Endocrine cells in the upper gastrointestinal tract in relation to gastrointestinal dysfunction in patients with familial amyloidotic polyneuropathy

Metabolomics analysis for diagnosis and biomarker discovery of transthyretin amyloidosis

Untargeted metabolomics is a well-established technique and a powerful tool to find potential plasma biomarkers for early diagnosing hereditary transthyretin amyloidosis. Hereditary transthyretin amyloidosis (ATTRv) is a disabling and fatal disease with different clinical features such as polyneuropathy, cardiomyopathy, different gastrointestinal symptoms and renal failure. Plasma specimens collected from 27 patients with ATTRv (ATTRV30M), 26 asymptomatic TTRV30M carriers and 26 control individuals were subjected to gas chromatography (GC)- and liquid chromatography (LC)-mass spectrometry (MS)-based metabolomics analysis. Partial least squares discriminant and univariate analysis was used to analyse the data. The models constructed by Partial least squares-discriminant analysis (PLS-DA) could clearly discriminate ATTRV30M patients from controls and asymptomatic TTRV30M carriers. In total, 24 plasma metabolites (VIP > 1.0 and p < .05) were significantly altered in ATTRV30M patient group (6 increased and 18 decreased). Eleven of these distinguished the ATTRV30M group from both controls and TTRV30M carriers. Plasma metabolomics analysis revealed marked changes in several pathways in patients with ATTRV30M amyloidosis. Statistical analysis identified a panel of biomarkers that could effectively separate controls/TTRV30M carriers from ATTRV30M patients. These biomarkers can potentially be used to diagnose patients at an early stage of the disease.

Abnormal small bowel motility in patients with hereditary transthyretin amyloidosis

BACKGROUND

Gastrointestinal complications are common in hereditary transthyretin amyloid (ATTRm) amyloidosis. The underlying mechanisms have not been fully elucidated, and the patients' small bowel function remains largely unexplored. The aim of the present study was to compare the small bowel motility in ATTRm amyloidosis patients with that in non-amyloidosis patient controls.

METHODS

ATTRm amyloidosis patients undergoing evaluation for liver transplantation were consecutively investigated with 24-hour duodenojejunal manometry (n = 19). The somatostatin analogue octreotide was used to induce fasting motility. Patients with age at onset of ≥50 years were defined as late-onset cases. For each patient, three age- and sex-matched patient controls (n = 57) were selected from the total pool of investigated patients.

KEY RESULTS

Manometry was judged as abnormal in 58% of the patients and in 26% of the patient controls (P = .01). Patients displayed significantly more daytime phase III migrating motor complexes than patient controls (median 4 vs 2, P < .01), and had a higher frequency of low-amplitude complexes (16% vs 4%; however, this difference did not reach statistical significance, P = .10). Furthermore, late-onset patients showed a delay in octreotide response (5.4 vs 3.8 minutes, P < .01), but this was not observed for early-onset patients or within the control group.

CONCLUSIONS AND INFERENCES

Patients with ATTRm amyloidosis displayed abnormalities in their small bowel motility more frequently than non-amyloidosis patient controls, and the manometric pattern was probably best consistent with a combined neuromyopathic disorder. The delayed octreotide response in late-onset patients warrants further investigation.

Somatostatin analogues for refractory diarrhoea in familial amyloid polyneuropathy

INTRODUCTION

Familial amyloid polyneuropathy (FAP) is a genetic disease leading to the production of a variant transthyretin (TTR) or a beta variant β2-microglobulin. FAP may be associated with refractory diarrhoea. In this study, we assessed the efficacy and tolerance of somatostatin analogues in refractory diarrhoea associated with FAP.

METHODS

FAP patients from the French national referral center who received somatostatin analogues for a refractory diarrhoea were retrospectively studied. We assessed remission of diarrhoea, as defined by a stool consistence of five or less on the Bristol stool scale, assessed after three to six months of follow-up. Stool frequency and continence before and after three to six months of treatment were also compared by the means of Wilcoxon and McNemar's exact tests, respectively.

RESULTS

Fourteen patients treated with somatostatin analogues were evaluable. After three to six months of follow-up, 9/14 patients (64% 95%CI = [35%; 87%]) had remission of diarrhoea. This was significantly higher than a theoretical remission rate of 20% (p = 0.0004). There was a significant decrease of daily bowel movement from 6 to 2.5 per day (p = 0.002). Twelve/14 (85%) patients had incontinence at baseline vs 8/14 (57%) after three to six months of follow-up (p = 0.134). Three out of 14 patients (21%) had a severe adverse event; two patients had hypoglycaemia, and one had endocarditis due to an injection-site bacterial infection.

