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Digested wheat gluten inhibits binding between leptin and its receptor.

Jönsson T, Memon AA, Sundquist K, Sundquist J, Olsson S, Nalla A, Bauer M, Linse S - BMC Biochem. (2015)

Bottom Line: Non-degraded dietary wheat protein has been found in human serum at a mean level of 41 ng/mL.Heat-treated gluten digest did not inhibit leptin binding.Digested wheat gluten inhibits binding of leptin to the leptin receptor, with half-maximal inhibition at 10 ng/mL.

View Article: PubMed Central - PubMed

Affiliation: Center for Primary Health Care Research, Lund University/Region Skåne, Skåne University Hospital, Malmö, Sweden. Tommy.Jonsson@med.lu.se.

ABSTRACT

Background: Leptin resistance is considered a primary risk factor for obesity. It has been hypothesized that dietary cereal grain protein could cause leptin resistance by preventing leptin from binding to its receptor. Non-degraded dietary wheat protein has been found in human serum at a mean level of 41 ng/mL. Here, we report our findings from testing whether enzymatically digested gluten from wheat prevents leptin from binding to the leptin receptor in vitro. Gluten from wheat was digested with pepsin and trypsin under physiological conditions. Pepsin and trypsin activity was removed from the gluten digest with a 10 kDa spin-filter or by heat treatment at 100°C for 30 min. Binding to the leptin receptor of leptin mixed with gluten digest at a series of concentrations was measured using surface plasmon resonance technology.

Results: Binding of the gluten digest to the leptin receptor was not detected. Spin-filtered gluten digest inhibited binding of leptin to the leptin receptor, with 50% inhibition at a gluten digest concentration of ~10 ng/mL. Heat-treated gluten digest did not inhibit leptin binding.

Conclusions: Digested wheat gluten inhibits binding of leptin to the leptin receptor, with half-maximal inhibition at 10 ng/mL. The inhibition is significant at clinically relevant concentrations and could therefore serve as a novel pathway to investigate to understand the molecular basis of leptin resistance, obesity and associated disorders.

No MeSH data available.


Related in: MedlinePlus

SPR analysis of binding of leptin to the leptin receptor and its inhibition by the gluten digest.A) Examples of sensorgrams recorded during the injection of 30 nM leptin alone (black) or in the presence of 0.0022 (blue), 0.0045 (green), 0.018 (orange) or 0.3 (red) μg/mL gluten digest over a Sensor Chip with immobilized leptin receptor-Fc chimera. The pink dashed line is a fit to the black line using equation 2 (see Methods). B) Example of a sensorgram recorded during buffer flow after complete injection of 30 nM leptin (black). The pink dashed line is a fit to the data using equation 1 (see Methods). The two vertical lines occur during the extended time dissociation when the machine switches between its two pumps. C) Plot of relative intensity at the final leptin binding plateau during injection of 30 nM leptin versus gluten digest concentration. The error bars represent the standard deviation of three measurements.
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Fig1: SPR analysis of binding of leptin to the leptin receptor and its inhibition by the gluten digest.A) Examples of sensorgrams recorded during the injection of 30 nM leptin alone (black) or in the presence of 0.0022 (blue), 0.0045 (green), 0.018 (orange) or 0.3 (red) μg/mL gluten digest over a Sensor Chip with immobilized leptin receptor-Fc chimera. The pink dashed line is a fit to the black line using equation 2 (see Methods). B) Example of a sensorgram recorded during buffer flow after complete injection of 30 nM leptin (black). The pink dashed line is a fit to the data using equation 1 (see Methods). The two vertical lines occur during the extended time dissociation when the machine switches between its two pumps. C) Plot of relative intensity at the final leptin binding plateau during injection of 30 nM leptin versus gluten digest concentration. The error bars represent the standard deviation of three measurements.

Mentions: Attempts to monitor binding of gluten digest to the leptin receptor suffered from too low a signal-to-noise ratio and were therefore inconclusive. Instead, we studied binding to the leptin receptor of leptin alone and leptin mixed with gluten digest at a series of concentrations. Leptin alone was found to interact with the leptin receptor with high affinity (koff = 4.3.10-4 s-1, kon = 6.4.105 M-1 s-1, KD = 0.6 nM, Figure 1A,B), in line with earlier findings [21]. The heat-treated gluten digest did not inhibit binding of leptin to the leptin receptor. However, the spin-filtered gluten digest reduced binding of leptin to the leptin receptor in a concentration-dependent manner. Examples of SPR sensorgrams for a few concentrations of spin-filtered gluten digest are shown in Figure 1A, with the relative concentration of bound leptin at the plateau value shown for all concentrations in Figure 1C (see below). While experiments with non-purified proteolytic gluten digest would suffer from potential digestion of the receptor on the chip, we here evaluated two methods for protease inactivation/removal. While heat treatment followed by centrifugation seems to remove all protease activity (leptin bound with an undiminished signal during repeated injections), it also removed all leptin-inhibiting activity from the gluten digest. The use of molecular weight filters was successful and seems to remove all protease activity while leaving leptin-inhibiting activity intact in the remaining filtrate. The final leptin binding plateau value obtained in the absence or presence of the filtrated gluten digest is plotted versus the logarithm of the gluten digest concentration (Figure 1C). The gluten digest was found to dose-dependently inhibit binding of leptin to the leptin receptor. A sigmoidal curve was obtained, with half-maximal inhibition of leptin binding at a gluten digest concentration of ~10 ng/mL.Figure 1


Digested wheat gluten inhibits binding between leptin and its receptor.

