Table 2.

Biological effects of Ob and PUFAs (especially n-3 PUFAs) in preclinical in vivo models. Up arrows refer to increase and down arrows to decrease.

Molecule	In Vivo Model	Dose/Delivery Route	Main Effects	Specific Outcomes	Indications for Preventive-Therapeutic Strategies for ObOA	Ref.
N/A	Post-traumatic model of OA: ACLT model in rabbits	N/A	Early-stage OA affected FA composition towards a pro-inflammatory phenotype.	▪↓ n-3/n-6 PUFA ratio in the IFP.	Importance of preventing n-3/n-6 PUFAs imbalance/restoring n-3/n-6 PUFAs balance.	[132]
HFD (60% kcal fat)	Ob model: male C57BL/6J mice + HFD	-Group 1: control (10% kcal fat) -Group 2: HFD (60% kcal fat) Dietary supplementation	HFD caused moderate OA.	▪↑ Association with systemic biomarkers, e.g., IL-1β, glucose intolerance (metabolomic analysis); ▪↑ Cartilage destruction (Mankin score); ▪↑ BMD.	Avoiding HFD to prevent OA onset or delay OA aggravation.	[139]
MFD	Ob model: male C57BL/6J (B6) mice + MFD	-Group 1: control diet (4% fat; d omega-3/omega-6 ratio: 1.29) -Group 2: “Ob-induced diet” with medium fat content (11% fat); n-3/n-6 PUFA ratio: 3.48 for 24 weeks.	MFD promoted changes in immune metabolism and altered gut microbiota composition.	▪↑ Leptin; ▪Altered gut microbiota composition; ▪Modulated the immune metabolic response of adipose tissue.	Fat diet content above 11% induces metabolic changes.	[140]
HFD (60% kcal fat)	Ob model: male C57BL/6J mice + HFD	-Group 1: HFD -Group 2: control exercised (aerobic exercise: running wheel exercise) or sedentary mice Dietary supplementation	HFD promoted OA onset. Moderate exercise improved glucose tolerance without reducing body fat or cytokine levels.	HFD promoted OA onset by: ▪Increasing serum levels of leptin, adiponectin, KC (mouse analogue of IL-8), MIG and IL-1RN ▪Decreasing glucose clearance from the blood; ▪Increasing subchondral bone thickness and GAG loss; ▪Running wheel exercise produced modest changes in knee histopathology.	Avoid HFD for preventing OA onset or delaying OA aggravation. Recommend aerobic exercise in promoting joint health independently of weight loss.	[137]
PUFAs diet	ObOA model: DMM model in male mice + HFD (60% kcal fat)	-Group 1: HFD rich in n-3 PUFAs -Group 2: HFD rich in n-6 PUFAs -Group 2: HFD rich in SFAs -Group 2: control (10% kcal fat) Dietary supplementation	Protective role of dietary supplementation with n-3 PUFAs in mitigating OA changes was observed.	▪Negative correlation of serum n-3 PUFAs with OA; ▪Positive correlation of serum n-3 PUFAs with adiponectin and priming to M2 macrophages; ▪Positive correlation of serum n-6 PUFAs with OA and inflammatory adipokines.	Shifting the composition of Fas in the diet towards a low intake of n-6 PUFAs and SFAs and a high intake of n-3 PUFAs for mitigating OA.	[15]
PUFAs diet	ObOA model: DMM model in male mice + HFD	-Group 1: HFD + SFA -Group 2: n-3 PUFAs (8% by Kal) -Group 3: n-6 PUFAs Dietary supplementation	Dietary FA content modulated OA severity; small amounts of n-3 PUFAs could mitigate OA while independently increasing OA severity.	▪n-3 PUFAs reduced cartilage degradation synovitis and macrophage infiltration; ▪n-6 PUFAs increased cartilage degradation and bone erosion and exhibited synovitis and infiltrating cells; ▪SFA and n-6 PUFAs increased leptin concentrations; ▪n- 3 PUFAs increased adiponectin levels and reduced leptin and resistin levels.	Shifting of FA composition in diet toward a low intake of n-6 PUFAs and SFAs and a high intake of n-3 PUFAs for mitigating OA.	[141]