CONCLUSION

This study suggests that somatostatin analogues may benefit to patients with FAP and refractory diarrhoea. Approximately 20% of patients had severe adverse events, including hypoglycaemia.

Post hoc analysis of nutritional status in patients with transthyretin familial amyloid polyneuropathy: impact of tafamidis

INTRODUCTION

Gastrointestinal symptoms are common among patients with transthyretin familial amyloid polyneuropathy (TTR-FAP). This post hoc analysis evaluated the nutritional status of TTR-FAP patients treated with tafamidis while enrolled in clinical trials.

METHODS

Nutritional status was measured by the modified body mass index (mBMI = BMI × albumin level). Treatment-related changes in mBMI were reported for 71 Val30Met TTR-FAP patients who completed an 18-month, randomized, double-blind, placebo-controlled trial and who continued into its open-label, 12-month extension.

RESULTS

At month 18, mBMI worsened in the placebo group (n = 33) (-33 ± 16 kg/m(2) g/l, P = 0.04 versus baseline) but improved in the tafamidis group (n = 38) (+37 ± 14 kg/m(2) g/l, P = 0.01 versus baseline) such that the effect size between the groups was statistically significant (P = 0.001). By month 30 (completion of the open-label extension), placebo patients with 12 months of tafamidis treatment and tafamidis-treated patients with 30 months of treatment both tended to increase their mBMI (28 ± 19 kg/m(2) g/l and 16 ± 18 kg/m(2) g/l, respectively). Increase in BMI was most pronounced in patients with low BMI at entry into the studies.

CONCLUSIONS

mBMI is well suited to monitor disease progression in TTR-FAP patients. The delay in neurological deterioration brought about by tafamidis treatment in clinical trials is associated with improvements in, or maintenance of, mBMI.

FUNDING

This study was sponsored by Pfizer Inc., New York, USA.

THAOS: gastrointestinal manifestations of transthyretin amyloidosis - common complications of a rare disease

Background

Transthyretin amyloidosis is a systemic disorder caused by amyloid deposits formed by misfolded transthyretin monomers. Two main forms exist: hereditary and wild-type transthyretin amyloidosis, the former associated with transthyretin gene mutations. There are several disease manifestations; however, gastrointestinal complications are common in the hereditary form. The aim of this study was to explore the prevalence and distribution of gastrointestinal manifestations in transthyretin amyloidosis and to evaluate their impact on the patients’ nutritional status and health-related quality of life (HRQoL).

Methods

The Transthyretin Amyloidosis Outcomes Survey (THAOS) is the first global, multicenter, longitudinal, observational survey that collects data on patients with transthyretin amyloidosis and the registry is sponsored by Pfizer Inc. This study presents baseline data from patients enrolled in THAOS as of June 2013. The modified body mass index (mBMI), in which BMI is multiplied with serum albumin, was used to assess the nutritional status and the EQ-5D Index was used to assess HRQoL.

Results

Data from 1579 patients with hereditary transthyretin amyloidosis and 160 patients with wild-type transthyretin amyloidosis were analyzed. Sixty-three percent of those with the hereditary form and 15% of those with the wild-type form reported gastrointestinal symptoms at enrollment. Unintentional weight loss and early satiety were the most frequent symptoms, reported by 32% and 26% of those with transthyretin gene mutations, respectively. Early-onset patients (<50 years) reported gastrointestinal complaints more frequently than those with a late onset (p < 0.001) and gastrointestinal symptoms were more common in patients with the V30M mutation than in those with other mutations (p < 0.001). For patients with predominantly cardiac complications, the prevalence of gastrointestinal manifestations was not evidently higher than that expected in the general population. Both upper and lower gastrointestinal symptoms were significant negative predictors of mBMI and the EQ-5D Index Score (p < 0.001 for all).

Conclusions

Gastrointestinal symptoms were common in patients with hereditary transthyretin amyloidosis and had a significant negative impact on their nutritional status and HRQoL. However, patients with wild-type transthyretin amyloidosis or transthyretin mutations associated with predominantly cardiac complications did not show an increased prevalence of gastrointestinal disturbances.

Loss of gastric interstitial cells of Cajal in patients with hereditary transthyretin amyloidosis

BACKGROUND

Hereditary transthyretin (TTR) amyloidosis is a systemic neuropathic disorder caused by TTR gene mutations. Gastrointestinal complications are common and the underlying mechanisms remain unclear. The interstitial cells of Cajal (ICC) function as pacemaker cells in the gastrointestinal tract and are important for gastrointestinal motility. The aim of this study was to investigate the densities of gastric ICC and nerves in patients with TTR amyloidosis compared to non-amyloidosis controls.

