoing bariatric surgery, and it decreases after weight loss.

Autoimmunity and hernia mesh: fact or fiction?

BACKGROUND

There is an increasing number of patients following hernia surgery with implanted mesh reporting symptoms that could indicate autoimmune or allergic reactions to mesh. 'Allergy' to metals, various drugs, and chemicals is well recognised. However, hypersensitivity, allergy or autoimmunity caused by surgical mesh has not been proven by a scientific method to date. The aim of this study was twofold: to describe the pathophysiology of autoimmunity and foreign body reaction and to undertake a systematic review of surgical mesh implanted at the time of hernia repair and the subsequent development of autoimmune disease.

METHODS

A systematic review using the PRISMA guidelines was undertaken. Pubmed (Medline), Google Scholar and Cochrane databases were searched for all English-written peer-reviewed articles published between 2000 and 2021. The search was performed using the keywords "hernia", "mesh", "autoimmunity", "ASIA", "immune response", "autoimmune response".

RESULTS

Seven papers were included in the final analysis-three systematic reviews, three cohort studies and one case report. Much of the current data regarding the association of hernia mesh and autoimmunity relies on retrospective cohort studies and/or case reports with limited availability of cofounding factor data linked to autoimmune disease such as smoking status or indeed a detailed medical history of patients. Three systematic reviews have discussed this topic, each with a slightly different approach and none of them has identified causality between the use of mesh and the subsequent development of autoimmune disease.

CONCLUSION

There is little evidence that the use of polypropylene mesh can lead to autoimmunity. A large number of potential triggers of autoimmunity along with the genetic predisposition to autoimmune disease and the commonality of hernia, make a cause and effect difficult to unravel at present. Biomaterials cause foreign body reactions, but a chronic foreign body reaction does not indicate autoimmunity, a common misunderstanding in the literature.

Total fecal IgA levels increase and natural IgM antibodies decrease after gastric bypass surgery

Obesity is associated with low-grade inflammation and increased systemic oxidative stress. Roux-en-Y gastric bypass (RYGB) surgery is known to ameliorate the obesity-induced metabolic dysfunctions. We aimed to study the levels of natural antibodies in feces, before and 6 months after RYGB surgery in obese individuals with and without type 2 diabetes (T2D). Sixteen individuals with T2D and 14 non-diabetic (ND) individuals were operated. Total IgA, IgG and IgM antibody levels and specific antibodies to oxidized low-density lipoprotein (oxLDL), malondialdehyde-acetaldehyde adducts (MAA adducts), Porphyromonas gingivalis gingipain A hemagglutinin domain (Rgp44) and phosphocholine (PCho) were measured using chemiluminescence immunoassay. Total fecal IgA was elevated, while total IgM and IgG were not affected by the surgery. Fecal natural IgM specific to oxLDL decreased significantly in both T2D and ND individuals, while fecal IgM to Rgp44 and PCho decreased significantly in T2D individuals. A decrease in IgG to MAA-LDL, Rgp44 and PCho was detected. RYGB surgery increases the levels of total fecal IgA and decreases fecal natural IgG and IgM antibodies specific to oxLDL. Natural antibodies and IgA are important in maintaining the normal gut homeostasis and first-line defense against microbes, and their production is markedly altered with RYGB surgery.

Selenium Deficiency Due to Diet, Pregnancy, Severe Illness, or COVID-19-A Preventable Trigger for Autoimmune Disease

The trace element selenium (Se) is an essential part of the human diet; moreover, increased health risks have been observed with Se deficiency. A sufficiently high Se status is a prerequisite for adequate immune response, and preventable endemic diseases are known from areas with Se deficiency. Biomarkers of Se status decline strongly in pregnancy, severe illness, or COVID-19, reaching critically low concentrations. Notably, these conditions are associated with an increased risk for autoimmune disease (AID). Positive effects on the immune system are observed with Se supplementation in pregnancy, autoimmune thyroid disease, and recovery from severe illness. However, some studies reported null results; the database is small, and randomized trials are sparse. The current need for research on the link between AID and Se deficiency is particularly obvious for rheumatoid arthritis and type 1 diabetes mellitus. Despite these gaps in knowledge, it seems timely to realize that severe Se deficiency may trigger AID in susceptible subjects. Improved dietary choices or supplemental Se are efficient ways to avoid severe Se deficiency, thereby decreasing AID risk and improving disease course. A personalized approach is needed in clinics and during therapy, while population-wide measures should be considered for areas with habitual low Se intake. Finland has been adding Se to its food chain for more than 35 years-a wise and commendable decision, according to today's knowledge. It is unfortunate that the health risks of Se deficiency are often neglected, while possible side effects of Se supplementation are exaggerated, leading to disregard for this safe and promising preventive and adjuvant treatment options. This is especially true in the follow-up situations of pregnancy, severe illness, or COVID-19, where massive Se deficiencies have developed and are associated with AID risk, long-lasting health impairments, and slow recovery.