Rama Jayasundar1, Somenath Ghatak1, Ariachery Ammini2, Ashok Mukhopadhyaya3, and Arundhati Sharma4
1NMR, All India Institute of Medical Sciences, New Delhi, India, 2Endocrinology, All India Institute of Medical Sciences, New Delhi, India, 3Laboratory Medicine, All India Institute of Medical Sciences, New Delhi, India, 4Anatomy, All India Institute of Medical Sciences, New Delhi, India
Synopsis
The
world is entering an era of personalised medicine and phenotyping individuals
is gaining much attention. In this context, genetic basis of the comprehensive
phenotyping in ayurveda, the indigenous medicine of Indian subcontinent has
drawn much scientific interest. This study reports an innovative application of
MR in providing the much needed objective parameters for some of the
phenotyping indices. Interestingly, the results show that the phenotypes mentioned
in ayurveda as being predisposed to diabetes are found to not only have
increased localised fat deposition (abdomen and thigh) (measured by MRI) and
triglyceride levels but also lower insulin sensitivity.Main text
Purpose
With
increasing interest in predictive and personalised medicine, the concept of
phenotyping an individual is evoking much attention. In this context, genome-wide analysis have shown a genetic basis for phenotypes
mentioned in ayurveda, the indigenous medical system of Indian subcontinent1,
2. Seven major phenotypes (labeled V, P, K, VP, PK, KV and VPK) based on
a comprehensive set of physical, physiological and psychological parameters are
mentioned in ayurveda3. This study has used an innovative
combination of MRI for objective assessment of physical phenotyping indices and
biochemical parameters for physiological indices and correlated them with
ayurvedic phenotypes.
Methods
Phenotyping: Thirty four
healthy volunteers (18 males, 16 females; age: 20-35 yrs) were recruited for
the study. A validated questionnaire based on ayurvedic phenotyping indices was
used to assess separately the physical, physiological and psychological constitution
types for each volunteer. Ethical clearance was obtained from the Institute to
carry out these studies.
MR
studies:
MRI evaluation of subcutaneous fat (SF) in abdomen (SFAbd) and thigh
(SFThigh) were carried out at 1.5 T (Avanto, Siemens): TR of 650 ms,
TE of 11 ms, 256 x 256 matrix and 8 mm contiguous slices. T1-weighted (T1W)
transverse images were obtained from abdomen (breath hold sequences) (T9
vertebra to the superior surface of hip joint) and thigh (superior surface of
hip joint to the lower end of medial condyle) regions. Area of SF and fat mass were
calculated for the entire region studied. Proton MRS was carried out in liver for
assessing the lipid levels.
Bio-impedance Analyser (BIA): Tanita TBF-215
analyser (Japan) was used to assess Body Mass Index (BMI), Basal Metabolic Rate
(BMR) and % body fat.
Biochemical
factors:
Total Cholesterol (TChol), Serum Triglycerides (TG) and Insulin Sensitivity
(IS) were assessed using standard procedures4.
Human
Leukocyte Antigen
(HLA): PCR Sequence-Specific Oligonucleotide
Probes (SSOP) was carried out in a PCR amplifier (Bio-Rad, USA) for HLA typing.
Data analysis: Pearson's correlation analysis was
used for statistical evaluation. P < 0.05 was considered statistically
significant. The occurrence of HLA-DRB1 alleles with volunteers’ phenotypes is
presented as a frequency distribution analysis.
Results and Discussion
The volunteers
were phenotyped as follows: Physical - KV (9), PK (11) and VP (14);
Physiological - KV (11), PK (9) and VP (14); Psychological - KV (20), PK (7)
and VP (7). KV also includes KP, PK includes PV, and VP that of VK. Figure 1
shows the entire data as a radial graph. It can be seen that different
parameters correlate with different phenotypes.
Physical phenotyping
Physical
correlates:
SFAbd , SFThigh and % body fat were maximum (p < 0.02)
in K dominated phenotypes (KV and KP) followed by those in P and V. These
observations are in agreement with the ayurvedic understanding of K and V
dominated phenotypes as having contrasting fat distribution with P dominated as
an intermediate. According to ayurveda, K dominated phenotypes are associated
with presence of more fat (and predisposed to obesity and diabetes) as opposed
to V types, who have very less fat and predisposed to diseases like
osteoarthritis.
Biochemical
correlates: K dominated
phenotypes showed positive correlation with TG and TChol. This observation
parallels the MRI correlation for SF in the K phenotypes. HLA- Figure 2 shows frequency
distribution of HLA - DRB1 alleles in different phenotypes for all the 34
volunteers. It is interesting to observe that K dominated phenotypes showed an
increased presence of the following HLA alleles - DRB1*11 (KV - 67 % and KP -
50%), DRB1*04 (KP - 50%) and DRB1*07 (KP - 60%). On the other hand, HLA -DRB*09
allele was observed more in VP individuals. This reiterates the genetic basis
for the ayurvedic phenotyping1, 2.
Physiological phenotyping
SFAbd was
significantly high (p< 0.05) in K dominated phenotypes which is in agreement
with that observed in the physical phenotypes. Insulin sensitivity was also significantly
high (p < 0.05) in VK and VP types and low in K predominant phenotypes. This
is in line with known decreased insulin sensitivity in obesity. HLA-
HLA - DRB1*11 allele was seen in 50% of KV and KP, DRB1*07 in 60% of KV and
DRB1*09 in 60% VP phenotypes.
Conclusion
Considering that
information on phenotypes are used in ayurveda to identify risk groups for
conditions such as obesity and diabetes, this approach using MR and biochemical
parameters for objective evaluation of ayurvedic phenotyping is innovative and
could provide the much needed objective parameters for phenotyping. Further
studies are under way.
Acknowledgements
This project was
funded by Institute Research Grant, All India Institute of Medical Sciences,
New Delhi, India.References
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