METHODS

Antral wall autopsy specimens from 11 Japanese ATTR V30M patients and 10 controls were analyzed with immunohistochemistry and computerized analysis. Antibodies to c-Kit and TMEM16A were used to assess ICC and an antibody to PGP 9.5 was used to assess nervous tissue. The study was approved by a Japanese ethical committee.

RESULTS

The densities of c-Kit-immunoreactive (IR) ICC were significantly lower in the circular and longitudinal muscle layers of patients compared to controls (p = 0.004 for both). Equivalent results were found for TMEM16A-IR ICC. There were no significant differences in PGP 9.5-IR cells in the circular or longitudinal muscle layers between patients and controls (p = 0.173 and 0.099, respectively).

CONCLUSIONS

A loss of gastrointestinal ICC may be an important factor for the digestive disturbances in hereditary TTR amyloidosis.

Gastric emptying in hereditary transthyretin amyloidosis: the impact of autonomic neuropathy

BACKGROUND

Gastrointestinal (GI) complications are common in hereditary transthyretin amyloidosis and an autonomic dysfunction has been considered to explain these symptoms. The aim of this study was to investigate the impact of autonomic neuropathy on gastric emptying in hereditary transthyretin amyloidosis and to relate these findings to nutritional status, GI symptoms, gender, and age at disease onset.

METHODS

Gastric emptying was evaluated with gastric emptying scintigraphy. Spectral analysis of the heart rate variability and cardiovascular responses after tilt test were used to assess the autonomic function. The nutritional status was evaluated with the modified body mass index (s-albumine × BMI).

KEY RESULTS

Gastric retention was found in about one-third of the patients. A weak correlation was found between the scintigraphic gastric emptying rate and both the sympathetic (rs = -0.397, P < 0.001) and parasympathetic function (rs = -0.282, P = 0.002). The gastric emptying rate was slower in those with lower or both upper and lower GI symptoms compared with those without symptoms (median T(50) 123 vs 113 min, P = 0.042 and 192 vs 113 min, P = 0.003, respectively). Multiple logistic regression analysis showed that age of onset (OR 0.10, CI 0.02-0.52) and sympathetic dysfunction (OR 0.23, CI 0.10-0.51), but not gender (OR 0.76, CI 0.31-1.84) and parasympathetic dysfunction (OR 1.81, CI 0.72-4.56), contributed to gastric retention.

CONCLUSIONS AND INFERENCES

Gastric retention is common in hereditary transthyretin amyloidosis early after onset. Autonomic neuropathy only weakly correlates with gastric retention and therefore additional factors must be involved.

Amyloidosis

The term amyloid describes the deposition in the extracellular space of certain proteins in a highly characteristic, insoluble fibrillar form. Amyloidosis describes the various clinical syndromes that occur as a result of damage by amyloid deposits in tissues and organs throughout the body. The clinical significance of amyloid varies enormously, ranging from incidental asymptomatic deposits to localized disease through to rapidly fatal systemic forms that can affect multiple vital organs. Currently available therapy is focused on reducing the supply of the respective amyloid fibril precursor protein and supportive medical care, which together have greatly improved survival. Chemotherapy and anti-inflammatory treatment for the disorders that underlie AL and AA amyloidosis are guided by serial measurements of the respective circulating amyloid precursor proteins, i.e. serial serum free light chains in AL and serum amyloid A protein in AA type. Quality of life and prognosis of some forms of hereditary systemic amyloidosis can be improved by liver and other organ transplants. Various new therapies, ranging from silencing RNA, protein stabilizers to monoclonal antibodies, aimed at inhibiting fibril precursor supply, fibril formation or the persistence of amyloid deposits, are in development; some are already in clinical phase.