Jönsson T, Memon AA, Sundquist K, Sundquist J, Olsson S, Nalla A, Bauer M, Linse S - BMC Biochem. (2015)

SPR analysis of binding of leptin to the leptin receptor and its inhibition by the gluten digest.A) Examples of sensorgrams recorded during the injection of 30 nM leptin alone (black) or in the presence of 0.0022 (blue), 0.0045 (green), 0.018 (orange) or 0.3 (red) μg/mL gluten digest over a Sensor Chip with immobilized leptin receptor-Fc chimera. The pink dashed line is a fit to the black line using equation 2 (see Methods). B) Example of a sensorgram recorded during buffer flow after complete injection of 30 nM leptin (black). The pink dashed line is a fit to the data using equation 1 (see Methods). The two vertical lines occur during the extended time dissociation when the machine switches between its two pumps. C) Plot of relative intensity at the final leptin binding plateau during injection of 30 nM leptin versus gluten digest concentration. The error bars represent the standard deviation of three measurements.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Fig1: SPR analysis of binding of leptin to the leptin receptor and its inhibition by the gluten digest.A) Examples of sensorgrams recorded during the injection of 30 nM leptin alone (black) or in the presence of 0.0022 (blue), 0.0045 (green), 0.018 (orange) or 0.3 (red) μg/mL gluten digest over a Sensor Chip with immobilized leptin receptor-Fc chimera. The pink dashed line is a fit to the black line using equation 2 (see Methods). B) Example of a sensorgram recorded during buffer flow after complete injection of 30 nM leptin (black). The pink dashed line is a fit to the data using equation 1 (see Methods). The two vertical lines occur during the extended time dissociation when the machine switches between its two pumps. C) Plot of relative intensity at the final leptin binding plateau during injection of 30 nM leptin versus gluten digest concentration. The error bars represent the standard deviation of three measurements.
Mentions: Attempts to monitor binding of gluten digest to the leptin receptor suffered from too low a signal-to-noise ratio and were therefore inconclusive. Instead, we studied binding to the leptin receptor of leptin alone and leptin mixed with gluten digest at a series of concentrations. Leptin alone was found to interact with the leptin receptor with high affinity (koff = 4.3.10-4 s-1, kon = 6.4.105 M-1 s-1, KD = 0.6 nM, Figure 1A,B), in line with earlier findings [21]. The heat-treated gluten digest did not inhibit binding of leptin to the leptin receptor. However, the spin-filtered gluten digest reduced binding of leptin to the leptin receptor in a concentration-dependent manner. Examples of SPR sensorgrams for a few concentrations of spin-filtered gluten digest are shown in Figure 1A, with the relative concentration of bound leptin at the plateau value shown for all concentrations in Figure 1C (see below). While experiments with non-purified proteolytic gluten digest would suffer from potential digestion of the receptor on the chip, we here evaluated two methods for protease inactivation/removal. While heat treatment followed by centrifugation seems to remove all protease activity (leptin bound with an undiminished signal during repeated injections), it also removed all leptin-inhibiting activity from the gluten digest. The use of molecular weight filters was successful and seems to remove all protease activity while leaving leptin-inhibiting activity intact in the remaining filtrate. The final leptin binding plateau value obtained in the absence or presence of the filtrated gluten digest is plotted versus the logarithm of the gluten digest concentration (Figure 1C). The gluten digest was found to dose-dependently inhibit binding of leptin to the leptin receptor. A sigmoidal curve was obtained, with half-maximal inhibition of leptin binding at a gluten digest concentration of ~10 ng/mL.Figure 1

Bottom Line: Non-degraded dietary wheat protein has been found in human serum at a mean level of 41 ng/mL.Heat-treated gluten digest did not inhibit leptin binding.Digested wheat gluten inhibits binding of leptin to the leptin receptor, with half-maximal inhibition at 10 ng/mL.

View Article: PubMed Central - PubMed

Affiliation: Center for Primary Health Care Research, Lund University/Region Skåne, Skåne University Hospital, Malmö, Sweden. Tommy.Jonsson@med.lu.se.

ABSTRACT

Background: Leptin resistance is considered a primary risk factor for obesity. It has been hypothesized that dietary cereal grain protein could cause leptin resistance by preventing leptin from binding to its receptor. Non-degraded dietary wheat protein has been found in human serum at a mean level of 41 ng/mL. Here, we report our findings from testing whether enzymatically digested gluten from wheat prevents leptin from binding to the leptin receptor in vitro. Gluten from wheat was digested with pepsin and trypsin under physiological conditions. Pepsin and trypsin activity was removed from the gluten digest with a 10 kDa spin-filter or by heat treatment at 100°C for 30 min. Binding to the leptin receptor of leptin mixed with gluten digest at a series of concentrations was measured using surface plasmon resonance technology.

Results: Binding of the gluten digest to the leptin receptor was not detected. Spin-filtered gluten digest inhibited binding of leptin to the leptin receptor, with 50% inhibition at a gluten digest concentration of ~10 ng/mL. Heat-treated gluten digest did not inhibit leptin binding.

Conclusions: Digested wheat gluten inhibits binding of leptin to the leptin receptor, with half-maximal inhibition at 10 ng/mL. The inhibition is significant at clinically relevant concentrations and could therefore serve as a novel pathway to investigate to understand the molecular basis of leptin resistance, obesity and associated disorders.

No MeSH data available.


Related in: MedlinePlus