HFD rich in n-6 PUFAs or control diet	ObOA model: DMM model + HFD in male and female fat-1 transgenic mice (encoding n-3 PUFAs desaturase)	-Group 1: fat-1 mice -Group 2: wild-type mice Dietary supplementation	Circulating FA composition and metabolic inflammation rather than “mechanical” factors were major risk factors for ObOA.	▪Conversion to n-3 PUFAs reduced OA and synovitis in a sex- and diet-dependent manner; ▪↓ Serum pro-inflammatory cytokines; ▪↑ Anti-inflammatory cytokines; ▪No changes in body weight.	Potential genetic use of ω-3 FA desaturase to reduce ObOA.	[142]
Standard diet	Obese model of OA: DMM model in fat-1 transgenic (TG) mice vs. Wild-type mice	-Group 1: fat-1 transgenic mice -Group 2: wild-type mice	Protective role of desaturase in mitigating OA, probably through inhibition of mTORC1, and the promotion of autophagy and cell survival in cartilage chondrocytes was observed.	▪TG mice increased levels ▪of n-3 PUFAs; ▪↓ MMP-13, ADAMTS; ▪↓ Cartilage destruction and osteophyte formation; ▪↓ TORC-1 activity; ▪↑ chondrocyte autophagy.	Potential genetic use of n-3 PUFAs desaturase to reduce ObOA.	[143]
Diet supplemented with 10% safflower oil and with 23% kcal fat, with an n-6:n-3 ratio of 274	Spontaneous OA model in fat-1 TG mice	-Group 1: fat-1 transgenic mice -Group 2: wild-type mice Life-long reduction	Cartilage degeneration and osteophyte formation was developed at levels comparable to WT mice.	▪The n-6:n-3 ratio was reduced twelve-fold in males and seven-fold and females; ▪no reduction in cartilage, synovium or bone-associated OA changes; ▪modest reduction in IL-6 and TNF-α levels.	Lower efficacy of n-3 PUFAs desaturase in spontaneous OA than post-traumatic OA models.	[144]
No diet	Ob models: leptin-deficient (ob/ob) and leptin-receptor-deficient (db/db) female mice No OA induction	N/A	Impaired leptin signaling significantly altered subchondral bone morphology without altering knee OA.	▪Increased body mass and fat; ▪Reduced subchondral bone thickness; ▪Increased relative trabecular bone volume in the tibial epiphysis; ▪No cartilage degeneration; ▪No changes in systemic inflammatory cytokines.	Leptin signaling is key to inducing systemic inflammation.	[145]
ALA, EPA, DHA	Ob models: - C57BL/6J mice + HFD (236 g/kg fat); - leptin-deficient (ob/ob) + HFD (236 g/kg fat)	C57BL/6J 16 weeks ob/ob mice for 6 weeks	Supplementation with EPA, but not ALA and DHA, could preserve glucose homeostasis in an obesogenic environment and limit fat mass accumulation.	HFD: ▪Three PUFAs incorporated into erythrocyte PLs (EPA, DHA > ALA); ▪↑ EPA, DHA in adipose tissue; ▪↓ Plasma cholesterol (EPA); ▪↓ Fat mass accumulation (EPA); ▪↓ Adipose cell hypertrophy (EPA); ▪↓ Insulin sensitivity and glucose tolerance. Ob/ob mice ▪Partial protection against glucose intolerance and IR (EPA); ▪↑ Adiponectin; ▪↑ Phosphorylation of Akt.	EPA is more effective in targeting specific Ob features.	[146]
n-3 PUFAs	Spontaneous model of OA (OA guinea pig)	-Group 1: n-3 PUFAs -Group 2: standard diet Dietary supplementation	Chondroprotective effects were observed.	▪↓ Cartilage score; ▪↑ GAG content; ▪↓ Denatured Coll II; ▪↓ MMP-2.	Relevance of a diet rich in n-3 PUFAs to counteract cartilage degradation.	[147]
GLM abundant in DHA	MIA-induced OA model in male Wistar rats	GLM (100–300 mg/kg) versus celecoxib (50 mg/kg) Oral administration (3 days from MIA injection)	Chondroprotective properties and a reduction in catabolic, inflammatory and necroptotic markers were observed.	▪↓ Pain; ▪↓ Cartilage destruction; ▪↓ T and B cell responses; ▪↓ MMP-1/-3/-13 in cartilage; ▪↓ IL-1β, IL-6, NF-KB, i-NOS in synovium; ▪↓ Necroptosis-related markers (RIPK1, RIPK3, pMLKL).	Potential candidate in targeting inflammation and necroptosis.	[115]
