Instrumental variables for lipidomes and VHFs
After stringent correlation filtering (p < 5×10− 8) and clumping (R2 = 0.001, window size = 10,000 kb),a total of 4427 instrumental variables were extracted from the GWAS of 179 lipidomes for viral hemorrhagic fever (Supplementary Table 1).
For reverse MR analysis, SNP selection for VHFs was based on p < 5×10− 8 and clumping (R2 = 0.001, window size = 10,000 kb).For VHFs,17 IVs were selected for Sterol ester (27:1/20:5) levels, Phosphatidylcholine (16:0_20:4) levels, and Phosphatidylcholine (O-18:0_20:4) levels (Supplementary Table 2).In our study, the F-statistic for IVs is greater than 10,indicating a low likelihood of bias from weak instrumental variables.
Results of the MR analysis
We used four MR methods to analyze the causal relationship between 179 lipidomes and VHFs. We identified potential causal relationships between 7 lipidomes and VHFs (Fig. 2).With IVW as the primary method and the other three methods as supplements, we cross-validated the potential causal relationships between 7 lipidomes and VHFs, ultimately confirming 3 lipidomes associated with VHFs (Fig. 3).We primarily focus on these 3 relatively robust causal relationships.
We also conducted Leave-one-out analysis on the identified significant lipidomes, further validating the robustness of our results(Fig. 4).In the absence of heterogeneity, horizontal pleiotropy, and outliers, the results of the MR analysis are reliable.
Red Lines Represent Estimations from the IVW Test.A.MR Leave-one-out sensitivity analysis for Sterol ester (27:1/20:5) levels on Viral haemorrhagic fevers,B.MR Leave-one-out sensitivity analysis for Phosphatidylcholine (16:0_20:4) on Viral haemorrhagic fevers,C.MR Leave-one-out sensitivity analysis for Phosphatidylcholine (O-18:0_20:4) levels on Viral haemorrhagic fevers.
The impact of 179 lipidomes on VHFs
Through IVW analysis, our study results (Table 2) significantly revealed a substantial negative association between three lipidomes and the risk of VHFs. These lipidomes include levels of stero lester (27:1/20:5) levels (OR[95%CI] = 0.777[0.668,0.904],P = 0.042),phosphatidylcholine(16:0_20:4) levels (OR[95%CI] = 0.788[0.689,0.902],P = 0.044),and phosphatidylcholine(O-18:0_20:4) levels (OR[95%CI] = 0.745[0.625,0.887],P = 0.05).
Sensitivity analyses were conducted for levels of stero lester (27:1/20:5), phosphatidylcholine(16:0_20:4), and phosphatidylcholine(O-18:0_20:4). The MR-Egger intercept test found no evidence of pleiotropy (P > 0.05) (Fig. 3).The test results showed no significant heterogeneity among the selected IVs(P > 0.05)(Fig. 3).MR-PRESSO did not detect horizontal pleiotropy (Fig. 3).Through heterogeneity and sensitivity analyses, we was found that the estimated values of sterol ester (27:1/20:5) levels, phosphatidylcholine(16:0_20:4) levels, and phosphatidylcholine (O-18:0_20:4) levels remained consistent across the four methods (Fig. 5).
Table 2
MR results of causal effects between 3 lipidomes and VHFs
exposure
|
outcome
|
method
|
nsnp
|
beta
|
se
|
p-value
|
or
|
or_lci95
|
or_uci95
|
Sterol ester (27:1/20:5) levels
|
Viral haemorrhagic fevers
|
IVW
|
25
|
-0.251993243
|
0.077013981
|
0.041641248
|
0.77724999
|
0.668351767
|
0.903891598
|
Phosphatidylcholine (16:0_20:4) levels
|
Viral haemorrhagic fevers
|
IVW
|
25
|
-0.237846298
|
0.068965819
|
0.043927638
|
0.788323849
|
0.68865194
|
0.902421753
|
Phosphatidylcholine(O-18:1_20:4) levels
|
Viral haemorrhagic fevers
|
IVW
|
21
|
-0.294355404
|
0.089240208
|
0.0505524
|
0.745011664
|
0.625461056
|
0.887413172
|
nsnp: number of single nucleotide polymorphism, WM: weighted median estimator, IVW: inverse-variance weighted method, OR: odd ratio, CI: confidence interval.
A.Sterol ester (27:1/20:5) levels, B. Phosphatidylcholine (16:0_20:4),C. Phosphatidylcholine (O-18:0_20:4).
Reverse MR analysis
Through reverse MR analysis, we did not find a reverse causal relationship between the three lipidomes and VHFs(Table 3).This result suggests that VHFs may not affect the corresponding lipidomes.
Table 3
MR results of causal effects between VHFs and lipidomes
exposure
|
outcome
|
method
|
nsnp
|
beta
|
se
|
p-value
|
or
|
or_lci95
|
or_uci95
|
Viral haemorrhagic fevers
|
Sterol ester (27:1/20:5) levels
|
IVW
|
17
|
0.011429995
|
0.018798063
|
0.543160199
|
1.011495567
|
0.974906015
|
1.049458375
|
Viral haemorrhagic fevers
|
Phosphatidylcholine (16:0_20:4) levels
|
IVW
|
17
|
-0.002428381
|
0.027777157
|
0.930334741
|
0.997574565
|
0.944715355
|
1.053391381
|
Viral haemorrhagic fevers
|
Phosphatidylcholine(O-18:1_20:4) levels
|
IVW
|
17
|
0.00158936
|
0.019103939
|
0.933696176
|
1.001590623
|
0.964780794
|
1.039804879
|
nsnp :number of single nucleotide polymorphism, WM: weighted median estimator, IVW: inverse-variance weighted method, OR: odd ratio, CI: confidence interval.
Co-localization results of Sterol ester(27:1/20:5) and VHFs
Co-localization analysis showed a significant correlation between Sterol ester(27:1/20:5) and VHFs(Fig. 6),that the P value of PP.H4(PP.H4/PP.H3 + H4)is 0.839.The results of co-localization analysis between Phosphatidylcholine(16:0_20:4) and VHFs were negative(Figure.6),that the P value of PP.H4(PP.H4/PP.H3 + H4) is 0.480.The results of co localization analysis between Phosphatidylcholine(O-18:0_20:4) and VHFs were negative(Figure.6),that the P value of PP.H4(PP.H4/PP.H3 + H4) is 0.422.