Distributions of the endocrine cells in the gastrointestinal tract of nectarivorous and sanguivorous bats: a comparative immunocytochemical study

The present study was conducted to clarify the influence of feeding habits on regional distribution and relative frequency of endocrine cells secreting cholecystokinin (CCK), gastrin (GAS), serotonin (5-HT) and enteroglucagon (GLUC) in the nectarivorous Anoura geoffroyi and Glossophaga soricina and the sanguivorous Desmodus rotundus bats of the Phyllostomidae family, by specific immunohistochemical methods. The regional distribution and frequency of the different types of endocrine cells varied according to their location in the GIT. 5-HT immunoreactive cells (IR), detected throughout the GIT of three bats, were the most predominant gastrointestinal endocrine cells. GAS-IR cells in A. geoffroyi were found at the base of the pyloric gland, while in G. soricina they could also be observed in the middle to basal portions of the gland. GLUC-IR cells were located in the fundic region of A. geoffroyi, G. soricina and D. rotundus. These endocrine cells were more abundant in the sanguivorous bat. In nectarivorous bats were compared to sanguivorous bat, which differ in dietary habits, difference in the distribution and relative frequency of gut endocrine cells would be predicted. The absence of some, and decrease in frequency of other, gastrointestinal endocrine cells may reflect, in part, its interspecies differences or dietary habits.

Liver transplantation in transthyretin-related familial amyloid polyneuropathy

PURPOSE OF REVIEW

Familial amyloid polyneuropathy (FAP) associated with mutations in the gene for transthyretin is a rare, progressively disabling and ultimately fatal inherited disease. Transthyretin is produced predominantly in the liver, and orthotopic liver transplantation (OLT) eliminates more than 95% of variant amyloidogenic transthyretin from the circulation. Liver transplantation remains the only potentially curative treatment in this disorder, but many recent studies have suggested that outcome following transplantation may be poorer than previously considered in some groups of FAP patients.

RECENT FINDINGS

We review here the available data on the use and clinical outcome of OLT in patients with FAP, and consider the significance of particular mutations and cardiac amyloid involvement. The practice of combined organ transplants and domino liver transplantation is also reviewed.

SUMMARY

Published data generally support OLT as a treatment for FAP, particularly in younger patients with the most prevalent transthyretin (TTR) Met30 variant, who have mild symptoms. Although excellent outcomes have been reported, including improvement in autonomic and to a lesser extent peripheral nerve function coupled with regression of visceral amyloid deposits, the results of OLT are influenced by many factors that include properties of particular transthyretin variants, nutritional status, age, severity of neuropathy and cardiac amyloid involvement. Paradoxical acceleration of transthyretin amyloid deposition following OLT may occur in the heart and certain other sites in some patients. The combination of kidney or heart transplantation with OLT may occasionally be appropriate. The long-term outcome of patients with FAP who have undergone OLT, and recipients of FAP domino liver transplants, remain to be determined.

Hereditary transthyretin amyloidosis from a Scandinavian perspective

Hereditary transthyretin (TTR) amyloidosis is a rare often fatal form of systemic amyloidosis, that until recently was considered intractable, with the patients dying from the disease 5-15 years after onset. The phenotype of the disease varies according to the type of mutation, but generally the heart and/or the nervous system is affected. Liver and in some cases heart transplantation has now been shown to stop the progress of the disease, but the outcome depends on the patients' status at the time of operation, as no substantial improvement of the patients' symptoms has been noted after the procedure. Thus an early diagnosis is of importance for the outcome. In the following, we summarize our knowledge of the amyloidogenic TTR mutations found in the Scandinavian countries, their symptoms, how to settle the diagnosis and the outcome of transplantation. Besides, the problems arising from our capability to genetically test asymptomatic members of affected families for the trait will be discussed.

Liver transplantation restores endocrine cells in patients with familial amyloidotic polyneuropathy

BACKGROUND

The aim of this study was to investigate familial amyloidotic polyneuropathy, Portuguese type patients' endocrine cell content in the stomach and duodenum before and after liver transplantation, and to relate the findings to the patients' gastrointestinal disturbances.

METHODS

Ten liver-transplanted familial amyloidotic polyneuropathy, Portuguese type patients and 10 healthy controls were seen. Endocrine cells were identified by immunohistochemistry and quantified with computerized image analysis. The activity of the cells was appraised by measurements of the cell secretory index and nuclear area. Clinical symptoms were obtained from the patients' medical records.

RESULTS

After transplantation, a significant increase of several endocrine cell types were noted, and the pretransplant depletion of several types of endocrine cells disappeared. For no type of endocrine cell was any difference compared with controls noted after transplantation. There was no significant decrease of the amount of amyloid in the biopsies after liver transplantation. The patients' symptoms remained generally unchanged after transplantation, although a substantial time lapse between pretransplant evaluation and transplantation was present.

CONCLUSIONS

Liver transplantation restores the endocrine cells in the upper part of the gastrointestinal tract. The restoration was not correlated with an improvement of the patients' symptoms. No decrease of the amyloid deposits was noted.