PDX (DHA metabolite)	MIA-induced OA model in Sprague–Dawley rats	10 µg/kg (every 3 days) Intraperitoneal injections	Chondroprotective and anti-inflammatory effects were observed.	▪↓ Cartilage degradation; ▪↑ Cartilage thickness and cartilage surface; ▪↓ TNF-α in the serum and intra-articular lavage fluid.	Potential tool to target inflammatory hallmarks.	[118]
DHA	Post-traumatic OA: ACLT-induced OA model in male Sprague–Dawley rats	1 mg/kg (two months) Injection in tail vein	Promotion of bone remodelling and cartilage reduction were observed.	▪↓ TRAP, RANKL, CD31, endomucin agents (markers of bone loss); ▪↓ OARSI score; ▪↓ MMP-13, collagen X.	Potential of targeting catabolic markers.	[148]
Antarctic krill oil (Euphausia superba) (rich in EPA and DHA)	DMM-induced OA in osteoporotic (ovariectomy) mice	Diet supplementation	Chondroprotection and reduction in inflammation were observed.	▪↓ NF-κB pathway through the activation of GPR120; ▪↓ Cartilage degeneration.	Potential of targeting inflammatory markers.	[134]
Triglyceride n-3 oil (rich in DHA + EPA)	Naturally occurring OA in dogs Prospective, randomized, double-blind, placebo-controlled clinical trial.	69 mg EPA + DHA/kg/day (84 days) Diet supplementation	Improvement in clinical markers of OA was observed.	▪↓ AA in blood; ▪↓ Effusion and pain from day 42.	Potential of reducing systemic inflammation.	[149]
EPA and DHA	OA horses	Diet supplementation	Increased storage pools of n-3 PUFAs in SF and anti-inflammatory effect	▪↑ n-3 PUFA in the SF; ▪↑ Surfactant glycerophosphocholines (GPC); ▪↓ Inflammation.	Potential to improve the resolution of inflammation.	[150]
17®-HDoHE (RvD2 precursor)	MIA model of OA + MNX model of OA	1 ng/μL (every day from 14 to 28 days) Intra-peritoneal administration	Long-term inhibitory effects on nociceptive signaling.	▪↓ Pain; ▪↓ Astrogliosis in the spinal cord; ▪↑ RvD2 in plasma.	Potential to exert analgesic potential.	[151]
Aspirin-triggered RvD1 (AT-RvD1) RvD1 isomer induced by aspirin and more resistant to enzymatic degradation than RvD1	Carrageenan-induced inflammatory or MIA-induced OA in male Sprague–Dawley rats	15 ng in 50 μL PBS (carrageenan model) 15 ng and 150 ng in 50 μL PBS (MIA model) Spinal treatment	The selective target of inflammation drives spinal hyperexcitability in nociceptive pathways (analgesic potential)	▪↓ Peripheral nociceptive fiber-evoked responses; ▪↑ ChemR23; ▪↑ FPR2/ALX; ▪↓ NMDA receptor activation.	Potential to exert analgesic potential.	[152]
RvE1/RvD1/PDX	Rat paws inflamed by carrageenan or histamine, 5-hydroxytryptamine, substance P or prostaglandin E2	20 RvE1, 100 RvD1,100 μg PDX mL−1 versus standard anti-inflammatory drugs (INDO, celecoxib and dexamethasone) Injection in the hind paws (10 min before the stimuli)	Analgesic and anti-inflammatory effects	▪↓ Inflammation (RvE1, RvD1); ▪Analgesic effects (RvE1, RvD1); ▪Cuperior effect of RvE1 than RvD1.	Rvs, as analgesic agents, may be a better therapeutic agent than NSAIDs.	[153]
MaR2	Lipopolysaccharide (LPS)-induced mechanical hyperalgesia capsaicin (TRPV1 agonist) or AITC (TRPA1 agonist).	3, 10 or 30 ng	Analgesic effect	▪↓ Cytokine; ▪↓ TRPV1, TRPA1 activation.	Potential analgesic effects.	[154]
Linseed oil (LO), soybean oil (SO) and peanut oil (PO) n-6/n-3 PUFA ratios: 1:3.85 (LO), 9.15:1 (SO) and 372.73:1 (PO)	DMM OA murine model	12 weeks Oral supplementation	Edible oils with low n-6/n-3 PUFAs exert an anti-inflammatory effect by inhibiting the NFκB pathway.	▪↑ Cartilage thickness (LO, SO); ▪↓ TNF-α in serum (LO, SO); ▪LO or SO activated GPR120 and attenuated EP4 (LO, SO); ▪↓ NFκB pathway; ▪↓ MMP-13, ADAMTS-5.	Anti-inflammatory potential of a low-n-6/n-3-PUFA diet.	[155]